Explosion Proof Procedure - 차스텍이앤씨

부록#4

Explosion Proof Procedure

기술사사무소차스텍이앤씨㈜부록#4 1 of 20

Table of Contents

SECTION SUBJECT

1. SCOPE OF WORK

2. PURPOSE

3. AUTHORITIES AND REPONSIBILITIES

4. TERMINOLOGY

4.1 AREA

4.2 CLASSIFICATION

4.3 FLAMMABLE LIQUID

4.4 COMBUSTIBLE LIQUID

4.5 FLASH POINT

4.6 FLAMMABLE LIMIT IN AIR

4.7 AUTO IGNITION TEMPERATURE

4.8 GROUP

4.9 MACIMUM EXPERIMENTAL SAFE GAP

4.10 MINIMUM IGNITING CURRENT RATIO

4.11 RELATIVE MAGNITUDES OF PROCESS EQUIPMENT

AND PIPING HANDLING COMBUSTIBLE


Table of Contents

SECTION SUBJECT

5. CALCULATION PROCEDURE

5.1 FLASH POINT

5.2 FLAMMABLE LIMIT

6. PROCEDURE FOR CLASSIFYING AREA

6.1 STEP ONE – DETERMINING NEED FOR

CLASSIFICATION

6.2 STEP TWO – GATHERING INFORMATION

6.3 STEP THREE – SELECTION THE APPROPRIATE

CLASSIFICATION DIAGRAM

6.4 STEP FOUR – DETERMINING THE EXTENT OF THE

CLASSIFIED AREA

7. REFERENCES


1.0 Scope of work

This procedure applies to those locations where flammable gases or vapors, flammable liquids, combustible liquids are processed or handled; and where their release into the atmosphere may result in their ignition by electrical systems or equipment

This procedure provides information on specific flammable gases and vapors, flammable liquids, and combustible liquids, whose relevant combustion properties have been sufficiently identified to allow their classification into groups NFPA 70, National Electrical Code for proper selection of electrical equipment in hazardous (classified) location. The tables in this document are not intended to be all-inclusive.

This applies to chemical process areas. As used in this document, a chemical process area may be a large, integrated chemical process plant or it may be a part of such a plant. It may be a part a manufacturing facility where flammable gases or vapors, flammable liquids, or combustible liquids are produced or used in chemical reactions, or are handled or used in certain unit operations such as mixing, filtration, coating, spraying, and distillation.

2.0 Purpose

2.1

This procedure is only for the process engineers to help them determine hazard area classification. Diagrams do not mention in this procedure.

The purpose of this procedure is to provide the user with a basic understanding of the parameters that determine the degree and the extent of the hazardous (classified) location. This procedure also provides the user with examples of the applications of these parameters.

2.2

Information is provided on specific flammable gases and vapors, flammable liquids, and combustible liquids, whose relevant properties determine their classification into groups. This will assist in the selection of special electrical equipment for hazardous (classified) locations where electrical equipment is required.

2.3

This recommended practice is intended as a guide and should be applied with sound engineering judgement. Where all factors are properly evaluated, a consistent area classification scheme can be developed.


3.0 Authorities and Responsibilities

The process engineer should inform some physical properties concerning hazardous materials to the electric department for performing of hazardous area classification work. The process engineer shall fill Chemical component name, chemical formula, CAS no., NEC group, flash point, autoignition temperature, flammable limits, vapor density compared to air density, normal boiling temperature in EDCS on each project according to the attachment A.

If unclassified or untested components are existing, the process engineer shall determine the hazard classification through the brainstorming with project engineers and electric engineers and mechanical engineers and related engineers.

4.0 Terminology

4.1 Area

4.1.1 Hazardous Area:

An area where fire or explosion hazards may exist due to flammable gases or vapors, flammable liquids, combustible dust, or ignitable fibers or flyings. Unless specifically indicated otherwise, locations containing combustible dust, ignitable fibers or flyings are outside the scope of this procedure.

Class I : the material is a flammable gas or vapor.

Class II : the material is a combustible dust.

Class III : the material is an ignitable fiber or flying.

4.1.2 Non-hazardous area:

An area not classified as Class I, Zone 0, Zone 1, or Zone 2.

4.2 Classification

4.2.1 NEC

Class I, Division 1

The location where (1) ignitable concentrations of flammable gases or vapors exist under normal operating conditions; or (2) ignitable concentrations of such gases or vapors may exist frequently because of repair or maintenance operations or because of leakage; or (3) breakdown or faulty operation of equipment or processes might release ignitable concentrations of flammable gases or vapors and might also cause simultaneous failure of electrical equipment.


Class I, Division 2

The location (1) in which volatile flammable liquids or flammable gases are handled, processed, or used, but in which the liquids, vapors, or gases will normally be confined within closed containers or closed systems from which they can escape only in case of accidental rupture or breakdown of such containers or systems, or in case of abnormal operation of equipment; or (2) in which ignitable concentrations of gases or vapors are normally prevented by positive mechanical ventilation, and which might become hazardous through failure or abnormal operation of ventilating equipment; or (3) that is adjacent to a Class I, Division 1 location, and to which ignitable concentrations of gases or vapors might occasionally be communicated unless such communication is prevented by adequate positive-pressure ventilation from a source of clean sir and effective safeguards against ventilation failure are provided.

4.2.2 IEC

A Class I, Zone 0 area is a location (1) in which ignitable concentrations of flammable gases or vapors are present continuously; or (2) in which ignitable concentrations of flammable gases or vapors are present for long periods of time.

A Class I, Zone 1 location is a location (1) in which ignitable concentrations of flammable gases or vapors are likely to exist under normal operating conditions; or (2) in which ignitable concentrations of flammable gases or vapors may exist frequently because of repair or maintenance operations or because of leakage; or (3) in which equipment is operated or processes are carried on, of such a nature that equipment breakdown or faulty operations could result in the release of ignitable concentrations of flammable gases or vapors and also cause the electrical equipment to become a source of ignition; or (4) that is adjacent to a Class I, Zone 0location from which ignitable concentrations of vapors could be communicated, unless communication is prevented by adequate positive pressure ventilation from a source of clean air and effective safeguards against ventilation failure are provided.

A Class I, Zone 2 location is a location (1) in which ignitable concentrations of flammable gases or vapors are not likely to occur in normal operation and if they do occur will exist only for a short period; or (2) in which volatile flammable liquids, flammable gases, or flammable vapors are handled, processed, or used, but in which the liquids, gases, or vapors normally are confined within closed containers of closed systems from which they can escape, only as a result of accidental rupture or breakdown of the containers or system or as a result of the abnormal operation of the equipment with which the liquids or gases are handled, processed, or used; or (3) in which ignitable concentrations of flammable gases or vapors normally are prevented by positive mechanical ventilation, but which may become hazardous as a result of failure or abnormal operation of the ventilation equipment; or (4) that is adjacent to a Class I, Zone 1 location, from which ignitable concentrations of flammable gases or vapors could be communicated, unless such communication is prevented by adequate positive-pressure ventilation from a source of clean air, and effective safeguards against ventilation failure are provided.


4.3 Flammable Liquid (NFPA)

Any liquid that has a closed-cup flash point 100℉ (37.8℃), as determined by the test procedures and apparatus set forth in 4.5. Flammable liquids shall be classified as Class I as follows;

4.3.1 Class I Liquid

Any liquid that has a closed-cup flash point below 100℉ (37.8℃) and a Reid vapor pressure not exceeding 40 psia (2068.6 mmHg) at 100℉ (37.8℃), as determined by ASTM D 323, Standard Method of Test for Vapor Pressure of Petroleum Products (Reid Method). Class I liquids shall be further classified as follows;

Class IA liquids shall include those liquids that have flash points below 73℉ (22.8℃) and boiling points below 100℉ (37.8℃).

Class IB liquids shall include those liquids that have flash points below 73℉ (22.8℃) and boiling points at or above 100℉ (37.8℃).

Class IC liquids shall include those liquids that have flash points at or above 73℉ (22.8℃), but below 100℉ (37.8℃).

4.4 Combustible Liquid

A combustible liquid shall be defined as any liquid that has a closed-cup flash point at or above 100℉ (37.8℃), as determined by the test procedures and apparatus set forth in 4.5. Combustible liquids shall be classified as Class II or Class III as follows;

4.4.1 Class II Liquid

Any liquid that has a flash point at or above 100℉ (37.8℃), as below 140℉ (60℃)

4.4.2 Class IIIA

Any liquid that has a flash point at or above 140℉ (60℃), as below 200℉ (93℃)

4.4.3 Class IIIB

Any liquid that has a flash point at or above 200℉ (93℃)

4.5 Flash Point

The minimum temperature of a liquid at which sufficient vapor is given off to form an ignitable mixture with air, near the surface of the liquid or within the vessel used, as determined by the test procedure and apparatus specified in NFPA 30.


4.6 Flammable Limit in Air

The percent concentration in air (by volume) is given for the lower (LFL) and upper (UFL) limit. The values, along with those in flash point and AIT, given an indication of the relative flammability of the chemical. The limits are sometimes referred to as “lower explosion limit” (LEL) and “upper explosive limit” (UFL).

4.7 Autoignition Temperature (AIT)

This is the minimum temperature at which the material will ignite without a spark or flame being present. Along with the values in flash point, it gives an indication of the relative flammability of the chemical.

4.8 Group

Class I combustible materials are divided into four groups;

Group A

Acetylene or gases, flammable liquid-produced vapor, or combustible

Group B

Flammable gas, flammable liquid-produced vapor, or combustible liquid-produced vapor mixed with air that may burn or explode having either a maximum experimental safe gap (MESG) value less than or equal to 0.45mm or a minimum ignition current (MIC ratio) less than or equal to 0.4. – A typical Class I, Group B material is hydrogen.

Group C

Flammable gas, flammable liquid-produced vapor, or combustible liquid-produced vapor mixed with air that may burn or explode having either a maximum experimental safe gap (MESG) value greater than 0.45mm and less than or equal to 0.75mm, or a minimum igniting current (MIC) ratio greater than 0.40 and less than or equal to 0.80 – A typical Class I, Group C material is ethylene.

Group D

Flammable gas, flammable liquid-produced vapor, or combustible liquid-produced vapor mixed with air that may burn or explode having either a maximum experimental safe gap (MESG) value greater than 0.75mm or a minimum igniting current (MIC) ratio greater than 0.80. – A typical Class I, Group D material is propane.


Table 4 – 8 Approximate Comparison of IEC Apparatus and NEC Gas Groups

IEC Group Designation NEC Article 505 Group Designation

NEC Article 500 Group Destination Typical Gas

IIC A Acetylene

(IIB + H2) B Hydrogen

IIB C Ethylene

IIA D Propane

4.9 Maximum Experimental Safe Gap (MESG)

The maximum clearance between two parallel metal surfaces that has been found, under specified test conditions, to prevent an explosion in a test chamber from being propagated to a secondary chamber containing the same gas or vapor at the same concentration.

4.10 Minimum Igniting Current (MIC) Ratio

The ratio of the minimum current required from an inductive spark discharge to ignite the most easily ignitable mixture of a gas or vapor, divided by the minimum current required from an inductive spark discharge to ignite methane under same condition the same test conditions.

4.11 Relative Magnitudes of Process Equipment and Piping Handling Combustible

Table 4 - 11

Process Equipment Units Small (Low) Moderate Large (High)

Size gal < 5,000 5,000 to 25,000 > 25,000

Pressure psi < 100 100 to 500 > 500

Flow Rate gpm < 100 100 to 500 > 500


4.12 Comparison Table

KS, JIS 유럽 (IEC) 독일 (VDE) 미국 (NEC)

(GROUP OF ENCLOSURE I)

I 메탄

(GROUP D)

메탄, 암모니아, 벤젠, 휘발유, 프로판, 톨루엔 등

(EXPLOSION CLASS 1)

메탄, 암모니아, 일산화탄소, 벤젠, 휘발유, 프로판 등

1 등

급

메탄, 암모니아, 일산화탄소, 벤젠, 휘발유, 프로판 등

II A)

암모니아, 일산

화탄소, 벤젠, 아세톤, 에탄올, 메탄올, 휘발유 등

GROUP C)

아세트 알데히

드, 에틸렌, 이소프렌, 프로판 등

2 등

급

석탄가스, 에틸렌, 에틸렌 옥사이드, 1,3 부타디엔 등

II B)

1,3 부타디엔, 에틸렌, 에틸렌 옥사이드, LPG 등

CLASS 2)

에틸렌 크로라 에틸렌, 에틸렌 옥사이드, LPG 등

GROUP B)

수소, 1,3 부타디

엔, 에틸렌 옥사

이드 등

3 등

급

수소, 아세틸렌, 유화탄소 등

II C)

수소, 아세틸렌

CLASS 3)

3A : 수소 3B : 유화탄소 3C : 아세틸렌

GROUP A)

아세틸렌

미국 (NFPA 497A)

GROUP E : 대기중에 함유된 연소성 금속 Dust (알루미늄, 마그네슘, 일반합금 및 기타 연소성 Dust)

GROUP F : 대기중에 함유된 연속성 CARBONACEOUS, CARBON BLACK, CHARCOAL, COAL 등 폭발성 위험이 현존하는 것

GROUP G : GROUP F에 포함되지 않은 것으로 밀가루, GRAIN (곡물: 예 옥수

수, 콩가루, 쌀), WOOD, PLASTIC, 염료, CHEMICAL (예: POLYETHYLENE RESIN, POLYPROPYLENE RESIN)


위험장소의 분류

위험물 분류 규 격

번호 구 분 미국 (NEC) 유럽 (IEC) 독일(VDE) KS, JIS

Class I

Division 1

ZONE 0

ZONE 1

ZONE 0

ZONE 1

0종 장소

1종 장소 1

GAS,

VAPORS

AND MIST Class I

Division 2 ZONE 2 ZONE 2 2종 장소

Class Ii

Division 1 2

COMBUSTIBLE

DUSTS Class II

Division 2

ZONE

20, 21

ZONE

20, 21

21종 장소

22종 장소

Class III

Division 1 3

FIBERS

AND

FLYINGS Class III

Division 2

- - -


5.0 Calculation Procedure

5.1 Flash Point

The flash point is one of the major physical properties used to determine the fire and explosion hazards of liquids. Flash points for pure components are easily determined experimentally.

Flash points can be estimated for multi-component mixtures if only one component is flammable and if the flash point of the flammable is known. In this case the flash point temperature is estimated by determining the temperature at which the vapor pressure at its flash point. Experimentally determined flash points are recommended for multi-component mixtures with more than one flammable component.

Example

Methanol has a flash point of 54℉ and its vapor pressure at this temperature is 62 mmHg. What is the flash point of a solution containing 75% methanol and 25% water by weight?

The mole fractions of each component are needed to apply Raoult’s Law. Assuming a basis of 100 pounds of solution.

Pounds MW Moles Mol. Frac.

Water 25 18 1.39 0.37

Methanol 75 32 2.34 0.63

3.73 1.00

Raoult’s Law is used to compute the vapor pressure (Psat) of pure methanol, based on the partial pressure required to flash.

P = x Psat

Psat = p / x = 62 / 0.63 = 98.4 mmHg

5.2 Flammable Limit

5.2.1 Vapor Mixtures

Frequently LFLs and UFLs for mixtures are needed. These mixture limits are computed using the Le Chatelier equation.

∑=

= n

i LFLiyi

LFLmix

1

1


Where

LFLi is the lower flammable limit for component i in volume % of component i in fuel and air.

yi is the mole fraction of component I on a combustible basis.

n is the number of combustible species.

Similarly,

∑=

= n

i UFLiyi

UFLmix

1

1

Where

UFLi is the upper flammable limit for component i in volume % of component i in fuel and air.

Example

What is the LFL and UFL of a gas mixture composed of 0.8% hexane, 2.0% methane, and 0.5% ethylene by volume?

The mole fractions on a fuel only basis are calculated below. The LFL and UFL data are obtained from the below table.

Volume

%

Mole frac. on combustible

basis

LFLi

(vol.%)

UFL

(vol.%)

Hexane 0.8 0.24 1.1 7.5

Methane 2.0 0.61 5.0 15.0

Ethylene 0.5 0.15 2.7 36.0

Total combustible 3.3

Air 96.7

= 2.53% by volume total combustibles.


396.01

7.215.0

0.561.0

1.124.0

11

1

=++

==

∑=

n

i LFLiyi

LFLmix

0.3615.0

0.1561.0

5.724.0

11

1

++==

∑=

n

i UFLiyi

UFLmix

= 13.0% by volume total combustibles.

Since the above mixture contains 3.3% total combustibles, it is flammable.

5.2.2 Flammability Limit Dependence on Temperature

In general, the flammability range increases with temperature. The following empirically derived equations are available for vapors.

( )[ ]HcTLFLLFLT Δ/2575.0125 −−=

( )[ ]HcTUFLUFLT Δ/2575.0125 −−=Where

ΔHc is the net heat of combustion, (kcal/mol)

T is the temperature, ℃

5.2.3 Flammability Limit Dependence on Temperature

Pressure has little affect on the LFL except at very low pressures (< 50mmHg absolute), where flames do not propagate.

The UFL increases significantly as the pressure is increased, broadening the flammability range. An empirical expression for the UFL for vapors as a function of pressure is available.

( )1log6.20 ++= PUFLUFLP

Where

P is the pressure, (mega pascals absolute)

UFL is the upper flammable limit, (volume % of fuel plus air at 1 atm)

Example


If the UFL for a substance is 11.0% by volume at 0.0 Mpa gauge, what is the UFL at 6.2 Mpa gauge?

The absolute pressure is P = 6.2 + 0.101 = 6.301 Mpa. The UFL is determined using the above equation.

( )1log6.20 ++= PUFLUFLP

( )1301.6log6.200.11 ++=PUFLUFLP = 48 volume % fuel in air

5.2.4 Estimating Flammability Limits

For some situation it may be necessary to estimate the flammability limits without experimental data. Flammability limits are easily measures; experimental determination is always recommended.

Jones found that for many hydrocarbon vapors the LFL and UFL are a function of the stoichiometric concentration (Cst) of fuel.

CstLFL 55.0=CstUFL 50.3=

Where, Cst is volume % fuel in fuel plus air.

The stoichiometric concentration for most organic is determined using the general combustion reaction.

CmHxOy + zO2 mCO2 + x / 2H2O

It follows from the stoichiometry that

Z = m + x / 4 – y / 2

Where z has units of moles O2 / mole fuel.

Additional stoichiometric and unit changes are required to determine Cst as a function of z.

Cst = x 100 = l 0

=

Moles Fue

r )
Moles Fuel + Moles Ai
= 0

)

부록#4 15 of 20

10

1 + (Moles Air / Moles Fuel

0
10
)
1 + (1 / 0.21) (Moles O2 / Moles Fuel
기

10

1 + (z / 0.21l

술사사무소차스텍이앤씨㈜

Substituting z and applying

( )138.219.176.4

10055.0+−+

=yxm

LFL

( )138.219.176.4

10050.3+−+

=yxm

UFL

Example

Estimate the LFL and UFL for hexane and compare the calculated limits to the actual values determined experimentally.

The stoichiometry is:

C6H14 + z O2 m CO2 + x/2 H2O

And z, m, x, and y are found by balancing this chemical reaction using the definitions in the above equation.

m = 6

x = 14

y = 0

The LFL and UFL are determined.

LFL = 0.55 (100) / [4.76 (6) + 1.19 (14) + 1]

LFL = 1.19 volume % versus 1.1 volume % actual

UFL = 3.5 (100) / [4.76 (6) + 1.19 (14) + 1]

UFL = 7.57 volume % versus 1.1 volume % actual

6.0 Procedure for Classifying Areas

6.1 Step One – Determining Need for Classification

The area should be classified if a combustible material is processed, handled, or stored there.


6.2 Step Two – Gathering Information

6.2.1 Proposed Facility Information

For a proposed facility that exists only in drawings, a preliminary are classification can be done so that suitable electrical equipment and instrumentation can be purchased. Plants are rarely built exactly as the drawings portray them, so the area classification should be modified later based upon the actual facility.

6.2.2 Existing Facility History

For an existing facility, the individual plant experience is extremely important in classifying areas within the plant. Both operation and maintenance personnel in the actual plant should be asked the following questions:

(a) Have there been instances of leaks?

(b) Do leaks occur frequently?

(c) Do leaks occur during normal or abnormal operation?

(d) Is the equipment in good condition, questionable condition, or in need of repair?

(e) Do maintenance practices result in the formation of ignitable mixtures?

(f) Does routine flushing of process lines, changing of filters, opening of equipment, and so forth, result in the formation of ignitable mixtures?

6.2.3 Process Flow Diagram

A process flow diagram showing the pressure, temperature, flow rates, composition and quantities of various materials (i.e. mass flow balance sheets) passing through the process needed.

6.2.4 Plot Plan

A plot plan (or similar drawing) is needed drawing all vessels, tanks, trenches, lagoons, sumps, building structures, dikes, partitions, levees, ditches, and similar items that would affect dispersion of any liquid, gas, or vapor. The plot plan should include the prevailing wind direction.

6.2.5 Fire Hazard Properties of Combustible Material

The properties needed for determining area classification for many materials are shown in the attachment.

If materials being used are not listed in the attachment or in other reputable chemical references, the needed information may be obtained by following.


(a) Contact the material supplier to determine if the material has been tested or group-classified. If tested, estimate the group classification using this procedure 4.0 and 5.0.

(b) Refer to 5.0 for a method for determining the group classification for some mixed combustible material streams.

6.3 Step Three – Selection the Appropriate Classification Diagram

Correlate the list of combustible materials from the process flow diagram and the material mass balance data with the quantities, pressures, flow rates, and temperatures to determine the following.

(a) Whether the process equipment size is low, moderate, or high

(b) Whether the pressure is low, moderate, or high

(c) Whether the flow rate is low, moderate, or high

(d) Whether the combustible material is lighter than air (vapor density < 1) or heavier than air (vapor density > 1)

(e) Whether the source of leaks is above or below grade

(f) Whether the process is a loading/unloading station, product dryer, filter press, compressor shelter, hydrogen storage, or marine terminal storage, or marine terminal.

6.4 Step Four – Determining the Extent of the Classified Area

6.4.1 Extent of Classified Areas

6.4.1.1

The extent of a Division 1 or Division 2; or Zone 0, Zone 1, or Zone 2 area requires careful consideration of the following factors:

(a) The combustible material

(b) The vapor density of the material

(c) The temperature of the material

(d) The process or storage pressure

(e) The size of release

(f) The ventilation


6.4.1.2

The first step is to identify the materials being handled and their vapor densities. Hydrocarbon vapors and gases are generally heavier than air, while hydrogen and methane are lighter than air. The following guidelines apply:

(a) In the absence of walls, enclosures, or other barriers, and in the absence of air currents or similar disturbing forces, the combustible material will disperse. Heavier-than-air vapors will travel primarily downward and outward; lighter-than-air vapors will travel upward and outward. If the source of the vapors is a single point, the horizontal area covered by the vapor will be a circle.

(b) For heavier-than-air vapors released at or near grade level, ignitable mixtures are most likely to be found below grade level; next most likely at grade level; with decreasing likelihood of presence as height above grade increases. For lighter-than-air gases

(c) In case where the source of the combustible material is above grade or below grade or in cases where the combustible material is released under pressure, the limits of the classified are altered substantially. Also, a very mild breeze may extend these limits. However, a stronger breeze may accelerate dispersion of the combustible material so that the extent of the classified area is greatly reduced. Thus, dimensional limits recommended for either Class I, Division 1 or Division 2; or Class 1, Zone 0, Zone 1, or Zone 2 classified areas must be based on experience rather than relying solely on the theoretical diffusion of vapors.

6.4.1.3

The size of a building and its design may influence considerably the classification of the enclosed volume. In the case of a small, inadequately ventilated room, it may be appropriate to classify the entire room Class I, Division 1 or Class I, Zone 1.

6.4.1.4

When classifying buildings, careful evaluation or prior experience with the same or similar installations should be made. It is not enough to merely identify a potential source of the combustible material within the building and proceed immediately to defining the extent of either the Class I, Division 1 or Division 2; or Class I, Zone 1 or Zone 2 classified areas. Where experience indicates that a particular design concept is sound, a more hazardous classification for similar installations may not be justified. Furthermore, it is conceivable that an area might be reclassified from either Class I, Division 1 to Division 2, or from Class I, Division 2 to unclassified or from Class I, Zone 1 to Zone 2, or from Class I, Zone 2 to unclassified based on experience.



7.0 References

- NFPA 497 RP for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas – 1997 Edition

- NFPA 325 Guide to Fire Hazard Properties of Flammable Liquids, Gases, and Volatile Solids – 1994 Edition

- API RP 505 for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Zone 0, Zone 1, and Zone 2 – First Edition, November 1997

- Chemical Process Safety Fundamentals with Applications – Daniel A. Crowl and Joseph F. Louvar

- KOSHA CODE – 2001

- HPGCL CODE – 2001

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