You thinking of bidding on it? It's a water cooled compressor. The
whole compressor head and cylinder has a jacket around it and it's a
double acting cylinder, at least ours were. They were quite and
The old Ingersoll Rand compressors with the 300
RPM synchronous motors
direct-driving the crank were also pretty quiet.
I think they were about 100 Hp.
The motors looked like something from 1900,
salient pole motors with wound
field coils on the rotor. They used a phase angle
meter to adjust the field current
to act as a "synchronous condenser" to correct the
plant's power factor.
(only older EE's know this, but a synchronous
electric machine, if the field is overexcited, run
with leading power factor, acting as large
capacitors, to correct for
the usual lagging phase angle of most other
I saw a couple of them at the Emerson Electric
defense plant, they were put in in 1951.
A compressor that size is only "quiet" when in the best location. Note
the size of the intake piping, and that it goes out of sight to some
distant place. There won't be anyplace that you can have the
air-intake opening located in a residential neighbourhood and still
stay free of being shot by some irate citizen if you buy it. The
noise these make is not quite like the Sears stuff, but imagine the
effect of multiplying that 5HP noise maker you have now by 15 plus
The intake noise is similar to a "concussion" noise when running.
Somebody here mentioned Joy in Cambridge. Just up the road in Hespeler
at one of the textile mills they had a 100HP one that was fairly quiet
in the building. You could hear the piston slap it was so quiet. But
you couldn't talk or hear if you were within 100 feet of the intake
outside. Awesome sound !!
The suction of ours went up just past the top of the compressor and
had a large filter can. When it was running, we could carry on a
normal conversation while standing next ti it. The company later addas
an Atlas Copco rotary compressor next to it. That thing screamed!
Could not stand to be around it with the cabinent door open
That's how they usually installed monsters like that - it has an
unloader and runs constantly, the unloader cuts it in as the mainline
pressure demand calls for.
They only had to spin it up once in the morning, before the other
big loads in the factory.
I thinl you have a smaller example of this in your collection. In a
residence you don't get billed for Demand Current, so a start surge
isn't a problem- as long as it doesn't trip the Main Breaker or cause
computers to reboot and lose unsaved data...
But on commercial service, starting and stopping a 150-HP motor
several times a day (with all the other loads running) will spike the
demand meter, and the demand factor adjustments could literally double
the monthly power bill.