- It is important that a suitable gas detection device is used that can detect the trace
gas that is selected.
- Set the gas detection limit for 10% R-134a based trace gas to 0.078 Oz/Yr R-143a.
4. Add dry nitrogen to the chiller until the pressure reaches 100 psig (690 kPa).
5. To ensure that the concentration of trace gas has reached all parts of the system, slightly
open the oil sump drain service valve and test for the presence of the trace gas with a leak
detector. Continue to vent in this manner until the trace gas is detected and close the service
valve
6. Before beginning the trace gas testing, ensure that any vented gas has been adequately
vented from the chiller area so that there are no false positive indications. It may be
necessary to reset the test probe in an outdoor space.
7. test around each joint and factory weld carefully and thoroughly.
8. To check for tube or tube joint leaks, complete the following steps:
a. Isolate and drain the condenser and evaporator waterboxes.
b. Purge the waterboxes and tubes with dry nitrogen through the vents or drains until the
detector does not indicate any evidence of refrigerant.
c. Close the vents and drains and wait an hour.
d. Open a drain and insert the leak detector.
9. If a tube leak is suspected, complete the following steps:
a. Remove the waterboxes to facilitate application of the soap solution to the tube sheets.
b. To test for tube wall leaks, insert a rubber cork in both ends of each tube, and leave
pressurized for at least 8 hours.
c. If a leak is present, the pressure pushes the cork out of the tube. If this occurs, the tube
must be plugged or have other options explored.
d. If a tube or tubesheet leak is confirmed, contact product technical support (PTS) for
guidance on repair procedures.
10. When all leaks have been identified, recover the test gas as applicable, make the necessary
repairs, repeat the leak tests, evacuate the chiller, and perform the time-based pressure hold
test.
System evacuation
Vacuum dehydration
Before performing the final evacuation and system charging, you must obtain a sufficiently dry
system. The following instructions provide an effective method for evacuating and dehydrating
a system in the field. Although there are several methods of dehydrating a system, the following
method produces one of the best results, and provides accurate readings as to the extent of
dehydration.
The equipment required for this method of dehydration consists of the following items:
• High resolution vacuum gauge (microns below 500)
• Chart that shows the relationship between dew point temperature and pressure in microns
(vacuum), see Table 102
• Vacuum pump capable of pumping a suitable vacuum on the system
Follow the dehydration steps as closely as possible to prevent moisture becoming trapped in the
system.
149
YMC
2
Mod B with OptiView Control Center
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