As a professional dealing with refrigeration compressors daily I have
several comments n the use of them as air compressors.
-
In the US there is a very hefty fine for dealing with many of the
refrigerants if you are not certified. Get your used compressor from
someone who can certify that the refrigerant was recovered / disposed
etc. properly. -
Refrigeration compressors are designed to utilize the cooling from
the returning refrigerant to keep the compressor cool. This might
cause a problem compressing air if running too long of a time. Copper
tubing wrapped around the compressor shell with water circulating
through it would be one method of keeping the compressor cool enough
for continuous running. -
Normally there are three lines / stubs on the shell of the
compressor if it is a reciprocating type. The largest diameter is the
suction line for return or intake gases, the smallest is the high
pressure outlet and the stub usually welded shut (or perhaps with an
access fitting only ) is the process stub used to add the refrigerant
at the manufacture then sealed. (Many small window units,refrigerators
etc. now use rotary compressors which are cylindrical tubes. (Vs ovoid
shaped) and the connections are somewhat different.) -
Personally I think a used dental compressor would be a better idea
as it is designed for work with air and would probably have less oil
carryover, overheating, and not have the “freon” refrigerant
liabilities.
Dan Wellman
Heating Ventilating Air Conditioning Refrigeration
(HVACR) Serviceman