M a i n t e n a n c e | R e l i a b i l i t y | e n g i n e e R i n g | P R o d u c t i o n

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Special Report

SponSored by

compressedair

2

ContentsBack to the BasicsClick here p 3

Compressor Selection BasicsClick here p 8

Simplified Test Codes for Blowers Click here p 11

Calculate CapacityClick here p 15

The Pulse of Dust CollectorsClick here p 20

wwwPLANTSERVICESCom

3

Leaks happen There is quite simply no way around it Theyrsquore in every compressed air system even in systems with the newest pipe and the most energy-efficient and most technologically advanced compressors Due to material thermal stresses leaks will appear costing you money Pos-sibly a lot of money

While itrsquos sometimes impractical to eliminate them com-pletely itrsquos possible to manage them and greatly reduce their impact on your operating costs Having a program to find tag and fix compressed air leaks will keep them in check prolong equipment life and add money back to your bottom line Herersquos how

Begin WiTh Buy-inMany companies make the mistake of starting with a leak-detection audit but unless you control all the resources needed to find tag and repair the leaks you need to start with getting buy-in for establishing a sustainable leak-reduction program from those who do If there is no buy-in there will be no follow-through Without buy-in you will find yourself with a completed leak-detection audit a list of leaks and not much else This is where so many plants fall short They pay for the audit and tag the leaks but never fix them The tags remain attached to the leaks fade or get covered in dust and over time people stop noticing them or worse they are hastily removed before a high-level plant inspection Meanwhile the same existing leaks may worsen as new ones develop

If however you begin by getting everyone on board with a leak-reduction program rather than a leak detection audit you will have a better chance of successfully managing the leaks and proactively contributing to your plantrsquos ongoing energy efficiency efforts

Money talks Use it to convince colleagues and upper management to back your leak-reduction program Some managers acknowledge they have leaks but assume they arenrsquot worth the time and money to fix given other priori-ties But until you get at least a solid estimate of your leak situation you canrsquot make an informed decision The true benefit comes from setting a baseline following up with leak detections and making subsequent repairs

While you may not know how much money you are losing each month to leaks you can make the point by sharing the cost of a single leak (Figure 1) Then point out that leaks are very common They can occur at every connection from the compressor discharge flange in dryers and filters through-out the distribution piping and on down to the point of use at the FRLs and fittings on the production equipment Hoses and quick-release fittings are notorious for leaks So are un-derground air pipes Some of the largest leaks are within the production equipment Wersquove seen annual leak losses from $3000 in a small system to more than $600000 in large systems Individual leaks are commonly between $200 and $1200 but some are much worse (Figure 2)

Finally point out how much you are paying for power to run the compressors If you donrsquot know how much you are

get to the Bottom of Leaks in your Compressed Air System

By Michael Camber and Waheed Chaudhry Kaeser Compressors

wwwPLANTSERVICESComcompressedair

4

paying to run your compressors you can calculate it

Compressor input power (kW) x Op-erating Hours x Energy Cost ($kWh)

And if you want to know how to calculate the cost of a particular leak for your system here is the formula

Leak Rate (cfm) x System Efficiency (kWcfm) x Operating Hours x Energy Cost ($kWh)

For many this will be enough to get the support you need If not consider that the US Department of Energy estimates that as much as 25 of all compressed air is wasted through leaks wersquove seen worse If possible take a stroll through the plant when you are not in production and listen mdash do you hear hissing If you can hear a leak you should im-mediately fix it Itrsquos that simple

Are the compressors running when you are not in production This is an-other sign of leaks even if you cannot hear them Note how many hours they run when they shouldnrsquot be

Numerous companies with plans to expand their plant operations have been able to avoid capital expenses simply by fixing their leaks and relying on their existing compressor equip-ment so you should definitely assess your leaks before buying morelarger compressors to meet new demand

Another point to make is that more leaks mean more compressor run time which has cost implications for parts and service in addition to energy After you have buy-in you can move forward with getting a thorough leak-detection audit

Find your ldquoLeAKneSSrdquoThere are different methods for leak detection each with advantages and disadvantages and each method has a place in an ongoing leak-reduction

program Your hearing sight and sense of touch may help clue you in to the fact that you have leaks but they are limited For the purposes of gath-ering concrete measurable data that you can use to help you prioritize how you want to fix the leaks ultrasonic leak detection is the most effective

Ultrasonic leak detection is the in-dustry standard because it is fast and accurate and it can detect leaks far better than human senses No physical contact or plant downtime is required

hoSe LeAKSFigure 2 Leaks commonly occur in hoses and fittings

WhATrsquoS A LeAK CoST

Diameter of leak

CFM of air lost at 100 psig

x 60 = cubic ft lost per hour

x 24 = cubic ft lost per day

x 365 = cubic ft lost per year

Annual cost at $018 per 1000-cu-ft

Annual cost at $032 per 1000-cu-ft

132rdquo 162 97 2333 851472 $153 $272

116rdquo 649 389 9346 3411144 $614 $1091

18rdquo 26 1560 37440 13665600 $2459 $4372

14rdquo 104 6240 149760 54662400 $9839 $17491

38rdquo 234 14040 336960 122990400 $22138 $39356

12rdquo 415 24900 597600 218124000 $39262 $69799

34rdquo 934 56040 1344960 490910400 $88363 $157091

1rdquo 1661 99660 2391840 873021600 $157143 $279366

Figure 1 According to Compressed Air Challenge of the US Department of Energyrsquos Office of Industrial Technologies the total cost of 100 psig compressed air has been calculated to be between $0181000-cu-ft and $0321000-cu-ft Fixing a single small leak in a plant quickly pays for itself (Source Compressed Air Challenge wwwcompressedairchallengeorg)

compressedair

5

so it is safe and convenient This method works because when compressed air is released into the atmosphere the turbulence creates ultrasonic noise which is usually inau-dible to the human ear but detectable with the right equip-ment Ultrasonic leak detection equipment typically consists of directional microphones amplifiers and audio filters and it usually has either visual indicators or earphones to help the auditor to identify the leaks (Figure 3)

Since ultrasonic is a high-frequency signal the sound from a compressed air leak is both directional and localized to the source This allows the ultrasonic detector to sense the leak even in loud noisy environments and to pinpoint the source Some ultrasonic devices are also able to estimate and record the magnitude of each leak based on its sound The logged data can then be downloaded to a spreadsheet for reporting analysis and prioritizing repair efforts (Figure 4)

When selecting an ultrasonic leak auditor remember that not all are equal A good leak detection auditor shouldbull be well prepared and have the tools experience and the

credentials to work in your plantbull clearly identify each leak with an easily recognized tag that

includes the date and a unique identifying codenumberbull provide a list of leaks with each onersquos location unique

identifier and magnitudebull estimate the costpotential savings of each leak and enable

you to sort the list by leak severityAsk to see a sample report so you will know what to expect

at the end of your audit Since this is the data yoursquoll be using to implement your comprehensive leak-reduction program the report should be thorough user-friendly and should pri-oritize the leaks to give you a clear picture of the leak situation in your plant The estimated cost savings included is some-thing to share with upper-level management to help strength-en their buy-in for the repairs yoursquoll be recommending

TAg iT Then PrioriTize And rePAirWhether you do it in-house or hire a leak auditor to do it you want to physically tag each leak for three reasonsbull to make it easy to find the leaks during the repair phasebull to remind you and your staff that the leak is still therebull to send the message to all that eliminating waste is a prior-

ity but this only works if the leaks get fixed (Figure 5)

ConCreTe dATA Figure 3 Ultrasonic leak detection is safe and convenient and it gives concrete data on the leak volume

compressedair

6

Once you have the audit report that lists each leak loca-tion and severity itrsquos time to develop a plan for prioritizing and repairing them If you have any leaks that pose a safety hazard or could cause any kind of failure or breakdown or lead to production downtime fix those immediately Then sort the list by magnitude and start with the worst You might find that leaks may follow the 8020 rule mdash that is 80 of the leakage occurs in 20 of the leaks A good goal would be to have those completed within one to two weeks Within the next three to four months address the next larg-est leaks that still account for a significant loss but not the top 20 Finally all of the remaining small leaks should be monitored on a regular basis and repaired if they worsen

Leaks recur so plan to repeat the process The time between audits should depend on the severity of leakage found in the initial audit If you found a lot of leaks or at least several major leaks you should schedule the second audit sooner rather than later Frequency of the subsequent audits should be based on the savings realized in leak repair versus the opportunity costs of not doing something else that generates more savings or increased revenue for the same cost and effort

Be sure to inform all concerned about the savings realized to keep the program going Educate your employees on what you expect them to do if they suspect or find a leak Develop guidelines for classifying a leak as small medium or large once an employee finds one and have the employee tag it Some plants have an incentive program where employees are rewarded for finding leaks and even more important taking initiative to fix them Having everyone on the lookout is the best way to keep the leaks under control

Long-TerM SuCCeSSAfter eliminating the majority of the leaks in your system

consider having a more comprehensive compressed air system audit Now that you have eliminated wasted air an audit will indicate if your system is operating at a higher pressure than necessary is oversized needs better controls or presents other areas for optimization Leak detection and compressed air audits go hand in hand for ongoing energy management Leaks happen but how you manage them can have a huge impact on your bottom line

Michael Camber is marketing services manager at Kaeser Compressors Contact him at Michaelcam-berkaesercom

Waheed Chaudhry is engineering manager at Kaeser Compressors Contact him at waheedchaudhrykaesercom

TAg yoursquore iTFigure 5 Use a physical tag to clearly

label each leak in your plant

MeThod ACTorS

Method Advantages Disadvantages

Listen and Feelbull Simplebull Quickly identifies large leaksbull No special tools required

bull Only effective for large leaksbull Requires direct physical contactbull Must be able to hear above plant equipmentbull Will not work for most leaksbull Gives no information on volume of leak

Soapy Waterbull Reliablebull Simplebull No special tools required

bull Time consumingbull Requires direct physical contactbull Gives no information on volume of leak

Ultrasonic

bull Versatilebull Less laborbull Safermdashno direct physical contactbull Faster and more accuratebull Most sensitive methodbull No downtimebull Get scalar data

bull Requires special equipment

Figure 4 Of the three methods for leak detection ultrasonic is the industry standard The other two methods however can still be helpful tools in your ongoing leak management efforts

compressedair

6

Once you have the audit report that lists each leak loca-tion and severity itrsquos time to develop a plan for prioritizing and repairing them If you have any leaks that pose a safety hazard or could cause any kind of failure or breakdown or lead to production downtime fix those immediately Then sort the list by magnitude and start with the worst You might find that leaks may follow the 8020 rule mdash that is 80 of the leakage occurs in 20 of the leaks A good goal would be to have those completed within one to two weeks Within the next three to four months address the next larg-est leaks that still account for a significant loss but not the top 20 Finally all of the remaining small leaks should be monitored on a regular basis and repaired if they worsen

Leaks recur so plan to repeat the process The time between audits should depend on the severity of leakage found in the initial audit If you found a lot of leaks or at least several major leaks you should schedule the second audit sooner rather than later Frequency of the subsequent audits should be based on the savings realized in leak repair versus the opportunity costs of not doing something else that generates more savings or increased revenue for the same cost and effort

Be sure to inform all concerned about the savings realized to keep the program going Educate your employees on what you expect them to do if they suspect or find a leak Develop guidelines for classifying a leak as small medium or large once an employee finds one and have the employee tag it Some plants have an incentive program where employees are rewarded for finding leaks and even more important taking initiative to fix them Having everyone on the lookout is the best way to keep the leaks under control

Long-TerM SuCCeSSAfter eliminating the majority of the leaks in your system

consider having a more comprehensive compressed air system audit Now that you have eliminated wasted air an audit will indicate if your system is operating at a higher pressure than necessary is oversized needs better controls or presents other areas for optimization Leak detection and compressed air audits go hand in hand for ongoing energy management Leaks happen but how you manage them can have a huge impact on your bottom line

Michael Camber is marketing services manager at Kaeser Compressors Contact him at Michaelcam-berkaesercom

Waheed Chaudhry is engineering manager at Kaeser Compressors Contact him at waheedchaudhrykaesercom

TAg yoursquore iTFigure 5 Use a physical tag to clearly

label each leak in your plant

MeThod ACTorS

Method Advantages Disadvantages

Listen and Feelbull Simplebull Quickly identifies large leaksbull No special tools required

bull Only effective for large leaksbull Requires direct physical contactbull Must be able to hear above plant equipmentbull Will not work for most leaksbull Gives no information on volume of leak

Soapy Waterbull Reliablebull Simplebull No special tools required

bull Time consumingbull Requires direct physical contactbull Gives no information on volume of leak

Ultrasonic

bull Versatilebull Less laborbull Safermdashno direct physical contactbull Faster and more accuratebull Most sensitive methodbull No downtimebull Get scalar data

bull Requires special equipment

Figure 4 Of the three methods for leak detection ultrasonic is the industry standard The other two methods however can still be helpful tools in your ongoing leak management efforts

compressedair

7

COMPRESSORS

Kaeser Compressors Inc bull 866-516-6888 bull kaesercomPSBuilt for a lifetime is a trademark of Kaeser Compressors Inc copy2015 Kaeser Compressors Inc customeruskaesercomka

ese

rc

om

Go ahead Take a good look This compressorrsquos got nothing to hide

Because maintenance should be simple

At Kaeser we design our compressors for faster easier service

Kaeserrsquos open package layout makes all major components easily accessible That along with other features like TEFC motors zero maintenance drive couplings and external motor grease fittings dramatically reduce preventive maintenance time (as much as 50 when compared to some models) Whether you are doing the maintenance yourself or letting our prorsquos do it time is money

Add in Kaeserrsquos built-for-a-lifetime reliability and energy efficiency advantage and you can rest assured that these units will continue to deliver exceptional performance and savings year after year

Thatrsquos the Kaeser way of doing compressed air

compressedair

8

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CoMPreSSor SeLeCTion BASiCSPositive displacement compression vs dynamic compression

By deepak Vetal Atlas Copco Compressors

There are two basic principles of air or gas compression positive dis-placement compression and dynamic compression

PoSiTiVe diSPLACeMenT CoMPreSSionIn positive displacement compres-sion the air is drawn into one or more compression chambers which are then closed off from the inlet The enclosed volume of each chamber decreases through the displacement of one or more moving parts and the pressure increases compressing the air inter-nally Once the pressure reaches the maximum pressure ratio a port or valve opens the continued reduction of volume in the compression chamber dis-charges the air into the outlet system

Positive displacement compression occurs in the following types of com-pressors piston vane scroll liquid ring rotary screw tooth and roots blower compressors

dynAMiC CoMPreSSion (TurBoCoMPreSSorS)In dynamic compression air is drawn between the blades on a rapid rotating compression impeller and accelerates to high velocity The air or gas is then discharged through a diffuser where the kinetic energy is transformed into static pressure Most dynamic com-pressors are turbocompressors with an axial or radial flow pattern and are often designed for large-volume flow rates Unlike a positive displace-ment compressor which works with a constant flow a dynamic compressor works at a constant pressure Dynamic compression occurs in radial axial and ejector compressors (Figure 1)

PreSSure And FLoW rATe CoMPAriSonAt a constant rotational speed the pressureflow curve for a dynamic compressor (turbocompressor) dif-fers significantly from an equivalent curve for a positive displacement compressor Turbocompressors operate with a variable flow rate and variable pressure characteristics but in comparison displacement com-pressors operate with a constant flow rate and variable pressure

VAriABLeS AFFeCTing PoSiTiVe diSPLACeMenT And dynAMiC CoMPreSSionPositive displacement and dynamic compression are affected by different variables The following calculations

show the inf luence of factors such as inlet pressure inlet air temperature volume f low mass f low and pres-sure ratio on power consumption and performance

Positive Displacement Inlet pres-sure volume f low and pressure ratio are the only variables that inf luence the power consumption in positive displacement compressors Inlet air temperature and mass f low (density) have no effect on power

P1 Inlet pressureV1 Volume flow (not mass flow)P2P1 Pressure ratio

dynAMiC dATAFigure 1 Unlike a positive displacement compressor which works with a constant flow a turbocompressor works at a constant pressure Dynamic compression occurs in radial (centrifugal) axial and ejector compressors

DischargePressure

Power atCoupling

Flow (volume)

Designpoint Decrease in air temperature

increases flow

Increase in air temperaturereduces power

A I R I N L E T T E M P E R A T U R E

Surg

e lin

e

Increase in air temperaturereduces flow

Decrease in air temperatureincreases power

DischargePressure

Power atCoupling

Flow (volume)

Decrease in inlet pressurereduces power required

I N L E T P R E S S U R E

Surg

e lin

e

Decrease in inlet pressurereduces flow

DischargePressure

Power atCoupling

Flow (volume)

Designpoint Increase in mole weight

increases flow

Decrease in mole weightreduces power

M O L E C U L A R W E I G H T

Surg

e lin

e

Decrease in mole weightreduces flow

Increase in mole weightincreases power

DischargePressure

Power atCoupling

Flow (volume)

Colder waterincreases flow

Warmer water decreasespower requirement

C O O L I N G W A T E R T E M P E R A T U R E

Surg

e lin

e

Warmer waterdecrease flow

Colder water increasespower requirement

compressedair

9

Dynamic Compression Inlet temperature and mass flow (density) have a direct effect on the power of dynamic compressors

H Isentropic headR Real gas constantT1 Inlet temperatureK Spec heat ratio cpcvP2P1 Pressure ratio

As inlet air temperature decreases flow and power increases As molecu-lar weight increases flow and power increases As the cooling water tem-perature decreases flow and the power requirement increases (Figure 2)

PoSiTiVe diSPLACeMenT or dynAMiC CoMPreSSionSelection of either technology de-pends on the application but there is a rule of thumb Dynamic com-pression technology is best suited for base load requirements while positive displacement compression is better suited to variable load For larger f lows and variable demand applications a combination of both technologies often helps to reach the optimal usage of compressed air while simultaneously reducing energy consumption

deepak Vetal is product marketing manager mdash zh and high Pressure

uS oil-Free Air division at Atlas Copco Contact him at deepakvetalusatlascopcocom

PerForMAnCe eFFeCTSFigure 2 The diagrams illustrate the effect of inlet temperature molecular weight and cooling water temperature on the performance of a dynamic compressor

DischargePressure

Power atCoupling

Flow (volume)

Designpoint Decrease in air temperature

increases flow

Increase in air temperaturereduces power

A I R I N L E T T E M P E R A T U R E

Surg

e lin

e

Increase in air temperaturereduces flow

Decrease in air temperatureincreases power

DischargePressure

Power atCoupling

Flow (volume)

Decrease in inlet pressurereduces power required

I N L E T P R E S S U R E

Surg

e lin

e

Decrease in inlet pressurereduces flow

DischargePressure

Power atCoupling

Flow (volume)

Designpoint Increase in mole weight

increases flow

Decrease in mole weightreduces power

M O L E C U L A R W E I G H T

Surg

e lin

e

Decrease in mole weightreduces flow

Increase in mole weightincreases power

DischargePressure

Power atCoupling

Flow (volume)

Colder waterincreases flow

Warmer water decreasespower requirement

C O O L I N G W A T E R T E M P E R A T U R E

Surg

e lin

e

Warmer waterdecrease flow

Colder water increasespower requirement

DischargePressure

Power atCoupling

Flow (volume)

Designpoint Decrease in air temperature

increases flow

Increase in air temperaturereduces power

A I R I N L E T T E M P E R A T U R E

Surg

e lin

e

Increase in air temperaturereduces flow

Decrease in air temperatureincreases power

DischargePressure

Power atCoupling

Flow (volume)

Decrease in inlet pressurereduces power required

I N L E T P R E S S U R E

Surg

e lin

eDecrease in inlet pressure

reduces flow

DischargePressure

Power atCoupling

Flow (volume)

Designpoint Increase in mole weight

increases flow

Decrease in mole weightreduces power

M O L E C U L A R W E I G H T

Surg

e lin

e

Decrease in mole weightreduces flow

Increase in mole weightincreases power

DischargePressure

Power atCoupling

Flow (volume)

Colder waterincreases flow

Warmer water decreasespower requirement

C O O L I N G W A T E R T E M P E R A T U R E

Surg

e lin

e

Warmer waterdecrease flow

Colder water increasespower requirement

DischargePressure

Power atCoupling

Flow (volume)

Designpoint Decrease in air temperature

increases flow

Increase in air temperaturereduces power

A I R I N L E T T E M P E R A T U R E

Surg

e lin

e

Increase in air temperaturereduces flow

Decrease in air temperatureincreases power

DischargePressure

Power atCoupling

Flow (volume)

Decrease in inlet pressurereduces power required

I N L E T P R E S S U R ESu

rge

line

Decrease in inlet pressurereduces flow

DischargePressure

Power atCoupling

Flow (volume)

Designpoint Increase in mole weight

increases flow

Decrease in mole weightreduces power

M O L E C U L A R W E I G H T

Surg

e lin

e

Decrease in mole weightreduces flow

Increase in mole weightincreases power

DischargePressure

Power atCoupling

Flow (volume)

Colder waterincreases flow

Warmer water decreasespower requirement

C O O L I N G W A T E R T E M P E R A T U R E

Surg

e lin

e

Warmer waterdecrease flow

Colder water increasespower requirement

compressedair

10

wwwPLANTSERVICESCom

ENGINEERING YOUR SUCCESSwwwparkercomTransair 480 830 7764

TOGETHER WE CANbull Wirelessly MONITOR your compressed air piping systembull ALERT you to system changesbull Provide DATA that reduces downtime and increases productivity

WATCH OUR VIDEO HERE CLICK HERE TO LEARN MORE

The next evolution of compressed air piping

Transairreg powered bySCOUTtrade Technology

compressedair

10

wwwPLANTSERVICESCom

ENGINEERING YOUR SUCCESSwwwparkercomTransair 480 830 7764

TOGETHER WE CANbull Wirelessly MONITOR your compressed air piping systembull ALERT you to system changesbull Provide DATA that reduces downtime and increases productivity

WATCH OUR VIDEO HERE CLICK HERE TO LEARN MORE

The next evolution of compressed air piping

Transairreg powered bySCOUTtrade Technology

compressedair

SIMPLIFIED TEST CODES FOR BLOWERS

Blower manufacturers offer packaged centrifugal compressors and blowers in both a serial-production man-ner and made to order The blower package is fitted with all of the necessary ancillary devices for operation and is marketed as a standard offering by manufacturers

Existing test codes provide for detailed measurement of the core or bare blower but no test standard was avail-able to measure a blowerrsquos package performance There-fore the Compressed Air and Gas Institute (CAGI) took on the task of developing supplementary codes referenc-ing the existing f lange-to-f lange blower mdash compressor codes ISO 1217 and ISO 5389 The industry and the blow-er users needed a standard method of rating performance of the entire package This provides relevant accurate information about performance of the entire package mdash true wire-to-air performance

The development of a standard for measuring package performance in the blower industry builds on work that was done with compressor standards many years ago The result is a simplified test code for the many types of dynamic blowers along with a standardized performance reporting data sheet template

CAGI BL 5389 Simplified Acceptance Test of Electric Driven Low Pressure Turbocompressor Air Blower Pack-age is a relatively new standard that provides a simplified wire-to-air performance test that is applicable to a packaged atmospheric air turbocompressor

This code was developed as part of a broader standard that addresses all types of blowers and as an Annex (G) to ISO 5389 Turbocompressors mdash Performance test code Second edition 2005-12-15 The existing code was simplified to ac-count for the lack of interstage cooling

The turbocompressor package is defined as a blower with an electric motor drive direct geared or gearless The drive can be via a conventional electric motor with or without an inverter or by a high-speed motor with an inverter The inverter can be integrated into the package or shipped loose

Within the criteria of the existing packaged compressor test standard (ISO 5389 E52b) the definitions of limits to a moderate pressure ratio (le 3) and an adherence to Table E1 for ideal gas behavior the compression process of the package is considered isentropic mdash adiabatic and reversible The com-pressibility factor (Z) of the air in this range is equal to 1

To simplify calculations and the test procedure correc-tions for Reynolds number and Mach number are consid-ered negligible This is accomplished by holding that pre-dicted and measured impeller speed should be within 3

A standardized data sheet is developed for fixed-speed and variable-speed packages The manufacturer provides the flow and specific power to achieve the stated flow at pressure increments of 2 psig

The possibility for a Class A test (data sheet performance verification) and Class B test (client specified performance verification) is also provided

By rick Stasyshan and the CAgi Blower Section

BL 5389 STAndArd ProVideS Wire-To-Air PerForMAnCe TeST For Air TurBoCoMPreSSorS

11

wwwPLANTSERVICESComcompressedair

12

wwwPLANTSERVICESCom

BL5389 dATA SheeT A sample data sheet for a standard packaged high-speed-turbo blower package reported delivered volume flow of the machine and the corresponding specific power for the stated operating speed (Figure 1)

The information in the data sheet also can be expressed as a chart (Figure 2)

The stated performance is the volume flow and specific power at site conditions of 147 psia 68 degF and 36 rh

The test holds a positive 4 tolerance on work and vol-ume This means that the machine may produce 4 more air than predicted when it is tested It follows that 4 more work would be needed to compress the air

A plusmn4 tolerance on specific power is used This is a prac-tice followed in other industry test standards and allows for the normal variability of manufacturing

TeSTingClass A mdash Data sheet performance verification The objec-tive of testing is to confirm that the stated performance of a manufacturerrsquos standard package meets the published performance on each of the tabulated points

The as-built package would be tested for volume flow (FAD) and power at the prevailing ambient conditions For variable-speed machines measurements are taken at maximum mini-mum and three equally spaced speed points along the lines of constant pressure The speed is noted for each of the operating points For fixed speed packages only the information for the maximum (nominal driven) speed is recorded

Flow and power are measured and correlated back to FAD conditions The package is then rated as passfail on each of the points For a failure of any point the data sheet verifica-tion is a fail

Model Data ndash Option A Standard Conditions

1 Manufacturer CAB Blower Co Date 612014

2 Model Number CAB101-VSD

o Main Drive Motor o Gearbox o Lubrication System o VFD o Inlet Air Filter o Harmonic Filter o Inlet Guide Vanes o Driver Cooling System o Inlet Throttle Valve

Value Units

3 Rated Capacity (FAD) at Rated Operating Pressure 3643 cfm

4 Rated Operating Pressure ndash p2 10 psig

5 Drive Motor Nameplate Rating 200 hp

6 Compressor Rated Speed 3000C rpm

7 Performance Tablea (based on reference inlet conditions of p amb=147 psia Tamb=68 degF RH=36)

Discharge Pressure p2 (psig)bDelivered Air Flow - FAD (cfm)

Maximum FAD2 FAD3 FAD4 Minimum

12 psig

FAD 3297 2930 2563 2195 1828

Specific Power 444 439 434 430 435

RPM 29985 29018 28100 27289 26615

10 psig

FAD 3481 3027 2574 2120 1666

Specific Power 411 392 375 364 364

RPM 29989 28256 26742 25532 24585

8 psig

FAD 3578 3052 2526 2000 1475

Specific Power 383 347 314 299 305

RPM 29998 27334 25065 23432 22233

6 psig

FAD 3645 3050 2454 1859 1264

Specific Power 353 299 253 235 238

RPM 30000 26269 23144 21032 19434

notesa See CAGI BL 5389 standard for definition of terms and performance guaranteesb Discharge pressure shall be in -2 psig increments starting at max rated operating pressure A total of 4 discharge pressures shall be tabulatedc Intermediate data points (FAD2 3 and 4) are nominal equal spacing between 100 and minimum flow (lowest turned down FAD)d Specific power (kW100 cfm)

Figure 1 A sample data sheet shows delivered volume flow of the machine and the corresponding specific power for the stated operating speed

SAMPLe dATA

compressedair

13

wwwPLANTSERVICESCom

Measurement inaccuracy is a part of any test No measurement uncer-tainty tolerances are to be a part of this simplified test All test data is to be considered absolutely accurate All manufacturers participating in CAGI have the needed provisions to provide certifications of accuracy of instru-ments as part of his quality procedure

Class B mdash Client specified perfor-mance verification A Class B test was developed in response to a market need for testing of a custom or stan-dard package to contract-specified guarantee points

Following a Class A test methodol-ogy a Class B uses the same methodol-ogy The ldquoas-tested performance datardquo is corrected to the contract-specified reference preconditions of a package in-let rather than to the data sheet values

This type of testing could be used if the site conditions are much higher (ap-proximately 50 degF28 degC) than the speci-fiedguaranteed ambient inlet tempera-ture The machine might need to operate at a significantly different speed in the field than at the test cell conditions

The change in speed could depart enough to introduce some error in the predicted performance when corrected to site conditions A means of correct-ing for this is taken with defined limits for a machinersquos Mach number

This allows for testing of a custom package in a standard test cell instead of in an environmental test cell The

cost to perform a test in a standard test cell is much lower in this method

BoTToM LineThe test procedures developed in CAGI BL 5389 provide uniform verification of the performance of the range of turbomachinery packages offered to the marketplace The procedures are robust and accurate Standardized data sheets for commercially offered packages are being prepared by the members of CAGI These will be published in fall of 2014 The third-party independent verification program now being used for compressor packages also is being discussed for blower packages

rick Stasyshan is technical director of the Compressed Air and gas institute Con-tact him at cagicagiorg

ChArTing ProgreSS

Figure 2 The sample sheet data can be represented as a chart

The Compressed Air and Gas Institute is the united voice of the compressed air industry serving as the unbiased authority on technical educational promotional and other matters that affect the compressed air and gas equipment suppliers and their

customers CAGI educational resources include e-learning coursework on the SmartSite selection guides videos and the Compressed Air amp Gas Handbook For more information visit wwwcagiorg

The development of a standard for measuring package performance in the blower industry builds on work that was done with compressor standards many years ago

500

450

400

350

300

250

20

12 psig

10 psig

8 psig

6 psig

1000 1500 2000 2500 3000 3500 4000

Spe

cific

P

ower

(kW

10

0 c

fm)

Capacity FAd

compressedair

14

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15

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itrsquos critical to look properly at all potential causes for a compressor problem in a plant Itrsquos amazing how much we donrsquot know about what we donrsquot know Itrsquos interesting how much operators donrsquot know about compressors theyrsquove operated for many years Itrsquos also amazing how much com-pressor engineers donrsquot know about the operation of the rest of the plant where theyrsquove worked for years Therefore itrsquos critical to get input from other engineers and techni-cians who notice the problem who are affected by it and who are actually related to it

Itrsquos often useful to collect input from other engineers one at a time Otherwise for example in a formal meeting engineers or operators tend to be inhibited about offering their impressions of the real causes of problems

Itrsquos generally a good practice to identify alternatives for approaches to resolve a compressor problem In other words brainstorm for solutions to a problem Brainstorm-ing is collecting as many ideas as possible And the next step is screening them to find the best idea Other impor-tant aspects of the compressor problem-solving process is continual observation and feedback

CASe STudy 1This first case study is about the intersection temperature measurement for a centrifugal compressor with a side-stream to measure temperature inside the compressor before and after the sidestream The operator team claimed that intersection temperature measurements werenrsquot pro-vided and that they were unable to determine the actual compressor performance and monitor the compressor operation They also highlighted they were unable to detect emerging problems or properly adjust the anti-surge

By Amin Almasi rotating equipment Consultant

Provide adequate compressor power for sidestream mixing

CALCULATECAPACITY

compressedair

16

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system because of the lack of the intersection temperature measurement This is a request that a machinery engineer may face for any compressor with a sidestream

A quick assessment of any conventional-type centrifu-gal compressor with a sidestream can show that installing temperature measurement sensors inside the compressor is a very risky task that requires lots of effort Itrsquos an ex-tremely difficult task to provide direct temperature sens-ing for the process gas inside a compressor in predefined locations of a complex mixing section The compressor can be seriously damaged or even destroyed in the modi-fication process at site

Investigations showed that temperatures inside the com-pressor before and after sidestream mixing arenrsquot neces-sary to estimate power and performance of a centrifugal compressor with a sidestream The following equation can be used to calculate the power and efficiency of a centrifu-gal compressor with a sidestream (Figure 1)

PCOM = m3 h3 - m1 h1 - m2 h2 (Equation 1)= (m1+m2) h3 - m1 h1 - m2 h2

WherePCOM represents compressor power (with a sidestream)m represents mass flowh represents enthalpy

The isentropic efficiency could be calculated by compar-ing the ideal power and the actual power

To better explain the presented method the compressor performance can be viewed as an overall performance mdash a compressor overall efficiency mdash which includes the stages (impellers) from the inlet to the sidestream (Section 1) the sidestream mixing section and the stages (impellers) from the sidestream to the outlet (Section 2) For a compressor with a sidestream there are some losses at the sidestream mixing section The overall efficiency of a centrifugal com-pressor with a sidestream is lower than one for a compa-rable centrifugal compressor without a sidestream

Based on experiences unfortunately some compres-sor manufacturers calculate the efficiency of compres-sors with sidestreams neglecting the sidestream mixing section losses They just simulate impellers and sections without any losses in sidestream mixing sections Alter-natively some other vendors may consider these losses but with inaccurate methods which result in losses lower than actual ones This also helps vendors to claim better efficiency and performance which may be good for their sale and advertising The compressors with sidestreams are usually used in special processes such as ammonia syngas or propane where the ASME PTC-10 type-1 performance test cannot be implemented in the vendor shop The ASME PTC-10 type-2 test has many shortfalls for compressors with sidestreams and this test canrsquot identify the above-mentioned efficiency gap The unrealistic efficiencies claimed by vendors never tested before the commissioning of the plant This efficiency gap between the actual performance and the vendor-claimed efficiency due to sidestream mixing section losses has been identified for many compressors A machinery engineer should always expect this efficiency gap for any compressor with sidestreams

The compressor theoretical efficiency depends on many details such as the impeller specific-speed and impeller design as well as details of sections but this is usually limited to approximately 70ndash79 for a compressor with traditional 2D impellers Many compressors with side-streams using conventional 2D impellers have claimed efficiencies in the range of 72-77

PoWer And eFFiCienCyFigure 1 This schematic shows a conventional-type centrifugal compressor with a sidestream

3

1

2

Compressor Outlet

Combined StreamsCompressor inlet

main Stream

Compressor inlet side Stream

compressedair

17

wwwPLANTSERVICESCom

However the actual efficiency for these machines could be 65-71 and for some machines even below 65 The reason is the losses in mixing sections These losses are relatively high if mixing sections were not designed properly or in cases that there are operational deviations When operating process conditions in inlet or sidestream donrsquot fully match with design conditions much higher losses compared to losses at design conditions can be expected For example pressure deviations at a sidestream mdash sidestream pressure lower or higher than the rated pressure mdash can result in great losses and operational problems

Another issue is that the operation team needed the tem-perature after the sidestream to properly operate and adjust the anti-surge system The fact is the gas temperature after the sidestream can be properly estimated using compressor formulations mdash no need for the direct measurement The following equations can be used for the mixing section

PA=PB=PC (Equation 2)

mC=mA+mB (Equation 3)

hC= (mA hA + mB hB)mC (Equation 4)

Where A represents the discharge of Section 1B represents the sidestreamC represents the mixed suction to Section 2m represents mass flowP represents pressureT represents temperatureh represents enthalpy

TC can be found by working back through the gas property mdash for example Mollier diagram mdash know-ing hC and PC

hC= (mA hA + mB hB)mC (Equation 5)

TC may also be approximated by the following rough formulation

TC= (mA TA + mB TB)mC (Equation 6)Section 1 from suction to sidestreamSection 2 from sidestream to discharge

inTegrALLy geAred CoMPreSSorAn integrally geared compressor for a critical service in a plant could not achieve 99 availability defined by the risk assessment team for the commercial viability of the plant (Figure 2) The team asked what should be done to this ma-chine to achieve availability greater than 99 Investigations showed a backup or standby compressor for this machine is necessary if 99 availability should be achieved There are many options mdash for example an oil-flooded screw com-pressor another similar integrally geared compressor or a conventional-type centrifugal compressor After a study of all options the best recommendation was to buy a backup or standby compressor that uses the similar compressor model with an improved packaging concept The new com-pressor will be a standby or backup machine This should be similar to the existing compressor model to reduce spare parts and operational and maintenance complexity This

selection can also provide a reasonable cost because an integrally geared compressor is cheaper than a comparable conventional-type centrifugal compressor

The following improvements were recommended for the compressor package1 Two identical E-motor driven lubrication oil pumps

should be used instead of a single pump in the existing compressor package (electric power supplied from differ-ent electrical sources)

2 The existing compressor used an inlet throttle valve (ITV) for the capacity control A better capacity control method inlet guide vane (IGV) system should be used

3 Combined anti-surgecontrol system is recommended The proposed control option is a combined control sys-tem rather than two independent control loops used in the existing package This control solution should use the anti-surge valve (bypass) only for the anti-surge applica-tion This can eliminate the root cause of some control issues Trip and alarm parameters and limits should also be improved for a better operation

4 An optimum and improved system of condition monitor-ing for the package including compressor and electric motor should be considered Online vibration monitoring should be provided for the electric motorThis new compressor skid can also be used as an example

to improve the existing skid

compressedair

18

wwwPLANTSERVICESCom

Another proposal was to purchase a spare bare compressor (compressor frame) and keep it in the warehouse for a quick compressor replacement in case of any issue This proposal was rejected

More than 65 of all compressor package issues and problems are related to auxiliaries and accessories rather than the compressor frame itself

A spare machine not a spare part should always be installed and opera-tional It is a mistake to buy a machine such as a pump or a bare compressor and keep it in the warehouse There were cases in which a spare machine in the warehouse couldnrsquot be matched inside its package In most cases ma-chines were damaged or destroyed in the warehouse Machines are complex and delicate systems and require con-stant attention and monitoring to make sure they will work when needed

CASe STudy 2The operations team reported a poor temperature control of a lubrication

oil system in a critical compressor package They asked for a new three-way temperature control valve with internal thermostat to replace the existing two-way valve and modify the existing lubrication oil system The lubrication oil system of this machine has a two-way temperature control valve (TCV) supplied by a reputable valve vendor in a cooler bypass line There is a separate tem-perature sensor at downstream and a dedicated control loop This TCV and temperature control arrange-ment is acceptable as per API-614 Changing this valve to a three-way temperature control valve cannot be a good idea The three-way temperature control valves with internal thermo-stat had been used in lubrication oil systems of many rotating machines The operations team had experiences with those machines and assumed that those lubrication systems didnrsquot have temperature control problems because they used three-way valves

with a special trade name However the performance and reliability of these three-way temperature-control valves with internal thermostat are actually not better than the two-way temperature control valves in the cooler bypass line such as one installed in this oil system It should be noted that as per API-614 the oil bypass valve should be a flanged and pneumatically operated (air-to-open fail-close) and both a two-port or three-port temperature control valve are acceptable In fact a two-way temperature-control valve installed in the cooler bypass line is the recom-mended design in API-614 and theoretically this could be considered a better solution compared to some three-way temperature-control valves with internal thermostat The three-way temperature control valve with an internal thermostat is also accept-able but as an alternative option

The operation of the TCV and control system was investigated The operational investigations showed the two-way valve needed maintenance and some adjustments after many years of operation The valve perfor-mance was acceptable after this brief adjustment

Amin Almasi is a rotating equipment consultant in Australia hersquos a chartered professional engineer of engineers

Australia (MieAust CPeng mdash Mechanical) and iMeche (Ceng MiMeche) in addition to holding an MS and BS in mechanical engineering hersquos a registered professional engineer in Queensland he specializes in rotating machines including centrifugal screw and reciprocating compressors gas turbines steam turbines engines pumps offshore rotating machines Lng units condition monitoring and reliability Almasi is an active member of engineers Australia iMeche ASMe and SPe he has authored more than 100 papers and articles dealing with rotating equipment condition monitor-ing offshore and reliability

inTegrALLy geAred CoMPreSSorFigure 2 This integrally geared compressor is a well-designed package that can achieve a high availability

compressedair

19

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20

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By hank van ormer Air Power uSA

compressed airrsquos role in minimizing cost and maximizing system efficiency

Many production facilities have a significant number of dust collectors Many have continuing problems with short bag life and low-pressure problems at the farthest points from the central air system They often run on timers When they try to run on demand control they often get extreme short cycling which causes even more bag prob-lems On at least half of the dust collectors most have gauges at the entry some of the gauges are even operational Often the compressed air feed lines are the same size as the connector opening

Proper operation of dust collec-tors is critical to minimizing cost and maximizing system effectiveness There are many types and sizes and many use a pulse of compressed air to clear the bag or filter The pulse usu-ally is controlled by a timer that might have an auxiliary demand control The timers generally are set by the opera-tors to what they believe is appropriate for proper cake removal and bag life

PuLSe JeT duST CoLLeCTorIn a pulse jet dust collector the dust is collected on the bag or fingers and when the cake of dust is of appropri-ate thickness and structure a pulse or pulses of compressed air hit or shock the bag and knock the cake off This pulse might sometimes be accompa-

nied by physical shaking and even reverse air flows depending on design

When the cake is removed correctly from the dust collector the system re-moves dust from its assigned environ-ment and has a normal bag life When the cake is not removed efficiently the dust collector doesnrsquot remove dust effectively from its assigned environ-

ment and the bag life can be signifi-cantly shortened

Dust collection system designs specify the compressed air inlet pressure to the manifold and pulse valves necessary for effective dust removal The pulse valve sends a given volume or weight of air to the bag at a predetermined velocity to strike and clear the cake The actual

Calculating Pulse rate of Flow to dust Collectors

objective Size storage to allow pulse 21 ft3 in 5 seconds to only drop 4 psig

6 valves x 35 ft3 = 21 ft3 21 ft3 x 60 sec divide 5 sec = 2520 cfm rate of flow

Calculating Storage Size

T = Time (seconds) V = Volume storage (ft3) C = Capacity cfm (2520) rate of flow Pa = Psia (145) P1 = Initial receiver pressure (100) P2 = Final receiver pressure (96)

V = (C) (Pa) T (P1 ndash P2) (60 seconds)

V = (2520) (145) 5 (100 ndash 96) (60 seconds)

V = 36540 5 240

V = 18270 240 V = 76 ft3 76 ft3 x 748 gallonsft3 = 568 gallons or more receiver size required

Calculating 7-Second refill rate of Flow

Time allowed = 6 sec 21 ft3 x 60 sec divide 6 sec 2109 cfm rate of flow Effect on header Negligible

Table 1 Appropriate storage and piping can be an effective correction

CALCuLATionS

compressedair

21

wwwPLANTSERVICESCom

amount of weight of air depends on the pulse nozzle being fed compressed air at a predetermined and steady pressure The dust collector must receive the correct pressure or close to it and a steady repeatable pressure level for each pulse particu-larly if timers control the pulses The operator may experiment to find the right timing sequence at a desired compressed air inlet pressure However if this pressure varies then perfor-mance wonrsquot be consistent or satisfactory

inSTALLATion ConSiderATionS For ProPer CoMPreSSed Air SuPPLyShort bag life usually comes from the pulsers hitting the bag when the cake isnrsquot ready to flake off or the cake has gone too long between pulsing and grown too thick and heavy to clean effectively This causes short bag life and poor performance and there usually are several basic causes for thisbull Incorrect timer settings for the operating conditions The

actual requirement for the optimum timer setting might change as various product runs change or even seasonally These settings have to be set carefully to begin with and have to be monitored regularly

bull Lack of sufficient storage or compressed air supply near the inlet manifold to supply the required pulse air without collapsing the inlet pressure With inlet pressure thatrsquos too

Figure 1 This is an example of using storage

Supply AirCIP Solenoid

Instrument Air

Supply Feed from System

Supply AirCIP Solenoid

Instrument Air

Supply Feed from System

Regulator Regulator

1 frac12

1 frac12

1 frac12

1 frac12

frac12 frac12

2 21Cashco

Regulators105 psig

Filter

FilterRegulator

Check Valve

Air to Pulsers

90 psigto

50 psig

Process Air SupplyAuxiliary Storage to Stabilize the System

CheckValve

MeteringValve

2 2 2

2Filter

FilterRegulator

bull 90 psig required at processbull 8 cubic feet of air in frac34 second - rate of flow 640 cfmbull Regulators too slowbull 1 pipe too small

bull Eliminate in pipe and reulatorbull Size receiverbull Pressure drop now 7 to 8 psigbull Refill 8 cubic feet in 4 seconds - lower rate of flow to 120 cfm

Flow Alarm

STorAge uTiLizATion

Figure 2 When the sensor detects compressed air flow the light turns on

Supply AirCIP Solenoid

Instrument Air

Supply Feed from System

Supply AirCIP Solenoid

Instrument Air

Supply Feed from System

Regulator Regulator

1 frac12

1 frac12

1 frac12

1 frac12

frac12 frac12

2 21Cashco

Regulators105 psig

Filter

FilterRegulator

Check Valve

Air to Pulsers

90 psigto

50 psig

Process Air SupplyAuxiliary Storage to Stabilize the System

CheckValve

MeteringValve

2 2 2

2Filter

FilterRegulator

bull 90 psig required at processbull 8 cubic feet of air in frac34 second - rate of flow 640 cfmbull Regulators too slowbull 1 pipe too small

bull Eliminate in pipe and reulatorbull Size receiverbull Pressure drop now 7 to 8 psigbull Refill 8 cubic feet in 4 seconds - lower rate of flow to 120 cfm

Flow Alarm

ALArMing FLoW

compressedair

22

wwwPLANTSERVICESCom

low the mass weight of the air pulse is too low which then becomes ineffective in removing the cake

bull A feed line thatrsquos too small to the dust collector entry This will have the same effect as lack of air supply

bull Too small or an incorrect regulator This will make it unable to handle the required rate of flow required by the dust collectors

PuLSe JeT duST CoLLeCTor oPerATionImproper compressed air delivery and supply may create an ineffective pulsebull Use proper line size to handle rate of flow without high

pressure lossbull Use storage to supply air without pulling down feed to

receivercollectorbull Monitor inlet pressure and drop at pulsebull Monitor flow

One common installation or system situation causes restricted air flow It occurs when prior to installation or before some operational change the proper flow rate wasnrsquot identified for the dust collector cleaning action Feed-line sizing regulator sizing and air supply all require an identi-fied flow rate flow you canrsquot use average flow rate

rATe oF FLoWFlow rate is the average flow of compressed air in ft3min either required by a process or delivered to the system Rate of flow is the actual rate of flow of compressed air demand expressed in ft3min regardless of duration Even relatively small air demands in ft3 can have a very high rate of flow if they occur over a very short time period Dust collectors have this characteristic

Sequence controllers can have a significant impact on the required rate of flow For example pictured is a dust col-lector system that has six pulsing valves that use 35 ft3 over a half-second for each pulse When this is a problem ap-propriate storage and piping can be an effective correction when properly implemented (Table 1 and Table 2)

The impact of two different rates of flow would show similar differences in regulator sizing if theyrsquore used on the feed line flow The high flow velocities entering the manifold and controls for the pulse valves will create extra pressure loss through the nozzle affecting the performance of the pulse cleaner The same effect would show up in air receiver sizing to minimize system and feed line pressure drop if that is a question (Figure 1)

Typical Sizing (Each Valve Uses 35 scfmpulse mdash 6 Valves on Collector)

Rate of Flow amp Sizing With One Valve Hitting Every 7 Seconds

Rate of Flow amp Sizing With Six Valves Opening at Once Every 7 Seconds

Rate of Flow = (1) x (35) = 35 x 60 divide 5 = 420 scfm Rate of Flow = (6) x (35) 21 x 60 divide 5 = 2520 scfm

The line size recommendation from the air supply to the dust collector = 90 psig line pressure = 2 in to 3 in

The line size recommendation from the air supply to the dust collector ndash 90 psig line pressure = 4rdquo to 6rdquo

bull A 2-in feed line will handle the 420 cfm flow at 90 psig line pressure with a velocity of 43 fps which is about as high as it should go

bull A 3-in feed line will handle the 420 cfm flow at 90 psig with a velocity of about 19 fps mdash very conservative

bull A 2-in line would have a pressure loss of about 1 psid every 100 ft at 420 scfm flow which may be acceptable depending on feed line design and length

bull A 3-in line would have pressure loss of less than 10 psid per 100 ft at 420 scfm flow which should be very acceptable

bull A 6-in feed line will handle the 2520 cfm flow at 90 psig line pressure with a velocity of about 30 fps which is conservative in this application

bull A 2-in line at 2520 cfm would have a minimum pressure loss of 30-50 psid depending on timing and turbulence This would be completely unacceptable

bull A 4-in line would have a pressure loss of about 11 to 12 psid per 100 ft at 90 psig and combined with moderate velocity should be acceptable depending on the length and design of the feed line

bull A 6-in line would have a minimum pressure loss of 15 to 20 at 90 psig with very low velocities and should be acceptable with ldquonormalrdquo installations

Table 2 When properly implemented appropriate storage and piping can be a very effective correction

TyPiCAL Sizing

compressedair

23

wwwPLANTSERVICESCom

AddiTionAL inSTALLATion guideLineSWe recommend that every feed line has a quality pressure gauge installed near the dust collector entry Observe the pressure gauge when the pulser hits If the pressure drop is too high (more than 10-20 psig) start looking for the cause Record the specifications on the dust collector (cfm per pulse feed line pressure time per pulse cycle time between pulses) Calculate the rate of flow and check line size and storage If additional storage is required it can be calculated by using the previous formula

The sequence and pulse jet nozzle size depends on the number of bags type of bags length of the bags and the materials being trapped These will vary by make and model Some rules of thumb that often apply arebull 12-sec is commonly used for the pulse durationbull Air flow per pulse jet often is from 35 to 10 ft3bull Dust collector capacity often is increased first by lengthen-

ing the bags andor increasing the number of bags in the housing

bull As the bag length increases the pulse jet air demand in-creases In one example increasing from 18 in length bags to 84 in length bags increases the pulse demand about 25 incrementally

bull As the number of bags of the same design increase the pulse air required increases about the same percentageThe number of pulse jets sequence and air demand is

needed to install any dust collector correctly to ensure an adequate flow of compressed air at the proper pressure

With the variety of filters of modern high performance materials available many operations are modifying their older dust collectors however too often the effect on the compressed air requirements is not considered

Pulse jet dust collectors are a continuing source of leaks particularly when pulse jet diaphragms fail which can become a very large compressed air leak An open frac34 in dia-phragm pulse valve can leak up to 200-250 cfm 50 to 60-hp worth of compressed air = about $24000year

These often are hard to hear and sometimes when first heard are ignored hoping someone else will notice and repair it After all it is a hot or cold dusty noisy job often above ground

Some excellent electronic monitoring systems are available that will identify leaks from failed solenoid pulse jet valves These also can monitor filter perfor-mance and condition and monitor the systemrsquos capability to stay in compliance

For these systems to perform as designed the compressed air supply should deliver solid consistent performance at the point of use

Note that a paddle switch visual alarm can easily be in-

stalled on the air supply pipeline Whenever the paddle sen-sor sees compressed air flow the light turns on (Figure 2)

When the pulse jet hits the light turns on and then turns off when it closes If the light stays on there is continuous flow mdash a leak

reMoTe gAuge reAdingItems such as the Cypress remote gauge reader can be mounted on critical pressure gauges in hot dirty hard-to-reach to places They record the local gauge reading digitize it and send the information electronically through a collec-tor to a control monitoring point where performance can more easily be continually or routinely monitored

AuToMATiC PreSSure diFFerenTiAL PuLSe ConTroLLerSAutomatic pressure differential pulse controllers are effective in optimizing compressed air usage and are always recom-mended However the storage and piping has to be correct for proper operation When not installed properly the negative im-pact may be significant A chart of typical compressed air use indicates estimated compressed air savings based on valve size mdash a 10-row pulse jet dust collector between pressure differen-tial control and times control set at 356 pulseshour (Figure 3)

Once yoursquore sure the installation is correct running from a demand-side controller is always suggested This senses the filter condition and only pulses the bag at the right time Some excellent electronic control systems are available that can be economical and usually will improve bag life and reduce air usage

SuMMAryWhen a plant or operation with significant dust collecting is audited itrsquos rare to find anyone in operations who is aware of what the dust collectorsrsquo operating specifications are and how or why the pipe sizes were selected When you get the facts and go by the book an amazing thing happens mdash they work like theyrsquore supposed to work

Valve Size Standard Pulse with Demand Control

Continuous 356 pulsehour

$ Year Avg scfm $ Year Avg scfm

34 $1007 107 $3205 3205

1-18 $2040 204 $6109 6109

1-12 $3550 355 $10610 10661

2 $4890 489 $14663 14663

Figure 3 Compressed air savings can be based on valve size (Source FilterSense)

TyPiCAL CoMPreSSed Air uSe

compressedair

24

wwwPLANTSERVICESCom

duST CoLLeCTor TrouBLeShooTing And MAinTenAnCe TiPSAll dust collectors need routine maintenance of clearing plugged tubes in addition tobull continuous diaphragmvalve repairbull cleaning and checking magnehelic gauges and other critical

sensorsbull reset timers if required

When pulse valve diaphragms become worn and donrsquot seal filter cleaning becomes ineffective and often the operators adjust the timers to a more frequent cycle which offsets the lack of performance

Generally all diaphragms should be replaced within three to five years Ideally when replacing one replace them all Obviously different operating conditions and controls will yield varying results

Proper operating valves and diaphragms will allow better filter cleaning reduce particle emission and use less com-pressed airbull A frac34-in ASCO type pulse valve diaphragm kit retails for

approximately $20-$25 each

bull A frac34-in pulse valve leak may well be as high as 200 cfm 1-12-in and 2-in valves can or do leak up to 1000 cfm

bull Monitor all control sensors mdash DeltaP pressures time delays cycle times and cleaning times mdash per manufacturer specifi-cations

bull Pulse cleaning never stops when it should (check if the pres-sure tubing is disconnected check electrical connections and check high and low pressure points)Diaphragm and valve maintenance often is overlooked in

many plants until they grow to the magnitude where therersquos not enough air to feed the hungry leaks at which time a crisis arises possibly leading to the purchase of additional com-pressed air Itrsquos obvious that poorly operating and even more so leaking valves and diaphragms can use significant volumes of very expensive compressed air It behooves any plant that operates pulse jet dust collectors to know them well and main-tain them properly

hank van ormer is president of Air Power uSA Contact him at hankairpowerusainccom and (740) 862-4112

The dust collector feeds areare not generally well sized and each doesdoes not have an air receiver or adequate effective storage between it and the collector Observation of the operation and discussions with plant personnel indicate the demand controls areare not working well and the bags sloughing off properly All units areare not running on timers There doesdoes not appear to be a problem of pulling low pressure in surrounding lines and also low pressure to the collector There areare not enough appropriately installed gauges to observe the operation at the time of the audit

When the feeds and installation are operating properly the dust collector air usage will operate with less overall demand and better performance with a demand controller The demand controller when used without proper compressed air feed conditions may use more air and decrease bag life and performance

Recommended Project (22) Modify the dust collectors by adding receiver capacity reducing flow restrictions and providing several indicator lights These indicators could include a warning light with a pressure differential switch to indicate increased flow when maintenance is quickly required a pulsed light during normal operation and a steady light when a leak is present

Total cfm saved cfmRecoverable savings from air flow reduction [Section 23] $ cfm yrTotal annual electrical energy savings $ yrTotal project cost $ Note to Auditor This section will have to be modified or rewritten to fit the local situation

Unit

Pulse Jets Sequenced

Pulse Duration

Pressure In at Blow

Pressure Full at Reset

Controls ∆P Timer

Avg Net Cfm Savings

Recommended Action

By Initials

Due Date

PhASe 2 reCoMMendATion After the system is stabilized and reconfigured review each dust collector operation to ensure proper bag sloughing and working demand controls and make sure there are no negative effects on adjacent equipment

compressedair

25

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26

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26

extensive compressed air Whitepaper LibraryKaeser Compressors Inc has published numerous whitepapers to an online whitepaper library

Kaeser subject matter experts weigh in on key industry topics including ldquoTurning Air Compressors

into an Energy Sourcerdquo ldquoApplying Variable Speed Compressors in Multiple Compressor Applica-

tionsrdquo ldquoBasics of Rotary Screw Compressor Lubricantsrdquo ldquoComprehensive Compressed Air Audits

The 5-Step Processrdquo and ldquoHybritec Combination Dryersrdquo To download any of Kaeserrsquos free white-

papers visit wwwkaesercomwhitepapers

httpuskaesercomAdvisorwhite_papersdefaultasputm_source=PlantServicesamputm_

medium=ebookamputm_campaign=PSJanEbook-resource

Transairreg powered by scoUTtrade TechnologySCOUTtrade Technology is a state-of-the-art wireless solution that enables you to view the performance of

a compressed air system 24 hours a day through a web-based dashboard Data is gathered compared

and analyzed providing customers with both a quick snapshot and a complete in-depth analysis of the de-

mand of a compressed air system The dashboard is fully customizable to fit your data monitoring needs

http httppromoparkercompromotionsitetransairusenproductsCondition-Monitoring

sullair always There for Local FabricatorAs Sullair celebrates its 50th year providing compressed air solutions ndash hear from satisfied customer Gerry

Bauer how Sullair keeps its promise of Always Air Always Therereg Bauer president of EccoFab in Rockford

IL purchased his Sullair compressor in 1979 ndash and more than 35 years later it continues to run strong

httpswwwyoutubecomwatchv=8R9O3gW8_dgampfeature=youtube

What do You mean compressed air isnrsquot FreeEnergy savings can be realized without major capital expenditures Compressed air is a costly utility

that is often taken for granted It is not free In fact it is one of the most costly utilities in plants today

A comprehensive program of leak repair that includes education of plant personnel planning training

methods of identifying and repairing leaks and a system of reporting survey results can lead to reduc-

tion of energy use increased profitability and an improved carbon foot print A compressed air leak

survey is a truly ldquogreenrdquo way to improve profitability

httpwwwuesystemscomnewwp-contentuploads201208Compressed_Air_Isnt_freepdf

Vortec case study Berry plastics reduces compressed air Usage by 70Berry Plastics operates over 60 plastic manufacturing plants throughout the US The companyrsquos

facility in Hot Springs Arkansas produces over 13 million plastic bottle caps per day and targeted

air lines play an important role in keeping the production line moving This case study shows how

Berry Plastics was able to reduce compressed air consumption by 70 with the use of Vortec

model 1202 blow off nozzles as an air-assist device at the Hot Springs facility saving the company

$300000 a year in compressed air costs

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