4-6. SERVICING THE REFRIGERANT SYSTEM. - Continued.
(3) Testing Method. There are two acceptable methods for leak testing the refrigeration system.
(a) 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
The electronic refrigerant gas leak detector is highly sensitive to the presence of a
minute quantity of gas in the air, and due to this factor is quite effective in the
detection of small leaks. However, due to the rapid dispersion of refrigerant gas
into the surrounding air, difficulty may be encountered in pinpointing large leaks.
The detector must be used in a well ventilated but draft-free area.
(b) 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.
If the soap solution testing method is used, thoroughly rinse with fresh water after
testing is completed. A residual soap film will attract and accumulate an excessive
amount of dust and dirt during operation.
(4) Testing Procedures. To perform leak testing by use of the electronic detector, it is necessary that the
system be pressurized with a proportion of refrigerant gas. To perform leak testing by use of the soap solution method,
the system may be pressurized with dry nitrogen alone.
Connect the refrigerant 22 cylinder so that only gas will be used for pressurization.
(a) Connect a drum of refrigerant 22 to the manifold.
(b) Open the charging manifold valves.
(c) Open the refrigerant drum valve slightly and adjust as needed to prevent formation of frost, and allow
system pressure to build up until the gauges read 30 psig (2.1 kg/cm ).
(d) Close the charging manifold valves and the refrigerant drum valve.
(e) Remove the refrigerant 22 cylinder from the center hose connection.