TM 9-4120-403-14
(e) Remove the dehydrator (filter-drier), and blow down each leg of the refrigeration system. To do this,
connect a cylinder of dry nitrogen to each dehydrator connection, in turn, and open the cylinder shutoff valve for at least
30 seconds at 50 psig (3.5 kg/cm2) pressure. Remove dry nitrogen connection.
(f)
Bypass dehydrator fittings with a jumper, locally manufactured from refrigerant tubing and fittings.
(g) Clean system by back-flushing with liquid R11 (item 12, Appendix E) from pressurized cylinder with
pressure of at least 100 psig.
(h)
Connect the R11 tank to the discharge line of the refrigerant system.
(i)
Connect a line containing a filter to the suction line in the unit.
NOTE
An unused dehydrator or other suitable medium may be used as a filter.
(j)
The other end of the temporary suction line should be connected to a small drum or suitable reservoir.
(k)
Open R 11 tank valve. Continue filling the reservoir with refrigerant, R11, until it begins to pour out of
the return line. Continue flushing slowly for at least 15 minutes.
(1) Connect R11 tank to the suction connections, replace the filter with a new filtering medium, open tank
valve, and backflush the system for an additional 15 minutes.
(m) Remove the filter and dehydratorjumper.
Place an empty container below the compressor
connections, and connect a cylinder of dry nitrogen to each dehydrator connection in turn. Blow down each leg of the
system at 50 psig (3.5 kg/cm2) for at least 30 seconds.
(n) Disconnect the dry nitrogen cylinder. Cap or plug open connections if compressor and dehydrator are
not to be installed immediately.
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