1
I
l
5. MAINTENANCE AND INSPECTION
&;
Removal and evacuation
When breaking intothe refrigerant circuitto make repairs or for anyother
purpose
conventional
procedures
shallbe used. However, it isimportant that bestpractice is
followed since flammabilityis a consideration.The following
procedure
shall beadhered to:
. Remove refrigerant;
. Purge thecircuit with inertgas;
. Evacuate;
. Purge againwith inert
gas;
.
Open the
circuit
by
cutting or
brazing.
The refrigerant chargeshall
be
recoveredinto the correctrecovery
cylinders.The system
shall be
"flushed"with
OFN torender the unitsafe. This
process
may needto be repeated
several times. Compressed air or oxygen shall not be
used
for thistask.
Flushing shall beachieved by
breakingthe
vacuum inthe system withOFN and continuing
to fill untilthe
working
pressureis
achieved,
thenventing
to atmosphere,and finally
pulling
down to avacuum.
This
process
shall
berepeated until norefrigerant is withinthe system.
When the final OFN charge
isused,
the
systemshall be venteddown to atmospheric
pressure
to enablework to takeplace.
Thisoperation is absolutelyvital if brazing
operations on
the
pipe-work
are
totake
place.
Ensure that theoutlet for thevacuum
pump
isnot
close
toany
ignition
sourcesand there
is
ventilation available working on them.
§i
Labeiling
Equipment shall
belabelled
stating thatit has beende-commissioned and emptiedof
refrigerant.
The
label
shall bedated and signed. Ensure that there
are labels
on
the
equipment stating theequipment contains
flammablerefrigerant.
Recovery
When removing refrigerantfrom a system,eitherfor
servicingor decommissioning, itis
recommended
good practicethat
all
refrigerantsare removed safely.
When transferring
refrigerantinto cylinders, ensurethat only appropriaterefrigerant
recovery cylinders areemployed.
Ensure thatthe correct numberof
cylinders forholding
the total systemcharge
is available.All cylindersto be usedare designated forthe
recovered refrigerant and labelled for that
refrigerant
(i.e.
special
cylinders for the recovery
of refrigerant). Cylindersshall be completewith
pressure
reliefvalve and associatedshut-
off valvesin
good
workingorder. Emptyrecovery cylinders areevacuated and,
if
possible,
cooled before
recoveryoccurs.
The recovery equipmentshall be ingood
working orderwith a setof instructions
concerning the equipmentthat is athand and shallbe
suitable forthe recovery of
flammable refrigerants.
lnaddition, a setof calibrated weighingscales shall beavailable
and in
goodworking
order. Hoses shall
becomplete with leak-freedisconnect couplings
and in
goodcondition.
Before usingthe
recovery machine,check that itis in satisfactory
working
order, has been
properly
maintained and thatany associated
electrical
components are sealedto
prevent
ignitionin the eventof a refrigerantrelease.
Consult
manufacturer if in doubt.
The recovered refrigerantshall be
returned to the refrigerantsupplier
in
the correct
recovery cylinder, and the relevantWaste
Transfer Note arranged. Do not mixrefrigerants
in
recovery
unitsand especially notin cylinders.
lf compressors orcompressor
oils areto be removed,
ensure
that
theyhave been
evacuated to anacceptable
level tomake certain thatflammable refrigerant doesnot
remain within
the
lubricant.
The evacuation
process
shall be carried
out
prior
to
returning
the compressor tothe suppliers. Onlyelectric
heating tothe compressor bodyshall be
employed to acceleratethis
process.
Whenoil is drainedfrom a system,it shall becarried
out safely.
19
20
5. MAINTENANCE
AND INSPECTION
€!
Decommissioning
Before carrying
outthis
procedure,
itis essentialthatthe
technician iscompletely
familiirr
with the equipmentand
all itsdetail. lt isrecommended
good practicethat
all refrigerantr;
are recovered
safely. Priortothe task beingcarried
out, anoil
and
refrigerantsample
slr;rl
be taken incase
analysis isrequired
prior
tore-use
of reclaimedrefrigerant.
lt isessentiirl
that
electrical
poweris
available
beforethe task
iscommenced.
a) Become familiarwith
the equipmentand its
operation.
b)
lsolate system
electrically.
c) Before attemptingthe
procedure
ensurethat:
.
Mechanical handling
equipment is available,
if required, forhandling
refrigerant cylin<lr:r
.
Allpersonal
protective
equipmentis available
andbeing used
correctly;
. The recovery
process
issupervised
at alltimes by acompetent
person;
.
Recovery equipmentand
cylinders conformto
the appropriatestandards.
d) Pump down
refrigerant system,
if
possible.
e)
lf avacuum is notpossible,
make amanifold
so thatrefrigerant can beremoved from
various
parts
ofthe system.
f)
Make surethat
cylinder
issituated
on thescales
before recoverytakes
place.
g)
Start therecovery
machine
andoperate in accordancewith
manufacturer's instruction:;
h) Do notoverfill
cylinders.
(Nomore
than 80% volume liquidcharge).
i) Do notexceed
the maximumworking
pressure
ofthe
cylinder,even temporarily.
j)When
thecylinders have beenfilled
correctly
andthe
process
completed,make
sure lhir
the
cylinders andthe equipment
areremoved from
sitepromptly and allisolation valves or
the equipment
areclosed off.
k)
Recovered refrigerantshall
not becharged
into anotherrefrigeration
system unlessit
has
been cleanedand
checked.
@Charging
procedures
ln
addition toconventional charging
procedures,the
following
requirementsshall
be
followed.
- Ensure
that contamination
of different refrigerants does
notoccur when
using charginrl
equipment.
Hoses orlines shall
beas short
aspossible to minimisethe
amount of
refrigerant
contained in them.
-
Cylinders shall
be kept upright.
- Ensure that
therefrigeration
system
isearthed
prior
tocharging
the systemwith
refrigera
nt.
-
Label the systemwhen
charging iscomplete
(if
notalready).
- Extreme
care shallbe taken
notto overfill
therefrigeration
system.
Priorto rechargingthe
system
itshall be
pressuretested
with
OFN.The systemshall be
leak tested
oncompletion of chargingbut
prior
tocommissioning. Afollow
up leaktest shirl
be carried
outprior to leavingthe
site.
&The
safety wire
model is 5-20_5A/250VAC,And
must meetthe
explosion-proof
requirements
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