is 5571- selection of electrical installation for hazardous

7/28/2019 Is 5571- Selection of Electrical Installation for Hazardous

1/12

mu!lw)Indian Standard

GUIDE FOR SELECTION OF ELECTRICALEQUIPMENT FOR HAZARDOUS AREAS

(Second Revision)

ICS 28.260.20

0 BIS 2000BUREAU OF IN DIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARGNEW DELHI 110002

August 2000 Price Group 5


2/12

Electrical Apparatus for Explosive Atmospheres Sectional Committee, ET 22

FOREWORDThis Indian Standard (Second-Revision) was adopted by the Bureau of Indian Standards, after the draft finalizedby the Electrical Apparatus for Explosive Atmospheres Sectional Committee had been approved by theE]ectFotechnical Division Council.This standard is intended to provide guidance for selection of electrical equipment for use in hazardous areas,such as, petroleum refineries and petrochemicaland chemical industries. In this standard, the selection ofelectrical equipment has been based on the classification of hazardous areas given in IS 5572 : .1994Classification of hazardous areas (other than mines) having flammable gases and vapours for electricalinstallation (second revision), in conjunction with which this standard shall be read and interpreted.

This standard was first published in 1970. The first revision was carried out toremove difficulties faced duringthe implementation of this standard and also to take into account the latest developments in the field ofelectrotechnology.The second revision has been undertaken to include latest development taking place for updation of IECstandards for use of electrical equipment in hazardous area.While preparing this standard the statutory regulations in this country have been kept in mind to see that noprovision goes against such regulations. However, if there is a conflict between statutory regulations in forcein any areas and this standard, the provisions of the former will prevail.No account is taken in this standard of the toxic risks which are associated with most combustible materials inconcentrations which are ust.diy very much less than the lower explosive (flammable) limit. In locations wherepersonnel maybe exposed to potentially toxic concentrations of combustible materials, particular precautions,which are outside the scope of this standard, should be applied.For the purpose of deciding whether a particular requirement of this standard is complied with, the final value,observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance withIS 2:1960 Rules for rounding off numerical values (revised). The number of significant places retained inthe rounded off value should be the same as that of the specified value in this standard.


3/12

IS 5571:2000

Indian StandardGUIDE FOR SELECTION OF ELECTRICALEQUIPMENT FOR HAZARDOUS AREAS

(Second Revision)1 SCOPE1.1 This standard provides guidance for selection ofelectrical equipment for hazardous areas.1.1.1 This standard does not ap~ly to:

a) the areas in undergkmnd mines,b) the areas having ignitable dusts and fibres, andc) inhenmtly e~plbki~etitmospheres,for ex mple,

Axplosives manufa~t~~g and proces g.I II1.2 Precautionsttwltmay@ necessary against effectsof static electricity, , li$hltning, high frequencyelectromagnetic rits&thni and pyrophoric ignition arealso outside the scdpe of this standard.

NOTE Detailed guidance on protection against risk due tostatic electricity maylbe fourmdp IS 7689 and against lightningprotection in IS 2309.

2 REFERENCESThe list of Indian Standards given in Annex A arenecessary adjuncts to this standard.3 TERMINOLOGY AND EXPLANATIONS OFTERMSFor the purpose of this standard, -the followingdefinitions shall apply.3.1 Flash PointThe minimum temperature at which the liquid givesso much vapour that this vapour, when mixed with air,forms an ignitable mixture and gives a momentaryflash on application of a small pilot flame under thespecified conditions of test,3.2 Ignition TemperatureThe lowest temperature at which ignition occurs in amixture of explosive gas and air when the methodspecified in IS 7820 is followed.3.3 Maximum Surface TemperatureThe highest temperature attained under practicalconditions of operation within the rating of theapparatus and recognized overloads, and includingdefined fault conditions, if any, associated therewithby an accessitrle surface the exposure of which to anexplosive atmosphere may involve a risk,

NOTE For apparatus with type of protection d flameproofenclosure, the surface to be considered is the external surface.For apparatus with other types of explosion protection, internalsurfaces are equally important if the explosive gas/air mixturehas access to them.

3.4 Grouping of Flammable Gases and VapoursTheIndianStandardgroupclassification of flammablegases and vapours on the basis of maximumexperimentalsafe gas (MESG) andminimumignitingcurrents(MIC) is given in IS 9570.3.5 Temperature ClassA system of classification by which an electricalapparatus is allocated temperature classes accordingto its maximum surface temperature.The permitted maximum surface temperatures havebeen classified in IS 13346 as follows:lTemprature

~3.6 Enclosure Protection

i

T685C

The measures applied to the enclosures of apparatusto provide protection fo~a) persons against contact with live or movingparts inside the enclosure and protection forthe apparatus against ingress of solid foreignbodies; andb) the apparatus against ingress of liquids.

3.7 Degrees of Protection of EnclosuresThese have been defined in IS 4691 and 1S 13947reference to which should be made.3.8 Classification of Hazardous AreaThis standardis based on the concept of dealing withthe risk of tire and explosion by area classification.This concept recognizes the different degrees ofprobability with which explosive (flammable)concentrations of combustible gas or vapour may arisein installations in terms of both the frequency ofoccurrence and the probable duration of existence oneach occasion.

1


4/12

IS 5571:2000The detailed considerations which shall be taken intoaccount in area classification are described in IS 5572.For completeness, the definitions appropriate to areaclassification are given below:

a) Zone O In which an explosive gas/air mix-ture iscontinuously present, or present for longperiods.b) Zone 1 In which an explosive gas/air mix-ture is likely to occur in normal operation.c) Zone 2 In which an explosive gas/air mix-ture is not likely to occur in normal operation,and if it occurs, it will exist only for a shorttime.

4 STATUTORY REQUIREMENTSAttention is invited to the fact that the manufacture anduse of electrical equipment in the country is controlledby the concerned statutory authorities for the area oftheir jurisdiction. The statutory authorities, at present,are:a) The Directorate General of Mines Safety,Dhanbad (Bihar);b) The Chief Controller of Explosive, Depart-ment of Explosives, Nagpur (Maharashtra);and

c) The Directorate General Factory AdviceServices and Labour Institutes, Mumbai(Maharashtra).The testing facilities for flameproof electricalapparatus are available, at present, in the CentralMining Research Institute, Dhanbad.5 ELECTRICALEQUIPMENTFORCLASSIFIED AREAS5.1 Procedure for Selecting Electrical EquipmentFollowing factors shall be considered for properselection of electrical apparatusand equipment forareaswhere flammable gas or vapour risks may arise:a) Area classijkation, that is, Zone O,1 or 2.

b) -Gas group classification, that is, gas group.The characteristics of the gas or vapour in-volved in relation to:1) igniting current or minimum ignitionenergy in case of installations of intrin-sically safe apparatus, or2) maximum Experimental Safe Gap datain case of installations for flameproof

enclosures.as per IS 2148.c) Temperature classificationThe ignition temperature of the gas or vapourinvolved, or the lowest value of ignitiontemperature if more than one combustiblematerial is present.The maximum surface temperature of any un-protected surface of electrical equipment

d)

should not exceed the ignition temperature ofthe gas or vapour. For electrical apparatus, nomargin of safety need be applied between max-imum surface temperature and ignitiontemperature. The ignition temperature ofcombustible gases and vapours are measuredin accordance with the test method prescribedin IS 7820.Environmental conditions in which aD-paratus is installed. Apparatus and its co;-ponent parts should be constructed so as toguard against electrical and mechanicalfailures in the intended conditions of use.Particular attention should be given to the needfor protection against the weather, the ingressof liquids and particulate matter, corrosion, theeffect of solvents and of heat from adjacentequipment.

For further details reference may be made to IS 13408(Part l&6 SELECTION OFTYPE OF PROTECTIONSThe selection of type of protection of electricequipment for different zones of hazardous areas shallbe made in accordance with Table 1.Table 1 Selection of Apparatus According to

Zone of RiskZone Type of Protection Ref to

IS No.

o L 5780I Any explosion protection

sui~able for Zone Oandd 2148ib 5780o (see Note 1, Table 2) 7693p(see Note 2, Table 2) 7389 (Part 1),,q 7724,,s

2 Any explosion protectionsuitable for Zones Oor 1 ande (see Note 2, Table 2) 6381n (see Note 2, Table 2) 8289p (see Note 2, Table 2) 7389 (Part 1)

NOTE For definitions of types of protections, refer IS ]MUor above referred standards.

7 SELECT-IONOF APPA&fTUS7.1 Requirementof electrical equipment installed inhazardousareasare indicated inTable 2.

2


5/12

IS 5571:2000Table 2 Features of Electrical Equipment(Clause7.1)

Equipment Zone O Zone 1 Zone 2i) Motors . . ,,, ,. . . . . ... . . . .. . .. . . . . . ., s.-.No motor snail oe useo aj motor wm :ype or protection o

in this area b) Motors witlitype of protection pa) Moror suname rormne I areab) Motors with type ofprotection n and e.However ail normally sparkingparts such as slip-rings andbrushes shall be provided withtype of protection d or p.Motors provided with acombination of the above formsof protection. For example,slip-ring motors in which themain enclosures and windings areoftype e but the normally sparkingparts of type d protection (see Note1)

ii) Transformersand capacitors

iii) Lighting fittings(see Note 2)

iv) Switchgearand control-gear

No transformer or a) All power and distribution trans-capacitor shall be used fororers and capacitors with type din this area protection

b) For control and instrumentationpurposes, type of protection itransformers and capacitors shallform part of a flameproof orintrinsically safe equipment

No lighting fitting shall All switches, circuit breakers, fusesbe used and other equipment shall be

housed inan enclosure with type dprotection.

No switchgear and All switches, circuit breakers, fusescontrolgear shall be and other equipment, the enclosureused. When not together with the enclosedpracticable use ty~ i apparatus shall be type dprotection protection.

Transformers and capacitors suitablefor zone 1 areas.Transformers and capacitors thatare dry type or containing liquidsthat need not have any specialenclosure provided that thefollowing requirements aresatisfied:a) Cable boxesshall be suitable forspecifid level of current and faultclearing time.b) Only off-circuit manuallyoperated tap changers shall beallowed with provision for lockingthe operating handle in position.c) Auxiliary devices shall beintrinsically safe or if they havesparking contacts,these shall be:i) TyP d or hermetically sealedii) under adequate head of oiliii) of mercury in glass type withadequate mechanical protectioniv) of enclosed break type or,alternatively, auxiliary devices maybe deleted or installed in a safe zonerendered safe by pressurization.d) Any other sparking accessories orswitches shall comply with therequirements for Zone 1 area.Where oil filled transformers areused, necessary precautions againstspread of tire (see IS 1646) shall becomplied with.a) Lighting fittings for Zone 1b) Lighting fittings with type ofprotection e or n.All equipment where arcing mayoccur under normal conditions ofoperation shall be type d, unlessthe interruption of current occurs ina hermetically sealed chamber andthe equipment is provided with ageneral purpose enclosure and alsoif the current internspting contactsare oil-immersed, enclosed breakswitches for lighting, etc, withflameproof breaking chamber,mercury in glass switches andenclosed break micmswitches.

3


6/12

Is 5571:2000Table 2 (Concluded)

v) Generators No generators shall be Generators with Type d and p Equipment suitable for Zone 1areas

vi) Diesel engines Un2,cceptttble

vii) Storagebatteries

used protection Generators with type nprotectionor e and having brush lessexcitation system and sparkingparts, if provided shall comply withZone 1 requirements.The use of permanently installeddiesel engines to be avoided.Equipment suitable in Zone 1 areas.

Shall not be used Storage batteries shall be of type eprotection (see Annex Cl,

The use of permanently installeddiesel engines to be avoided.Where necessary, they shall beprotected as given in Annex BStorage batteries shall not beinstalled inZone 1areas,except thosein portable torches where theenclosures housing the bulb, switchandbattery shall be flameproof type.

NOTES1 Motors intended for use inhazardous areas wbicb are tobe supplied atvarying frequency and voltage by a converter sh;dl be tested,

certified and approved as a unit in association with the converter.2 a) Lamps containing free metallic sodium, forexample, low pressuressodium va~rrr lamps) arenot permittedfor use in hazardousmtxs.s.b) Fluorescent tubes shall not k used or transported through areas with group IIC gases/vaprrs.

7.2 Even though, in general, use of increased safetyequipment in Zone 1 areas is not permitted, certainequipment having a combination of Ex (e) and Ex (d)protection or a combination of Ex (e) and hermeticallysealed apparatus may be used in Zone 1 areas,provided the Ex (e) protection is limited to thetermination of cable/wires only.7.3 Equipment having combination of various typesof protection, for example, Ex (e), Ex (i), Ex (d) mayalso be used in Zone 1 or Zone 2 areas provided thatthe sparking parts are having Ex (d) protection.7.4 Electric Heat Tracing

a)b)

c)

Electric heat tracers shall not be installed inZone O.Electric heat tracing system for installation inZone 1 areas shall be suitable and certified foruse in Zone 1 areas.Electric heat tracer and accessories for instal-lation in Zone 2 areas shall be suitable andcertified for use in Zone 2 areas.

8 GENERAL REQUIREMENTS8.1 Wiring System8.L1 Types of cables or wiring and systems whichmay be used for installation in h~zardous areas are:a) Cables drawn into screwed solid drawn orseamless conduit, andb) Cables or wires which are otherwise suitably

protected against mechanical damage.Requirements for the installation of power systemsmay not apply to the -installation of apparatus andsystems with type of protection i-intrinsic safety.For intrinsically safe circuits, there isnormally no needto have special enclosures for the conductors.However, some protection between conductors of

intrinsically safe circuits and those of any other systemshall be required asper IS 5780 to avoid the possibilityyof arcing occurring at the point of contact orelectrostatic or electromagnetic induction. Inaddition, the conductors shall be protected againstmechanical damage.The diameter of each strand of the conductor shall benot less than 0.300 mm.of copper or equivalent size ofconductor specified in IS 9968 (Part 1) or IS 9968(Part 2) in the case of aluminium conductors.For (b) the following types of cables maybe used inprinciple:a)

b)

c)d)

e)

Thermoplastic or elastomer insulated,screened or armoured cable without 2 leadsheath and with polyvinyl chloride


7/12

a result of its rigidity or where corrosion orexcessive internal condensation of moisture islikely to occur. Sealing conduits withpourable epoxy to be used within 450 mmof the opening entry to prevent pressurepiling.b) PVC insulated and armoured cable, com-plying with IS 1554 (Part 1) and/or XLPEinsulated. and armoured cable, complyingwith IS 7098 (Part 1), IS 7098 (Part 2) with anextruded plastic outer sheath may be used forabove ground or underground installation.Lead sheathed cable should be used wherespillages may affect the integrity of the cableand/or allow migration of the liquid throughthe cable.c) For telecommunication circuits, plastic in-sulated and armoured telephone cablescomplying, where applicable, with theappropriate Indian Standards may be used.

8.2 Flexible Cables8.2.1 Flexible cables for portable and transportableapparatusmay be protected by a poiychloroprene,PVC or similar sheath, and may have an overallflexible metallic screen. Where necessary, anadditional earth continuity conductor should beincorporated. It should be insulated to the samestandards as the live conductors, and should beincorporatedwithin the cable sheath. The earthcontinuity conductor and screen should be bonded tothe appropriate metal work of the apparatus and to theearthing pin of the plug.For portable and transportable apparatus with ratedvoltages not exceeding 650 V, the supply cablesshould be of heavy duty type.For portable apparatus with rated current and voltage,not exceeding 1.6 A and 250 V respectively, mediumduty supply cables may be used. The conductorsshould be of copper having a minimum cross-sectionalarea of 1.5 mm2.

NOTE Flexible cables with aluminium conductors-shall notbe permissible to be used in hmndous areas.

8.2.2 An effective cable clamping device, sodesignedas not to damage the insulation of the flexible cable,should beprovided at the points of entry of the flexiblecable to the apparatus and plug. In addition, meansshould be provided to prevent sharp bending of thecable at both points of entry.8.3 Portable Apparatus8.3.1 Portable Hand-LumpsPortable hand-lamps (whether self-contained or mainsoperated) shall be either flameproof or intrinsicallysafe. Torches shall be intrinsically safe and shall

IS 5571:2000conform to IS 5780. They shall be designed in such amanner that hot filament ignition problem is avoided.8.3.2 Portable Apparatus with Permanent WiringThe connections for portable and transportableapparatus shall be in accordance with the requirementsgiven in 7.1.8.3.3 Telephone and Other CommunicationEquipment and Allied InstrumentsThese equipment shall be either of the intrinsicallysafe type or flameproof or increased safety type withsparking parts enclosed in flameproof enclosure.8.3.4 Portable and Trartsportable Apparatus and ItsConnections

a)b)

c)

Only certified portable electrical apparatusshould be used in a hazardous area.Flameproof switched sockets and plugs shouldincorporate suitable electrical and/or mechani-cal means interlock to prevent danger of igni-tion during the insemionor removal of the plug.Apart from self-powered apparatus and fromhand lamps whi~h shall meet above require-ments, earth-leakage protection, or earth-monitoring or both, should be included in theprotection of the apparatus. Protection of thecirculating current type which automaticallycuts off the supply tin the event of the earthcontinuity conductor becoming disconnected,may with advantage, be adopted as the earth-monitoring device.

8.4 Light Metal as Constructional MaterialsParticular consideration should be given to thelocation of apparatus which incorporates aluminiumor light alloys in the construction of its enclosure. Thepropensity for such materials to give rise to sparkingwhich is incendive under conditions of frictionalcontract has been well established. Suitableprecautions should, therefore, be taken to ensure thatsuch frictional contact is avoided.8.4.1 The term light metal refers to such materials asaluminium, magnesium and titanium which arecharacterized by their ability where produced in finelydivided form due to impact, friction or frictionalimpact to react exothermically with atmosphericoxygen and as a result to ignite a flammableatmosphere. The term light alloy refers to an alloycontaining at least 5.0 percent of a light metal byatomic proportions. Light metal alloy used forconstruction of flameproof enclosures should fulfilrequirements of 9.0 of IS13346.8.4.2 Provided that the protective cowls for lightmetal fans (for example, on motors) are designed sothat they are not readily deformed, such fans may beused in Zone 2 areas since other modes of failure (for


8/12

Is 5571:2000example, bearing failure) are more likely tocreate asource of ignition. If non-metallic fans or cowls areused as alternatives, they should be of anti-staticmaterial.8.4.3 For internal wiring copper is to be used but forexternal connections aluminium maybe used.8.5 Enclosures of Plastic Non-metallic MaterialNon-metallic materialplasticused foreclosures shallhave mechanical, electrical, thermal and chemicalproperties suitable for the application. In particular,the comparative tracking index (see IS 2824) of thematerial shall not be less than 500 V and thetemperature index of the material (see IS 8504) shallbe atleast 10C above the maximum servicetemperature. The plastic material shall haveself-extinguishing property (see IS 4249).Enclosures made of plastic material shall bedimensionally stable for the storage and servicecondhions.

NOTE Moisture absorption under humid conditions canaffect the dimensional stability of plastic components.

Special care muy be necessary in the selection of thematerial and in the design of the enclosure.

Enclosures of plastic material shall be thermallystable, the relevant type tests are specified in thethreaded holes inenclosures for fasteners which securecovers intended to beopened in service for adjustment,inspection and other operational reasons shall be oneof the following types:

a)

b)

c)

Tapped metal inserts for metal fasteners,The inserts shall be permanentlyfixed in the plastic material of theenclosure,Tapped holes in plastic enclosures for metalfasteners,The thread forin shall be compatible with theplastic material, andTapped holes in plastic enclosures for plasticfasteners.The thread form and the plastic materials shallbe compatible and of adequate strength anddurability.


9/12

IS 5571:20004

IS No.1554(Part 1): 1988(Part 2): 1988

2148:19812309:1988

2824:1975

3043:19874249:1967

4691:1985

5572:1994

5780:1970

6381:1972

ANNEX A(Clause 2)

LIST OF REFERRED INDIAN STANDARDS

TitlePVC insulated (heavy duty)electric cables:For working voltages up to andincluding 1 100 VFor working voltages from3.3 kV up to and includingllkVFlameproof enclosures ofelectrical apparatusPractice for the protectionof buildings and allied structuresagainst lighting Code ofpracticeMethod for determining thecomparative tracking index ofsolid insulating materials undermoist conditionsCode of practice for earthingClassification and methods oftests for non-ignitable and self-extinguishing properties -of solidelectrical insulatingmaterialsDegree of protection providedby enclosure for rotatingelectrical machineryClassification of hazardous areas(other than mines) havingflammable gases and vapours forelectrical installation (secondrevision)Intrinsically safe electricalapparatus and circuit electricalequipment with type ofprotection iConstruction and testing ofelectrical apparatus with type ofprotection e

ISNo.7098(Part 1): 1988(Part 2): 19857689:19897820:19738289:19768504 (Part 1):1994

9570:1980

.13346 :1992

13408 (Part 1):1992

TitleCrosslinked polyethyleneinsulated PVC sheathed cables:For working voltages up to andincluding 1 100 VFor working voltages from3.3 kV up to and including 33 kVGuide for the control ofundesirable static electricityMethod of test for ignitiontemperatureElectrical equipment with typeof protection nGuide for determination ofthermal endurance properties ofelectrical insulating materials:Part 1 General guidelines foraging procedures and evaluationof test resultsClassificationof flammable gasesor vapours with air according totheir maximum experimentalsafe gaps and minimum ignitingcurrentsGeneral requirements forelectrical apparatus forexplosive gas atmospheresCode of practice for theselection, installation andmaintenance of electicalapparatus for use in potentiallyexplosive atmospheres (otherthan mining application orexplosive processing andmanufacture) : Part 1 Generalrecommendations


10/12

Is 5571:2000ANNEX B(Table 2)

RECOMMENDATIONS FOR THE PROTECTION OF DIESEL ENGINE FORPERMANENT INSTALLATION IN HAZARDOUS AREAS

B-O To ensure a maximum degree of safety in theevent of a permanently installed diesel engine beingnecessary in Zone 1 or 2 it is recommended that itshould have the following protection.B-1 The starter shall be either of flameproof electricaltype (usually operated from the mains supply) or of thefollowing non-electric types:

a) Pneumatic,b) Hydraulic,c) Spring recoil,d) Inertia, ore) Hand start.

Any other electrical equipment associated with theengine shall be flameproof. Electrical equipment shallbe effectively earthed and bonded.B-2 Cooling fan blades shall bemadefrom non-metallicmaterials wh~chdo not accumulate electrostatic charge.B-3 All belts shall be of antistatic fire resistant type.B-4 In order to contain discharge of sparks or flamesfrom the exhaust system, a gas conditioner box and aflame Irap -shall be installed. Alternatively, theexhaust should be designed to discharge to a locationwithin a safe area.B-5 To prevent flashback through induction system,wherever possible, air intakes for engines shall belocated in a safe area. Alternatively, a flame trapshould be installed.B-6 The surface temperature of the engine andexhaust system shall not exceed 250C when testedunder full load conditions. In some situations coolingof the exhaust manifold and piping maybe necessary,using water jacketing or finned coolers and/or hightemperature cut-outs or alarms should be provided.However, when either the free movement of air isrestricted by thermal or acoustic shielding or theignition temperature of the surrounding flammableatmosphere is below 200C, exposed surfacetemperature of engine shall not exceed the minimumignition temperature of the gases involved.

B-7 To prevent overspeeding of the engine due toinduction of flammable gases or vapours, means shallbe provided to stop the engine. It can be eithe~a) a valve to close the air intake, orb) a system to inject carbon dioxide into the airintake.

B-8 Alarms or automatic shutdown devices shall beprovided, activated by excessive water temperatureand low lube-oil pressure.B-9 A system using an alarm or trip device to protectthe engine from excessive vibration should beconsidered.B-10 An engine having a crankcase volume of over0.5 m3 shall beprovided with relief devices. Reliefvalves or breathers on engines shall be fitted withflame traps or discharge into the induction systemdownstream of the flame trap, if fitted, and upstreamof the shut-off valve, if fitted, as specified in B-7.Dipsticks and/or filler caps should be screwed oreffectively secured by other means.B-n Intakeandexhaust systemdesign shallmeetthefollowing minimumrequirements:

a)b)

c)

d)

The length of the flame path through or acrossany joint shall be not less than 13 mm,Suitable metal-clad or other acceptable joint-ing material shall be interposed between alljoint faces to ensure that leakage does notoccur,Where valve spindles pass through thewalls of any component of the inductionsystem. The diametrical clearance shall notexceed 0.13 mm for an axial length of not lessthan 25 mm unless end caps are fitted, andNo screw, stud or bolt-hole shall pass throughthe wall of any component of the system.

B-12 Decompression system should not normally beprovided. However, if they are essential, then thedecompression parts should be provided with flametraps and ducted away to safe area.B-13 The fuel injection pump and governor, wherefitted, should be so designed that reverse running ofthe engine is not possible.


11/12

IS 5571:2000ANNEX C(Table 2)

RECOMMENDATIONS FOR STORAGE BATTERIES FOR USE IN ZONE 2 AREASC-O Storage batteries for use in Zone 2 atms shall beof increased safety type. These shall meet thefollowing requirements.C-1 Celluloid and similar combustibles shall not betrsedas constructional materials.C-2 Battery containers as well as fittings andinsulating parts outside the enclosed cells shall notconsist of porous materials, for example, wood orother flammable materials and shall be resistant toflame and the action of electrolytes.C-3 Openings of cells necessary for the escape of thegases given off shall be so constructed as to preventsplashing of the electrolyte.C-4 The exterior of the cells shall-be so constructedas to resist impact and the cell cases shall be firmlyfixed.C-5 The cells shall be so built into the containers thatloose working of connection of the cells with oneanother is impossible and normally a discharge voltageexceeding 24 volts shall not appear between adjacentrows of cells.The creepage distance between two poles of adjacentcells shall not be less than 35 mm. Where thedischarge voltage exceeds 24 volts, the creepagedistance shall be correspondingly increased by 1 mmper 2 volts.

Where voltage of batteries is not less than 50 volts,either the battery case shall be sub-divided bypartitions or the batteries shall be grouped intocontainers so that in no grouping does a voltageexceeding 50 volts occur. In these cases, the partitionsor the containers shall have heights at least half that ofthe battery case.C-6 The battery case shall be so constructed as toensure sufficient ventilation in order to preventaccumulation of gases given off from the battery andthe free space within the case shall be as small aspossible.C-7 The metallic cover of the battery case shall belined with materials resistant to electrolyte.C-8 The cover of the battery case shall have specialfastenings.C-9 Exposed live parts of battery contained in a caseshall be protected with rubber or equivalent insulatingmaterials. However, the opening for checking voltagemay be provided.

NOTE Charging of storage batteries shatl be conducted innon- hazardous location, while the cover of the battery enclosureis kept open.


12/12

Bureau of Indian StandardsBIS is a statutory institution established under the Bureau oj Zndian Standards Act, 1986 to promoteharmonious development of the activities of standardization, marking and quality certification of goodsand attending to connected matters in the country.CopyrightBIS has the copyright of all its publications. No part of these publications may be reproduced in any formwithout the prior permission in writing of BE3. This does not preclude the free use, in the course ofimplementing the standard, of necessary details, such as symbols and sizes, type or grade designations.Enquiries relating to copyright be addressed to the Director (Publications), BIS.Rwiew of Indian StandardsAmendments are issued to standards as the need arises on the basis of comments. Standards are also reviewedperiodically; a standard along with amendments is reaffirmed when such review indicates that no changes areneeded; if the re~iew indicates that changes are needed, it is taken up for revision. Users of Indian Standardsshould ascertain that they are in possession of the latest amendments or edition by referring to the latest issue ofBIS Catalogue and Standards: Monthly .Additions.This Indian Standard has been developed from Doc : No. ET 22( 3856).

Amendments Issued Since PublicationAmend No. Date of Issue Text Affected

BUREAU OF INDIAN STANDARDSHeadquarters :Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi 110002 Telegrams : ManaksansthaTelephones :3230131,3233375,3239402 (Common to all offices)

Regional Offices : TelephoneCentral : Manak Bhavan, 9 Bahadur Shah Zafar Marg{

3237617NEW DELHI 110002 3233841

Eastern : 1/14 C. I. T. Scheme VII M, V, I. P. Road, Kankurgachi{

3378499,3378561CALCUTTA 700054 3378626,3379120

Northern : SCO 335-336, Sector 34-A, CHANDIGARH 160022{

603843602025Southern : C. I. T. Campus, IV -Cross Road, CHENNAI 600113

{2350216,235 W 422351519,2352315

Western : Manakalaya, E9 MIDC, Marol, Andheri (East){

8329295, %327858MUMBAI 400093 8327891,8327892

Branches : AHMADABAD, BANGALORE. BHOPAL. BHUBANESHWAR. COIMBATORE.FARIDABAD. GHAZIABAD. GUWAHATI. HYDERABAD. JAIPUR. KANPUR.LUCKNOW. NAGPUR. PATNA. PUNE. RAJKOT. THIRUVANANTHAPURAM.Printed at : Frahhat Offset Press, New Delh;~2

is 5571- selection of electrical installation for hazardous

Documents