5-6. PURGING REFRIGERATION SYSTEM-Continued.
The refrigeration system must be purged with dry nitrogen, Appendix F, Item 2, before any brazing
or brazing is performed on any component. A flow of dry nitrogen at the rate of. 1 to 2 cfm (O 028
to 0.057 m3/rninute) should be continued during all brazing or debrazing operations to minimize
internal oxidation and scaling.
a. Be sure that refrigerant has been discharged. See para 5---5
b. Connect the charging nose (yellow) 3/8" from charge port to nitrogen regulator and dry nitrogen tank
Loosen low pressure hose (blue) at compound gage port oil service manifold.
d. Open pressure gage on valve on service manifold
e. Open charging valve on service man fold.
Open the nitrogen cylinder valve and adjust the regulator so that 1 to 2 cfm (0.028 to 0.57 m3rnminute) of
nitrogen flow rate is established.
g. Check to ensure that nitrogen is flowing from loosened hose at compound gage port of the service manifold.
h. Allow nitrogen to sweep through ,'he system for a minimum of 5 minutes before brazing or debrazing
operations are started Continues sweep during the operation, and for 5 minutes alter completion.
Close nitrogen cylinder valve, service manifold valves, and high and low pressure service valves on the unit.
Disconnect hose from nitrogen regulator and return it to the hose rack