19XR (PIC II) Hermetic Centrifugal Liquid Chillers 50 Hz - Carrier

8. Dissolved oxygen: Any sudden change in water oxygenation
conditions must be avoided. It is as detrimental to
deoxygenate the water by mixing it with inert gas as it is
to over-oxygenate it by mixing it with pure oxygen. The
disturbance of the oxygenation conditions encourages
destabilisation of copper hydroxides and enlargement of
particles.
9. Specific resistance – electric conductivity: the higher the
specific resistance, the slower the corrosion tendency.
Values above 3000 Ohm/cm are desirable. A neutral
environment favours maximum specific resistance values.
For electric conductivity values in the order of 200-6000
S/cm can be recommended.
10. pH: Ideal case pH neutral at 20-25°C
7 < pH < 8
If the water circuit must be emptied for longer than one month,
the complete circuit must be placed under nitrogen charge to
avoid any risk of corrosion by differential aeration.
Charging and removing heat exchange fluids should be done
with devices that must be included on the water circuit by the
installer. Never use the unit heat exchangers to add heat
exchange fluid.
Piping systems must be properly vented, with no stress on
waterbox nozzles and covers. Use flexible connections to
reduce the transmission of vibrations. Water flows through the
cooler and condenser must meet job requirements. Measure the
pressure drop across cooler and across condenser and compare
this with the nominal values (see selection document).
If the optional pumpout storage tank and/or pumpout system
are installed, check to ensure the pumpout condenser water has
been piped in. Check for field-supplied shutoff valves and
controls as specified in the job data. Check for refrigerant leaks
on field-installed piping. See Fig. 19 and 20.
4.1.8 Check Relief Devices
Be sure that relief devices have been piped to the outdoors in
compliance with standard EN 378-2. Piping connections must
allow for access to the valve mechanism for periodic inspection
and leak testing. 19XR relief valves are set to relieve at 1275 kPa
chiller heat exchanger design pressure.
4.2 - Chiller Tightness
4.2.1 - Check chiller tightness
Figure 25 outlines the proper sequence and procedures for leak
testing.
19XR chillers are shipped with the refrigerant contained in the
condenser shell and the oil charge shipped in the compressor.
The cooler will have a 225 kPa refrigerant charge. Units may
be ordered with the refrigerant shipped separately, along with a
225 kPa nitrogen-holding charge in each vessel. To determine if
there are any leaks, the chiller should be charged with refrigerant.
Use an electronic leak detector to check all flanges and solder
joints after the chiller is pressurized. If any leaks are detected,
follow the leak test procedure.
40
If the chiller is spring isolated, keep all springs blocked in both
directions in order to prevent possible piping stress and damage
during the transfer of refrigerant from vessel to vessel during the
leak test process, or any time refrigerant is transferred. Adjust
the springs when the refrigerant is in operating condition, and
when the water circuits are full.
4.2.2 - Refrigerant Tracer
Carrier recommends the use of an environmentally acceptable
refrigerant tracer for leak testing with an electronic detector.
Ultrasonic leak detectors also can 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.
4.2.3 - Leak Test Chiller
Due to regulations regarding refrigerant emissions and the difficulties
associated with separating contaminants from refrigerant,
Carrier recommends the following leak test procedures. See
Fig. 25 for an outline of the leak test procedures.
1. If the pressure readings are normal for chiller condition:
a. Evacuate the holding charge from the vessels, if
present.
b. Raise the chiller pressure, if necessary, by adding
refrigerant until pressure is at equivalent saturated
pressure for the surrounding temperature. Follow the
pumpout procedures in the Transfer Refrigerant from
Pumpout Storage Tank to Chiller section, Steps 1a - e.
WARNING: Never charge liquid refrigerant into the
chiller if the pressure in the chiller is less than 241 kPa
for HFC-134a. Charge as a gas only, with the cooler and
condenser pumps running, until this pressure is reached,
using PUMP-DOWN LOCKOUT and TERMINATE
LOCKOUT mode on the PIC II. Flashing of liquid
refrigerant at low pressures can cause tube freeze-up
and considerable damage.
c. Leak test chiller as outlined in Steps 3 -9.
2. If the pressure readings are abnormal for 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 207 kPa. Soap test all joints.
If the test pressure holds for 30 minutes, prepare the
test for small leaks (Steps 2g - h).
c. Plainly mark any leaks which 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
system. This can be accomplished by following the
dehydration procedure, outlined in the Chiller Dehydration
section below.