The refrigeration system must be purged with dry nitrogen from nitrogen
cylinder (Appendix E, item 2) before any brazing is performed on any
component. A flow of dry nitrogen between 1 and 2 cfm (0.028-0.057)
m3/minutes) should be continued during all brazing operations to minimize
internal oxidation and scaling.
(2) Connect the center hose from the charging manifold to a nitrogen regulator
(3) The hose from the high pressure service valve to the charging manifold must be
(4) The hose from the low pressure service valve must be disconnected from the
(5) Close the unused valve on the charging manifold, and open the one with the nitrogen
tank hook up.
(6) Open the nitrogen cylinder valve and adjust the regulator so that 1 to 2 cfm (0.028-
0.057 m3/minute) of nitrogen flows through the system.
(7) Check discharge from hose attached to the low pressure charging valve to be sure
that no oil is being forced out of the system.
(8) Allow nitrogen to sweep through the system at the rate of less than 1 - 2 cfm
(0.028-0.057 m3 minute) for a minimum of 5 minutes, before starting any brazing
operation. Then allow it to continue to flow at the same rate until all brazing
operations are completed (See para. 5-9 for brazing/debrazing procedures).
(9) After installation brazing operations are completed, allow nitrogen to flow for a
minimum of 5 minutes.
(10) Close nitrogen cylinder valve, nitrogen regulator and charging manifold valve.
(11) Disconnect the hose from the nitrogen tank.