General Maintenance; Refrigerant Properties; Adding Refrigerant; Adjusting The Refrigerant Charge - Carrier AquaEdge 19XR Start-Up, Operation And Maintenance Instructions Manual

GENERAL MAINTENANCE

Refrigerant Properties

The standard refrigerants for the 19XR chiller are HFC-134a/
R-513A. At normal atmospheric pressure, HFC-134a/R-513A
will boil at –14°F (–25°C)/ –28°F (–33°C) and must, therefore,
be kept in pressurized containers or storage tanks. The refriger-
ant is practically odorless when mixed with air and is noncom-
bustible at atmospheric pressure. Read the Material Safety Data
Sheet and the latest ASHRAE Safety Guide for Mechanical Re-
frigeration to learn more about safe handling of this refrigerant.
HFC-134a/R-513A will dissolve oil and some nonmetallic
materials, dry the skin, and, in heavy concentrations, may
displace enough oxygen to cause asphyxiation. When han-
dling this refrigerant, protect the hands and eyes and avoid
breathing fumes.

Adding Refrigerant

Follow the procedures described in Trim Refrigerant Charge
section, this page.
CAUTION
Always use the compressor pumpdown function in the
PUMPDOWN/LOCKOUT feature to turn on the cooler
pump and lock out the compressor when transferring refrig-
erant. Liquid refrigerant may flash into a gas and cause pos-
sible freeze-up when the chiller pressure is below 35 psig
(241 kPa) for HFC-134a or 39 psig (268 kPa) for R-513A.

Adjusting the Refrigerant Charge

If the addition or removal of refrigerant is required to improve
chiller performance, follow the procedures given under the
Trim Refrigerant Charge section, page 44.

Refrigerant Leak Testing

Because HFC-134a is above atmospheric pressure at room tem-
perature, leak testing can be performed with refrigerant in the
chiller. Use an electronic halogen leak detector, soap bubble solu-
tion, or ultrasonic leak detector. Ensure that the room is well venti-
lated and free from concentration of refrigerant to keep false read-
ings to a minimum. Before making any necessary repairs to a leak,
transfer all refrigerant from the leaking vessel.

Leak Rate

It is recommended by ASHRAE that chillers be taken off line
immediately and repaired if the refrigerant leak rate for the en-
tire chiller is more than 10% of the operating refrigerant charge
per year.
In addition, Carrier recommends that leaks totaling less than
the above rate but more than a rate of 0.1% of the total charge
per year should be repaired during annual maintenance or
whenever the refrigerant is transferred for other service work.

Test After Service, Repair, or Major Leak

If all the refrigerant has been lost or if the chiller has been
opened for service, the chiller or the affected vessels must be
pressure tested and leak tested. Refer to the Leak Test Chiller
section on page 23 to perform a leak test.
WARNING
HFC-134a/HFO-513A should not be mixed with air or oxy-
gen and pressurized for leak testing. In general, this refriger-
ant should not be present with high concentrations of air or
oxygen above atmospheric pressures, because the mixture
can undergo combustion.
DANGER
TESTING WITH REFRIGERANT TRACER
Use an environmentally acceptable refrigerant as a tracer for
leak test procedures. Use dry nitrogen to raise the machine
pressure to leak testing levels.
TESTING WITHOUT REFRIGERANT TRACER
Another method of leak testing is to pressurize with nitrogen
only and to use a soap bubble solution or an ultrasonic leak de-
tector to determine if leaks are present.
TO PRESSURIZE WITH DRY NITROGEN
NOTE: Pressurizing with dry nitrogen for leak testing should
not be done if the full refrigerant charge is in the vessel be-
cause purging the nitrogen is very difficult.
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 chiller and close the reg-
ulating valve when the pressure reaches test level. Do not
exceed 140 psig (965 kPa).
5. Close the charging valve on the chiller. Remove the cop-
per tube if it is no longer required.
Repair the Leak, Retest, and Apply
Standing Vacuum Test
After pressurizing the chiller, test for leaks with an electronic
halide leak detector, soap bubble solution, or an ultrasonic leak
detector. Bring the chiller back to atmospheric pressure, repair
any leaks found, and retest.
After retesting and finding no leaks, apply a standing vacuum
test. Then dehydrate the chiller. Refer to the Standing Vacuum
Test and Chiller Dehydration sections (pages 23 and 25) in the
Before Initial Start-Up section.

Checking Guide Vanes

During normal shutdown, when the chiller is off, the guide
vanes are closed. Check that the coupling is tight on the shaft
and make sure that the guide vane shaft is closed. Complete the
following steps to adjust position (see Fig. 39-43):
1. Remove the set screw in the guide vane coupling.
2. Loosen the holddown bolts on the guide vane actuator.
3. Pull the guide vane actuator away from the suction housing.
4. If required, rotate the guide vane sprocket fully clockwise
and spot-drill the guide vane actuator shaft. Spot-drilling
is necessary when the guide vane actuator sprocket set
screws on the guide vane actuator shaft need to be re-
seated. (Remember: Spot-drill and tighten the first set
screw before spot-drilling for the second set screw.)

Trim Refrigerant Charge

If to obtain optimal chiller performance it becomes necessary
to adjust the refrigerant charge, operate the chiller at design
load and then add or remove refrigerant slowly until the differ-
ence between the leaving chilled water temperature and the
cooler refrigerant temperature reaches design conditions or be-
comes a minimum. Do not overcharge.
Refrigerant may be added either through the storage tank or di-
rectly into the chiller as described in the Charge Refrigerant
into Chiller section.
To remove any excess refrigerant, follow the procedure in
Transfer Refrigerant from Chiller to Pumpout Storage Tank
section, Steps 1a and b, page 42.
44