air compressor speed and duty cycles

Old 10-08-10, 01:49 PM
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air compressor speed and duty cycles

I have two old compressors. I would like to figure out pulley sizes to use on them. the first is a 1946 westinghouse it has a fairly large two stage pump. I bought just the pump and tank. I have a motor to put on it, but I don't know what size pulley to put on the motor. I want the pump to work quickly giving a fast recovery time but don't want to go so fast that I burn up the pump. the second is a 1978 speedaire two stage compressor, I have the factory set up but wonder if I could put a little larger pulley on the motor to make it run the pump a little faster. Is there any problem with doing this assuming the motor can handle it? Also does anybody know what the duty cycles are on these...continuous? both of the motors I have on them are continuous duty motors.
Old 10-08-10, 02:59 PM
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No one could say for certain how fast you can turn those pumps without the manufacturers info sheets.
The problem is that you could have the same pump body with a different bore and stroke which would take a very wide motor size range.

The Westinghouse might be a problem but there will be a lot of info available on the Speedaire.
Post the model number of the Speedaire for both compressor unit and pump and we may have some info on that.
Also, post the size of the pulley on the Westinghouse pump along with the voltage, hp and RPM of the motor you want to use.
Old 10-08-10, 11:10 PM
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Most compressors of a size suitable to a home shop can be run as fast as 900 rpm without problem. It isn't the rpm so much as it is piston speed in feet-per-minute. A long stroke compressor will have a faster piston speed than will a comparably sized (output CFM) compressor with a short stroke. A pressure-lubricated compressor will take faster speeds than will a splash-lubricated model. Increased speeds WILL however increase wear.

Understand also that increasing the speed of the compressor will require more horsepower from the motor.
Old 10-10-10, 01:16 PM
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duty cycle

Just from experience of dealing with both - the Westinghouse, if it's in good shape, can be run continiously (really meaning longer than 10 minutes at a time). It's pressure lubed and ridiculously overbuilt. The Speedaire is the lesser of the two, try not to overwork it or the valves will go fast. Keep it around 85%, giving it a chance to cool. As furd pointed out, try not to exceed 900rpm on both.

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