SERVICE LEAK TEST

TM 9-4120-425-14&P

REFRIGERATION SYSTEM SERVICING (LEAK TEST) - Continued

0052-00

SERVICE LEAK TEST

General

The entire repaired area should be thoroughly leak tested after repair or replacement of any component, before it is

recharged with refrigerant-22. Leak testing is also the method for troubleshooting when a system has lost all or part of its

refrigerant charge through an undetermined cause.

Testing Method

There are two acceptable methods for leak testing the refrigeration system.

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 9-4940-509-14&P, "Leak Detector, Refrigerant Gas".

NOTE

The electronic refrigerant gas leak detector is highly sensitive to the presence of a

minute quantity of gas in the air, due to this factor it is quite effective in the

detection of a small leak. 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.

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.

Testing Procedure

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.

To pressurize a system that has some refrigerant charge, for either leak testing method:

Remove the hose connection protective caps from the high and low pressure service valves.

Connect the hoses from a charging manifold to the service valves.

NOTE

If it is possible that the problem may not be a leak and that you may not have to

replace a refrigeration system component, refrigerant-22 may be substituted for the

nitrogen in the following test. If nitrogen is used, you will have to discharge,

evacuate, and recharge the system after this test is completed.

Connect a nitrogen pressure regulator and nitrogen bottle to the center hose connection of the charging

manifold.

Open the unit service valves and the charging manifold valves.

Open the nitrogen tank valve and pressurize the system to 300 PSIG (21.2 kg/cm2).

Perform leak tests.

0052-00-2