En-2
CAUTION
2-2Work
Priortobeginningworkonsystemscontainingammablerefrigerants,safetychecks•
are necessary to ensure that the risk of ignition is minimized. For repair to the refrig-
erating system, the precautions in 2-2 to 2-8 shall be complied with prior to conduct-
ing work on the system.
Workshallbeundertakenunderacontrolledproceduresoastominimizetheriskof•
aammablegasorvapourbeingpresentwhiletheworkisbeingperformed.
Allmaintenancestaffandothersworkinginthelocalareashallbeinstructedonthe•
nature of work being carried out.
Workinconnedspacesshallbeavoided.•
The area around the workspace shall be sectioned off.•
Ensurethattheconditionswithintheareahavebeenmadesafebycontrolofam-•
mable material.
2-3 Checking for presence of refrigerant
The area shall be checked with an appropriate refrigerant detector prior to and during •
work,toensurethetechnicianisawareofpotentiallyammableatmospheres.
Ensurethattheleakdetectionequipmentbeingusedissuitableforusewitham-•
mable refrigerants, i.e. nonsparking, adequately sealed or intrinsically safe.
2-4Presenceofreextinguisher
If any hot work is to be conducted on the refrigeration equipment or any associated •
parts,appropriatereextinguishingequipmentshallbeavailableathand.
Have a dry powder or CO•
2
reextinguisheradjacenttothechargingarea.
2-5Noignitionsources
Nopersoncarryingoutworkinrelationtoarefrigerationsystemwhichinvolves•
exposinganypipeworkthatcontainsorhascontainedammablerefrigerantshall
useanysourcesofignitioninsuchamannerthatitmayleadtotheriskofreor
explosion.
Allpossibleignitionsources,includingcigarettesmoking,shouldbekeptsufciently•
far away from the site of installation, repairing, removing and disposal, during which
ammablerefrigerantcanpossiblybereleasedtothesurroundingspace.
Priortoworktakingplace,theareaaroundtheequipmentistobesurveyedtomake•
surethattherearenoammablehazardsorignitionrisks.“NoSmoking”signsshall
be displayed.
2-6Ventilatedarea
Ensure that the area is in the open or that it is adequately ventilated before breaking •
into the system or conducting any hot work.
Adegreeofventilationshallcontinueduringtheperiodthattheworkiscarriedout.•
Theventilationshouldsafelydisperseanyreleasedrefrigerantandpreferablyexpel•
itexternallyintotheatmosphere.
2-7 Checks to the refrigeration equipment
Whereelectricalcomponentsarebeingchanged,theyshallbetforthepurpose•
andtothecorrectspecication.
Atalltimesthemanufacturer’smaintenanceandserviceguidelinesshallbefollowed.•
If in doubt consult the manufacturer’s technical department for assistance.•
Thefollowingchecksshallbeappliedtoinstallationsusingammablerefrigerants.•
- The charge size is in accordance with the room size within which the refrigerant
containing parts are installed.
- The ventilation machinery and outlets are operating adequately and are not
obstructed.
- If an indirect refrigerating circuit is being used, the secondary circuit shall be
checked for the presence of refrigerant.
- Marking to the equipment continues to be visible and legible. Markings and signs
that are illegible shall be corrected.
- Refrigeration pipe or components are installed in a position where they are unlikely
tobeexposedtoanysubstancewhichmaycorroderefrigerantcontainingcompo-
nents, unless the components are constructed of materials which are inherently
resistant to being corroded or are suitably protected against being so corroded.
2-8 Checks to electrical devices
Repair and maintenance to electrical components shall include initial safety checks •
and component inspection procedures.
Ifafaultexiststhatcouldcompromisesafety,thennoelectricalsupplyshallbecon-•
nected to the circuit until it is satisfactorily dealt with.
If the fault cannot be corrected immediately but it is necessary to continue operation, •
an adequate temporary solution shall be used.
This shall be reported to the owner of the equipment so all parties are advised.•
Initial safety checks shall include.•
-Thatcapacitorsaredischarged:thisshallbedoneinasafemannertoavoidpos-
sibility of sparking.
-Thattherenoliveelectricalcomponentsandwiringareexposedwhilecharging,
recovering or purging the system.
- That there is continuity of earth bonding.
CAUTION
3-Repairs to sealed components
Duringrepairstosealedcomponents,allelectricalsuppliesshallbedisconnected•
from the equipment being worked upon prior to any removal of sealed covers, etc.
If it is absolutely necessary to have an electrical supply to equipment during servic-•
ing, then a permanently operating form of leak detection shall be located at the most
critical point to warn of a potentially hazardous situation.
Particularattentionshallbepaidtothefollowingtoensurethatbyworkingonelectri-•
cal components, the casing is not altered in such a way that the level of protection is
affected.
Thisshallincludedamagetocables,excessivenumberofconnections,terminalsnot•
madetooriginalspecication,damagetoseals,incorrectttingofglands,etc.
Ensure that apparatus is mounted securely.•
Ensure that seals or sealing materials have not degraded such that they no longer •
servethepurposeofpreventingtheingressofammableatmospheres.
Replacementpartsshallbeinaccordancewiththemanufacturer’sspecications.•
NOTE:Theuseofsiliconsealantmayinhibittheeffectivenessofsometypesofleak
detection equipment.
Intrinsically safe components do not have to be isolated prior to working on
them.
4-Repair to intrinsically safe components
Donotapplyanypermanentinductiveorcapacitanceloadstothecircuitwithout•
ensuringthatthiswillnotexceedthepermissiblevoltageandcurrentpermittedfor
the equipment in use.
Intrinsically safe components are the only types that can be worked on while live in •
thepresenceofaammableatmosphere.
The test apparatus shall be at the correct rating.•
Replacecomponentsonlywithpartsspeciedbythemanufacturer.•
Other parts may result in the ignition of refrigerant in the atmosphere from a leak.•
5-Cabling
Checkthatcablingwillnotbesubjecttowear,corrosion,excessivepressure,vibra-•
tion, sharp edges or any other adverse environmental effects.
The check shall also take into account the effects of aging or continual vibration from •
sources such as compressors or fans.
6-Detectionofammablerefrigerants
Undernocircumstancesshallpotentialsourcesofignitionbeusedinthesearching•
for or detection of refrigerant leaks.
Ahalidetorch(oranyotherdetectorusinganakedame)shallnotbeused.•
7-Leak detection methods
Electronicleakdetectorsshallbeusedtodetectammablerefrigerants,butthe•
sensitivitymaynotbeadequate,ormayneedre-calibration.(Detectionequipment
shallbecalibratedinarefrigerant-freearea.)
Ensure that the detector is not a potential source of ignition and is suitable for the •
refrigerant used.
Leak detection equipment shall be set at a percentage of the LFL of the refrigerant •
and shall be calibrated to the refrigerant employed and the appropriate percentage of
gas(25%maximum)isconrmed.
Leakdetectionuidsaresuitableforusewithmostrefrigerantsbuttheuseof•
detergents containing chlorine shall be avoided as the chlorine may react with the
refrigerant and corrode the copper pipe-work.
Ifaleakissuspected,allnakedamesshallberemoved/extinguished.•
If a leakage of refrigerant is found which requires brazing, all of the refrigerant shall •
berecoveredfromthesystem,orisolated(bymeansofshutoffvalves)inapartof
the system remote from the leak.
Oxygenfreenitrogen(OFN)shallthenbepurgedthroughthesystembothbefore
and during the brazing process.
8-Removal and evacuation
Whenbreakingintotherefrigerantcircuittomakerepairs–orforanyother •
purpose–conventionalproceduresshallbeused.
However,itisimportantthatbestpracticeisfollowedsinceammabilityisaconsid-
eration.
Thefollowingprocedureshallbeadheredto:
remove refrigerant•
purge the circuit with inert gas•
evacuate•
purge again with inert gas•
open the circuit by cutting or brazing•
The refrigerant charge shall be recovered into the correct recovery cylinders. •
Thesystemshallbe“ushed”withOFNtorendertheunitsafe.•
This process may need to be repeated several times. •
Compressedairoroxygenshallnotbeusedforthistask.•
FlushingshallbeachievedbybreakingthevacuuminthesystemwithOFNand•
continuingtolluntiltheworkingpressureisachieved,thenventingtoatmosphere,
andnallypullingdowntoavacuum.
This process shall be repeated until no refrigerant is within the system. •
WhenthenalOFNchargeisused,thesystemshallbeventeddowntoatmospheric•
pressure to enable work to take place.
This operation is absolutely vital if brazing operations on the pipe work are to take •
place.
Ensure that the outlet for the vacuum pump is not close to any ignition sources and •
there is ventilation available.
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