Operating instructions
37
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.
If repairs are required, do not use R-134a, as it is not
designed and should not be used for leak detection.
WARNING: Do not use air or oxygen to pressurize the
chiller. Mixtures of R-134a and air can undergo combustion.
Check the optional pumpout compressor piping.
4.2.2 - Leak test chiller
Due to regulations on refrigerant emissions and the difficul-
ties associated with separating contaminants from refrigerant,
Carrier recommends the following leak test procedures.
1. If the pressure readings correspond to the chiller
operating conditions:
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 sections 4.11 and 4.12
“Chiller equalization without pumpout unit” and
“Chiller equalization with pumpout unit”.
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 PUMPDOWN LOCKOUT and
TERMINATE LOCKOUT mode on the PIC. 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 do not correspond to the
chiller operating conditions:
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 to 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 chapter 4.4 “Chiller dehydration”.
h. Progressively raise the system pressure to a maxi-
mum of 1103 kPa but no less than 241 kPa for
HFC-134a by adding refrigerant. 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.
• Dissolved oxygen: Any sudden change in water oxygena-
tion 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.
• Specific resistance – electric conductivity: the higher the
specific resistance, the slower the corrosion tendency.
Values above 30 Ohm·m are desirable. A neutral
environment favours maximum specific resistance
values. For electric conductivity values in the order of
20-60 mS/m can be recommended.
• 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 pipes 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 isolation valves
and controls as specified in the job data. Check for refrige-
rant leaks on field-installed piping. See Figs. 18 and 19.
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 1250 kPa.
4.2.1 - Check chiller tightness
Refer to Fig. 31.
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 refrigerant charge that is compressed
to 225 kPa. Units may be ordered with the refrigerant
shipped separately, along with a compressed 225 kPa
nitrogen-holding charge in each vessel. To detect 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 procedure described in chapter 4.2.2.