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Refrigerant Tracer
Carrier recommends the use of an environmentally acceptable
refrigerant tracer for leak testing with an electronic detector.
Ultrasonic leak detectors can also be used if the chiller is under
pressure.
WARNING
Do not use air or oxygen as a means of pressurizing the chiller.
Mixtures of HFC-134a and air can undergo combustion,
resulting in equipment damage and possible personal injury.
Leak Test Chiller
Due to regulations regarding refrigerant emissions and the diffi-
culties associated with separating contaminants from the refriger-
ant, Carrier recommends the following leak test procedure. Refer
to Tables 5 and 6 for refrigerant pressure/temperature values.
1.
If the pressure readings are normal for the chiller condition:
a. Evacuate the holding charge from the vessels, if present.
b. Raise the chiller pressure, if necessary, by adding refrig-
erant until pressure is at the equivalent saturated pressure
for the surrounding temperature. Follow pumpout proce-
dures in the Transfer Refrigerant from Pumpout Storage
Tank to Chiller section, Steps 1a-e, page 42.
c. Leak test chiller as outlined in Steps 3 to 9.
CAUTION
Never charge liquid refrigerant into the chiller if the pressure
in the chiller is less than 35 psig (241 kPa) for HFC-134a or
less than 39 psig (268 kPa) for R-513A. Charge as a gas only,
with the cooler and condenser pumps running, until this pres-
sure is reached, using PUMPDOWN/LOCKOUT (located in
the Maintenance menu) and TERMINATE LOCKOUT mode
on PIC6 control interface. Flashing of liquid refrigerant at low
pressures can cause tube freeze-up and considerable damage.
2.
If the pressure readings are abnormal for the chiller condition:
a. Prepare to leak test chillers shipped with refrigerant
(Step 2h).
b. Check for large leaks by connecting a nitrogen bottle and
raising the pressure to 30 psig (207 kPa). Soap test all
joints. If the test pressure holds for 30 minutes, prepare
the test for small leaks (Steps 2g and 2h).
c. Plainly mark any leaks that are found.
d. Release the pressure in the system.
e. Repair all leaks.
f. Retest the joints that were repaired.
g. After successfully completing the test for large leaks,
remove as much nitrogen, air, and moisture as possible,
given the fact that small leaks may be present in the sys-
tem. This can be accomplished by following the dehy-
dration procedure outlined in the Chiller Dehydration
section, page 25.
h. Slowly raise the system pressure to a maximum of
160 psig (1103 kPa) but no less than 35 psig (241 kPa)
for HFC-134a by adding refrigerant (below 35 psig
refrigerant must be added as a gas). Proceed with the test
for small leaks (Steps 3 to 9).
3.
Check the chiller carefully with an electronic leak detector
or soap bubble solution.
4.
Leak Determination — If an electronic leak detector indicates
a leak, use a soap bubble solution, if possible, to confirm.
Total all leak rates for the entire chiller. Leakage at rates
greater than 0.1% of the total charge per year must be
repaired. Note the total chiller leak rate on the start-up report.
5.
If no leak is found during the initial start-up procedures,
complete the transfer of refrigerant gas from the storage
tank to the chiller. Retest for leaks.
6.
If no leak is found after a retest:
a. Transfer the refrigerant to the storage tank and perform a
standing vacuum test as outlined in the Standing Vacuum
Test section, below.
b. If the chiller fails the standing vacuum test, check for
large leaks (Step 2b).
c. If the chiller passes the standing vacuum test, dehydrate
the chiller. Follow the procedure in the Chiller Dehydra-
tion section, page 25. Charge the chiller with refrigerant.
7.
If a leak is found after a retest, pump the refrigerant back
into the storage tank or, if isolation valves are present,
pump the refrigerant into the non-leaking vessel. See the
Transfer Refrigerant from Pumpout Storage Tank to
Chiller section on page 42.
8.
Transfer the refrigerant until the chiller pressure is at
18 in. Hg (40 kPa absolute).
9.
Repair the leak and repeat the procedure, beginning from
Step 2h, to ensure a leak-tight repair. (If the chiller is
opened to the atmosphere for an extended period, evacuate
it before repeating the leak test.)
Standing Vacuum Test
When performing the standing vacuum test or chiller dehydration,
use a manometer or a digital vacuum gage. Dial gages cannot indi-
cate the small amount of acceptable leakage during a short period
of time.
1.
Attach an absolute pressure manometer or digital vacuum
gage to the chiller.
2.
Evacuate the vessel to at least 18 in. Hg vac (41 kPa
[abs]), using a vacuum pump or the pumpout unit.
3.
Valve off the pump to hold the vacuum and record the
manometer or indicator reading.
4.
Check the leakage rate.
a. If the leakage rate is less than 0.05 in. Hg (0.17 kPa) in
24 hours, the chiller is sufficiently tight.
b. If the leakage rate exceeds 0.05 in. Hg (0.17 kPa) in
24 hours, re-pressurize the vessel and test for leaks if
refrigerant is available. If not, use nitrogen and a refrig-
erant tracer. Raise the vessel pressure in increments
until the leak is detected. If refrigerant is used, the max-
imum gas pressure is approximately 70 psig (483 kPa)
for HFC-134a at normal ambient temperature. If nitro-
gen is used, limit the leak test pressure to 160 psig
(1103 kPa) maximum.
5.
Repair the leak, retest, and proceed with dehydration.
23
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