Which Motor for a Compressor

[rtbcomp]

A while ago I fished a compressor out of a skip and it only has a half-horse motor on it.

I'm looking to fit a 2 HP motor, and was wondering what the pros and cons are 2 pole vs 4 pole.

I understand the speed implications, but are there other considerations?

Thanks!

PS - single phase 220v

 

[rusty69bus]

not sure that i understand but, make sure it it won't trip out the circuit breakers when it starts up

 

[shenion]

2 pole /4 pole set the speed.

2 pole is usually 2950 RPM
4 pole is usually 1450 RPM

You would want to match the speed of the old motor. Faster will wear out the compressor.

If you can find a make/model of the pump, you might be able to find is max rated speed.

 

[rtbcomp]

2 pole /4 pole set the speed.

2 pole is usually 2950 RPM
4 pole is usually 1450 RPM

You would want to match the speed of the old motor. Faster will wear out the compressor.

If you can find a make/model of the pump, you might be able to find is max rated speed.

Unfortunately it's a home-brew. Like I said I'm not querying the speed, just wondering if there was anything else I should consider?

The pump is a twin-cylinder Westinghouse brake compressor, I can't find any info on the 'net.

 

[shenion]

Check the direction, some pumps only work in one direction.

 

[Luke]

If you fancy fitting a 3ph motor, i know someone who could sort you out with a Siemens variable speed inverter drive :P

 

[rtbcomp]

If you fancy fitting a 3ph motor, i know someone who could sort you out with a Siemens variable speed inverter drive :P

A bit OTT for a compressor!

Although thinking about it, I could run it at high speed whilst blasting but at low speed during off-peak electricity to keep the noise down.

 

[Luke]

SEE!!!

hehehehehe

 

[hareng]

Mine is a 3hp ok up to 14 cfm.

 

[rtbcomp]

Mine is a 3hp ok up to 14 cfm.

Is it 2 or 4 pole?

 

[hareng]

I will have a look, back later just hard plumbing it in.
Not a current Machine Mart Raider compressor looks like its recently superced with a twin V pump, still a ****** jobby though.
Fairly sure its 1450rpm or 4 pole as most machinery use it unless direct driven.

 

[rtbcomp]

I will have a look, back later just hard plumbing it in.
Not a current Machine Mart Raider compressor looks like its recently superced with a twin V pump, still a ****** jobby though.
Fairly sure its 1450rpm or 4 pole as most machinery use it unless direct driven.

Thanks!

 

[hareng]

Ignore the last its a Boxer.

Motor is Italian surprise CIMA 2700RPM 2.2KW drawing 15 amps with twin cap start.
750W = 1HP so a tad over 3Hp


Off to finish plumbing it in making up numerous 3/4", 1/2", 1/4" BSP fittings aint no joy.

 

[rtbcomp]

Ignore the last its a Boxer.

.........making up numerous 3/4", 1/2", 1/4" BSP fittings aint no joy.

Childs play, my combined compressed air and heating system has a Clarke 14cfm 3hp jobbie, 6 fridge motors and now this one all plumbed together and working off timed circuits

 

[eil]

Westinghouse! is it an old fridge comp do you think , all cast iron jobbie? if it is they were made to run at a range of speeds to give the requiered capacity.

 

[rtbcomp]

Never thought of it as a fridge compressor. It's got two horizontal cylinders (side by side) just a bit smaller than my Clarke machine. It's cast iron with an aluminium sump and an oil filler/dipstick arrangement on the top. A friend of mine has a very similar one with vertical cylinders. The pulley is a triple groove one, although that may not be original.

 

[eil]

na then it wouldent have a dipstic if off a fridge, being a home brew i suspect sombody fitted a half horse and it couldent cope so slinged it. would most probs be a 4pole motor needed, youve got a 2hp 4pole so connect up and check current draw when building up to building up to pressure. depends how hot the head and cyls get when dooing this would be a good indication i would imagine. sorry cant help anymore than that