I'm interested in a 1/2 to 3/4 HP silent air compressor with about a 4 gallon tank running between 84 and 114 PSI with a regulator.
Ever since I got one cheap ($50, in pieces which I reassembled) from
an art shop I had been noticing silent compressor models.
Practically all then ones I have come across are basically
refrigerator compressors, given a fancy air tank, a carrying handle,
some plumbing, regulators and a bright paint job.
Mine is rated at 1.38 amp which is around 1/5 hp. It seems unlikely
that “silent/household” fridge motors will go larger than 1/3 hp
although I cannot say for sure. Mine delivers enough pressure to
burst a 175 psi rated PVC tube when I let the pressure build up
without an air bleed connection (hadn’t installed a regulator then).
What shocked me was the price - $650 new - which costs more than
fridge such a compressor would have powered. The same "power
which was what the unit looked like but fitted with a larger tank and
carrying handle was given a different model name and had another $120
added to the price. And there were price variations like that just
for the furniture differences.
I came across a hobby webpage that gave instructions how to convert
an old fridge compressor to make your own silent compressor.
Contractor grade compressors are rated at 175/180 psi and there are
(8 gal?) tire air tanks available from any hardware shop for around
$20 - $30. Otherwise the places to look for compressors are Art and
Drafting Supplies Shops, and dental equipment suppliers. Be prepared
for price sticker shock.