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istorically, hazardous area classification

has been the responsibility of the plant

electrical engineer In actuality, how-

ever, many projects were being designed with

minimum input from plant engineering. Most

consulting firms would use an ultra-conservative

approach with little input from process engineers

and no consideration for potential cost savings.

The existing national standards and guidelines are

written to provide safety and flexibility of design

and are difficult for the inexperienced engineer to

interpret Even for the experienced engineers, this

flexibility often leads to different interpretations

for similar situations. In 1993 a small group of

electrical engineers recognized a need for stan-

dardization without compromising safety, and

formed a technical committee to address this issue

This paper will present the result of the commit-

tee’s work as a corporate engineering technical

guideline that is currently being used by Eli Lilly

and Company.

It must be stressed that the purpose of this

guideline is to provide guidance for the design,

construction, opera tion, and maintenance of facili-

ties for Eli Lilly and Company only. It is based on

more than 158 years of engineering and opera-

tional experiences, national guidelines, and stan-

dards. Other companies may find this article useful

in developing their own guidelines for hazardous

area classifications; however, Eli Lilly and Com-pany takes no responsibility for their decisions in

classifying areas

The guideline is intended to assist in theclassification of most (about 90%) hazardous

Thzs artzcle appeared zn zts orzgznal i r m a t the 1995

Petroleum and Chemzcal InduJ-try Conference.

Hernandez zs chazrman o f the Elz Lzlly Hazardous

Areas Tech nzcal Commzttee Other members znclude

Barry A Bradley, Ronald W. Crooke, Eric B

Faulkner, Wzllzam M LewzJ-,VzetQ Maz, KennethA.

Mes~zck,ames K Mzles, and Kevzn D Wzlhelm.

locations encountered a t this company as de-

fined by the Nat ional Electrical Code, and does

not cover unique installatio ns The guideline is

intended to

II increase consistency from project to project

by standardizing the classification approval

procedure and the final documentation

improve and ensure personnel safety and pre-

vent property loss

W deliver a facility fo r the lowest cost without

compromising safety

II speed design

II make future changes and revisions easier

w define involvement of the appropriate indi-

viduals needed for the classification process

improve communications of hazardous loca-

tions to personnel by providing clear refer-

ences and documents

In the past, hazardous area classifications were

done in a variety of ways, often resulting in bad ex-

periences, such as improper classifications and

finger-pointing among the design team. At our

company, a design team for a project is usually

composed of an engineer of each discipline (chemi-

cal, electrical, process control , mechanical, struc-

tural) all led by a project engineer who usually has

no electrical background and is mostly focused on

budget and schedule. This team operates from a

central location and is usually not in tune with in-

dividual plant operations The same team format

existed at the consulting firm with even less plant

operations experience Due to personnel turnover

at the company and at the consulting firm, therewere communication gaps that led to errors in clas-

sification. Because of the ultra-conservative nature

of the classifications, we have experienced no

physical losses or injuries due to improper classifi-

cation. The only losses experienced were financial,

due to the excessive cost of equipment and the dif-

ficulty of designing to satisfy restrictive classifi-

cation requirements.

Due to the guideline, several projects have pro-

gressed smoothly throughout the design and con-

IFFFlndosfry App/imfions Mugazine Murc h/Ap rill997m 1077-2618/97/$10 0001997 IEEE

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struction phases. Especially the electrical

classification portion and the HVAC design. Due

to standardizing on practices, equipment issues

have saved time and money. Drawings and other

suppor ting documentation are easier to follow.

Some of the key elements that made the guideline a

success are:

1. Clearly stated goals

2. Easy-to-follow procedures

3. Clear definition of responsibilities

4. Identification of required documentation

5 . Standardization and simplification of draw-

ings and documentation

6. Identification of al l resources

7 . Clear definitions

8. Recommended standard equipment

To successfully write your own guideline, iden-

tify the gaps in your classification process. Estab-

lish some goals and a clear scope. Then develop an

outline to provide the framework for the body of

the technical guideline.

AcknowledgmentsThe committee would like to acknowledge the fol-

lowing peers for helping in the review of this

guideline: Robert W. Butler, Stephen I. Meiners,

Steven A. Mezsick.

Following is the technical guideline; comments

are shown in bold italics.

Engheering Technical Guideline

for Hazardous (Classified) locations

I. Scope

The main purpose of this guideline is to com-

municate philosophies in order to design, build,

maintain, and operate facilities at Eli Lilly and

Company.

This guideli ne is intended to assist in the

classification of most hazardous locations as

defined by the National Electrical Code

(NEC) in the Unite d States and Puerto Rico.

Uniq ue instal lations may not be covered in

this guideline.

Eli Lilly Tippecanoe Laboratories near Lafayette,

Ind. Photo by Gale C Whyte.

The guideline intends to educate consultingfirm s w orking i n projects f o r the company, pro-

cess engineers, a nd other engineers involved in

the classification of areas. U ltim ate ly it prevents

the classification of areas wi thout inp ut from a n

electrical engineer.

11. Basis of Technical Guideline

This guideline is based on the following:A. NFPA Articles

1. 30-1993-Flammable and Combust ible

2. 70-1993-National Electrical Code 1993

3. 325M-1991-Fire Hazard Properties of

Flammable Liquids, Gases and Volatile Solids

4. 496- 1993-Purged and Pressurized Enclo-

sures for Electrical Equipment

5 . 497A-1992-Classification of Class I Haz-

ardous (Classified) Locations for Electrical Installa-

tions in Chemical Process Areas

6. 497B-1991-Classification of Class II Haz-

ardous (Classified)Locations for Electrical Installa-

tions in Chemical Process Areas7. 497M-1991-Classification of Gases, Va-

pors and Dusts for Electrical Equipment in Haz-

ardous (Classified) Locations

8. 654-1994-Standard for the Prevention of

Fire and Dust Explosions in the Chemical, Dye,

Pharmaceutical and Plastic Industries

B. El i Lilly and Company Engineering Techni-

cal Guidelines (ETG’s)

1. 15801-Ventilation Design of Hazardous

Areas

2. 16910-Instrumentation and Enclosures in

Hazardous Areas

C. Instrument Society of America

1. ISA 12.1-1991-Electrical Instruments inHazardous Atmospheres

2. ISA 12.4-1970-Instrument Purging for

Reduction of Hazardous Area Classification.

3. ISA 12.6-1987-Installation of Intrinsically

Safe Systems for Hazardous (Classified) Locations

4 . ISA 12.10-1988-Area Classif ication in

Hazardous Dust Locations

5 . ISA-S12.12-1984-Electrical Equipment

for Use in Class I, Division Hazardous (Classified)

Locations

D. American Petroleum Institute-Recom-

mended Practices API-RP500

E. Operating experiences at Eli Lilly and Com-

panyThe guidel ine i s based on dated standards

an d publ icat ions . Whenever they change, then

the guideline w ill be researched an d changed ac-cordingly

Liquids Code

111.Definitions

Adequate Ventilation is defined in ETG #1580 1.

Authority having jurisdiction-the organization,

office or individual responsible for approving

equipment, an installation or a procedure. (Note:

The phrase “authority having jurisdiction” is used

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in NFPA documents in a broad manner since juris-

dictions and approval agencies vary, as do their re-

sponsibilities. Where public safety is primary, the

authority having jurisdiction may be a federal,

state, local or other regional department or indi-

vidual such as a fire chief, fire marshal, chief of a fire

prevention bureau, labor department, health de-

partment, building official, electrical inspector, orother having statutory authority. For insurance

purposes, an insurance inspection department , rat-

ing bureau or other insurance company representa-

tive may be the authority having jurisdiction. In

many circumstances the property owner or his des-

ignated agent assumes the role of the authority

having jurisdiction.)

Auto-Ignition Temperature (A1T)-the mini -

mum temperature required to initiate or cause self-

sustained combustion of a solid, liquid, or gas in-

dependently of the heating or heated element as

defined in NFPA 497M-1991.

Combustible liquid-A liquid having a flash

point at or above 100 degrees Fahrenheit (37.8de-

grees Celsius).

Flammable liquid-A liquid having a flash

point below 100 degrees Fahrenheit (37.8degrees

Celsius).

Flash point-the min imum temperature at

which a liquid gives off vapor in sufficient concen-

tration to form an ignitable mixture. (See NFPA

Intrinsically sa$-equipment and wiring which

is incapable of releasing sufficient electrical or

thermal energy under normal or abnormal condi-

tions to cause ignit ion of a specific hazardous at-

mospheric mixture or hazardous dust layer.Lower explosive limit (LEL)-the min im um

amount of gas or vapor that must be mixed with air

to produce an explosive mixture.

Non-incendive-equipment and wiring which in

its normal operating condition i s incapable of ig-

niting a specific hazardous atmosphere or dust

layer.

Upper explosive l im i t (UELj-the maximum

amount of gas or vapor that can be mixed with ai r

to produce an explosive mixture.

325M-1991 )

IV. Goals

The goals of this technical guideline are to :

A. Standardize design, construction, and pur-

chased equipment for hazardous (classified) loca-tions.

B. Increase consistency from project to project

and site to site.

C. Improve and ensure personnel safety and

avoid property loss.

D. Make future changes and revisions easier.

E. Deliver a facility for the lowest cost without

F. Create a standardized classification approval

compromising safety.

procedure.I

/E€ndusfryApplicofionsMogozine M Morch/Apri/ 1997

G Develop standard drawing elements and

H. Improve communication of hazardous (clas-

I Speed design and construction of hazardous

J. Standardize equipment specificationsfor haz-

K Provide a guide and reference for operations

L Standardize documentation

V Classification Procedure

A Responsibility

1 Engineering

a It will be the responsibility of the electrical

engineer, as designated by project management or

area management, to interpret the tules and regu-

lations as set forth in the NFPA codes, standards,

and recommended practices for establishing the

classification of an area

b It will be the responsibility ofthe designated

electrical engineer or the assigned representative to

provide the required electrical hazardous (classi-

fied) area design The electrical, mechanical and

general design shall meet the conditions described

by NFPA regulating codes and insurance carriers

The electrical hazardous (classified) area design

will include:

Th e designuted electricul engineer will nor-

mally be the plant electrical enginee r or project

electrical engineer. However, project manage-

m e n t m a y d e s i gn u te un electricul engineer fr om

an outs ide consult ing compuny involved in th e

project.

(1)Criteria for the classification including:E Air Flow Direction-Auto-Ignition Tem-

Division

Group

Boundaries

Typical Hazardous Classification Charts

I Electrical Hazardous Locations Investigation

(2 Documented information related to the

electrical classification design for the operating

area to post in the area affected Special operating

conditions, if any, relating to the classified area

and/or equipment shall also be posted

definitions for classified location drawings

sified) locations.

(classified) facilities

ardous (classified) locations

personnel

perature (AIT)

Report

2. Operating Division

a It will be the responsibility of the operating

division to provide information regarding the pro-

cess conditions and operating procedures of the

area to establish the classification

b. It will be the responsibility of the operating

ision to post the classification of the area and

special operating conditions, if any, relating to the

classified area and/or equ ipment .

c It will be the responsibility of the operating

division to function within the limits of the classi-

fication established and to cause a review using this

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guideline to re-classify an area if changes in meth-

ods, equipment, or operations occur that might af-

fect the previously specified classification.

3. Insurance Approvals

It will be the responsibility of the fire protec-

tion representative to obtain fire insurance approv-

als if required.

4. Electrical Engineering ConsultantIt will be the responsibility of the Electrical En-

gineering Consultant to advise he designated elec-

trical engineer or the assigned representative on

the application of NFPA codes, other governing

codes, and adopted standards.

A t Eli Lilly, Electrical Engineering Consu lt-

a n t i s a ti t le given to an experienced engineer

who has the respon sibility to coordinate wo rk of

other electrical engineers. Th ere i s no “Electrical

Engineering” departmen t.

5 . Investigation Committee

It will be the responsibility of the Investigation

Committee to discuss the operating procedures in-

cluding the materials and arrive at a decision as tothe proper electrical classification of an area.

6. Approval Group

It will be the responsibility of the Approval

Group to review and approve the Investigation

Committee’s proposed classification.

B. General Work Procedure

1.Request to Classify or Reclassify

A request to classify or reclassify an area can

originate from either the operating or engineering

division and shall be submitted to the designated

electrical engineer. The designated electrical engi-

neer will convene the Investigation Committee.

The recommended membership shall be:

a. Representative(s) of the operating divisionb. Designated building and/or plant electrical

c. Plant safety representative

d. Plant fire protection representative

e. Design engineers

(1)Designated Process Engineer

( 2 )Designated Mechanical Engineer

(3)Designated Civil Engineer

The sign-offprocedure assures there w il l be a

plantlbuilding electrical engineer or project

electrical engineer involved, even i f a n outside

consultdnt i s designated t o develop the classifi-

cation.

engineer

2 . Reviews for ConsistencyAll requests to classify or reclassify an area will

be reviewed by the Approval Group and returned

to the originaror. This review is made to assure, as

near as possible, consistencyof interpretation and

application o fNFPA codes, other governing codes,

and adopted standards.

The Approval Group will consist of:

a. Plant electrical engineer

b. Plant fire protection representative

c. Area supervision

d. Electrical Engineering Consultant

e. Building engineer (where applicable)

Th is assures there i s enough thought given to

the ared classification. Also, it assures consis-

tency in the approachdnd nd result of the area

classification.

VI . Classification Forms

A. PurposeThe purpose of the classification forms is to pro-

vide consistent guidance for classifying or re-

classifying an area. They also serve as standard and

official documents of hazardous (classified) loca-

tions.

Th e for ms convey the philosophy of consider-

able quantit ies present in the area to be classi-

fie d. T his dddresses the fact that if there are not

considerable quan tities , perhaps the ared should

not be classified a s strictly.

B. Procedure and Responsibility

Refer to Section V.

C. Document Retention

After the forms are approved by the Investiga-tion Committee and Approval Group, the master

form will be kept in the project file and a copy of

each form will be sent to the Plant Electri-

cal/Building Engineer. The master copy will later

be transferred to the building’s users when the

project is closed out.

D. Revision or Addition to Forms

All revisions and/or additions to the forms must

be submitted to the Chairman of the Hazardous

Locations Technical Committee. See Section XVI.

E. Location and Owner of Forms

The Chairman of the Hazardous Locations

Technical Committee is the owner of the forms.

Blank forms will be electronically stored in a pub-lic folder.

Blank forms are kept in an electronic public

folder which i s available to anyone working in

classifying a n a rea.

VII. Classification Charts

A. Purpose

1. The primary purpose of the classification

charts is to recommend a classification for the most

common areas and equipment types likely to be en-

countered.

2 .The secondarypurpose is to offer a blank tem-

plate to use for a new area classification or for a re-

classification.

3. These charts can offer a check in classifying

an area or equipment.

B. Using these charts:

1.For Class I areas use the ROOMiAREA chart .

2 . For Class I equipment use the EQUIPMENT

3 . For Class I1 areas or equipment use the DUST

Note: For Group E dusts consult NFPA 497B-

chart.

chart.

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mond. The group will identify the Class I or Class

I1 area.

6. Air-flow arrows are a useful part of the Haz-

ardous (Classified) Locations series drawings be-

cause they

are required for insurance approval

determine if an area has been properly classi-

help when reclassifying an area

E clarify the area for containment and opera-

Consult with the project’s Mechanical Engineer

in order to show the air flow arrows in the Hazard-

ous (Classified) Locations series drawings.

7 .Conductive floors shall not be shown in Haz-

ardous (Classified)Locations series drawings. Refer

to Engineering Technical Guideline 16456.

8. For any revisions to Hazardous (Classified)

Locations series drawings follow SectionV of this

Technical Guideline.

fied

tions purposes

IX. Chemical Data TableA. Purpose

The purpose of the chemical data table is to pro-

vide a list of material characteristics for the most

common chemicals and solvents that are used at Eli

Lilly. These characteristics should be considered

when classifying an area fo r electrical equipment.

B. Using This Table

1. Identify the chemicals that you have in the

area.

2. Utilize the listed material characteristics to

assist in classifying the area for electrical equip-

ment.

3. If you can not find the chemical on the table,

refer to the Material Safety Data Sheet (MSDS),which can be found on the Engineering VAX sys-

tem.

4 . Additional information can be found in

NFPA 497M-1991, 30-1993, and 325M-1991.

5 . Consult with the project’s process engineer if

information cannot be found in the above re-

sources.

C. Explanation of Table Columns

1. Upper Explosive Limit (UEL) is the maxi-

mum limit on the percentage of gas or vapor that

can be mixed with air to produce an explosive mix-

ture.

2 . Lower ExplosiveLimit (LEL) is the minimum

amount of gas or vapor that can be mixed with airto produce an explosive mixture.

3. Refer to Sections I11 and VI1 for other defini-

tions.

D. Revisions or Additions to the Table

Please submit any revisions or additions to this

table to the chairman of the Hazardous Locations

Technical Committee. See section XVI.

E. Location and Owner of the Table

The chairman of the Hazardous LocationsTech-

nical Committee is the owner of this Table. The

chairman has this table stored on a public folder.

See Section XVI.

X. References To Hazardous (Classified) Loca-

tions

The following documents refer to hazardous

(classified) locations. They provide input and dis-

cussions on proper designs.

A. ETG 01540-Fire Protection and Loss Con-trol Design Criteria

B. ETG 01590-Process Safety Considerat ions

for New Operations

C. ETG 11000-Shipping and Receiving

Docks

D. ETG 15501-Insurance Considerations

E. ETG 15801-Ventilation Design of Haz-

XI. Class I And I1 Locations

Th e following requirem ents are based on

years of operating experience. Many require-

ments could be interpretedas not complying wi th

codes an dst an dar ds, however, it i s our belief tha t

these requirements are safe anda dequ ate for ourapplications, and they do meet codes and stan-

dards.

ardous Areas

A. Requirements

1. Adjustable Speed Drives (ASDs)

The application of ASDs and Motors is ad-

dressed more completely in specification

16154-Motors. In general ASDs should be lo-

cated outside of classified areas and TEFC motors

in Division 2 areas driven by ASDs should have

sealed contact thermostats imbedded in the wind-

ings because of the uncertainties of the operation

temperatures at various speeds and supply voltage

wave shapes.

2 . Automatic DoorsRefer to Engineering Technical Guideline

3. Calculators

Hand-held calculators shall be permit ted in Di-

4. locks

Only labeled or listed clocks shall be permitted

in Division 1classified locations. Battery operated

clocks without make-or-break contacts shall be

permitted in Division 2 classified locations.

08460-Automatic Doors for details.

vision 1 and 2 classified locations.

5. Conductive Floors

The requirement for conductive floors is out-

lined in ETG 16456-Bonding and Electrostatic

Grounding and is beyond the scope of this guide-line. It is also covered in the El i Lilly Safety Manual

and ETG 01588-Avoidance of Dus t Explosions.

6. Flashlights

Only labeled or listed flashlights shall be per-

mitted in Division 1classified locations. For Divi-

sion 2 locations, flashlights must be approved by

plant electrical engineering or building engineer.

7. Fork Trucks

NFPA 505 covers the use of fork trucks in elec-

trically classified hazardous areas. I n summary:

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Class I and 11, Division 1, Groups D and

G-Type EX units are allowed. Class I and 11, Di-

vision 2, Groups D and G-Type DY, EE, and EX

are allowed. In addition Type DS, ES, GS, LPS or

GS/LPS may possess sufficient safeguards to be

used in Class I and 11,Division 2, Groups D and G

areas The author ity having jurisdiction can

authorize their use, taking into account the quan-t i ty of flammable material that might escape in

case of accident, the adequacy of ventilation, the

total area involved, etc. In most cases these type of

units are acceptable for operations outdoors and

within warehouses at Eli Lilly and Company

8. Grounding and Bonding

Refer to ETG 16456-Bonding and Electro-

9 Hearing Aids

Hearing aids are considered non-incendive, and

10 HVAC

Design shall meet or exceed the design criteria

11 Intercoms

Use Intercom Systems approved for hazardous

conditions Refer to ETG 16760- Intercom Sys-

tems for details.

static Grounding

are acceptable for use in classified locations.

specified n ETG 15801 foral l classified locations

12 . NEMA/NFPA vs. IEC

In making the decision to use IEC-rated equip-

ment over NEMA-rated equipment in NFPA haz-

ardous areas, the engineer should employ sound

engineering judgment to hazardous design Using

IEC standards, the selection procedure is more in-

volved and requires the engineer to address addi-

tional considerations in order to achieve the desired

performance IEC equipment is rated closer to its

capabilities than a corresponding NEMA equip-

ment, and cost savings can be achieved with under-

standing the comparisons between IEC and

NEMA.

IEC standards use Zones to identify the Iikeli-

hood of explosion Zone 0 has an explosivemixture

continuously present Zone 1has an explosivemix-

ture likely to occur in normal operating condi-

tions Zone 2 has an explosive mixture not likely to

occur in normal operating conditions IEC classi-

fies the enclosuresas flameproof “d” and increased

safety “e” Flameproof “d”must contain an internal

explosion without permanent distortion, guaran-

tee the flame cannot be transmitted to the sur-

rounding atmosphere, and present an external

surface temperature that is lower than the ignition

temperature of the surrounding gases and vapors

Increased safety “e”electrical devices must not pro-

duce arcs, sparks or excessive temperature in nor-

mal operation

IEC Zone 0 is roughly equivalent to NFPA

Class I or IUDivision 1 Zone 1 is roughly equiva-

lent to NFPA Class I or II/Division 1or 2 Zone 2 is

roughly equivalent to NFPA ClassI or IIiDivision

2 If IE C rated equipment is to be used, a review by

the insurance carrier, the Manager of Property Loss

Prevention and Control and the Manager of Elec

trical Engineering should be undertaken Overall

IEC rated equipment can translate to NEMA rated

equipment in most situations, but NFPA codes

and philosophies must be met for most locations in

the United States and Puerto Rico.

13. Non-IncendiveiIntrinsically SafeRefer to defini t ions and ETG 16910-

14 Pagers

Only labeled or listed pagers shall be permitted

in Division 1 and 2 classified locations.

13 Pallet Jacks and Material Handling Equip-

ment

Only labeled or listed electric pallet jacks or

material handling equipment shall be permi tted in

Division 1 and 2 electrically classified hazardous

locations

Instrumentation and Enclosures in Hazardous Areas

16. Portable Radios

Only labeled or listed radios shall be permitted

17 Power transformers

Avoid transformers in Division 1 and 2 classi-

18 Purging

Refer to ETG 16910-Instrumentation and

Enclosures in Hazardous Areas

19. Sealing and drainage

Place equipment outside hazardous areas or use

factory-sealedequipment where practical to elimi-

nate the need for seal-offs Drains shall be used

where there is a probability that liquid or other

condensed vapor may be trapped with in the enclo-

sure or raceway system due to temperature differ-

ences and exposure to moisture. Examples: outdoor

installations, chill rooms, wash-down areas, etc

Consult NFPA 70-501-5 for the need for seal-offs

and drains

in Division 1 and 2 classified locations.

fied locations.

20 Signs

Place a sign mounted on the doors or approach

entering a hazardous area, measuring twelve inches

by twelve inches with yellow background black

letters, stating.

THIS AREA ISAN ELECTRICALLY CLASSI-

FIED HAZARDOUS AREA FOLLOW APPRO-

PRIATE SAFETY GUIDELINES.

21 Smoke DetectorsiHeat Detectors

Refer to Engineering Technical Guideline

22 Solenoids

For Division I , solenoid enclosures shall be ap-

proved for the area Solenoids without make-or-

break contacts are permitted in non-rated enclo-

sures for Division 2 locations.

16720

23 Speakers

For lay-in or plaster ceiling-mounted speaker in

Division 2 situations use standard speaker and

housing with trim pot mounted internal to hous-

ing, accessible to qualified personnel only. For

IEEElndusiryApplicufioiis Maguzine V March/April1997

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surface-mounted speakers use speakers approved

for hazardous conditions. Refer to Engineering

Technical Guideline 16770, Emergency An-

nouncement System, ETG 16760, Intercom Sys-

tems and 16770, Emergency Announcement

System (Public Addrcss) for details.

24. Telephones

LJse telephones approved for hazardous condi-tions. Rcfer to Engineering Technical Guideline

16745-Telecommunications and ETG 16760-

Intercom Systems for details.

25. Testing Equipment, Meters, Sensors, Scanners

Permanent:

Only approved equipment shall be permitted in

classified locations.

Portable or temporary:

Equipment which is not approved shall be per-

mitted when “Open Flame” procedures have been

followed. Portable equipment shall not be applica-

ble for use in Division 1 locations.

Non-listed or non-labeled equipment:

Must he approved by plant electrical en&’eer,

building engineer, or Hazardous Locations Tech-

nical Committee.

26. Watches

Watches are considered non-incendive, and are

XII. Class I Locations Only

A. Requirements

1 . Diethyl Ether

Diethyl ether is a group C material with an

Auto-Ignition Temperature of 160 degrees (320

degrees F)-the Chemical Data Tables (see sample

table) have more chemical characteristics for this

material. In mosr cases, the equipment use in

area(s) processing diethyl ether do not require a

groupC rating, except fo r Class I Division 1 area(s).The main concern is the maximum surface opcrat-

ing temperature. The equipment’s maximum sur-

face operating temperature shall be 80%) of the

AIT or less. or having a T rating of‘l‘3C or higher.

If a group C rating is required, consult other src-

tions in this guideline for proper classification and

recommendations of equipment to be used with

Diethyl Ether.

acceptable for use in classified locations.

2. Hydrogen

A three-foot, Division 2bubble around the hy-

drogen line I S not necessary according to the Na-

rional Electric Code, section jOO-S(b). FPN nu111.

2. , if the pipe handling the hydrogen is welded.

However, where there are valves, checks, meters,

and similar devices, according to NFPA 497 Fig-ure 1-4.27, hese devices require a fifteen foot ra-

dius, Division 2 , Group B bubble around the

device.

Division 1, GroupC and D enclosures that are

located at or below the level of the previously men-

tioned devices can be within this fifteen-foot-

radius bubble, because the pressure inside the

Group C and D enclosure will not he negative with

respect to the atmosphere. Also, hydrogen is at a

low pressure is lighter than air, and it will dissipate

rapidly once released to the atmosphere. All these

facts virtually eliminate the possibility of hydro-

gen entering the groupC an d D enclosures. Never-

thelcss, use sound engineering judgment when

designing hydrogen systems.

3. Laboratory HoodsGenerally laboratory hoods shall beconsidered

as unclassified electrically with respect to NFPA

45.All receptacles, switches, and controls shall be

located as not to be subject to liquid spills. If there

is engineering judgment that a specific operation

creates a hazard then the hazard should be evalu-

ated in terms of likeli hood, severity, and the conse-

quences of an explosion, as well as the protection

required to substantially reduce the hazard. In

these cases all wiring and appurtenances, appara-

tus! lighting, signal systems, alarm systems, re-

mote control systems, o r parts thereof, shall

comply with Article 500 of NFPA 70, The Na-

tional Electrical Code.

4. ighting

A common practice is to classify the area abovea

ceiling as non-hazardous and use non-rated l ight-

ing in these areas where a room might be Division

2. If surface-mounted or suspended fixtures are

used, then either the appropriately rated fixture

must be provided or the area must be de-rated in

the area of the light fixtures. The most common

problem associated with proper lighting applica-

tion in Division 2 areas is the proper T-rating. If a

fixcure does not have a T-rating lower than the AIT

of the potential hazardous atmosphere, then the

surface temperature of the lamp muct he less than

8 0 2 of the AIT or i t must be approved for Class I,

Division I .

5 . Motors

For Division 2 equipment, groupdesignation is

insignificant, and Division 1 or “explosion-proof

motors are not required. The important criterion is

the surface operating temperature or T-number.

The T-number is derived from tests at a specified

ambient temperature and can sometimes be ad-

justed, but it must always be considered for Divi-

sion I or 2 locations. For Division 1 locations, we

have an understanding with our insurers that

where we classify areas Division 1 , Group C matr-

rials arc so rarely used that the area is really Divi-

sion 2. Therefore, motors can normally he applied

which are rated for Group D, Division 1 only, pro-

vided that the T-number is appropriate. A specialcircumstance where a GroupC material will be rou-

tinely open will still require Group C-approved

equipment. TEFC or ODP 3-phase motors are safe

in Division 2 areas without special approval because

a 3-phase squirrel cage motor has no arcing or spark-

ing components to provide an ignition source under

normal operation. The NEMA standard for maxi-

mum operating temperature with classB insulation

~

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is 80 degrees Centigrade. Class B rise is what is

specifiedwith Class F insulation for an added safety

factor. Maximum design temperature for class F

insulation (at service factor) is 105 degrees Centi-

grade. This is well below80% of the AIT of Hydra-

zine, agroupC chemical, which has the lowestAIT

which can be identified (0.8 x 156 = 125).

6. Quantities Class IIn non-processing areas such as laboratories and

developmental facilities the quantity of flammable

liquids is a critical factor in determining the need

t o classify. Other factors include venti lation, con-

tainment, drains, ignition sources,and skillsitrain-

ing of lab personnel. Generally “lab quantities” are

less than 1 gallon (4 liters approximately) of each

liquid, and total for the lab would not exceed 100

gallons. In most cases labs do not haveor handle suf-

ficient quantities to justify classifying these rooms.

7. Refrigerators

Domestic refrigerators shall comply with

NFPA45

Standard on Fire Protection for Labora-

tories using Chemicals (Chapter 9 and Table 1).

8. Relationship of exposure levels to explosive

limits in classified location A decision between Di-

vision 1or Division 2 can often be clarified by con-

sidering the lower exposure limits and operating

procedures. The exposure limit of most flammable

liquids handled and processed at this campany is

much lower than the lower explosive limit percent-

age. Normally the lower exposure level is less than

25% of the lower explosive imit. Therefore, ifper-

sonnel can be in the areas without being required to

wear respirators, then the containment or ventila-

tion or both are adequate to prevent explosive con-

centrations, and a Division 1classification may notbe required.

9 . Safety Disconnect Switches

In Division 1 areas, all switches must be ap-

proved for the area and group. For Division 2 areas,

switches intended to interrupt current in the nor-

mal performance of the function for which they are

installed shall be provided with enclosures ap-

proved for Division 1 locations, unless the contacts

are hermetically sealed, oil-immersed, or within a

factory-sealed explosion-proof chamber. I t is the

current practice that motor safety disconnect

switches will be NEMA 4 or 4 X in Class I or Class

11, Division 2 areas to provide an additional level of

safety and to provide wash-down capability. If

safety disconnect switches are installed in Division

2 areas where it will be normal operation for them

t o interrupt current, then explosion-proof enclo-

sures will be required. Also, if isolating (non inter-

rupting) switches are used in Division 2 areas, the

switches can be non-rated, and must be labeled

“DoNot Open Under Load”.

XIII . Class I1 Locations Only

A. Requirements

1.Lighting

A common practice at Eli Lilly and Company is

to classify the area above a ceiling as non-hazardous

and use non-rated lighting in thes’e areas where a

room might be Division 2 . If surface-mounted or

suspended fixtures are used, then either the appro-

priately rated fixture must be provided or the area

must be de-rated in the area of the light fixtures.

The most common problem associatedwith properlighting application in Division 2 areas is the

proper T-rating. If a fixture does not have a T-

rating lower than the AIT of the potential hazard-

ous atmosphere, then the surface temperature of

the lamp must be less than 80% of the AIT or it

must be approved for Class 11, Division 1. Docu-

mented housekeeping procedures can justify

downgrading a classification from Class 11, Divi-

sion 1 to Class 11, Division 2.

2 . Magnesium and Metal Dusts

Metal dusts are considered Division 1,Group E.

Metal shavings and pellets are not considered

metal dusts. Water-reactive dusts should not be

considered when classifying an area for electrical

equipment.

3. Motors

For Division 2 equipment, group designation s

insignificant, and Division 1 or “explosion-proof’

motors are not required. The important criterion is

the surface operating temperature, or T-number.

The T-number is derived from tests at a specified

ambient temperature and can sometimes be ad-

justed, but it must always be considered for Divi-

sion 1or 2 locations. TEFC or ODP +phase motors

are safe in Division 2 areas without special approval

because a 3-phase, squirrel cage motor has no arc-

ing or sparking components to provide an ignition

source under normal operation. For Class 11,Divi-

sion 1 areas, the important criterion is operation

under the specified temperature with a dust layer.

Motors must be labeled for use in Class IT, Division

1areas. Documented housekeeping procedures can

justify downgrading a classification from Division

1 to Division 2.4 . Quantities

In non-processing areas such as laboratories and

developmental facilities, the quant ity of ignitable

dusts is a critical factor in determining the need t o

classify. Other factors include ventilation, contain-

ment, drains, ignition sources, and skillsitraining

of lab personnel. Generally “lab quan tities” are less

than 1 pound (454 grams) of each dust, and total

for the lab would not exceed 100 pounds. In most

cases labs do not have or handle sufficient quanti -

ties to justify classifying these rooms.

5 . Safety Disconnect Switches

In Division 1 areas, al l switches must be ap-

proved for the area and group. For Division 2 areas,

switches intended to interrupt current in the nor-

mal performance of the function for which they are

installed shall be provided with enclosures ap-

proved for Division 1 locations, unless the contacts

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are hermetically sealed, oil-immersed, or within a

factory-sealed explosion-proof chamber. It is the

current practice that motor safety disconnect

switches will be NEMA 4 or 4 X in Class I or Class

11, Division 2 areas to provide an additional level of

safety and to provide wash-down capability. If

safety disconnect switches are installed in Division

2 areas where it will be normal operation for them

to interrupt current, then explosion-proof enclo-

sures will be required. Also, if isolating (non-

interrupting) switches are used in Division 2 areas,

the switches can be non-rated, and must be labeled

“Do Not Open Under Load”. Documented house-

keeping procedures can justify downgrading a clas-

sification from Division 1 to Division 2 .

6. Sealing

Sealing in Class I1areas is significantly different

than in Class I, NFPA 70-502-5 shall be consulted

Material

for requirements. I n general, place equipment out -

side the hazardous area where practical.

XIV. Class I11 Locations

This Technical Guideline does no t cover Class

XV. Interpretation

The Hazardous Locations Technical Commit-

tee is the owner of this Technical Guideline; there-

fore it will interpret the intent of this document.

The Committee will be responsible for resolving

differences of opinion whenever these arise. For any

changes or suggestions to this Technical Guide-

line, please contact any committee member.

I11 locations.

XVI. Consultation

For any questions about how to use this guide-

William M. Lewis, 317-277-1409

Electrical Engineering Consultant

line or for further direction, contact:

Group AIT (C) Flash PI (C ) LE1(%) UEL (%) VD (Vapor Density)

1. Chemical Data Table-SAMPLE(Class I Chemicals as Defi ned i n NFPA 30)*

Material

Acetc Acid

Acetc Anydride

1 Chemicals which are commonly used or produced atElLilly for consideration when classifying areas for electrical equipment: I

Group AIT (C ) Flash PI (C) LE1(%) UEL (%) VD (Vapor Density)

D 464 39 4 19.9 2.1

D 316 49 2.7 10.3 1.1

1 Class IChemicalsas Defined n NFPA 30 I

Material

Analine

BenzylChloride

Cyclohexanol

Group AlT (0 Flash Pt (C) LE1(%) UEL (% ) VD (Vapor Density)

D 615 70 1.3 11.1 3.2

D 585 67 1.1 4.4

D 300 68 3.5

1 Acetaldehyde 1 C I175I Acetone I D 14651 Acetonitrile I D I524 14.4 11.4 I1 Class IIChemicals as Defined in NFPA 30: I

I Cyclohexanone I D 1245 144 11.1 19.4 13.4 I 1 Class MA Chemicalsas Defined in NFPA 30: I

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ELECTRICAL H ~ ~ ~ R ~ ~ U STI^̂^INVESTIGATION R E P O R T

1 Are flammable iiquids, vapors or gases likely to b e present inquantrtles sufficient to produ ce

explosive or ignltlble mixtures'

Ar e combustible liquids likely to be handled, processed, or stored at temperatures above their flashpoints in quantities sufficient to produce exploslve or ignitlble mixtures?

2

1.

2.

is an ignitible atmospheric mixture ikelyto exist under normal operating conditions?

Is an ignitible atmospheric mlxture ikely to occur frequently due to maintenance, repairor leakage?

3. Would a failure of process equipment, storage vessels, or piping systems be likelyto cause a failure of

the electrical system simukaneously with the release of the combustible material?

4. Is a piping system containing a combustible material in an inadequately ventilated space, and is thepiping system likely to leak?

is the space or area in question belowgrade leve l such that vapors may accumulate therein?.

6. Are pressure relief valve discharges located within the area?

Division 2 locations are distinguisticd by an affirmative a i ?w e r io air#on6! of the f:J liuwing qcicstiuns:

1. Is a piping system containing a combustible material n an inadequately ventilated space, and is thepiping system not likely to leak?

Is a process equipment system containing a combustible material in an inadequately ventilated space,and can the material escape only during abnormal situations, such as a failure of a gasket or packing?

2.

3. Is the location adjacent and open to a Division1 location, or can gas or vapor be transmitted from aDivision 1 location to the location n question by trenches, pipes, or ducts?

4. If mechanical VentilationIsused. can failure or abnormal operation of the ventilation equipmentpermit an ignitible atmospheric mixture?

Are the operations In this area likelyto require a R ivision2 classification inthe near future?.

References: Extentof a hazardous location maybe determined rom diagrams, figures 3-4.1 through 3-4.34NFPA Code 497A, efiective2/10/92

Lllly Safety Information Manual, Sec. p.10Lilly EngineeringTechnical Guidelines 01555 (Hazardous Locations C lass ifications)

iNSWER

lNSWER

Rev. 12115194

Fig . 1A. Investig ation report-Class I locations.

/€ Endusfry ApplicationsMagazine I orch/Apri/ 1997

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DATE: REQUESTER: AREA:

REASON F ~ ~ . ! . ~ . ~ . ~ S ~ ~ ~ ~ ~ ! ~ ~ 1Y.f% DE ~ ~ V ~ ~ T ~ - A ~ ~ ~ ~

P rocess Cha nge New Project Locationto be Classified 0

Equipment Changes Other U Location to be Re-classified

PRESENT CLASS IF ICAT ION

0eneralClass I 0 GroupA 0 GroupE 0 Division 1 0 Purpose

Class II 0 GroupB 0 GroupF 0 Division 2 0

Class 111 0 GroupC 0 GroupG 0 N/A 0

Group D 0

Investtgattian Committee

Chairman Member MemberElectrical Engr. Operation Rep. Process Engineer

Member Member Member


Fire Protection Rep. P lant Safety Rep Mechanical Engineer

Bullding Engineer Civil Engineer Other

DESC PTlON

MEW CLASSIFICATION

Class I 0 0 ~ r o u p ~U

Class I1 0 GroupB

Class 111 GroupC 0GroupD 0

Class I op y

Chairman

Drawing No.

Electrical Engineer

Drawings U pdated

(Date)

Area Posted

(Date)

GroupE c]

GroupF 0

GroupG c]

Division 1 0

Division 2

0 ~A 0Approval Group

Plant Electrical Engr.

P lant Fire P rotection Representative

Area Supervision

Initials Building Engineer

Electrical Engineering ConsultantRev 12/16!94

Initials

Class ICopy

Fig. 1B . Class I invest igat ion report (continued) .

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Need for classification, if the following ques tion IS answered aftirmarive

ANSWER

Ia. Are combustible dusts likely to be present inquantltles sufficient to produce explosive or Ignitible

mixtures? 11Division 1 iocationlit aredistinguished hy an afllrinntivc answer to ai?* oi3e of tiic ioiiowing questions:

a.

b.

Is a Group E dust present in hazardous quanlities?

is a dust likely to be in suspension n air continuously, periodically. or intermttentiy under normalconditions n quantities sufficienttoproduce explosive or ignitible mixtures?

c. Will mechanicai ailure orabnormal operation of machinery or equipment cause such explosive orignitible mixturesto be produced, and might it also provide a source of ignition through simultaneous

failureof electrical equipment operation of protective devices or from other causes?

d. Are there dust layers or accumulations on surlaces deeper than 118in. (3.18 mm)?

tNSWER

Division 2 laciltiafls lor Group Fo r G dusts are dirjlinguishlrc! ay dii affirniatrve ISWB to any 0118 l the followingquestions:

IANSWER

a. Is the dustnotnormally in suspension n the air in quantities sufficient to produce explosive orignitible mixlures, but could be thrown into suspension by infrequent malfunctioningof handlingor processing equipment?

b. Are the dust accumulations nsufficient to interfere with the normal operationof electrical equipment,but could the accumulations be ignited by the abnormal operation or failure of electrical equipment?

c.

d.

isthere a dust layerthat makes the colors of the surfaces indiscernible?

Would the failure of mechanicai dust collection allow an ignitible suspensionof dust or a layer deeperthan 1/8 in (3.18mm) to build up?

References: Extent of a hazardous ocation maybe determined from diagrams, figures 5-3.1 through 5-3.9NFPA Code 4978, effective 2/08/91Liliy Safety Information Manual,Sec. p.10Lllly Engineering Technical Guidelines 01555 (Hazardous L ocations Classifications)

I-

Fig . 2A. Investig ation report-Class I1 ocations.

/E€€ lndusfryApplicationsMagazine March/Aprrl 1997m

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DATE REQUESTER AREA

EASPN FO R INVESTIGATION TYPE OF N ~ ~ S ~ ~ A T I ~ ~

Process Change 0 New Project 0 Location tobe Classified 0

Equipment Changes Other U Location to be R e-class~fied 0

_ _ ~ _ ~ _ _ _ _ -RESENT C LASSIFICATION

Class I 0 GroupA 0 GroupE 0 Division 1 ~ 0

Class II GroupB GroupF 0 Division 2

Class111 0 GroupC GroupG 0 MA 0GroupD

Investigation Committee

Chairman Member MemberElectrical Engr. Operation Rep. Process Engineer


Fire Protection Rep. PlantSafety Rap. Mechanical Engineer


Building Engineer Civil Engineer Other

DESCRIPTION:

\

NE-W CJ LASSIFICATION

Division 1 0 Generalurpose 0Class I 0 GroupA 0 Group E 0Class II Group8 GroupF 0 Division 2 0 N/A

Class 111 [7 GroupC 0 GroupG 0 0Approval Group

Plant Electrical Engr

Plant Fire Protection Representative

GroupD [7

Cha inan

DrawingNo

Electrical Engineer

Area Supervision

Drawings Updated

(Date) Initials Building Engineer

Area Posted

(Date) lnnials Electrical Engineering ConsultantRev2,,6184

Fig . 2 B . Class I inves t iga t ion report (cont inued) .

I€€€ndusfry Applirofions Mogozhe I orch/April I 997

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