TM 9-4120-388-14
5-8. PURGING THE REFRIGERANT SYSTEM - Continued.
The hose from the high pressure service valve to the charging manifold must be connected.
d.
The hose from the low pressure service valve must be disconnected from the charging manifold.
e.
f.
Open both service valves on the unit.
Close the unused valve on the charging manifold, and open the one with the nitrogen tank hook up.
g.
Open the nitrogen cylinder valve and adjust the regulator so that less than 1-2 cfm (0.028-0.057 m3/minute)
h.
of nitrogen flows through the system.
i.
Check discharge from hose attached to the lower pressure charging valve to be sure that no oil is being forced
out of the system.
Allow nitrogen to sweep through the system at the rate of less than 1-2 cfm (0.028-0.057 m3/minute) for a mini-
j.
mum 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 paragraph 5-9 for brazing/debrazing procedures.)
k.
After installation brazing operations are completed, allow nitrogen to flow for a minimum of 5 minutes.
l.
Close nitrogen cylinder valve, nitrogen regulator, charging manifold valve, and both high and low pressure ser-
vice valves on the unit.
m.
Disconnect the hose from the nitrogen tank.
5-17
