inspection of electrical eqpuipment in hazardous area

8/17/2019 Inspection of Electrical Eqpuipment in Hazardous Area

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Inspection of ElectricalEquipment in Hazardous

area


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Electrical Sparks

To ignite a ammable mixture ofhydrogen and air requires only

2 micro !oules" the energyproduced as a result of a breakof #$ mS duration in a circuitcarrying 2m% in $ The'oltage le'el has an inuence onho( incendi'e a spark (ill be#

)lammable gases and 'apours aremore readily ignited at high

'oltages than of lo( 'oltages"and is basically (hy IS circuitsare seldom designed from useabo'e *


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Hot SurfacesThe o( of current through" forexample the (indings of anelectric motor in'ariably producesheat (hich (ill raise the surfacetemperature of the motor# If the

motor is excessi'ely o'erloadedand the thermal o'erload de'iceis incorrectly set" the surfacetemperature of the motor may(ell exceed it+s T,rating#


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-atteries

-atteries are a potential source ofignition as they (ill produce

incendi'e sparks if theirterminals are short,circuited#.urrent of the order of $%can be generated

if the terminals of a car battery areshort,circuited# The certi/cationof portable equipment may onlyallo( their use in hazardous

areas if po(ered by lo(,po(erbatteries# 0eplacement ofbatteries must only be carriedout in non,hazardous areas#


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)riction1

The abrasi'e (heels ofportable grinding machinesare more capable ofproducing incendi'esparks" and hot surfaceslocally at the point ofcontact by the abrasi'e

(heel# o(er tools unlesscerti/ed shall not be usedin hazardous areas#


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3echanical Impact

The combination of rusty iron orsteel" aluminium and impactbet(een the t(o is a likelysource ignition of ignition"kno(n as thermite action" (hichcan produce sparks capable of

igniting a ammable gas or'apor# %luminium ladders aretypically not used in hazardousareas due to fact#


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HAZARDOUS AREAS

Hazardous areas are those areas (here there is a risk 4continuous or

intermittent5 of the presence of a ammable atmosphere arising from drillior (ell6testing operations#

These areas are further classi/ed in three zones#

7one

7one $

7one 2


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HAZARDOUS AREA – ZONE CLASSIFICATION

The 8egree of Explosion Hazard at a particular place has been clainto three principal zones 4 as per IS199:2" IE.1:;6$5" depend

upon the probability of formation of potentially explosi'e mixt'iz#"

• Zones 0 (Div. 0): Areas !ere an E"#$osive %as A&'os#!ere is #resen& a&i'e i&! ver !i! #ro*a*i$i& o+ e"#$osion !a,ar-. No E$e&ria$ 'o&ora$$oe- &o *e /se-.

• Zone I ( Div. I): Areas !ere a''a*$e ases are #resen& oasiona$$ a

e"#$osion 'a *e #resen& /n-er -/rin nor'a$ o#era&ion. E$e&ria$ 1oi&! e"#$osion on&ain'en& (E"2-2) or i&! E"#$osion 3reven&ion ( E" 4#a$$oe- &o *e /se-.

• Zone II ( Div II ): Areas !ere an E"#$osive %as A&'os#!ere is no& $i5e$ o/r -/rin nor'a$ o#era&ion an- i+ i& -oes i& is on$ +or s!or& #erio-.E$e&ria$ 1o&ors i&! Inrease- Sa+e& +ea&/res ( E" 4e26 E" 4n2 ) are a$$o

*e /se-.


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RE7UIRE1ENTS OF DRI8E 1OTORS FORHAZARDOUS AREAThe basic principle behind the explosion protection includes the techniques

pre'ent the simultaneous occurrence of formation of explosi'e mixture arelease of energy in su


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I13ORTANT TER1INOLO%9 – FLA1E 3ROOF1ACHINES

!oint1 T!e #$ae !ere orres#on-in s/r+aes o+ -ieren& #ar&s o+ an en$os/re'a&e6 an- &!e a'e #a&!s +ro' insi-e &o o/&si-e o+ &!e en$os/re is -e;ne-

a$on &!is o''on s/r+aeCength of e=ecti'e ame path1 4(idth of the Doint5 1 T!e s!or&es&

/nin&err/#&e- -is&ane 'eas/re- a$on &!e i-&! o+ &!e


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FEATURE OF NON=S3AR>IN% E?2N2 1OTORS• Non= s#ar5in ( vi*ra&ion #roo+ &er'ina$s)

• A-e@/a&e Cree#ae -is&ane an- $earanes.

• A-e@/a&e &i!&ness o+ ro&or *ars in &!e s$o&s an- *ra,e- en- rins &o #reven& s#ar5in !i$

s&ar&in.

• A-e@/a&e $earane *e&een s&a&or an- ro&or.

• A-e@/a&e a"ia$ an- ra-ia$ $earane *e&een &!e +an neares& s&a&ionar #ar&s.

• I3 en$os/re * vir&/e o+ &!e $oa&ion

• Ter'ina$ *o" &o i&!s&an- &!ro/! +a/$& i&!o/& -a'ae

• Res&ri&ion o+ s/r+ae &e'#era&/re &o B00 -e. C +or &e'#era&/re $ass T -/rin nor'a$o#era&ion.

S/r+ae &e'#era&/re $i'i&a&ion is no& a##$ia*$e &o a*nor'a$ o#era&ion i.e. s&ar&in on-i&ion/n$ess i& is #ar& o+ &!e -/& $e.


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FEATURES OF 3RESSURIZED E?232 1OTORS

T!e *asi #rini#$e o+ #ress/ri,e- 'o&ors is &o #reven& &!e inress an- a/'/$a&ions o+ e"#$o

'i"&/re i&!in &!e en$os/re * a-o#&in +o$$oin 'eas/res:

• A #ro&e&ive as ( iner& as or air) is on&in/o/s$ 'ain&aine- a& a 'ini'/' over#ress/re a*o+ e"&erna$ a&'os#!ere. T!is is 5non as 3ress/ri,a&ion i&! $ea5ae o'#ensa&ion or #ress/ri,a&ion as #er IS G.

• A #ro&e&ive as in s/Jien& @/an&i& is s/##$ie- on&in/o/s$ &o &!e 'o&or en$os/re &o -i$/onen&ra&ion o+ e"#$osive as 'i"&/re.

In &!e even& o+ $oss o+ #ress/re o+ +ai$/re in s/##$ o+ #ro&e&ive as6 &!e #oer s/##$ &o &!e '&o *e /& o. T!e 'o&or s!o/$- *e #/re- i&! #ro&e&ive air * a& $eas& ;ve &i'es &!e +rees#ae vo$/'e i&!in &!e en$os/re a+&er $oss o+ #ress/ri,a&ion. 3/rin is 'ean& &o -rive o/!a,ar-o/s as 'i"&/res !i! 'a !ave see#e- in&o &!e en$os/re !i$e &!e 'o&or as a

In or-er &o on&in/o/s$ s/##$ an- re/$a&e &!e #ro&e&ive air as &o &!e 'o&or en$os/re6 aso#!is&ia&e- #ress/re on&ro$ /ni& is 'o/n&e- on &!e 'o&or. A 'ini'/' air #ress/re o+ '0. '*ar is 'ain&aine-).


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TKO 3ROTECTION T93ES

Exp 6 ressurisationThe system is only safe once purged and remaining at a pressure abo'e the

outside pressure#

%n alarm needs to be /tted for loss of pressure#

Separate the gas from the hot components

-reak the /re triangle by separation#


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Exd Explosionroof %n Explosion IS %llo(ed I?SI8Ethe enclosure#

3aintained )lamepaths

%ll bolts secured?B ignition BTSI8E


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Exd Explosion roof Exd contains the explosion

% pipe ange contains the pressure

% pressure test on a pipe

% drip on a pipe is seen

%ny comparison#


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Exd Explosion roof % pipe ange contains the pressure

A Exd contains the explosion

% pressure test on a pipe

Check the famepath and bolts

% drip on a pipe can be seen

Gas getting in unseen

AND

The equipment still working

Co/n& &!e *o$&s

Co/n& &!e *o$&s &!a& arese/re

I& IS s&i$$ or5in

Is i& SAFE


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No& a Car&oonM


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inspection of electrical eqpuipment in hazardous area

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