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Leak Test
Perform the leak test by pressurizing nitrogen gas to 400 psi on both the liquid and gas pipes. Test with the piping service valves closed. If the pressure
does not drop for twenty-four (24) hours, the system passes the test. If the pressure drops, there is a nitrogen leak in the system. Find the leak, repair,
and then test again.
Figure 48: Leak Test Diagram
Leak Test Using Nitrogren Tank
Indoor Unit
Outdoor Unit
Soap Water Method - Leak Testing
1. Remove the caps from the 2-way and 3-way valves. See Figure 46.
2. To open the 2-way valve turn the valve stem counter-clockwise
approximately 90°, wait for about 2~3 sec, and close it.
3. While running the nitrogen gas tank hookup, apply a soap water
or a liquid neutral detergent on the indoor unit connection or
outdoor unit connections by using a soft brush.
4. While running the pressure gauge system, observe the connec-
tions for any leakage.
• If you see bubbles appearing at any of the connection points/joints
(at either inside and outside units), it is an indication of leakage.
5. Make a note of where the leaks are coming from along the liquid
and gas piping.
6. Disengage the nitrogen pressure by loosening the charge hose
connector at the Nitrogen cylinder (Figure 48 above).
7. Once system pressure is reduced back to normal range, discon-
nect hose from the cylinder.
8. At this point you will need to make all repairs to connections and
piping where bubbles were observed.
9. Once all repairs are made, repeat soap testing using nitrogen
cylinder and check for any further leaks.
10. Once system is leak free, proceed to Evacuation steps on next
page.
REFRIGERANT PIPING CONNECTIONS
Manifold Valve
Pressure
Gauge
Lo
Hi
Charge Hose
Nitrogen Gas
Tank (Upright
Position)
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Leak Test/Soap Method Check
Pressure Gauge Hookup
1. Connect the manifold valve (which includes the pressure gaug-
es), along with dry nitrogen gas cylinder to the service valves
using charge hose (Figure 48).
2. Pressurize the system to maximum 150 P.S.I.G. with dry nitrogen
gas and close the cylinder valve when the gauge reading reaches
150 P.S.I.G.
Using combusitble gases such as nitrogen runs the risk of fire, explosion
and personal injury. Inert gas (nitrogen) should be used when checking
plumbing leaks, cleaning or repairs of pipes, etc.
• To avoid nitrogen entering the refrigerant system in a liquid state,
the top of the cylinder must be higher than its bottom when you
pressurize the system.
• Be sure cylinder is used in a vertical standing position.
Leak Test Ambient Temperature Correction
If the ambient temperature changed between the time when
pressure was applied and when the pressure drop was checked,
adjust results by factoring in approximately 1.45 psi for each 2°F of
temperature difference.
Correction formula = (Ambient temperature when pressure was ap-
plied - Ambient temperature when pressure drop was checked) x 0.01.
Example:
When pressure (550 psig) was applied, the ambient temperature
was 80.6 °F; 24 hours later when pressure drop (540 psi) was
checked, ambient temperature was 68 °F.
Thus, 80.6 - 68 x 0.01 = 0.126. In this case, the pressure drop of
0.126 was due to temperature difference, therefore, there is no leak
in the refrigerant piping system.
41
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