5-8. LEAK TESTING REFRIGERATION SYSTEM-Continued.
Refrigerant gas leak detector. If an electronic refrigerant gas leak detector is available, it should be used in
accordance with the procedures contained in TM 9-4940-435--14, "Leak Detector, Refrigerant Gas".
If the soap solution testing method is used, thoroughly rinse with fresh water after
testing is complete. A residual soap film will a ttract and accumulate an excessive
amount of dust and dirt during operation.
Soap solutions. In this method, a strong solution of a liquid detergent and water is brushed onto all points of
possible leakage while closely watching for the formation of bubbles.
To perform leak testing with soap solution method, the system may be pressurized with dry nitrogen alone.
Install service manifold in accordance with installation instruction. See para 4-6.
Observe compound and pressure gages. If system pressure is 50 psig or higher, proceed to step (7); if not,
continue with step (3).
Remove 1/4" yellow hose from hose rack and connect to a cylinder of refrigerant-22.
Open refrigerant-22 cylinder valve and loosen hose at charge port, allowing refrigerant to purge for 3-5
seconds, then tighten.
Open charging valve and pressure gage valve and allow refrigerant to enter system until compound and
pressure gages indicate a minimum pressure of 50 psig, then close charging valve.
Close refrigerant-22 cylinder valve and remove yellow hose.
Connect 1/4" yellow hose to a regulated dry nitrogen cylinder.
Open nitrogen cylinder valve and adjust regulator to a pressure 10 psi greater than system pressure.
Loosen 1/4" yellow hose at charge port and purge for 3-5 seconds, then tighten.
(10) Open charging valve and adjust nitrogen regulator to slowly raise compound and pressure gage reading
to 300 psig.
(11) Using a halon leak detector or soap solution, check all fittings, connections and components for leaks.
Ensure pressure remains at 300 psi; add more nitrogen if necessary.
(12) Close charging valve and nitrogen cylinder valve and remove yellow hose from nitrogen regulator and
connect to service manifold hose rack.
(13) Evacuate refrigerant system. See para 5-9.