PURGING THE REFRIGERANT SYSTEM.-Continued

TM5-4120-383-14

5-12.

PURGING THE REFRIGERANT SYSTEM.-Continued

The refrigeration system must be purged with dry nitrogen, item 8,

Appendix E before any brazing is performed on any components. A

flow of dry nitrogen at the rate of 1 - 2 cfm (0.028 - 0.057

m /minute) should be continued during all brazing operations to

minimize internal oxidation and scaling.

Nitrogen cylinders are pressurized containers. The

pressure in the cylinder can exceed 2000 psi. A

nitrogen pressure regulator should be used at all

times when nitrogen is used for leak check or purge

operations.

Nitrogen is an inert gas; however, it also presents

danger as a suffocant and, therefore must also be

discharged in a ventilated location.

Assuming that the system has been discharged (para 5-11), see

figure 5-6 and proceed as follows:

See specific component removal instructions.

It may be

necessary to remove top rear cover prior to connecting hoses to

service valves.

b. Be sure that refrigerant has been discharged.

(See para

5-11.)

c. Connect center hose from charging manifold to a nitrogen

regulator and dry nitrogen bottle.

d. The hose from the high pressure charging valve to the

charging manifold should be connected.

e. The hose from the low pressure charging valve should be

disconnected from the charging manifold.

Open both charging valves on unit.

g. Close the unused valve on the charging manifold and open the

one connected to the high pressure hose.

h. Open the nitrogen cylinder valve and adjust the regulator so

that approximately 1 - 2 cfm (0.028 - 0.057 m /minute) of nitrogen

flows through the system.

i. Check discharge from hose attached to the low pressure

charging valve to be sure that no oil is being forced out of the

system.

5-29