Conducting The Optional Trace Gas Leak Test - York YVAA Installation Operation & Maintenance

SECTION 9 - MAINTENANCE
5. Mix together soap and water. This solution forms
bubbles when leaking vapor passes through it.
6. Use the soap solution to test around each unit fit-
ting joint and weld seams carefully and thorough-
ly.
7. To enhance the test, use an ultrasonic leak detec-
tor. These devices are reliable at finding leaks in
low pressure testing where soap bubble testing
may not provide results.
8. When all leaks have been identified, vent the ni-
trogen vapor, make the necessary repairs to the
chiller, and repeat the gas pressure hold test until
a satisfactory hold test is achieved.

Conducting the optional trace gas leak test

1. To monitor the system pressure over time, install
a high-quality, high-resolution analog pressure
gauge on one of the service valves. Use a pressure
gauge that has a resolution of 2 psi increments
with a dial face at 3 in. in diameter or greater.
2. Ensure all the system valves including manual
valves and EEVs are 100% open. Make sure that
all valves to the atmosphere are closed with flare
caps in place, if applicable.
3. Before proceeding, make sure that the unit is at
the initial evacuation level of 5 mmHg.
Important: To prevent freezing of any moisture
that may inhibit the system, do not go below 5
mmHg. See System evacuation for more details.
4. With the system evacuated, charge with a vapor
only for a 10% trace gas (R-134a/R-513A based
on nameplate) into the chiller until the system
pressure reaches 10 psig (69 kPa).
• When using a refrigerant-based trace gas, you
must always charge with vapor only to reach the
initial 10 psig pressure.
• The use of trace gas must adhere to local policies
in regard to venting or recovery of the gas. This is
dependent on the gas that is selected.
Important: Use a suitable gas detection device
that can detect the trace gas that is selected.
• Set the gas detection limit for 10% R-134a/R-513A
based trace gas, as required, to 0.078 oz/year.
164
5. Connect hoses to high and low side of the system
and add dry nitrogen into the chiller until the pres-
sure reaches 100 psig (690 kPa). Pressure can be
increased upto 150 psig to detect very small leaks.
6. To make sure that the concentration of trace gas
has reached all parts of the system, complete the
following steps:
a. Slightly open the condenser service valve
on the liquid line to vent.
b. Test for the presence of the trace gas with
a leak detector.
c. Continue to vent in this manner until the
trace gas is detected.
7. 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 might be necessary to reset the test
probe in an outside space.
8. Test around each joint and factory weld carefully
and thoroughly.
9. To check for tube or tube joint leaks, complete the
following steps:
a. Isolate and drain the 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. Wait an hour.
d. Open a drain and insert the leak detector.
10. If a tube leak is suspected, complete the following
steps:
a. Remove the waterboxes to facilitate applica
tion of the soap solution to the tubesheets.
b. To test for tube wall leaks, insert a rubber
cork in both ends of each tube, and leave pres
surized for at least 12 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 ex
plored.
d. If a tube or tubesheet leak is confirmed,
contact product technical support (PTS) for
guidance on repair procedures.
Form 201.47-ICOM1
Issue date: 17/11/2022
JOHNSON CONTROLS