Leak Testing

WARNING

To avoid possible explosion, use only returnable (not disposable) service cylinders when removing refrigerant from a system.

•Ensure the cylinder is free of damage which could lead to a leak or explosion.

•Ensure the hydrostatic test date does not exceed 5 years.

•Ensure the pressure rating meets or

exceeds 400 psig.

When in doubt, do not use cylinder.

WARNING

To avoid the risk of fire or explosion, never use oxygen, high pressure air or flammable gases for leak testing of a refrigeration system.

1.Before testing, ensure both hand valves on the gauge manifold are closed relative to the center port (i.e., turned IN all the way.)

2.Attach the gauge manifold to the service valves on the unit (see Figure 4).

Do not open the unit service valves.

Do not use refrigerant from the unit for leak testing. The refrigerant in your unit has been precisely mea- sured at the factory for optimum performance.

3.Connect a cylinder of dry nitrogen to the center port on the gauge manifold.

WARNING

To avoid possible explosion, the line from the nitrogen cylinder must include a pressure regulator and a pressure relief valve. The pressure relief valve must be set to open at no more than 150 psig.

4.Open the hand valve a minimal amount on the line coming from the nitrogen cylinder.

5.Open the high pressure valve on the manifold gauge. Pressurize the refrigerant lines and the indoor coil to 150 psig (1034 kPA). To reach 150 psig, you may need to further open the hand valve on the nitrogen cylinder.

WARNING

To avoid possible explosion or equipment damage, do not exceed 150 psig when pressure testing.

6.Close the valve on the nitrogen cylinder and discon- nect it from the gauge manifold.

7.Check for leaks. Apply a soap solution on all connec- tions and joints. If you see bubbles, you have a leak. Mark these locations.

NOTE: If you use an electronic leak detector to test for leaks, add a trace of R-22 to the system (if permitted by current EPA regulations) before testing.

8.Using the gauge manifold, carefully release the nitro- gen from the system. If leaks are found, repair them. After repair, repeat the above pressure test. If no leaks exist, proceed to ID Coil and Line Sets Evacuation.

ID COIL AND LINE SETS EVACUATION

THERMOCOUPLE

VACUUM

GAUGE

DIAL-A-CHARGE

CHARGING CYLINDER

LOW SIDE

HIGH SIDE

GAUGE

PORTS OF

GAUGE

COND. UNIT

HIGH VACUUM

MANIFOLD

LARGE DIAMETER

BRAIDED VACUUM

HOSES

A. LOW SIDE VALVE

B. HIGH SIDE VALVE

C. VACUUM PUMP

D.THERMOCOUPLE GAUGE

E.MANIFOLD GAUGE

F. CHARGING CYLINDER

HIGH VACUUM PUMP

Figure 2

Step 1. Confirm Proper Pump And Gauge Operation

a. Connect vacuum pump, high vacuum manifold set with high vacuum hoses, vacuum gauge and charging cylinder to unit service valves as shown in Figure 2. Ensure all manifold valves are fully closed.

b. Open the shutoff valve leading to the vacuum pump (Figure 2) (C), start the pump, and watch the gauge manifold. The readings in the gauge manifold should drop to approximately 29 inches Hg. If this does not happen, there is probably a leak in the pump and gauge system. Repair the leak and test again.

c. Open the vacuum gauge valve (D) and evacuate to 250 microns or less. If the system cannot be evacu- ated, replace the vacuum pump equipment and repeat steps (a) through (c) again. Otherwise, the pump and gauge are operating properly and you can continue on to the next step; evacuating the system. Before proceeding, be sure to close the valve (D) to the vacuum gauge to avoid “pegging the meter” and potential gauge damage.

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