General Maintenance; Procedures; Refrigerant Properties; Adding Refrigerant - Carrier 17 Start Up & Operation Manual

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GENERAL MAINTENANCE

Refrigerant Properties —
refrigerant in the 17/19EX. At normal atmospheric pressure,
HFC-134a will boil at −14 F (−25 C) and must, therefore, be
kept in pressurized containers or storage tanks. The refrig-
erant is practically odorless when mixed with air. This re-
frigerant is non-combustible at atmospheric pressure. Read
the Material Safety Data Sheet and the latest ASHRAE Safety
Guide for Mechanical Refrigeration to learn more about safe
handling of this refrigerant.
HFC-134a will dissolve oil and some non-metallic
materials, dry the skin, and, in heavy concentrations, may
displace enough oxygen to cause asphyxiation. In han-
dling this refrigerant, protect the hands and eyes and avoid
breathing fumes.
Adding Refrigerant —
scribed in Charge Refrigerant into Machine section, page 57.
Always use the compressor pumpdown function in the
Control Test mode to turn on the evaporator pump and
lock out the compressor when transferring refrigerant.
Liquid refrigerant may flash into a gas and cause pos-
sible freeze-up when the machine pressure is below
30 psig (207 kPa) for HFC-134a.
Removing Refrigerant —
out system is used, the 17/19EX refrigerant charge may be
transferred to a storage vessel, or within the utility vessel.
Follow procedures in the Pumpout and Refrigerant Transfer
Procedures section when removing refrigerant.
Refrigerant Leak Testing —
above atmospheric pressure at room temperature, leak test-
ing can be performed with refrigerant in the machine. Use
an electronic detector, soap bubble solution, or ultra-sonic
leak detector. Be sure that the room is well ventilated and
free from concentration of refrigerant to keep false readings
to a minimum. Before making any necessary repairs to a leak,
transfer all refrigerant from the leaking vessel.
Leak Rate —
ASHRAE recommends that machines should
be immediately taken off line and repaired if the refrigerant
leakage rate for the entire machine is more than 10% of the
operating refrigerant charge per year.
Additionally, Carrier recommends that leaks totalling less
than the above rate but more than a rate of 1 lb (0.5 kg) per
year should be repaired during annual maintenance or when-
ever the refrigerant is pumped over for other service work.
HFC-134a is the standard
Follow the procedures de-
When the optional pump-
Because HFC-134a is
Test After Service, Repair, or Major Leak —
all refrigerant has been lost or if the machine has been opened
for service, the machine or the affected vessels must be pres-
sured and leak tested. Refer to the Leak Test Machine sec-
tion (page 48) to perform a leak test.
HFC-134a MUST NOT be mixed with air or oxygen
and pressurized for leak testing. In general, this refrig-
erant should not be allowed to be present with high con-
centrations of air or oxygen above atmospheric pressures,
as the mixture can undergo combustion.
REFRIGERANT TRACER — Use an environmentally ac-
ceptable refrigerant as a tracer for leak test procedures.
TO PRESSURIZE WITH DRY NITROGEN — Another
method of leak testing is to pressurize with nitrogen only
and use a soap bubble solution or an ultrasonic leak detector
to determine if leaks are present. This should only be done
if all refrigerant has been evacuated from the vessel.
1. Connect a copper tube from the pressure regulator on the
cylinder to the refrigerant charging valve. Never apply
full cylinder pressure to the pressurizing line. Follow the
listed sequence.
2. Open the charging valve fully.
3. Slowly open the cylinder regulating valve.
4. Observe the pressure gage on the machine and close the
regulating valve when the pressure reaches test level. Do
not exceed 140 psig (965 kPa).
5. Close the charging valve on the machine. Remove the
copper tube if no longer required.
Repair the Leak, Retest, and Apply Standing
Vacuum Test —
After pressurizing the machine, test for
leaks with an electronic leak detector, soap bubble solution,
or an ultrasonic leak detector. Bring the machine back to at-
mospheric pressure, repair any leaks found, and retest.
After retesting and finding no leaks, apply a standing vacuum
test, and then dehydrate the machine. Refer to the Standing
Vacuum Test and Machine Dehydration in the Before Initial
Start-Up section, pages 49 and 51.
Checking Guide Vane Linkage —
If slack develops in the drive chain, backlash can be elimi-
nated as follows:
1. With machine shut down (guide vanes closed), remove
chain guard, loosen actuator holddown bolts and remove
chain.
2. Loosen vane sprocket set screw and rotate sprocket wheel
until set screw clears existing spotting hole.
3. With set screw still loose, replace chain and move vane
actuator to the left until all chain slack is taken up.
4. Tighten actuator holddown bolts and retighten set screw
in new position.
5. Realign chain guard as required to clear chain.
67
If
Refer to Fig. 35.
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