3M™ CNG Fuel Tank Instructions for Installation...

3M Operation Manual v. 2.0 Expires: July 2014 © December 2013 3MTM CNG Fuel Tanks Page 1

3M™ CNG Fuel Tank Instructions for Installation, Inspection, and

Maintenance

Service Pressure: 3600 psig (24821 kPa) / 21°C (70°F) Certified to: ANSI/CSA NGV2 – 07 Fuel: Compressed Natural Gas

! DANGER: Failure to follow all instructions contained in this document will result in death,

serious injury, and property damage:

Always read this entire manual before proceeding with the handling, storage, and installation

of any 3M™ CNG Fuel Tank.

Installation of compressed natural gas (CNG) fuel tanks should only be performed by

qualified system installers.

Retain these instructions for future reference.

3M™ CNG Fuel Tanks are inspected at the manufacturing site prior to shipping to the customer.

Receiving customers must conduct a receiving inspection to ensure that the 3M™ CNG Fuel

Tank packaging shows no damage which occurred during shipping. Any damage during shipping

is to be reported promptly upon receipt to the shipping carrier. Subsequently, when the receiving

customer has opened the packaging and is installing the fuel tanks, the fuel tanks should be

examined according to guidelines in CGA C -6.4 Methods for External Visual Inspection of

Natural Gas Vehicle (NGV) and Hydrogen Vehicle (HV) Fuel Containers and Their

Installations, to determine if the 3M™ CNG Fuel Tanks inside the undamaged packaging were

damaged during shipping.

! DANGER: 3M™ CNG Tanks or valves that appear to be damaged during shipping must not

be installed. Contact 3M at 800-364-3577 for further instructions. See important safety

information in Section 1.0.

! DANGER: Do not attempt to service or remove any valves without following

depressurization procedures in Section 6.1.3.1. Failure to do so may result in death or serious

injury and property damage. See important safety information in Section 1.0


Contents

1.0 Safety Information ......................................................... 4

1.1 Intended Use ..................................................................................................................... 4

2.0 Introduction ................................................................... 8

2.1 Distribution and proper use of this manual ...................................................................... 8

3.0 Product description and operational limits .................... 8

3.1 Fuel Tank Construction .................................................................................................... 9 3.2 Fuel Tank Labels ............................................................................................................ 10 3.3 Valve Description ........................................................................................................... 12

4.0 Fuel tank handling and storage ................................... 14

4.1 Handling ......................................................................................................................... 14 4.2 Storage ............................................................................................................................ 14

5.0 Installation ................................................................... 15

5.1 Fuel tank protection ........................................................................................................ 17

5.2 Mounting fuel tanks ....................................................................................................... 17 5.3 Strap or band (“belly”) mounting ................................................................................... 18

6.0 Fuel Tank filling (fueling) and defueling ...................... 23

6.1 Filling (fueling) .............................................................................................................. 23

6.1.1 Initial filling (fueling) and purging ......................................................................... 24 6.1.2 Standard fill ............................................................................................................. 25 6.1.3 Defueling (Depressurization) and Valve Removal ................................................. 26

7.0 Inspection Procedures ................................................ 36

7.1 Qualified inspectors........................................................................................................ 37

7.2 When fuel tanks should be inspected ............................................................................. 37 7.3 Inspection Data Recording ............................................................................................. 38

7.4 Preparation for inspection .............................................................................................. 38 7.5 General Guidelines and Preparation Recommendations ................................................ 39

7.6 Mounting bracket inspection .......................................................................................... 39 7.7 Fuel system inspection ................................................................................................... 40

7.7.1 Valve, PRD, and solid plug inspection – visual inspection only ............................ 41 7.8 Fuel tank inspection ....................................................................................................... 42 7.9 Inspection tools .............................................................................................................. 44 7.10 Types of damage and measurement ............................................................................ 45

7.10.1 Impact damage ........................................................................................................ 47

7.10.2 Cut and scratch/gouge damage and measurement .................................................. 48 7.10.3 Chemical attack ....................................................................................................... 53

7.10.4 Abrasion damage and measurement ....................................................................... 54 7.10.5 Fire and excessive heat damage .............................................................................. 55 7.10.6 Weathering .............................................................................................................. 57 7.10.7 Delamination ........................................................................................................... 57 7.10.8 Gas leakage ............................................................................................................. 58

7.10.9 Illegible labels ......................................................................................................... 58 7.11 Summary table of damage levels ................................................................................ 59


8.0 3M™ CNG Fuel Tank Repair Procedures .................. 60

8.1 Determining if repair is appropriate ............................................................................... 60 8.2 Repair tools .................................................................................................................... 61

9.0 Valve Installation ......................................................... 65

10.0 Destruction of condemned or expired tanks ............... 71

11.0 Warranty ..................................................................... 74

Appendix 1: 3M™ CNG Fuel Tank Inspection Form ........... 75

References: ......................................................................... 77


1.0 Safety Information

! DANGER: Read, understand, and follow all safety information contained in these

instructions prior to the installation and use of the 3M™ CNG Fuel Tank. Failure to do so

can result in death, serious injury and property damage. Retain these instructions for future

reference.

1.1 Intended Use

3M™ CNG Fuel Tanks are designed to contain CNG (compressed natural gas) fuel for vehicles

used for transportation. 3M™ CNG Fuel Tanks are designed and manufactured per the ANSI

NGV2 Standard for Compressed Natural Gas Vehicle Fuel Containers, and must only be used

within the conditions and applications for which they were designed. Use in any other

application or condition has not been evaluated by 3M and may lead to an unsafe condition. It is

expected that all users will be fully trained in the safe handling, installation, and operation of

3M™ CNG Fuel Tanks.

! DANGER: To reduce the risk of asphyxiation, which if not avoided, will result in death or

serious injury:

When venting and flushing with inert gases (such as nitrogen) in a confined area, provide

proper ventilation, and always use gas monitoring equipment to ensure safe and adequate

oxygen concentration.

! DANGER: To reduce the risk of explosion and fire, or asphyxiation from compressed natural

gas (CNG), which if not avoided will result in death or serious injury:

Do not puncture or drop fuel tank. Do not modify fuel tank, mounting brackets or

delivery system in any way. Never expose fuel tank to temperatures exceeding 180 °F (82

°C).

Immediately remove from service any fuel tank involved in a motor vehicle accident or

fire.

This fuel tank must be visually inspected by a qualified inspector as described in CGA

Pamphlet C-6.4 for damage and deterioration after a motor vehicle accident or fire, and at

least every 36 months or 36,000 miles, whichever comes first. This fuel tank must be

installed in a horizontal orientation only.

Explanation of Signal Word Consequences

DANGER: Indicates a hazardous situation which, if not avoided, will result in

death or serious injury

WARNING: Indicates a hazardous situation which, if not avoided, could result in

death or serious injury

CAUTION: Indicates a hazardous situation which, if not avoided, could result in

minor or moderate injury or property damage.


Both ports of the PRD must be properly piped away as described in Section 3.3. Always

ensure that the connections of PRD are plumbed using only ½” – 20 UNF fittings. Also,

an internal tubing diameter of no less than 0.32 inches must always be maintained on

PRD blow down lines.

The pressure relief device (PRD) must not be shielded in any way. Shielding will prevent

the PRD from functioning properly in a fire situation which may result in fuel tank

failure. None of the PRD ports should be plugged after installation is complete.

When working with flammable gases in a confined area always use gas-monitoring

equipment, and be sure to ground (earth) all equipment.

Always follow proper depressurizing procedures prior to servicing or decommissioning

the fuel tank.

Do not vent CNG in enclosed spaces. Breathing CNG can cause asphyxiation; a high

pressure stream of CNG can penetrate skin, and a nearby source of ignition could spark

an explosion.

Gas venting should only take place outdoors or following an alternative method which is

in compliance with NFPA 52. This is to avoid the possibilities of asphyxiation or

accumulation of an explosive gas mixture.

In all respects, the requirements of NFPA 52 must be followed for proper safe

depressurization of 3M™ CNG Fuel Tanks.

Always electrically ground the fuel tank, fuel system, or vehicle whenever a CNG fuel

tank is being filled or defueled. Failure to do so may result in explosion or fire.

Remove all oxidants (including air) from a fuel tank before filling the fuel tank with

CNG. Be aware that air may enter the fuel tank and form an explosive air/fuel mixture

whenever the fuel tank has been vented to less than 5 psig or exposed to atmospheric

pressure.

Do not fill the 3M™ CNG Fuel tank with any other type of fuel. The 3M™ CNG Fuel

Tank must be used with CNG (Compressed Natural Gas) fuel only.

For an initial fill, the fuel tank must first be purged with an inert gas to ensure that no

explosive mix is formed at any time.

Never use ambient air as the purging gas. Ambient air has the potential to form an

explosive air/gas mixture.

All inspections must be completed by a qualified inspector as described in CGA

Pamphlet C-6.4. Conduct fuel tank inspections upon receipt from the manufacturer, when

removed from storage, and on a regularly scheduled basis, according to applicable federal

state, and local regulations.

Have the fuel tank inspected by a qualified inspector as described in CGA Pamphlet C-

6.4 immediately in the case of unusual behavior by the fuel tank, or if the tank has been

involved in a motor vehicle accident, fire, or any other incident that may cause damage to

the fuel tank.

Do not attempt to disassemble the valve, PRD or solid plug. The valve, PRD, and solid

plug contain no user serviceable parts.

Never use an open flame or ignition source to test for gas leaks.

3M™ CNG Fuel tanks are shipped with the OMB Lyra CV solenoid valve with the

manual tap in closed position and containing approximately 20 psig of shipping pressure.


During any installation, inspection and tank maintenance ensure that the manual tap is

completely closed.

New valve installation can only proceed after proper defueling/depressurization, and

valve removal procedure has been followed as described in Section 6.1.3

Reject valves or fuel tanks with damaged thread. Also, reject fuel tanks with o-ring

groove damage since these damages prevent a safe and effective seal.

! WARNING: To reduce the risk of impact and fire, which if not avoided may result in death

or serious injury and property damage:

Installation of Compressed Natural Gas (CNG) fuel tanks should be performed only by

qualified Natural Gas Vehicle (NGV) system installers following applicable federal,

state, and local codes and regulations.

Store fuel tanks only in a clean, dry, location, out of sunlight, at temperatures between

-40°F (-40°C) and 180°F (82°C).

Follow 3M instructions for proper securing measures during shipping and transport.

When connecting a high pressure line to the cylinder valve, only use approved hoses and

fittings.

Do not use pipe wrenches on the boss or the valve. Do not allow any type of tool damage

to the boss or valve.

The valve installed in each cylinder has been torqued to a specific setting. Do not tighten

or loosen. Misuse could result in gas leakage and associated fire hazards.

Do not remove or replace factory installed valves. Failure to use 3M approved valves and

pressure relief devices (PRDs) in specified locations might cause fuel tank rupture in case

of a fire.

Always ensure that the fuel tank, when mounted on vehicle, is properly enclosed around

its periphery to prevent exposure to damaging road debris, cargo, and sunlight.

When using the strap or “belly” mounting design, a rubber strip must be installed

between the fuel tank and each metal mounting strap to protect the fuel tank’s composite

exterior. Using only the brackets designed for 3M™ Fuel Tanks ensures that the tank is

allowed to appropriately expand and contract during filling and use.

While installing the rubber strip on the metal mounting strap, make sure that the metal

strap has a uniform curvature across the whole strap, especially across rivet and u-strap

joint points as illustrated in Figure 8.

Locking nut fasteners must be torqued only to specifications listed in these instructions.

Failure to follow correct procedure will cause tank mounting to become unstable or

constricted.

Replace any rubber strip that appears to be worn or damaged with a new strip.

Torque the nylon insert locking nut in the bracket strap closure to the proper torque

specified in Section 5.3.

Any time a bracket strap is loosened after being in use, visually check for any wear that

may have occurred to the strap. If wear has occurred, a new replacement rubber strip

must be used to ensure all torque settings are correct to allow for expansion and

contraction of the fuel tank during fueling and de-fueling. Contact 3M if a replacement

rubber strip is needed.

Adjust metal brackets according to correct torquing procedures described in this manual.


Allow fuel tank and all mounting hardware to acclimate to ambient indoor workspace

temperature, prior to installation and pressurization.

Do not proceed with initial fill if a leak of CNG is detected or suspected: including but

not limited to, emission of a natural gas odor, unexpected loss of pressure in the fuel

system, rattling or other indications of loose connections, or unusual hissing or snapping

sounds.

When filling the fuel tank with CNG, make sure that the fill nozzle at the CNG filling

station is compatible with the fill fitting on the fuel tank or the vehicle. Also make sure

the pressure rating at the CNG filling system is compatible with the fuel tank pressure

rating.

Never fill a 3M™ CNG fuel tank such that the pressure exceeds 4500 psig at any

temperature.

Use the required diameter and length of discharge setup into the vent stack. Use of

incorrect size tubing/piping can cause damage to valve and fuel tank and injuries or

death.

Always ensure the tank valve is properly grounded in compliance with NFPA 52

requirements.

Reject and remove from service any CNG fuel tank that either lacks a label containing

mandatory information or if all main labels are illegible.

! WARNING: Not using the proper tool to remove or install the valve can cause damage to the

valve and PRD, resulting in serious hazardous conditions.

! CAUTION: To reduce the risk of impact, which if not avoided may result in minor or

moderate injury:

Always wear appropriate personal protective equipment according to your local

workplace practices when handling, storing, installing, or inspecting 3M™ CNG Fuel

Tanks.

! CAUTION: To reduce the risk of inhalation of dust, impact, cuts, abrasion, or chemical

exposure, which if not avoided may result in minor or moderate injury:


workplace practices when repairing 3M™ CNG Fuel Tanks.

Read and follow all manufacturers’ instructions for use and Material Safety Data Sheets

prior to use of epoxy and acetone.

! CAUTION: To reduce the risk of muscle strain during the decommissioning process,

especially when water is used to flush the tank, which may result in minor injury:

Never attempt to lift 3M™ CNG fuel tanks by hand.

Always use appropriate mechanical lifting or rigging means for handling 3M™ CNG fuel

tanks.


2.0 Introduction This manual describes the operation and maintenance of 3M™ CNG Fuel Tanks, which are

designed to contain CNG (compressed natural gas) fuel for vehicles used for transportation.

These high pressure composite fuel tanks are designed to withstand the normal usage they will

receive. However, like all compressed gas equipment they must be properly installed, used, and

maintained. This manual is intended to support trained personnel in installing, using, inspecting

and maintaining 3M™ CNG Fuel Tanks. Refer to Safety Instructions in Sect. 1.0.

The vehicle operator must be familiar with the equipment manufacturer’s and installer’s

instructions about properly and safely filling 3M™ Fuel Tanks, the requirements of periodic

inspections, and with all applicable guidelines, requirements, regulations, and laws of all

appropriate federal, state and local authorities. The CNG fuel system installer must be trained

and employ competent personnel who are familiar with and will comply with first fill and

defueling operations, as well as the applicable laws, codes and standards, including but not

limited to ANSI/NFPA 52 Vehicular Gaseous Fuel Systems Code, U.S. Federal Motor Vehicle

Safety Standard 49 CFR 571.303 Fuel System Integrity of Compressed Natural Gas Vehicles,

U.S. Federal Motor Vehicle Safety Standard 49 CFR 571.304 Compressed Natural Gas Fuel

Container Integrity, ANSI/IAS NGV 2 Standard for Compressed Natural Gas Fuel Containers,

Compressed Gas Association CGA C-6.4 Methods for External Visual Inspection of Natural Gas

Vehicle (NGV) and Hydrogen Vehicle (HV) Fuel Containers and Their Installations, ANSI /

AGA NGV3.1 / CGA 12.3 Fuel System Components for Natural Gas Powered Vehicles, and any

other applicable federal, state and local codes and standards.

The rights, obligations, and/or duties of the upfitter, installer and/or customer are set forth in the

original purchase agreement and warranty. 3M assumes no liability for errors or for any damage

that results from the use of this instruction manual. 3M reserves the right to cancel, change, or

alter any parts and assemblies, described in this manual, without prior notice.

2.1 Distribution and proper use of this manual

It is intended that this manual be provided to all parties involved in the handling, installation, and

inspection of 3M™ CNG Fuel Tanks. The manual may be reproduced to provide enough copies

for this purpose, but its contents must not be altered in any way. 3M accepts neither

responsibility nor liability for consequences resulting from unauthorized alterations to this

manual or for failure to follow the instructions herein.

3.0 Product description and operational limits 3M™ CNG Fuel Tanks are supplied with an installed OMB Lyra CV solenoid valve on one end

and a plug on the opposite end. The solenoid valve contains an integral Pressure Relief Device

(PRD) which activates in the event of a fire. Each end of the 3M™ CNG Fuel Tank is covered

by a black foam bumper, which helps to protect the fuel tank from incidental damage in

shipping, handling, installation, and use. Each new 3MTM

fuel tank is also supplied with a small


amount of inert gas (nitrogen) shipping pressure inside to increase the ease of installation and

ensure the tank remains clean and ready for use in the fuel system.

The fuel tank itself is comprised of a number of layers which provide gas containment and

structural reinforcement. The general construction of the wall of the CNG tank is described in

Section 3.1.

3M™ CNG Fuel Tanks are designed and manufactured per the ANSI NGV2 Standard for

Compressed Natural Gas Vehicle Fuel Containers, and must only be used within the conditions

for which they were designed.

Temperature Range of fuel tank: -40°F (-40°C) to 180°F (82°C)

Service Pressure: settled gas pressure of 3600 psig at 70°F (21°C)

Maximum Pressure: 4500 psig under any conditions

Fuel Gas Composition: Compressed Natural Gas only, as specified in SAE J1616

Service Life: 20 years from date of manufacture. Expiration date is found on the center of

the main label (“Do not use after” date).

Figure 1. 3M™ CNG Fuel Tank

3.1 Fuel Tank Construction

3M™ CNG Fuel Tanks are Type IV tanks, meaning that they have a thermoplastic liner which is

fully covered with a high performance carbon composite, including an epoxy resin. Closer to the

outside of the tank, the black carbon composite is covered with a glass and epoxy composite

layer and, finally, a clear protective coating is applied to the outer-most surface. Both ends of the

fuel tank have precision machined 1.125 inch female threaded (12 UNF) fittings.


Figure 2. Drawing showing representative layers in the cross-section of a 3M™ CNG Fuel

Tank

3.2 Fuel Tank Labels

Each 3M™ CNG Fuel Tank is marked with several labels which contain important safety,

warning, use, and required regulatory information. The main labels are oriented along the center

of the length of the vessels as illustrated in Figure 3. An example of the information included on

the main label is shown in Figure 4.

Figure 3. Approximate location of the main label on the 3M™ CNG Fuel Tank

Clear Coating

Glass Composite

Carbon Composite

ThermoplasticLiner


Figure 4. Main label on each 3M™ CNG Fuel Tank

The left column and middle section of the main label contain information that is required for

regulatory purposes. The right column of the main label contains important safety, danger and

warning information. Note that the information in the center of the label is unique for each 3M™

CNG Fuel Tank manufactured and is shown in greater detail in Figure 5. For some products, the

left column and right-most column of the label have been combined into one separate label.

Figure 5. Information from the center of the main 3M™ CNG Fuel Tank label.

This label section contains the serial number, the manufactured date and the expiration (“DO

NOT USE AFTER”) date which will be unique for each individual fuel tank manufactured, as

well as other required regulatory information. This section of the label contains information

which is mandatory to report in the periodic inspections of the fuel tank and system conducted by

qualified inspectors.


3.3 Valve Description

! DANGER: Do not attempt to service or remove any valves without following

depressurization procedures in Section 6.1.3.1. Failure to do so may result in death or serious

injury and property damage. See important safety information in Section 1.0




ensure that the connections of PRD are plumbed using only ½” – 20 UNF fittings.

Also, an internal tubing diameter of no less than 0.32 inches must always be maintained

on PRD blow down lines.




3M™ CNG Fuel Tanks are supplied with an installed OMB Lyra CV solenoid valve on one end

and a plug on the opposite end. The valve contains an integral Pressure Relief Device (PRD)

which activates in the event of a fire. A brief overview and nomenclature and features of the

valve and the plumbing guidelines are given here:

Figure 6. OMB Lyra CV Valve with Description

G

F

A

A

B

B

C

D

E


A – These two ports are the Inlet/Outlet ports for the fuel and they can be used interchangeably.

These connections are sized to be ” – 18 UNF – 2B.

B – These two ports are the vent ports of the built-in Thermal Pressure Relief Device (PRD),

which is integral to the valve. These connections are sized to be ½” – 20 UNF – 2B. It is

absolutely essential to plumb both these ports to a safe, outside-the-shield location without

reducing the tubing internal diameter. In case of a fire and PRD activation, CNG will flow out of

these ports. Maintain an internal tubing diameter of no less than 0.32 inches. NFPA 52

requirements and conditions during qualification of the 3M™ CNG fuel tank require no

restriction to the gas flow after the PRD.

C – Manual Tap. This is the tap or hand wheel to open or close the valve manually. The valve

should be kept closed during storage and/or maintenance.

D – This is the automated part of the valve, also termed the solenoid. While the vehicle ignition

switch is shut off, this valve is in the closed position.

E – This is the Thermal Pressure Relief Device (PRD), which is integral to the valve and has an

activation temperature of 226.4 °F ± 10.8 °F. In case of fire actuation event, gas will be directed

out of the two vent ports labeled “B”.

F – Electrical Solenoid Connection Point.

G – Middle portion of Lyra CV Valve, appropriate location for temperature measurement.

The blue caps shown in Figure 6 are used during storage and shipping only and are used to

prevent any dirt, moisture and debris from entering the tank valve and also to protect the

threaded openings. These caps should be removed during installation. Once the installation is

complete, none of the blue caps should remain on the valve and all connections should have been

plumbed. Optionally, one of the fuel inlet/outlet ports (labeled as “A” in Figure 6) can be

plugged. Neither of the PRD blow down ports “B” should be plugged during or after install.

If for any reason, this valve needs to be replaced, it should be replaced with exactly the same

type of valve. In order to do valve replacement, the tank needs to be de-fueled first according to

the procedure described in Section 6.1.3. Once the de-fueling is complete, the procedure in

Section 9.0 should be followed to install the valve.


4.0 Fuel tank handling and storage

! DANGER: Improper handling and storage of 3M™ CNG Fuel Tanks may result in

personal injury, death, and/or property damage! See important safety information in the

following sections and in Section 1.0.

4.1 Handling

! DANGER: To reduce the risk of explosion, fire, and impact, which if not avoided will

lead to death or serious injury and property damage:

Do not puncture or drop container. Do not modify container in any way. Never

expose containers to temperatures exceeding 180 °F (82 °C).


moderate injury:


workplace practices when handling, storing, installing, or inspecting 3M™ CNG Fuel

Tanks.

3M™ CNG Fuel Tanks have been designed and tested to state-of-the-art durability and

robustness requirements; they can, however, be damaged by improper installation, careless

handling and accidents. To prevent damage to the fuel tank, 3M recommends the following:

Only handle 3M™ Fuel Tanks with equipment that will not damage them.

Do not handle fuel tanks with internal pressure above 3 bar (40 psi).

Do not drag, drop, or roughly handle the fuel tanks.

Protect the fuel tank labels to ensure they remain readable.

When transporting a fuel tank with an attached valve, protect the valve from damage and

properly secure the fuel tank. Never lift or handle fuel tanks by their fittings, valves,

pressure relief devices, piping, or hoses.

4.2 Storage

! WARNING: To reduce the risk of impact and fire, which if not avoided could result

in death or serious injury and property damage:


-40°F (-40°C) and 180°F (82°C).

Follow 3M instructions for proper securing measures during shipping and transport.

Protect fuel tanks in storage with the following precautions:

Restrain fuel tanks against rolling or moving during storage.


-40°F (-40°C) and 180°F (82°C).

If, for any reason, the tank has to be placed in outdoors during storage, it should be for

very short duration of time and should be away from rain and excessive moisture

conditions.


Protect fuel tanks from contamination and damage due to impact, excessive heat,

corrosive chemicals, excessive moisture or UV light (including sunlight).

For storage, do not remove the plugs or caps supplied in the valve and PRD vent line

outlets. These caps keep the fuel tank and attached equipment clean and dry, and prevent

dirt, moisture and debris from entering the tank, and also protect the threaded openings.

Do not remove the solenoid cable from the connector. Keeping the solenoid cable

connected will prevent moisture from getting into the connection point.

Do not remove the small amount of positive pressure stored in the tank during shipping.

This helps to ensure that the inside of the tank is clean and dry, and prepared for

installation. In order to ensure that positive pressure stays in the tank, keep the manual

valve tap closed during storage.

Figure 7. Plugs or caps (Blue in color in this Figure) should remain on the valve

during the storage period prior to installation. The solenoid cable should remain

attached to its connector during storage.

5.0 Installation ! DANGER: 3M™ CNG Fuel tanks must be installed into a vehicle using the guidelines

outlined in this section. Safe operation of a composite CNG fuel tank is dependent on

proper installation and use of safety devices. Failure to follow these instructions may result

in personal injury, death, and property damage. See important safety information in the


Installation and adjustments of CNG fuel systems should only be completed by a company

having competent personnel and appropriate facilities for the installation, repair, adjustment, and

Solenoid Cable

Connection Point


testing of CNG fuel systems because of the risks of severe injury or death from improper

installations and repair. Further, such companies should follow the requirements of the most up-

to-date revisions of ANSI/NFPA 52 Vehicular Gaseous Fuel Systems Code, U.S. Federal Motor

Vehicle Safety Standard 49 CFR 571.303 Fuel System Integrity of Compressed Natural Gas

Vehicles, U.S. Federal Motor Vehicle Safety Standard 49 CFR 571.304 Compressed Natural Gas

Fuel Container Integrity, ANSI/IAS NGV 2 Standard for Compressed Natural Gas Fuel

Containers, Compressed Gas Association CGA C-6.4 Methods for External Visual Inspection of

Natural Gas Vehicle (NGV) and Hydrogen Vehicle (HV) Fuel Containers and Their

Installations, ANSI / AGA NGV3.1 / CGA 12.3 Fuel System Components for Natural Gas

Powered Vehicles, and any other applicable federal, state and local codes and standards.

! DANGER: To reduce the risk of asphyxiation, explosion, fire or impact, which if not

avoided will result in death or serious injury and property damage:

Do not puncture or drop fuel tank. Do not modify fuel tank, mounting brackets or

delivery system in any way. Never expose fuel tank to temperatures exceeding 180 °F (82

°C).

This CNG fuel tank shall be installed in a horizontal position only.


ensure that the connections of PRD are plumbed using only ½” – 20 UNF fittings. Also,

an internal tubing diameter of no less than 0.32 inches must always be maintained on

PRD blow down lines.




When working with flammable gases in a confined area always use gas-monitoring

equipment, and be sure to ground (earth) all equipment.

! WARNING: To reduce the risk of impact and fire, which if not avoided could result in

death or serious injury and property damage:

Installation of CNG fuel systems should only be performed by qualified Natural Gas

Vehicle (NGV) system installers following applicable federal, state, and local codes and

regulations.


temperature, prior to installation and pressurization.

When connecting high pressure line to cylinder valve, only use approved hoses and

fittings.

Do not use pipe wrenches on the boss or the valve. Do not allow any type of tool damage

to the boss or valve.

The valve installed in each cylinder has been torqued to a specific setting. Do not tighten

or loosen. Misuse could result in gas leakage and associated fire hazards.

Do not remove or replace factory installed valves. Failure to use 3M approved valves and

pressure relief devices (PRDs) in specified locations might cause fuel tank rupture in case

of a fire.

Never fill a 3M CNG fuel tank such that the pressure exceeds 4500 psig at any

temperature


! CAUTION: To reduce the risk of impact, which if not avoided may result in death or

serious injury:


workplace practices when installing 3M™ CNG Fuel Tanks

5.1 Fuel tank protection

! WARNING: To reduce the risk of impact and fire, which if not avoided could result in


Always ensure that fuel tank is properly enclosed around its periphery when installed on

the vehicle to prevent exposure to damaging road debris and sunlight.

Per NFPA 52 requirements, when installed on the vehicle, CNG tanks must be protected with a

means to prevent damage that can occur due to road hazards, loading, unloading, direct sunlight,

exhaust heat, and vehicle use, including accidental cargo leakage. Shielding must be used to

protect the fuel tank from damage caused by road debris or contact with cargo or vehicle

components. The shielding protects the fuel tank, and it must be removed to read the labels on

the fuel tank during periodic inspections. Also per NFPA 52, the shields should be installed to

prevent direct contact between the shield and the fuel tank, and also to prevent trapping of solid

materials or liquids between the shield and fuel tank that could damage the fuel tank or its

coating.

To prevent damage to the fuel tank:

Prevent direct contact between the fuel tank and the shielding.

Prevent trapping solid debris or liquids (like rain or melted snow) between the shielding

and the fuel tank.

Prevent contact between the fuel tank and vehicle components (i.e., brake lines,

suspension links, etc.) and with vehicle cargo.

Prevent contact with heat sources on the vehicle.

Prevent exposure to corrosive liquids and gases.

Prevent extended exposure to direct sunlight.

Prevent contact with excessive moisture.

Mount the vessel on the vehicle so as to prevent contact with road or curb surface at any

time, especially if the vehicle has flat tire or during the tire repair/change process.

5.2 Mounting fuel tanks

! DANGER: Mounting of 3M™ CNG Fuel Tanks should only be performed by

qualified Natural Gas Vehicle (NGV) system installers following applicable federal, state

and local codes and regulations. Failure to follow these instructions may result in

personal injury, death, and/or property damage. See important safety information in the


Some 3M™ CNG fuel tanks use a strap or band (“belly”) mounting method. For strap-mounted

tanks, the fuel tank can only be mounted horizontally in the vehicle and held in place with metal

straps. The metal straps are made such that a rubber layer is always positioned between the 3M™

CNG fuel tank and the metal strap, so that friction and damage to the composite layers, and (in


certain cases) galvanic corrosion is prevented. The strap-mount brackets are custom-made for

each manufacturer’s CNG fuel tank. 3M™ CNG Fuel Tanks are designed to be used exclusively

with brackets sold by 3M for each individual fuel tank size. The brackets are designed to

accommodate expansion of the tank in circumferential (around the girth) and axial (lengthwise)

directions when it is pressurized.

The mounting methods shown below are typical, but do not cover every possible installation and

do not overrule or supersede the requirements for CNG fuel storage by the vehicle manufacturer.

Refer to applicable instructions and specifications provided by the vehicle manufacturer before

beginning to install CNG fuel tanks.

5.3 Strap or band (“belly”) mounting

! WARNING: To reduce the risk of impact and fire, which if not avoided may result in


When using the strap or “belly” mounting design, a new rubber strip must be installed

between the fuel tank and each metal mounting strap to protect the fuel tank’s composite

exterior. Using only the brackets designed for 3M™ Fuel Tanks ensures that the tank is

allowed to appropriately expand and contract during filling and use.

While installing the rubber strip on the metal mounting strap, make sure that the metal

strap has a uniform curvature across the whole strap, especially across rivet and u-strap

joint points as illustrated in Figure 8.

Locking nut fasteners must be torqued only to specifications listed in these instructions.

Failure to follow correct procedure will cause tank mounting to become unstable or

constricted.

Figure 8. Metal mounting strap location (indicated by arrows above) should be visually

inspected for smooth curvature, which results in uniform load distribution

especially across the rivets and u-strap joints


Figure 9 LEFT. Unacceptable bracket since curvature is not smooth and would result in

concentrated bracket load. Figure 9 RIGHT shows a bracket which has smooth curvature

and therefore result in uniform load distribution

All fuel tank and bracket installations must comply with the most up-to-date version of the

NFPA 52 standard.

The brackets for the 3M™ CNG Fuel Tanks must be mounted in a specific orientation with

respect to the fuel tank to ensure robust mounting.

Figure 10 illustrates the correct positioning of the brackets (in the hashed area) with respect to

the ends of a 21.5” x 60” long fuel tank. It is important to note that the dimensions shown in the

Figure are measured from the face of the boss or pole piece, not from the end of the plug or

valve.

The brackets can be positioned asymmetrically, between 10 and 19 inches from the face of the

boss or pole piece, on both ends of the 21.5” x 60” long fuel tank as shown in Figure 10.

LEFT RIGHT


Figure 10. Strap or band (“belly”) mounting showing the correct area for placement of the

brackets, for the 21.5” x 60” long fuel tank which can be placed symmetrically or

asymmetrically, between 10 and 19 inches in from the face of the pole piece or boss

It is important to note that the rubber strip supplied with each bracket must be installed such that

it is positioned between the composite fuel tank and the metal bracket prior to completing the

installation of the fuel tank in the vehicle (see Figure 11). The rubber strip prevents abrasion

damage to the tank, and allows the tank to be securely held by the brackets when it is fueled and

de-fueled as it expands and contracts. In certain cases, the rubber strip also prevents galvanic

corrosion between the composite tank and the metal straps.

Figure 11. Bracket used to mount the strap-mount 3M™ CNG Fuel Tanks to a vehicle

Nylon Insert Locking nutneeds to be torquedspecifically as described

Ribbed Rubber Stripmust be positioned between fuel tank and metal strap

Metal Strap

Base Plate

Mounting Holes


To get the best torque reading on the torque wrench while installing the nylon insert locking nut,

3M suggests that the locking nut be oriented in the top part of the bracket closure, with the

washer provided, as illustrated in Figure 11.

In this orientation, the bracket closure bolt is placed through the black toggle in the bottom of the

bracket closure and the nut is placed at the silver toggle in the top part of the bracket closure. A

deep well socket must be used with the torque wrench to accommodate the tightening of the

nylon insert locking nut. Following the bolt and nut placement recommendations illustrated in

Figure 12 LEFT will provide the installer with the most comfortable position while tightening

the bracket strap and torquing the nylon insert locking nut to the specified torque settings listed

in the bracket installation steps. Although this would be the most comfortable position for the

installer, the nut and bolt can be placed in opposite positions as shown in Figure 12 RIGHT. It is

important to ensure that sufficient rubber is present in either case to extend completely under the

toggle in all scenarios.

Figure 12 LEFT Close up view of bracket strap closure showing the bolt oriented in the

black toggle in the bottom strap, and the nylon insert locking nut oriented in the silver

toggle in the top part of the strap closure with the washer provided. Figure 12 RIGHT

shows that the opposite position for nut and bolt is also acceptable as long as proper torque

is achieved. From both Figures, it is clear that the rubber extends underneath and past the

toggle in all scenarios

Steps to install the fuel tank in the brackets with new rubber strips only:

1. Position brackets, with protective rubber strips between the metal strap and the fuel

tank, in the locations shown in Figures 10, 11 and 12.

2. Two mounting brackets must be used on the fuel tank, positioned laterally as shown

in Figure 10.

3. Make sure that each bracket and strap is positioned perpendicular to the cylinder. If

the straps are not positioned perpendicular to the cylinder, the bracket will move

when the strap is tightened.

LEFT RIGHT

Rubber

correctly

positioned

under metal

toggles of

bracket

strap.


4. The bracket strap is tightened using a torque wrench and a deep well socket on the

nylon insert locking nut.

5. The nylon insert locking nut should be torqued exactly as follows for an installation

of a new set of brackets on a composite tank. It is important that the torque be set

with the procedure and to the torque level specified to accommodate the expansion

and contraction that happens as the composite fuel tank is fueled and de-fueled, in

order to avoid damage to the tank and the serious injury that could result.

6. Torque the nylon insert locking nut to 35 ft-lbs using a torque wrench with a deep

well socket. This will help seat the rubber and establish initial rubber compression.

No waiting time is required before proceeding to Step 7.

7. Using a deep well socket and a wrench, loosen the nylon insert locking nut until the

bracket is loose on the fuel tank.

8. Finally, re-tighten the nylon insert locking nut to 26 ft-lbs using a torque wrench with

a deep well socket. This completes the installation of the tank in the bracket straps.



Replace any rubber strip that appears to be worn or damaged with a new strip.

Torque the nylon insert locking nut in the bracket strap closure to the proper torque

specified in Section 5.3.

Any time a bracket strap is loosened after being in use, visually check for any wear

that may have occurred to the strap. If wear has occurred, a new replacement rubber

strip must be used to ensure all torque settings are correct to allow for expansion and

contraction of the fuel tank during fueling and de-fueling. Contact 3M if a

replacement rubber strip is needed.

It is important to use the stress distribution backer plates supplied with the 3MTM

bracket to

distribute the mechanical load holding the brackets into the vehicle over a structurally significant

area. If the fuel system installer chooses not to use the 3MTM

stress distribution backer plates

when installing the brackets, they do so at their own risk. The fuel system installer should mount

the fasteners into or through a structural member of the vehicle. Any alternative stress

distribution backer plates or the structural member used for mounting must provide at least an

equivalent area and thickness of support to the stress distribution backer plates originally

supplied with the 3MTM

brackets.

Although the brackets themselves have been designed and tested to ensure NFPA 52 compliance,

it is the installers’ responsibility to ensure bracket installation is in compliance with the most

recent revision of NFPA 52.


6.0 Fuel Tank filling (fueling) and defueling ! DANGER: This section does not supersede or overrule any applicable regulations,

industry standards, or requirements of fuel storage system manufacturers or vehicle

manufacturers. Before filling the fuel tank, it is important to understand the characteristics

and hazards of CNG, including asphyxiation, explosion, and fire. See important safety

information in the following sections and in Section 1.0.

In order to work safely with CNG, do not allow dangerous gas concentrations to form within a

working environment or within a vehicle. Test all CNG fuel tanks and fuel systems in a well-

ventilated area that does not contain any ignition sources.

! DANGER: To reduce the risk of fire, explosion, and impact, which if not avoided will

result in death or serious injury and property damage:

Always electrically ground the fuel tank, fuel system, or vehicle whenever a CNG

fuel tank is being filled or depressurized. Failure to do so may result in explosion or

fire.

! DANGER: To reduce the risk of asphyxiation, explosion, impact and fire, which if not

avoided, will result in death or serious injury and property damage:

When working with CNG or other flammable gases in a confined area, always use

gas monitoring equipment to measure airborne gas concentrations.

6.1 Filling (fueling)

NOTE: During filling (fueling) and defueling the fuel tank will expand and contract due to

changes in internal pressure.

There are two types of fills for a CNG fuel tank:

Initial Fill

A CNG fuel tank must undergo an initial fill if there is a potential for an oxidant (including air)

to be present inside the fuel tank. This situation arises when the initial inert gas (nitrogen)

shipping pressure supplied in a new 3M™ CNG fuel tank is released or reduced to less than 5

psig, and any time the cylinder is depressurized or opened, such as to replace a valve/PRD

assembly or complete other service on the CNG fuel tank.

Standard Fill

A standard fill occurs when the CNG fuel system does not contain any air or other potential

oxidants, and would be used when the vehicle is routinely refilled so that it can continue to be

driven.


6.1.1 Initial filling (fueling) and purging

! DANGER: Always follow the fuel system manufacturer’s instructions on initial filling.

Failure to do so may result in serious injury of death. See important safety information in

the following sections and in Section 1.0.

! WARNING: To reduce the risk of impact and fire, which if not avoided, could result in

death or serious injury:


temperature prior to initial filling.

Do not proceed with initial fill if a leak of CNG is detected or suspected: including but

not limited to, emission of a natural gas odor, unexpected loss of pressure in the fuel

system, rattling or other indications of loose connections, or unusual hissing or snapping

sounds.

! DANGER: To reduce the risk of explosion, fire, and impact, which if not avoided will


Remove all oxidants (including air) from a fuel tank before filling the fuel tank with

CNG. Be aware that air may enter the fuel tank and form an explosive air/fuel mixture

whenever the fuel tank has been vented to less than 5 psig or exposed to atmospheric

pressure.

Follow initial fill procedure in cases where air (or other oxidant) is present in the CNG fuel tank,

due to service of the tank (for example, replacement of valve/PRD or plug), or when air can enter

the tank if the pressure has been reduced to less than 5 psig. An initial fill is required any time

there might be air or another oxidant present in the CNG fuel tank. If present, air will form an

explosive mixture with CNG gas and an explosion hazard

3M™ CNG Fuel Tanks are supplied with a small pressure (5-25 psig, depending on temperature

and altitude) of an inert, dry gas (nitrogen) inside them. This small amount of pressure is called

“shipping pressure,” and is used to avoid any contamination during storage or transportation of

the 3M™ CNG Fuel Tanks, prior to their first use in a vehicle. It is also present to provide safe

conditions for an initial fill in a new installation.

The initial fill procedure must be completed if the shipping pressure in a new 3M™ CNG Fuel

Tank is vented to less than 5 psig, and/or the fuel system installed on a vehicle has been bled

down to less than 5 psig for any reason, and/or the valve/PRD assembly or plug is removed from

the CNG fuel tank.

Perform the following initial fill procedure for removing oxidants (including oxygen in the air)

from the fuel tank prior to filling it with CNG.


! DANGER: To reduce the risk of fire and explosion, which if not avoided, will result

in death or serious injury and property damage:

The fuel tank must first be purged with an inert gas to ensure that no explosive mix is

formed at any time.



! DANGER: To reduce the risk of asphyxiation, which if not avoided, will result in


When venting and flushing with inert gases (such as nitrogen) in a confined area,

provide proper ventilation, and always use gas monitoring equipment to ensure safe

and adequate oxygen concentration.

Procedure for an initial fill of a CNG fuel tank that may contain an oxidant (air):

1. Fill the fuel tank with clean, dry, pure nitrogen gas, and equilibrate it to a minimum of

200 psig.

2. Vent the air/nitrogen mixture slowly (to avoid condensation on the fuel tank or valve)

from the CNG fuel tank through the Lyra CV valve such that no less than 10-20 psig

remains in the tank.

3. Once the system has been vented to 10-20 psig, the valve should be closed to prevent

escape of the remaining nitrogen gas and to prevent ingress of air into the fuel tank.

4. The fuel tank, containing a small pressure of nitrogen, can then be connected to the fuel

system, and charged with CNG gas.

6.1.2 Standard fill

! DANGER: To reduce the risk of fire, explosion and impact, which if not avoided, will


Do not fill the 3M™ CNG Fuel tank with any other type of fuel. The 3M™ CNG

Fuel Tank must be used with CNG (Compressed Natural Gas) fuel only.

! WARNING: To reduce the risk of impact and fire, which if not avoided, could result

in death or serious injury and property damage

When filling the fuel tank with CNG, make sure that the fill nozzle at the CNG filling

station is compatible with the fill fitting on the fuel tank or the vehicle. Also make

sure the pressure rating at the CNG filling system is compatible with the fuel tank

pressure rating.

Never fill a 3M CNG fuel tank such that the pressure exceeds 4500 psig at any

temperature

3M™ CNG Fuel Tanks and their constituent components have been designed for use with CNG

fuel only. The maximum allowable CNG service pressure in the United States is 3600 psig.

Under normal driving conditions, the CNG fuel tank and system do not contain any air, and the

residual CNG pressure in the fuel tank is approximately 300 psig minimum. In those situations, a

standard fill procedure can be used to refill the CNG fuel tank. Due to ambient weather


temperature variations and heat generated in a fast filling process, a CNG pressure greater than

3600 psig will sometimes occur during the filling process. These temporary excursions above

3600 psig are allowable, as long as the gas pressure never exceeds 4500 psig regardless of the

temperature. The settled gas pressure should be 3600 psig at a temperature of 70°F (21°C).

6.1.3 Defueling (Depressurization) and Valve Removal

6.1.3.1 Defueling (Safe Depressurization)

! DANGER: Do not attempt to service or remove the fuel tank, valves, or any fuel system

hardware without following depressurization procedures in Section 6.1.3.1. Failure to do so may

result in death or serious injury and property damage. See important safety information below

and in Section 1.0




this fuel tank.



an explosion.

Gas venting should only take place outdoors or following an alternative method which is

in compliance with NFPA 52. This is to avoid the possibilities of asphyxiation or

accumulation of an explosive gas mixture.

In all respects, the requirements of NFPA 52 must be followed for proper safe

depressurization of 3M™ CNG Fuel Tanks.

! WARNING: To reduce the risk of impact and fire, which if not avoided could result in death

or serious injury and property damage:

Use the required diameter and length of discharge setup into the vent stack. Use of

incorrect size tubing/piping can cause damage to valve and fuel tank and injuries or

death.

Always ensure the tank valve is properly grounded in compliance with NFPA 52

requirements.

It is the CNG Fuel System Installer or service provider’s responsibility to comply with all

applicable federal, state and local codes and regulations regarding de-fueling and flaring or

release of CNG.

3M™ CNG fuel tanks may need to be defueled for maintenance or service of tank or fuel system

after they have been in use for some time. The method of safe depressurization of the tank

described in this section is termed as atmospheric venting or flaring. Alternative method of

depressurization in accordance with NFPA 52 can be employed. The alternative method which

discharges the gas into a closed transfer system need to be devised by the fueling/defueling

station providing such a facility.


General Description of Safe Depressurization

The proper general method of safe depressurization involves two steps: The first step is to

activate the solenoid for purposes of opening the valve (procedure in Section 6.1.3.1). Once the

valve is open, depressurization will then take place. The second step is valve removal (procedure

in section 6.1.3.2).

! DANGER: It is mandatory that these instructions for safe depressurization be followed

exactly. Not following each step and in the order listed could result in serious hazardous

consequences.

The procedure outlined in Section 6.1.3.1 to defuel the CNG fuel tank restricts the flow of gas

out of the tank to maintain the tank and valve components safely within service temperature

limits allowed by NGV 2 specifications. In order to save time and de-fuel the tank in an efficient

manner it is recommended to drive the vehicle such that the fuel remaining in the tank is at a

minimum. It should be kept in mind that the vehicle should only be driven if it is safe to do so.

This section of the manual describes two procedures for activation of the solenoid valve to allow

fuel to flow out of the inlet/outlet port. The first procedure is electrical activation of the solenoid

and is the preferred method. The second procedure, manual activation of the solenoid, should be

performed if the electrical activation is not successful.

In the event that there is evidence of the solenoid valve being always open regardless of engine

ignition switch position (On/Off Position), follow step 1 through 10 in the procedure for

electrically activating the solenoid to de-fuel the fuel tank.

Procedure for electrically activating the solenoid to de-fuel the fuel tank

Personnel performing the depressurization should be properly trained to carry out

depressurization activity. Trained personnel must do the following:

1) Isolate the fuel tank to be de-fuelled from rest of the fuel system including any other

fuel tanks. Secure or restrain the fuel tank which is undergoing depressurization by

approved brackets which are properly mounted, or otherwise restrain the fuel tank to

prevent movement while it is under pressure.

2) As required in NFPA 52, use grounding cables and attachments to prevent static

electrical charge buildup. Rapid discharge of CNG can generate a static electrical

charge which can be sufficient to ignite the escaping gas. Ground both the Lyra CV

valve attached to the CNG fuel tank as well as the venting system. A 3-gauge copper

wire (for example a battery cable) should be used to connect the valve securely to an

appropriate grounding source such as a water pipe that extends at least 8 feet

underground. Alternatively an electrically conductive CNG hose connected to a

properly grounded structure can be utilized. This conductive CNG hose is shown in

Figure 13.


3) Ensure that the manual tap (labeled as letter “C” in Figure 6) of the OMB Lyra CV

valve is closed and that the lines connected to the valve have been properly de-

pressurized. Connect a quarter-turn valve approved for pressures greater than or equal

to 5000 psig to the end of the Lyra CV valve prior to where it enters the discharge

line as illustrated in Figure 13.

4) Connect a stainless steel discharge line or electrically conductive hose or tubing

approved for pressures greater than 5000 psig to the outlet port of the quarter-turn

valve. The inner diameter of the discharge line should be less than or equal to 0.25

inch. The length of the discharge line should be no less than 3 feet long, and

preferably longer than 3.5 feet in length. The diameter and length of the discharge

line are important to control the gas flow rate and to locate the gas expansion a

significant distance from the valve and the cylinder so that the most extreme cold

temperatures will be sufficiently far away from the most sensitive components. This

discharge line must be electrically conductive hose or tubing which is grounded in

compliance with NFPA 52. One such recommend hose is manufactured by Parker

with Parker catalogue part number 5CNG4 and shown in Figure 13. The conductive

hose or tube must be grounded or connected to a system which is grounded.


Figure 13. Arrangements for de-fueling/depressurizing CNG fuel tank

5) The outlet side of the discharge line must be connected to the 2” diameter Schedule

80 pipe for venting and must be grounded, as required by NFPA 52. One way to

achieve these requirements is illustrated in Figure 14.

6) When opening the discharge valve, the outlet should be pointed away from any

personnel in the vicinity.

7) Carefully connect the solenoid valve wiring on one end to the solenoid valve using

the solenoid connection point as illustrated by letter “F” in Figure 6 and the other end

to a 12V battery. As a good practice, it is recommended that the battery used for de-

fueling is different from the vehicle engine battery to increase the distance between a

potential spark source and any CNG which would potentially be released. The

connection of battery side needs to be secure and hands-free (with the help of

insulated alligator clips or clamps) as the solenoid cable will be kept wired until the

Fuel Tank must be properly

restrained using its brackets.

Quarter Turn Manual Valve

approved for pressures greater

than 5000 psig.

Electrically conductive CNG hose which

conforms to the requirements of NFPA

52 and is 0.25” internal diameter or less

and longer than 3.5 feet and is connected

to a means for grounding.


fuel tank has completely emptied. As soon as both electrical connections are made,

the solenoid valve will be forced to the open position.

Figure 14. Discharge Line connected to Nominal Pipe Size 2”- Schedule 80. In this case the

2” steel pipe is grounded


8) Open the Lyra CV manual valve by rotating the manual handle all the way counter

clockwise until it won’t rotate any further. The rotation direction of the valve is based

on you standing in front of and facing the valve. If the valve manual tap is upside

down then the manual handle will have to be rotated clockwise in order for it to open.

This step will effectively start flow of CNG out of the fuel tank. On the top of the

manual tap of the valve, “O” and “C” are marked with arrows to indicate directions of

rotation for the Open and Closed positions.

9) Slowly open the quarter-turn valve between the fuel tank and the vent system.

Initially the quarter-turn valve should be open to half of its open position (45 degree

turn instead of full 90 degree turn). If CNG starts flowing out of the tank, the gas flow

will be audible. A visual aid of condensation or ice forming over time on the front of

the tank or Lyra CV valve also indicates gas flow. The presence of condensation and

ice is climate and condition dependent. If ice formation is visible, the quarter-turn

valve should be moved towards its closing position in order to limit the flow of gas

out of the tank. This step will help reduce or eliminate the ice formation process. It is

advisable to use an infrared thermometer for temperature measurement during

depressurization. If an infrared thermometer is used for temperature measurement, the

best location to measure temperature would be the middle portion of Lyra CV valve

as illustrated by letter “G” in Figure 6. Make sure that there is no ice on the valve and

if there is ice then it should be scraped before a measurement is made. If the

temperature measured at location “G” is less than or equal to -30 °F (-35 °C), then

reduce the flow of gas by closing the quarter-turn valve. Controlling the temperature

so that is does not go below -30 °F (-35 °C) is important to protect the most sensitive

sealing components in the valve and the tank. Once completely empty, proceed to

valve removal as described in Section 6.1.3.2.

10) If the previous step does not result in CNG flowing out of the tank then it means that

the solenoid valve is not able to be opened electrically. In this case, further steps need

to be taken in order to de-fuel the tank.

Procedure for magnetically activating the solenoid to de-fuel the fuel tank

11) The Solenoid valve is supposed to be in the open position while the vehicle engine is

running and in the closed position when the vehicle ignition switch is in the off

position. Symptoms of fuel flow impedance may include but are not limited to

situations where engine tends to vibrate because of low fuel or switches over to

gasoline as if fuel is low (while in reality the CNG fuel is not low). In such cases, the

solenoid may have to be kept open forcefully with the help of a permanent magnet.

Follow the steps as described below:

a. First, make sure that the manual tap on the Lyra CV valve and the quarter-turn

valve is in the fully closed position.


b. Unscrew the silver colored hexagonally-shaped cap from the top of the

solenoid valve stem using a 22 mm wrench or any adjustable wrench which

can adjust to 22 mm. Carefully collect the cap once it has been removed as it

will include a small o-ring as shown in Figure 15.

Figure 15. Removal of Solenoid valve collar and cap from OMB Lyra CV Valve

c. Slide the black cylindrical ring-shaped solenoid collar off of the metal

solenoid post of the valve as illustrated in Figure 16.

Figure 16. Lyra CV Valve after Solenoid Collar was removed and a Permanent Magnet

Permanent

Magnet

Solenoid

Coil

Cap with

O-Ring

Solenoid Coil

with Cap

Solenoid

Metal Post


d. Place the permanent magnet over the empty solenoid metal post so that it

covers the metal post completely and hold the magnet securely down all the

way to the bottom of the post to obtain maximum flow and complete opening

of the valve as illustrated in Figure 17.

Figure 17. Lyra CV Valve with Permanent Magnet covering metal solenoid post. It

is essential to hold the magnet securely down to obtain maximum flow

e. As soon as you place the permanent magnet over the metal post, and open the

manual tap on the valve, gas will flow out through the valve. Slowly open the

quarter-turn valve and control and monitor gas flow and temperature as

described in Step 9 of Section 6.1.3.1 “Procedure for electrically activating the

solenoid to de-fuel the fuel tank”. Press down on the permanent magnet to

maintain the gas flow. After the first few instants of emptying, the pressure

on the magnet can be released and the gas will continue to discharge at a

lower rate. In order to maintain maximum flow out through the valve, the

permanent magnet must remain manually pressed down to the bottom of the

metal post.

Permanent magnet all the way

down on solenoid metal post

Push here


Figure 18. If Permanent Magnet is not held down by force, the gas will still escape

but at a lesser rate. To obtain maximum flow, hold the magnet down with force

f. Allow the gas to flow out of the fuel tank until the flow slows down. Hold the

permanent magnet firmly against the bottom of the metal post to ensure that

the last of the gas is released.

g. Keep the permanent magnet over the post of the solenoid until all of the gas

has been vented from the CNG fuel tank. CNG release would be audible as

well as visible due to formation of ice or condensation on the face of the Lyra

CV valve. Wait until the fuel tank is empty. Once completely empty, proceed

to valve removal as described in Section 6.1.3.2.

6.1.3.2 Valve Removal after Safe Depressurization

! WARNING: If the valve is difficult to remove, STOP. Do not attempt to remove the valve if

for any reason you suspect that the valve may be defective. A valve that is damaged or

malfunctioning may mistakenly cause you to think the fuel tank is empty when you do not hear

CNG being released. Handle all CNG fuel tanks; even those you think are empty, as though they

contained CNG under pressure. If the valve is difficult to remove, repeat the safe

depressurization procedure, making certain to press down on the permanent magnet so that it

fully covers the metal solenoid post, ensuring that the solenoid valve opens and that the

contained gas pressure is released in a safe and appropriate manner.

Permanent magnet not all the

way down on solenoid metal post


Procedure to Remove Valve after Safe Depressurization

1. Once it has been confirmed that the fuel tank is completely empty, the Lyra CV

Valve can be removed. In order to remove the valve, it is important that proper

tools are available. One of the necessary tools for valve removal is the proper

attachment for the wrench that is designed to fit the Lyra CV solenoid valve.

This has been illustrated in Figure 19. It is not necessary to use a torque

wrench for valve removal; any type of wrench would work as long as it can be

adapted to fit the OMB designed attachment Lyra CV valve. This OMB

attachment is OMB part number 69982222.

Figure 19. OMB Lyra CV Valve torque attachment with torque wrench and adapters.

These accessories are essential for valve installation and removal

2. Using the valve wrench available from OMB, gently unscrew the valve from

the CNG fuel tank. Using tools other than the proper valve wrench specifically

designed for the Lyra CV valve can result in damage to the valve and PRD. If

the valve/PRD assembly will be re-installed on the same cylinder, for example

after o-ring replacement, the damage from using the wrong wrench could cause

the valve/PRD assembly to malfunction in service, resulting in severe injury or

death.



3. Inspect the valve thoroughly once it has been removed. Check the valve

threads and fuel tank threads for damage. Clean the fuel tank valve threads and

o-ring groove with a clean, lint-free shop cloth, and isopropyl alcohol if

necessary to ensure that they are completely clean. Inspect the o-ring groove

for damage. Damage to the o-ring groove is not allowed because it can impede

a safe and effective seal for the CNG fuel, and result in escape of a flammable

gas. CNG fuel tanks with damage to the o-ring groove are considered having

OMB Lyra

CV Valve

Wrench

Wrench

Adapters

Torque Wrench


Level 3 damage and must be removed from service and decommissioned by

qualified service and repair personnel.

4. Anytime a valve is removed from a CNG fuel tank, the o-ring should be

replaced with a new, undamaged o-ring offered by OMB. O-rings should

never be re-used in the CNG fuel system application. Only a new OMB O-ring

should be used, and it has OMB part number 69388129F. This o-ring was

specially designed from a compound which tolerates the temperature extremes

experienced by the valve.


gas (CNG), which if not avoided will result in death or serious injury and property damage:

Always reject valves or fuel tanks with damaged threads and/or damaged o-rings.

Also, reject fuel tanks with o- ring groove damage since these damages prevent a safe

and effective seal.

7.0 Inspection Procedures This section describes the inspection procedures, frequency, and personnel who are qualified to

complete periodic inspections of the 3M™ CNG fuel tank. Methods to determine whether the

CNG fuel tanks need to be repaired or replaced are also discussed. See important safety

information below and in Section 1.0.

! DANGER: Do not attempt to service or remove the fuel tank or any fuel system

hardware without following depressurization procedures in Section 6.1.3.1. Failure to do so

may result in death or serious injury and property damage. See important safety

information below and in Section 1.0

This section provides guidelines for CNG fuel tank inspection and must not replace any

regulations required by law or by applicable industry standards. In case of a conflict between

this manual and regulations and/or applicable industry standards, they will supersede this manual

and shall be followed instead of this manual. 3M Company assumes no liability for errors or for

any damage that results from the use of this instruction manual.

An inspection includes examining the CNG fuel tank and the tank mounting system, and any

other fuel system components as dictated by federal, state, or local standards.


7.1 Qualified inspectors

! DANGER: To reduce the risk of fire or explosion, which if not avoided, will result in



Pamphlet C-6.4.

All obligatory inspections described in Sections 7.2 must be completed by a qualified inspector

as described in CGA Pamphlet C-6.4, Methods for external visual inspection of Natural Gas

Vehicle (NGV) and Hydrogen Vehicle (HV) fuel containers and their installations.

7.2 When fuel tanks should be inspected

! DANGER: To reduce the risk of fire, explosion and impact, which if not avoided will

result in death or serious injury:

Conduct fuel tank inspections upon receipt from the manufacturer, when removed from

storage, and on a regularly scheduled basis, according to applicable federal state, and

local regulations.

Have a qualified inspector as described in CGA Pamphlet C-6.4 inspect the fuel tank

immediately in the case of unusual behavior by the fuel tank, or if the tank has been

involved in a motor vehicle accident, fire, or any other incident that may cause damage

to the fuel tank

Federal Motor Vehicle Safety Standard 304, Compressed Natural Gas Fuel Container Integrity,

requires that the CNG fuel tank be visually inspected after a motor vehicle accident or fire, and at

least every 36 months or 36,000 miles driven, whichever comes first, for damage and

deterioration.

The fuel tank should also be inspected promptly by a qualified inspector if:

1. The fuel tank, or the vehicle it is installed in, has been involved in a fire

2. The fuel tank was been dropped or subjected to impact

3. The fuel tank has been exposed to excessive heat

4. The vehicle containing the fuel tank has been involved in a collision

5. The fuel tank is believed to have been damaged by cargo, the vehicle or components,

and/or environmental chemicals

6. The fuel tank is believed to have been damaged by any other means

7. The fuel system shows any unusual behavior. This may include, but is not limited to,

emission of a natural gas odor, unexpected loss of pressure in the fuel system, rattling or

other indications of loose connections, or unusual hissing or snapping sounds.

8. The fuel tank is transferred to another vehicle

9. Significant alterations are made to the fuel tank installation

10. The fuel tank has been re-installed after removal from the vehicle

11. The fuel tank is believed to have been pressurized above the design standard.

12. The mounting brackets show evidence of damage

13. The valve or PRD show evidence of damage


During inspection, the vehicle owner/operator should be questioned about any incidents or

conditions that may have caused damage to the tank, performance issues that may indicate a

problem, repairs made since the last inspection, unusual observations, and service history of the

fuel tank. Incidents include, but are not limited to: dropping the tank, impacts to the tank by

sharp or blunt instruments, exposure to fire or excessive heat, vehicle accidents including

collisions of 5 mph or more, or exposure to harsh chemicals. Performance issues may include,

but are not limited to: poor fuel system performance, too-frequent filling, and other unusual

performance by the fuel tank.

The fuel tank and fuel system inspection should be conducted according to CGA C-6.4, Methods

for external visual inspection of natural gas vehicle (NGV) and hydrogen vehicle (HV) fuel

containers and their installations, and any other applicable federal, state, and local requirements.

7.3 Inspection Data Recording

To aid the qualified inspector, Appendix 1 contains a CNG Fuel Tank Inspection Form, where

the tank serial number and inspector’s name are identified, as well as any findings from the

inspection activities.

To accurately complete the inspection, certain information from the label on the CNG fuel tank

must be able to be readily identified. All 3M™ CNG fuel tanks are identified by labels that

contain regulatory information as well as important safety and handling information. Section 3.2

Fuel Tank Labels contains images and Figures which show where the main fuel tank label is

located (Figure 3), as well as the requisite information located on the main fuel tank label (Figure

4).

7.4 Preparation for inspection

The routine formal visual inspection conducted to satisfy the Federal Motor Vehicle Safety

Standard does not require the breaking or opening of any fuel system connections or

depressurization of the fuel system, as long as the identification label of the CNG fuel tank (see

Figure 3) is visible.

! WARNING: To reduce the risk of impact, fire, or explosion, which if not avoided

could result in death or serious injury and property damage:

Reject and remove from service any CNG fuel tank that either lacks a label

containing mandatory information or if all main labels are illegible.

If maintenance is going to be performed on a CNG fuel tank or system and piping, and

connections will be opened (such as replacing a valve or a fitting), special safety considerations

and preparations must be undertaken.


hardware without following depressurization procedures in Section 6.1.3.1. Failure to do

so may result in death or serious injury and property damage. See important safety



7.5 General Guidelines and Preparation Recommendations


moderate injury:


workplace practices when inspecting 3M™ CNG Fuel Tanks.

1. Wear safety glasses, gloves and boots

2. Use correct tools and documentation

3. Ensure proper training and understanding of fuel systems

4. Assume the fuel tank and system is pressurized prior to conducting a safe

depressurization procedure

5. Eliminate any potential ignition sources

7.6 Mounting bracket inspection

! DANGER: If a mounting bracket is damaged during use, the user must have a qualified

inspector conduct a periodic inspection of the CNG Fuel Tank, since the tank may have

incurred damage in the same event which damaged the bracket. See important safety

information below and in Section 1.0.

Mounting bracket inspection includes the following specific areas:

1. Verify that the fuel tank is firmly held in place.

2. Verify that all the mounting bolts that secure the tank mounting brackets to the

vehicle are in place and tight.

3. Verify that the rubber strips between the mounting brackets and the fuel tank are in

place, centered on the brackets, undamaged, positioned per Section 5.3 (Figures 8-

12).

4. Verify that the mounting brackets are in good shape, free of severe rust or other

damage, and suitable for continued service.

5. Examine the brackets for any visible damage, such as wear indications.

The CNG fuel tank does not normally have to be removed from the mounting brackets for this

inspection.

If the fuel tank has to be removed to repair the brackets, the procedure should be completed only

by authorized repair facilities with competent personnel trained to work on CNG fuel systems,

and they must follow safe depressurization procedures.





New rubber strips between the fuel tank and the metal straps must be installed if either rubber

strip has been permanently deformed, worn, or damaged during use. Any time a bracket strap is


loosened after being in use, visually check for any wear that may have occurred to the strap. If

wear is visible, a new replacement rubber strip must be used to ensure all torque settings are

correct to allow for expansion and contraction of the fuel tank during fueling and de-fueling.

Replacement rubber strips are available through 3M. If the rubber strips are replaced, the nylon

insert locking nut which tightens the strap around the tank with the bolt may also need to be

replaced and torqued to the values as described in Section 5.3 of this manual. ½” – 13 UNC

Grade 8 Steel nylon insert hex lock nut should be used. Contact 3M at 800-364-3577 for

replacement rubber strips.



Any time a bracket strap is loosened after being in use, visually check for any wear that

may have occurred to the strap. If wear is visible, a new replacement rubber strip must be

used to ensure all torque settings are correct to allow for expansion and contraction of the

fuel tank during fueling and de-fueling. Adjust metal brackets according to correct

torquing procedures described in Section 5.3 of this manual.

If the mounting bracket strap bolts are loosened or removed during bracket inspection, or the fuel

tank is removed from the brackets for any reason, then the torque values listed in Section 5.3 will

not be correct to properly secure the fuel tank, due to potential wear of the rubber strip. The fuel

tank expands and contracts in diameter and length as the internal pressure increases or decreases,

but it must remain secured in place at all internal pressure levels without overstressing the

mounting straps or abrading the outer surface of the fuel tank. For these reasons, if the bracket

strap bolts are ever loosened or the tank is removed from the brackets for any reason, the rubber

strips must be inspected thoroughly and if showing signs of wear then they should be replaced

with new ones (contact 3M for replacement rubber strips) and then torqued per the specifications

in Section 5.3 of this manual.

7.7 Fuel system inspection





Inspecting the fuel system includes checking all non-fuel tank components such as valves,

tubing, hoses, end plugs, fittings, and pressure-relief devices (PRDs). During inspection, make

sure that each piece of system hardware is properly and securely attached. If any hardware is

damaged or loose, the fuel system must be taken out of service and must be replaced by an

authorized repair facility with competent personnel trained to work on CNG fuel systems, and

they must follow safe depressurization procedures. The (non-fuel-tank) fuel system component

inspections should be conducted per the instructions outlined in CGA Pamphlet C-6.4 and any

other applicable federal, state and local codes and regulations.


7.7.1 Valve, PRD, and solid plug inspection – visual inspection only

! DANGER: To reduce the risk of impact, fire, and explosion, which if not avoided will


Do not attempt to disassemble the valve, PRD or solid plug. The valve, PRD, and

solid plug contain no user serviceable parts.

Each CNG fuel tank has one valve attached to the threaded fitting on one end of the cylindrical

fuel tank, and is protected by one thermally-activated pressure relief device (PRD) that is part of

the valve. Each CNG fuel tank has a plug threaded into the fitting on the opposite end of the fuel

tank from the valve.

Visual Inspection procedure for the valve, PRD, and plug:

1. Examine the valve/PRD assembly for damage. Note that the valve/PRD assembly should

not be deformed or show other signs of damage. Damaged valve/PRD assemblies must be

replaced by an authorized repair facility with competent personnel trained to work on

CNG fuel systems, and they must follow safe depressurization/de-fueling procedures. If

the valve/PRD assembly shows any signs of damage, the fuel tank should be inspected

for impact damage.

2. Examine the connection between the valve/PRD assembly and the tank port. These

connections should be tightly sealed with no gaps or evidence of looseness. Inspect for

displacement or cracks in the torque seal. Inspect for rubber shavings or other evidence of

O-ring damage at these connections. If there is evidence of looseness or o-ring damage,

then the fuel tank should be safely depressurized and evaluated by an authorized repair

facility with competent personnel trained to work on CNG fuel systems, and they must

follow safe depressurization procedures. Do not attempt to service or remove the fuel

tank or any fuel system hardware without following depressurization procedures in

Section 6.1.3.1. Failure to do so may result in death or serious injury and property

damage. See important safety information below and in Section 1.0

! DANGER: To reduce the risk of fire and explosion, which if not avoided will result in


Never use an open flame or ignition source to test for gas leaks

3. The connections between the valve and fuel tank and between the solid plug and fuel tank

should be tested for leaks. Use an electronic leak detector or a leak solution (“bubble test”

solution) to perform this test. If any leakage is suspected or observed, service should be

conducted by authorized repair facility with competent personnel trained to work on

CNG fuel systems, and they must follow safe depressurization procedures. Do not

attempt to service or remove the fuel tank or any fuel system hardware without following

depressurization procedures in Section 6.1.3.1. Failure to do so may result in death or

serious injury and property damage. See important safety information below and in

Section 1.0


4. The solid plug should be visually inspected for corrosion or damage during an inspection.

If the solid plug is corroded, or damaged it must be replaced only by an authorized repair

facility with competent personnel trained to work on CNG fuel systems, and they must

follow safe depressurization procedures.

Figure 20. Photograph of the plug which is installed on one end of the fuel tank. The

o-ring which provides a seal between the plug and the fuel tank is visible in this

image

Vent lines from the fuel tank and PRD must also be inspected to assure proper performance

during a fire. Verify there is no damage to the vent line(s) and no debris blocking the line or

its outlet. Special care should be taken to ensure no water or ice is blocking or contained

within the PRD blow down lines. Ice or water (which could be frozen to ice) would

detrimentally affect the operation and blow down of the PRD in the event of a fire situation.

Damaged or blocked vent lines must be replaced by an authorized repair facility with

competent personnel trained to work on CNG fuel systems, and they must follow safe

depressurization procedures.

7.8 Fuel tank inspection

! DANGER: To reduce the risk of impact, fire, or explosion, which if not avoided, will



Pamphlet C-6.4.

The following recommended inspection and damage grading criteria provided in this manual for

CNG fuel tanks are intended to supplement any processes established by regulatory agencies

either now or in the future. In the event of a conflict between the 3M criteria and a regulatory

requirement, please contact 3M for clarification.

A competent agency or person approved or recognized by applicable regulatory authorities (as

described in CGA C-6.4) must conduct the inspection in accordance with all applicable

regulations and 3M™ specifications. Under normal operating conditions, federal regulations

mandate that the vehicle user have the inspection performed by a qualified inspector every three

(3) years or 36,000 miles, whichever comes first. An additional inspection is required following

any vehicle accident or fire, as well as at the time of any fuel tank re-installation, and other

conditions as described in Section 7.2. For the lifetime of the fuel tank, records of all periodic

inspections should be retained by the vehicle user and provided, when necessary, to the qualified

inspector for subsequent periodic inspections.


The procedures below describe an examination of the fuel tank for external damage and

deterioration. This section does not address the condition of the fuel system plumbing or the fuel

tank mounting brackets (refer to above Sections 7.6 and 7.7). In the event of a vehicle accident or

fire, fuel tanks must be inspected and evaluated by a qualified inspector as described in CGA C-

6.4 to comply with government regulations. The information in the this section can be used as a

guide to determine whether the fuel tank can continue to be used, may be repaired and put back

into service, or must be removed from service, decommissioned, and destroyed.

CNG fuel tanks are designed and manufactured with a limited design life, which is displayed on

the label on the fuel tank. When inspecting a CNG fuel tank, always check the label first to make

sure the fuel tank has not exceeded its expiration date. The expiration date is located on the main

labels on the fuel tank (see Figure 3) and is indicated by the “DO NOT USE AFTER:” date, near

the center of the main label as shown in Figures 4 and 5.

! WARNING: To reduce the risk of impact, fire, or explosion, which if not avoided could


Reject and remove from service any CNG fuel tank that either lacks a label containing

mandatory information or if all main labels are illegible.


7.9 Inspection tools

Figure 21. Inspection Tools

Inspection tools, clockwise from top:

Dial indicator depth gauge

Scale (ruler)

Caliper with dial readout

Torque wrench

Digital camera

Mirror

Flash light

Tape measure

! CAUTION: To reduce the risk of impact, which if not avoided, may result in minor or

moderate injury:


workplace practices when inspecting 3M™ CNG Fuel Tanks.


7.10 Types of damage and measurement

This section only addresses the condition of the CNG fuel tank, not the condition of the fuel

system plumbing or the fuel tank mounting brackets (refer to above Sections 7.6 and 7.7). In the

event of a vehicle accident or fire, fuel tanks must be inspected and evaluated by a qualified

inspector as described in CGA C-6.4 to comply with government regulations. The information in

the table in this section can be used as a guide to determine whether the fuel tank can continue to

be used, may be repaired and put back into service, or must be removed from service,

decommissioned, and destroyed.

The table below lists the conditions to look for when conducting a general inspection and the

probable cause of the damage.

Table 1. Fuel Tank Damage

Type of Fuel Tank Damage

Signs of Fuel Tank Damage

Probable Cause of Damage

Impact Dents, scratches,

cracked or peeling

composite, crazing

(hairline cracking of

the composite)

Blunt object impact with the fuel tank,

the fuel tank being dropped or crushed

Cut and scratch Cut, scratch, gouge,

peeling composite

Impact from a sharp or pointed object

Chemical attack Discoloration, soft

spots, blistering,

swelling

Contact with a fluid that is corrosive or

damaging to the composite material or

clear coating

Abrasion Scuffs, parallel

scratches, dull or

whitish appearance, flat

spots on fuel tank

Friction or other contact damage

between the surface of the fuel tank and

another object.

Fire and excessive

heat

Charred surface of fuel

tank, discoloration, soft

spots, blistering,

swelling

Direct flame, excessive heat source in

contact with fuel tank or near fuel tank

(i.e., vehicle exhaust system or fire)

Weathering Fuzzy, cloudy

appearance/

discoloration, soft spots

Sunlight or exposure of composite to

rain or water which creates and gets

into surface cracks in the composite

Delamination Frayed, cut, or loose

composite strands

Blunt or sharp impact damage, fuel

tank being dropped or crushed, deep

cutting or gouging

It is worth noting that not all categories of damage have “Level 2” damage, which may be

repairable. Some types of damage cannot be repaired, so they might have only Level 1 (no

repair required) and Level 3 (remove from service and condemn) damage described.






The table below defines damage levels for a 3M™ CNG Fuel Tank. Tables in the following

sections provide more detailed descriptions and examples of specific types of fuel tank damage

and actions to address the damage. These definitions of damage levels are also used in the 3M™

CNG Fuel Tank Inspection Record form found in Appendix 1.

Table 2. Definition of Damage Levels

Level Damage Level Definition Action Required

N/A Not Applicable - a specialized case that

cannot be categorized, or does not apply

to a fuel tank under a specific condition.

Contact 3M at 1-800-364-3577

1 The fuel tank is slightly damaged but

can still be used.

Continue to use the fuel tank in its

current condition but prevent further

damage to the tank.

2a The fuel tank is damaged but can be

repaired.

Repair the fuel tank following the

procedures in Section 8.0 Repair

Procedures.

2b The fuel tank is damaged but may be

repaired upon consulting with the fuel

tank manufacturer.

Consult with 3M at 1-800-364-3577

to determine if fuel tank can be

repaired.

3 The fuel tank is damaged and cannot

safely continue to be used.

Qualified service and repair personnel

must immediately remove the fuel

tank from service and destroy it.


7.10.1 Impact damage

Unlike metal fuel tanks, composite fuel tanks typically do not exhibit permanent dents upon

being impacted; therefore, impact damage is not always obvious. Impact damage can be difficult

to assess because it can be within the composite and not easily visible. If a fuel tank is suspected

of having received a significant impact, by dropping, having a vehicle accident, or any other

adverse event then it is recommended that the user have a qualified inspector (as described in

CGA C-6.4) complete a periodic inspection.

Table 3. Assessment of Impact Damage

Level Severity of Damage Action Required

1 The fuel tank shows signs of minor

scratches or a whitish/frosted

appearance on the composite surface

less than 1.5 square inches (967 mm2) in

area.



damage to the tank.

3 The fuel tank shows signs of dents, flat

spots, cracking or peeling of composite,

and crazing (hairline cracks in the clear

coat).


must immediately remove the fuel

tank from service and destroy it.

Figure 22. Level 1 Impact Damage. Note: Minor scratches, as well a slight discoloration in

the clear coat and is less than 1.5 square inches in area


Figure 23. Level 3 Impact Damage. Clear coat shows severe cracking

7.10.2 Cut and scratch/gouge damage and measurement

The severity of cut, scratch, and gouge damage is based primarily on the depth of the flaw. The

fuel tank has an exterior layer of glass composite specifically included to be a sacrificial layer in

case the fuel tank sustains damage. Damage that does not penetrate through this glass composite

layer typically has not degraded the capability of the fuel tank. Flaw length is less critical,

although should be considered in the assessment of fuel tank capability. The most important

length of the flaw is the total length that cuts across the path of the fibers in the glass composite

or black structural carbon composite layers. Severe deep cuts and damage are often accompanied

by areas of fiber lifting or delamination in the composite layer.


Table 4: Assessment of Cut and Scratch/Gouge Damage

Level Severity of Damage- Flaw Classification

Action Required

Flaw Depth Flaw

Length

Number of

Permissible

Flaws

1 Less than 0.01

inch (0.25mm);

surface damage

only with no

visible composite

damage

Any length Single or

multiple flaws


current condition but prevent

further damage to the tank.

2a Greater than 0.01

inch (0.25mm)

and less than

0.02 inch

(0.5mm);

Damage

penetrates only

into the white

glass composite,

no black

composite is

visible at the

deepest depth of

the damaged

area.


multiple flaws

Remove the fuel tank from service

and repair according to the

procedure in Section 8.0

2b Greater than 0.02

inch (0.5mm)

less than 0.03

inch (0.75mm)

Damage

penetrates only

into the white

glass composite,

no black

composite visible

at the deepest

depth of the

damaged area.

Less than

1 inch

(25mm)

Single flaws Remove the fuel tank from service

and contact 3M at 1-800-364-3577


Table 4: Assessment of Cut and Scratch/Gouge Damage - Continued

Level Severity of Damage- Flaw Classification

Action Required

Flaw Depth Flaw

Length

Number of

Permissible

Flaws

3 Greater than 0.02

inch (0.5mm) less

than 0.03 inch

(0.75mm)

Damage penetrates

only into the white

glass composite,

no black

composite visible

at the deepest

depth of the

damaged area.

Less than

1 inch

(25mm)

Greater than 1

flaw

Remove the fuel tank from service

and contact 3M at 1-800-364-3577

3 Greater than 0.03

inch (.75 mm)

damage penetrates

into structural

black carbon

composite


multiple flaws

Qualified service and repair

personnel must immediately

remove the fuel tank from service

and destroy it.


Figure 24. Level 1 Cut Damage. The cut has just marred the exterior clear coating and has

not penetrated into the glass composite. The ruler is shown for relative size only, and is not

used to measure cut depth

Figure 25. Level 2 Cut Damage. The cut has penetrated into the glass composite layer, but

has not penetrated into the structural black carbon composite. No black carbon composite

is exposed at the bottom of the cut. The ruler is shown for relative size only, and is not used

to measure cut depth


Figure 26. Level 3 Cut Damage. The cut has penetrated the glass composite, and a hazy

white area of delamination is apparent above the cut. Lifted glass fibers are visible at the

cut edge. Black structural carbon composite is visible in the deepest part of the cut. Due to

the extent of the damage, the structural integrity of the fuel tank may have been reduced,

so it must be immediately and safely removed from service, decommissioned and destroyed

by a qualified repair facility with competent employees trained to work on CNG fuel

systems


Figure 27. Two Level 1 Cuts/Scratch Damage areas (top) and a Level 3 ‘gouge’ Damage

area (bottom). The upper scratches have not penetrated the clear coat. The lower gouge has

penetrated down to the black structural carbon composite. Due to the extent of the damage,

the structural integrity of the fuel tank may have been reduced, so it must be immediately

and safely removed from service, decommissioned and destroyed by a qualified repair

facility with competent employees trained to work on CNG fuel systems

7.10.3 Chemical attack

The resins and fibers used in composite fuel tank construction are usually resistant to the

chemicals found in a fuel system. But given the wide range of chemicals and solvents a fuel tank

may encounter during its working lifetime, damage due to chemical exposure is possible. This

problem can be largely prevented by preventing prolonged exposure to moisture, automotive

fluids, or corrosive materials like battery acid. To help ensure that fuel tanks do not experience

chemical attack, the area around the tank should drain freely, and should not allow moisture or

debris to become trapped or come in contact with the fuel tank. Clean the exterior of the fuel

tank with mild soap and water before inspecting for chemical attack.

Level 1

Level 3


Table 5: Assessment of Chemical Attack Damage


1 The area known to have been exposed

to chemicals appears no different than

the surrounding unaffected area, or has

a slight stain. There are no soft spots in

the clear coat or composite.



damage to the tank. Include a note in

the inspection records to identify the

location and chemical contact

situation.

3 Clear coat and/or composite show

signs of discoloration, blistering,

swelling, soft spots, or resin loss.


must immediately remove the fuel tank

from service and destroy it.

7.10.4 Abrasion damage and measurement

Abrasion damage may result from many cycles of something rubbing lightly against the fuel

tank, or a few cycles under a severe abrasion. Abrasion from light rubbing tends to polish the

tank’s outer surface. Abrasion from high loads looks like parallel gouges or cuts. Fuel tanks

showing evidence of abrasion under high loads should also be carefully examined as though the

surface was subjected to impact damage.

The severity of abrasion damage is based on the depth of the abrasion. This depth is determined

by measuring the depth of the deepest part of the abrasion, or the thickness of composite or resin

that has been removed, with a depth micrometer. Before measuring the depth of an abrasion, the

digital micrometer should be calibrated on an undamaged area of the fuel tank’s surface which

has roughly the same curvature.

If the depth of the abrasion damage cannot be accurately measured, establish a range that this

depth could be, and then classify it as the most severe in this range.

Table 6: Assessment of Abrasion Damage


1 Abrasion depth is less than 0.01 inch

(0.25mm)

Continue to use fuel tank in this

condition but prevent further damage

from taking place.

2a Abrasion depth is greater than 0.01

inch but less than 0.03 inch (0.75mm)

and less than 1 square inch in area.

Damage penetrates only into the white

glass composite; no black carbon is

visible in the bottom of the abraded

area.

Repair the cylinder by following the

procedures in Section 8.0

3 Abrasion depth is greater than 0.03

inch (0.75mm), and black carbon

composite is visible at the deepest part

of the abraded area.





Figure 28. Level 3 Abrasion Damage. This abrasion has penetrated the protective glass

composite. Note the appearance of black carbon composite at the bottom of the abrasion.

Level 3 abrasion damage as shown above is too extensive. Due to the extent of the damage,

the structural integrity of the fuel tank may have been reduced, so it must be immediately

and safely removed from service, decommissioned and destroyed by a qualified repair

facility with competent employees trained to work on CNG fuel systems

7.10.5 Fire and excessive heat damage

All CNG fuel tanks manufactured under NGV2 specifications have a maximum service

temperature of 180°F (82°C). The effects of exposure to fire or high heat are usually obvious.

Resin will darken more with higher temperature and longer exposure times. Exposure to

excessive heat may result from the fuel tank being improperly located relative to the vehicle

exhaust system, or exposure to a fire. It is possible for a CNG fuel tank that has been damaged

by fire or excessive heat not to show any sign of damage, so it is important to follow the

recommendations in the Table 7 below. Clean the affected area before inspecting.


Table 7: Assessment of Fire and Excessive Heat Damage


N/A Fuel tank is known or is suspected to

have been exposed to fire or excessive

heat but does not show any signs of

damage. Clear coat layer appears

smooth and clear, without any

blistering or degradation of laminate or

resin.

Contact 3M at 1-800-364-3577

3 There is evidence of exposure to fire or

excessive heat. This may include: soft

spots, melting, blistering, melted

labels, discoloration, charred laminate

in the clear coat or composite, etc.




Figure 29. Level 3 Fire or Excessive Heat Damage. Fire has caused blistering and distortion

of the protective clear coat and caused localized darkening of the composite and damaged

the composite layer underneath. Level 3 fire damage as shown above is too extensive. Due

to the extent of the damage, the structural integrity of the fuel tank may have been

reduced, so it must be immediately and safely removed from service, decommissioned and

destroyed by a qualified repair facility with competent employees trained to work on CNG

fuel systems


7.10.6 Weathering

Before assessing any weathering damage, wipe off the affected area of the fuel tank to remove

any dirt or foreign substances.

Environmental exposure to sunlight, road salts, and extreme heat and cold may cause a change in

the surface appearance of composite materials. Exposure to sunlight may cause a yellowish or

orange-ish color or flaking in the exposed area. Road salts may corrode exposed aluminum but

usually do not cause damage to composite materials. Extreme heat and cold can cause a mild

discoloration or craze-cracking of the surface resin (clear coat).

Table 8: Assessment of Weathering Damage


1 The clear coat has a whitish/cloudy or

yellowish appearance.

Continue using fuel tank in its current

condition, but prevent further damage.

2 Corrosion of exposed aluminum Contact 3M at 1-800-364-3577

3 Clear coat layer or composite shows

signs of cracking, blistering, soft spots,

or other characteristics of severely

degraded composite.




7.10.7 Delamination

Delamination is the separation of composite layers. Cut fibers are sometimes evident in

delaminated composites. It is usually caused by severe impact. Delamination normally appears as

a lighter colored area of composite surrounding an area of cut/gouge or impact damage.

Delamination can occur in the outer glass composite layers or the carbon composite layers.

Delamination is evident in Figure 26 as a slightly brighter white “cloudy” area on the composite

adjacent to the damaged area.

Because delamination is normally the symptom of significant damage to the fuel tank, no

delamination is allowed in the glass composite or the carbon composite. If the clearcoat (only) is

damaged or delaminated, it can be repaired as described in Sect. 8.0.

Table 9: Assessment of Delamintation Damage


1 N/A

2 Delamination of clear coat only.

Width of delamination may not be

wider than original damage from cut,

gouge or abrasion.

Repair following the instructions in

Sect. 8.0.

3 Anything more severe than Level 2.

Delamination visible in either the glass

composite layer or the carbon

composite layer or both layers.





7.10.8 Gas leakage

! DANGER: If a gas leak is suspected, immediately stop using the affected vehicle and

seek service by a company having competent personnel and appropriate facilities for the

installation, repair, and adjustment and testing of CNG fuel systems. See important safety

information in Section 1.0.

Because of the risks for severe injury or death from improper installation repair, and

decommissioning procedures, CNG fuel system service companies should follow the

requirements of the most up-to-date revisions of ANSI/NFPA 52, Vehicular Gaseous Fuel

Systems Code and any other applicable federal, state and local codes and standards. Such

qualified companies will be able to conduct an inspection and determine the source of the

suspected leak and the appropriate remedy. Fuel tanks with confirmed gas leaks must be

condemned and destroyed by a company competent in decommissioning CNG fuel systems.

7.10.9 Illegible labels



Reject and remove from service any 3M™ CNG Fuel Tank that either lacks a label

containing mandatory information or if all main labels are illegible.

As described in Section, 3.2 the main label on the fuel tank contains vital safety and

identification information. According to federal regulations, the information on the label must be

easily readable and accessible during periodic inspections. The labels are equally spaced around

the circumference of the tank.

If all the main labels around the circumference of the tank have been damaged so they are not

able to be read, this is considered Level 3 damage and the fuel tank must be removed from

service and decommissioned by company having competent personnel and appropriate facilities

for the installation, repair, adjustment and testing of CNG fuel systems because of the risks of

severe injury or death from improper installations, repair and decommissioning procedures.

Further, such companies should follow the requirements of the most up-to-date revisions of

ANSI/NFPA 52, Vehicular Gaseous Fuel Systems Code and any other applicable federal, state,

and local codes and standards.


7.11 Summary table of damage levels

Table 10: Damage Levels

Type of damage

N/A Not applicable in this situation.

Level 1 Damage that does not require repair.

Level 2 Damage that requires further inspection and repairs, and may

be severe enough to condemn tank.

Level 3 Damage that is not repairable, and is severe enough for tank

to be removed from service and condemned.

Impact

Level 1 A small, frosted white area in the clear coat layer less than

1.5 square inches (967 mm2) in area.

Level 2 N/A

Level 3 Any impact damage greater than Level 1 – any indentation,

fiber delamination, or major structural damage to any part of

tank.

Cut/gouge

Level 1 Any number of flaws of any length less than 0.01in.

(0.25mm) deep.

Level 2

Any number of flaws of any length between 0.01in.

(0.25mm) and 0.02in. (0.5mm) deep.

OR one single flaw between 0.02in. (0.5mm) and 0.03in.

(0.75mm) deep and less than 1.0in. (25.4mm) long.

Level 3

Any flaw greater than 0.03in. (0.75mm) deep or where the

black carbon composite is visible at the deepest part of the

cut/gouge

OR multiple flaws between 0.02in. (0.5mm) and 0.03in.

(0.75mm) deep

Chemical attack

Level 1 Stain on clear coat without visible damage or penetration.

Level 2 N/A

Level 3 Evidence of blistered, discolored, softened or dissolved resin

or composite, particularly if composite fibers are visible.

Abrasion

Level 1 Any sized area of abrasion less than 0.01in. (0.25mm) deep.

Level 2 Any abrasion between 0.01in. (0.25mm) and 0.03in. (0.75

mm) deep and less than 1.0 square inch (645mm2) in area.

Level 3 Any abrasion greater than Level 2 damage criteria in depth

or area.


Table 10: Damage Levels - Continued

Type of damage N/A Not applicable in this situation.

Level 1 Damage that does not require repair.

Level 2 Damage that requires further inspection and repairs, and may

be severe enough to condemn tank.

Level 3 Damage that is not repairable, and is severe enough for tank

to be removed from service and condemned.

Fire/heat

NA Known exposure to heat or fire, but the clear coat is smooth

and clear with no blistering, discoloration, or signs of

degradation.

Level 1 N/A

Level 2 N/A

Level 3 Evidence of burned or charred resin in any material layer, or

heat induced cracking or spalling of resin.

Weathering

Level 1 The clear coat has a whitish/cloudy or yellowish appearance.

Level 2 Corrosion of exposed aluminum.

Level 3 Clear coat layer or composite layer shows signs of cracking,

blistering, soft spots, or other characteristics of severely

degraded composite.

Delamination

Level 1 N/A

Level 2 Delamination of clear coat only. Width of delamination may

not be wider than original damage from cut, gouge or

abrasion.

Level 3 Anything more severe than Level 2. Delamination visible in

either the glass composite layer or the carbon composite

layer or both layers.

8.0 3M™ CNG Fuel Tank Repair Procedures

8.1 Determining if repair is appropriate

The most important step in repairing a 3M™ CNG Fuel Tank is to determine if it needs repair, if

it is damaged but repairable, or if it is so badly damaged that it must be decommissioned. See

Section 7.10 to determine which levels of damages from various causes are repairable, and which

are not.

Damage that penetrates the protective clear coat, white glass composite layer and affects the

black carbon composite layer is considered not repairable (Level 3 Damage), and the fuel tank

must be removed from service and decommissioned by an authorized repair facility with







information below and in Section 1.0 and Section 6.1.3 Depressurization and Valve

Removal.

If Level 2 damage has occurred and is classified as repairable, the method for fixing/filling

abrasions, impact damage, cuts, and gouges in the clear coat and glass composite layer of the

fuel tank is the same in all cases. The damaged area is abraded manually to create a good bond,

cleaned of debris, and a small amount of 2-part epoxy is applied to the damaged area. If the

repair technician has sufficient access to the damaged part of the fuel tank, then the fuel tank will

not have to be removed from the vehicle for repair. If the damage to the fuel tank is not

accessible, the fuel tank must be removed from service by an authorized repair facility with



8.2 Repair tools

! CAUTION: To reduce the risk of inhalation of dust, impact, cuts, abrasion, or chemical

exposure, which if not avoided may result in minor or moderate injury:


workplace practices when repairing 3M™ CNG Fuel Tanks.

Read and follow all manufacturers’ instructions for use and Material Safety Data Sheets

prior to use of epoxy and acetone.

Tools for repair of epoxy resin on fuel tanks include:

3M™ ScotchBrite™, red

3M™ DP 105 epoxy

3M™ epoxy dispenser

Plastic static mixing nozzle for epoxy

Lint-free shop rag

Safety glasses

Gloves

Dust mask

Acetone


Figure 30: Repair Tools

The repair procedure is as follows:

Step 1: Put on safety glasses, gloves, and a dust mask.

Step 2: Load 3M™ DP 105 epoxy into 3M™ epoxy dispenser. If this product is not available

you can also use an equivalent 5 minute cure, clear, two part epoxy.

Figure 31. Load the 3M™ DP 105 epoxy into 3M™ epoxy dispenser

Step 3: Sand or abrade the surface around and in the damage with 3M™ ScotchBrite™

(red/maroon color) or similar abrasive. Sanding should be done manually, without using power

tools (per CGA C-6.4, the use of a powered brush, sand or grit blasting, peening, power sanding,

grinding, or chemical strippers is prohibited on composite materials. Hand sanding with a fine


grit paper or ScotchBriteTM

is permissible to remove loose, deteriorated, or sharp edges in

preparation for repair.) The abrasion will prepare the area to make a good bond with the epoxy

used for repair.

Figure 32. Using 3MTM

ScotchBriteTM

lightly abrade the damaged area

Step 4: Use lint-free shop rag moistened with acetone to remove sanding dust and to clean up the

abraded area.

Figure 33. Wipe the abraded area with a lint-free shop rag to remove sanding debris

Step 5: Use 3M™ epoxy dispenser loaded with 3M™ DP105 (or equivalent) epoxy to dispense

enough mixed epoxy to fill the damaged area. Approximately 1 teaspoon (5 ml) of epoxy will be

enough to fill a small cut. Larger cuts or abraded areas will require more epoxy.


Figure 34. Apply mixed epoxy to the damaged area

Step 6: Apply the mixed epoxy to the damaged area with a suitable applicator. Push and wipe

the epoxy fully into any damaged indentations. Smooth the edges of the new epoxy with the

applicator, and avoid getting air bubbles in the wet epoxy. Do not allow the epoxy to drip or run.

Figure 35. Smooth the mixed epoxy resin into the damaged area

Step 7: Allow epoxy to cure according to manufacturer’s instructions.

Step 8: As an optional step, the cured new epoxy may be sanded again with 3M™ ScotchBrite™

to remove any roughness. It is not necessary to achieve a perfect surface match with the existing

resin surface.

Step 9: Clean the newly-sanded surface with a lint-free shop rag moistened with acetone.


9.0 Valve Installation ! DANGER: To reduce the risk of explosion and fire, or asphyxiation from compressed natural


3M™ CNG Fuel tanks are shipped with the OMB Lyra CV solenoid valve with the

manual tap in closed position and containing approximately 20 psig of shipping pressure.

During any installation, inspection and tank maintenance ensure that the manual tap is

completely closed.

New valve installation can only proceed after proper defueling/depressurization, and

valve removal procedure has been followed as described in Section 6.1.3

Do not attempt to disassemble the valve, PRD or solid plug. The valve, PRD, and solid

plug contain no user serviceable parts.

During normal operation, the OMB Lyra CV valve is expected to be robust and function

properly. However, sometimes, it might become necessary to replace the valve. 3M recommends

that installers, service personnel, and anyone not specifically trained by OMB to do so DO NOT

attempt to conduct any repairs on, or disassemble the valve internal components for safety and

warranty reasons. The work of installers and service personnel should be limited to valve

replacement only.

It is beneficial to have the minimum time required for the tank to be without a valve. This

reduces ingress of moisture, moist air, debris and oxygen. After removing the old valve, clean

the threads of the cylinder with a clean non-linting rag to ensure that all debris or metal shavings

that might be present have been removed.

Once you receive the new valve, the following components will be in the box:

a) OMB Lyra CV Valve as shown in Figure 36

b) White snap ring as shown in Figure 36

c) Black o-ring as shown in Figure 40

d) Micro-leak plugs, quantity two as shown in Figure 38

e) O-Ring placement cap as shown in Figure 39

f) Solenoid cable

g) Installation Instructions

Once all components are accounted for, follow the procedure outlined below:

1. Install the white snap ring over the threaded stem of the valve such that the ridge is

oriented down and it snaps securely into the groove outside of the o-ring as shown in

Figures 36 and 37.


Figure 36. OMB Lyra CV Valve with white snap ring

Figure 37. OMB Lyra CV Valve with O-Ring and Snap Ring in place

WWhite

Snap RingO-Ring

Threaded Stem of Valve

Part of Valve that Extends into CNG fuel

tank


2. DO NOT install the micro-leak plugs into the holes in the groove outside of the o-ring

near the white snap ring.

3. Install the two micro-leak plugs into the face of the fuel inlet and outlet ports as shown in

Figure 38. Make sure that these plugs are inserted completely so that they sit flush with

the face of the fuel inlet and outlet port. This is shown in more detail in the paper

instructions that are provided in the package with the new valve.

Figure 38. OMB Lyra CV Valve with Micro-Leak Plug installation ports

The small micro-leak plugs are supplied with each OMB Lyra CV valve, in a separate

small bag in the package with the valve (they are not pre-installed on the new valve).

The purpose of the micro-leak plugs is to better protect the internal parts of the valve

from exposure to humidity and dirt. If the micro-leak plugs are not installed in the valve

as shown in Figure 38, the valve will still function correctly, but the internal valve parts

will incur more exposure to external agents and dirt, which could eventually cause the

valve to require service.

Micro-leakPlug

Micro-leakPlug

Threaded Stem of Valve that extends into the CNG Fuel Tank


4. Inspect threads on valve and tank port to make sure they are not damaged.



Always reject valves or fuel tanks with damaged threads and/or damaged o-rings.

Also, reject fuel tanks with o- ring groove damage since these damages prevent a safe

and effective seal.

5. Clean threads and o-ring groove on valve as required with a clean lint-free shop cloth and

isopropyl alcohol. Only the OMB o-ring supplied with the new valve should be used

when installing a Lyra CV valve.

6. Dry threads and o-ring groove thoroughly with a clean lint-free cloth. Make sure threads

and o-ring sealing surfaces are clean, dry, and free of contaminants.

7. Lubricate the new o-ring on the valve with o-ring lubricant, Molykote 55 and install onto

threaded stem of valve as shown in Figures 39 through 43. By this method, the cap

supplied with the valve is used to cover the valve stem threads during installation to

ensure that the new o-ring is not damaged on the valve threads, and increases the ease of

o-ring installation. Use caution not to damage the o-ring. Ensure the o-ring is not twisted

once it is fully installed.

Figure 39. OMB Lyra CV Valve with o-ring placement cap covering threads of valve stem,

and o-ring lubricant


Figure 40. OMB Lyra CV Valve with o-ring placement cap and lubricated o-ring ready to

be installed while snap ring has already been installed

Figure 41. Press the lubricated o-ring over the cap all the way down until it sits flat on the

flat surface as illustrated in Figure 37

Figure 42. OMB Lyra CV Valve with o-ring placed successfully


Figure 43. Once the o-ring is placed as illustrated in Figures 37 and 42, remove the o-ring

placement cap covering the valve stem threads

8. Insert the valve into the cylinder port and hand tighten it to make sure the threads are

properly aligned.



9. Using the proper attachment for the torque wrench that is designed to fit the Lyra CV

solenoid valve, tighten the valve/PRD assembly to the torque value recommended by the

valve manufacturer, which is between 70 lbf-ft and 95 lbf-ft for the Lyra CV valve. This

torque wrench attachment and wrench and adapters are shown in Figure 19. This OMB

attachment that specifically fits the Lyra CV valve is OMB part number 69982222.

10. Apply torque seal to the fitting once proper torque has been achieved.

After valve replacement, specific procedures must be followed to safely achieve the first

fill. This is due to the fact that CNG/air mixture in the tank will pass through the

explosive limit as you fill tank. It is absolutely essential that no sources of spark are

present. Review and follow instructions in Section 6.1.1 carefully after valve replacement

to ensure that tank undergoes first fill in a safe manner.


10.0 Destruction of condemned or expired tanks ! DANGER: Proper decommissioning and destruction of 3M™ CNG fuel tanks is

MANDATORY, following their useful life, or if damage has occurred. When completed with

these steps, they must be properly drilled and marked “CONDEMNED”. Not following the steps

in Section 10.0 WILL result in the risk of death or serious injury or property damage. ! DANGER: During the decommissioning process PRIOR to drilling holes, it is first

MANDATORY that the proper depressurization and removal procedure outlined in Section 6.1.3

be followed. Not following the procedure presents a high risk of explosion during the drilling

step.




this fuel tank.



an explosion.

Gas venting should take place outdoors in order to avoid the possibilities of asphyxiation

or accumulation of an explosive gas mixture.

The fuel tank must first be purged with an inert gas to ensure that no explosive mixture is

formed at any time.



When venting and flushing with inert gases (such as nitrogen) in a confined area, provide

proper ventilation, and always use gas monitoring equipment to ensure safe and adequate

oxygen concentration.

Always ensure the tank valve is properly grounded prior to gas bleeding.

Tanks that have incurred Level 3 Damage and are condemned or tanks that have gone through

their useful life and have expired must be disposed of properly in accordance with applicable

federal, state, or local (city, municipality, etc) laws by a qualified repair facility with competent

employees trained to work on CNG fuel systems. Proper disposition of 3M™ CNG Fuel Tanks is

a three step process as described below:

1. The 3M™ CNG Fuel Tank must be removed from service and decommissioned by an

authorized repair facility with competent personnel trained to work on CNG fuel systems,

and they must follow safe depressurization procedures as outlined in Section 6.1.3.1.

2. Once the tank has been depressurized, it should be purged with Nitrogen at a pressure of

750 psig. This step is necessary in order to remove any flammable gas from the tank so

there is no risk of explosion during subsequent handling or drilling of the tank. If nitrogen

is not available, then the tank will have to be filled and flushed with water as described in

Step 3. Otherwise, to inert the tank with nitrogen, follow the steps outlined here:


a) One of the inlet/outlet ports of the tank valve should be plumbed to a pressure

gauge (range of 0 to 1000 psig would be sufficient) and a quarter turn valve so

that it can be used to discharge nitrogen/residual gas mixture after

pressurization. The pressure gauge is to be used to monitor and confirm pressure

in the tank.

b) The manual handle of the OMB Lyra CV valve, designated by letter “C” in

Figure 6 should be in open position.

c) The quarter turn valve should be in closed position.

d) In order to introduce Nitrogen through the tank valve, solenoid valve does not

need to be in open position.

e) Turn on the nitrogen source which is limited to 800 psig. Allow the nitrogen

source to supply the tank until such that the tank is pressurized to 750 psig on

the pressure gauge installed at the gas outlet of the tank valve, before the quarter

turn valve. Once 750 psig pressure is achieved in the tank, turn off the nitrogen

source. Wait for about one minute.

f) The gas bleeding (reduction in nitrogen pressure) will have to be done with the

solenoid in the energized (open) position. Ensure that the tank valve is properly

grounded. Carefully connect the solenoid valve wiring on one end to the

solenoid valve using solenoid connection point as illustrated by letter “F” in

Figure 6 and the other end to a 12V battery. The connection of battery side

needs to be secure and hands-free (with the help of insulated alligator clips or

clamps) as the solenoid cable will be kept wired until the fuel tank has

completely emptied.

g) As soon as both electrical connections are made, the solenoid valve will be

forced to the open position. Once the solenoid is energized, nitrogen starts to

flow out of the tank. Open the quarter turn valve so that nitrogen/residual gas

mixtures bleed off from the tank and the tank returns to around atmospheric

pressure. Explosive gas detectors like a cathometer or explosimeter should be

used to confirm that no explosive gas mix is present once purging is complete.

After this step, proceed to step number 4.

! WARNING: If the valve is difficult to remove, STOP. Do not attempt to remove the

valve if for any reason you suspect that the valve may be defective. A valve that is damaged

or malfunctioning may mistakenly cause you to think the fuel tank is empty when you do not

hear CNG being released. Handle all CNG fuel tanks; even those you think are empty, as

though they contained CNG under pressure. If the valve is difficult to remove, repeat the safe

depressurization procedure, making certain to press down on the permanent magnet so that it

fully covers the metal solenoid post, ensuring that the solenoid valve opens and that the

contained gas pressure is released in a safe and appropriate manner.


! CAUTION: To reduce the risk of muscle strain during the decommissioning process,

especially when water is used to flush the tank, which may result in minor injury:

Never attempt to lift 3M™ CNG fuel tanks by hand.

Always use appropriate mechanical lifting or rigging means for handling 3M™ CNG

fuel tanks.

3. If Nitrogen is not available, tank will have to filled and flushed with water. In order to fill

the tank with water, tank valve should to be removed by following valve removal

procedure outlined in section 6.1.3.2. Once the valve is removed, the tank should be

secured appropriately with the help of straps and braces. It is important to secure the tank

since tank filled with water will be quite heavy. The total weight of the tank with water

can weigh around 750 lbs. Once the tank is completely filled with water and then drained,

it should be checked with explosive gas detectors for presence of any explosive gas mix

using explosive gas detectors like a cathometer or explosimeter. After this step, proceed

to step number 4.

4. Tanks to be disposed of must be clearly marked “CONDEMNED”. The CONDEMNED

designation must be affixed to all of the main labels on the fuel tank. If it is difficult to

mark the label as the label is underneath the glass fiber, cover the label completely with

paint and mark “CONDEMNED” next to the label. Remove any valves, plugs and fittings

from the tank. In order to ensure that the fuel tank cannot be used anymore, drill two half-

inch diameter holes overlapping slightly, on one of the labels. Figure 44 shows how the

label would look like once it has been properly marked and drilled.

Figure 44. 3M™ CNG Fuel Tank Label marked “CONDEMNED” with two half-inch

diameter overlapping holes


11.0 Warranty

For provisions of the 3M warranty, please visit our website http://www.3m.com/cng

Click on the “Terms & Conditions” document in the Related Links section of our website.

For any questions, comments or suggestions related to the proper use, installation, or

maintenance of 3M™ CNG fuel tanks contact 3M at 800-364-3577.

http://www.3m.com/cng


Appendix 1: 3M™ CNG Fuel Tank Inspection Form

3M™CNG Fuel Tank Inspection Record Inspector’s Name

Inspection Date

Fuel Tank Model Number

Fuel Tank Serial Number

Fuel Tank Service Expiration Date

Fuel Tank Mounting Location

Vehicle Identification Number (VIN)

Vehicle Mileage

Accept Reject Comments (include damage level if

applicable)

Fuel tank has not exceeded its service

life

Fuel tank installation complies with

NFPA-52

Appropriate clearance between the

tank and shield tank when mounted

Tank and brackets are clean prior to

inspection

Rubber strips between tank and

mounting bracket are in good

condition

Cylinder is firmly held by brackets

(no looseness, rocking, or sliding)

All bracket and strap bolts are present

Brackets and straps are free of

corrosion

Mounting brackets are free from

bends, damage, or deformation

Area on fuel tank around mounting

brackets is undamaged

Bracket-to-vehicle connections show

no signs of damage

Vehicle history shows no events that

may possibly have damaged the fuel

tank

No signs of fuel tank exposure to fire

or extreme heat

No signs of fuel tank damage from an

accident


Fuel tank is free from impact damage

and shows no signs of surface

discoloration, cracked resin, chipping,

or loose fibers

Cuts, gouges and abrasions are no

deeper than clear coat layer

Fuel tank is free from corrosion or

etching on the outer surface

Composite surface is free from

bubbles or bulges

Valves, lines, and pressure relief

device (PRD) are not damaged

Fuel system hardware connections are

free of leaks

Main labels in place on fuel tank and

legible

Plug is undamaged

Fuel tank is properly vented outboard

of vehicle

Fuel supply lines mounted securely

Both vent lines are mounted securely

Both vent lines are clear of debris

Fuel tank body (cylinder) condition

Fuel tank dome (valve end) condition

Fuel tank dome (plug end) condition

Neither of the PRD vent ports are

plugged

New inspection sticker has been

applied

Interview owner/operator of vehicle.

Inquire about any adverse events or

repairs which have occurred since last

inspection


References:

National Fire Protection Agency 52 Vehicular Gaseous Fuel Systems Code

49 CFR 571.303 Fuel System Integrity of Compressed Natural Gas Vehicles, U.S. Federal Motor Vehicle Safety Standard

49 CFR 571.304 Compressed Natural Gas Fuel Container Integrity,

ANSI/IAS NGV 2 Standard for Compressed Natural Gas Fuel Containers,

Compressed Gas Association CGA C-6.4 Methods for External Visual Inspection of Natural Gas Vehicle (NGV) and Hydrogen Vehicle (HV) Fuel Containers and Their Installations,

ANSI / AGA NGV3.1 / CGA 12.3 Fuel System Components for Natural Gas Powered Vehicles, and any other applicable federal, state and local codes and standards.

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