Air compressor motor question..

[3dkustoms]

Got a great deal on a monster 3 phase 120 gallon compressor, Actually It was Free, they just wanted it moved out of the way.. I really could not pass that up. Now I need a little advise on what size single phase motor to replace the 3 phase that is on it. The 3 phase is a 10 hp but the only single phase 10 hp I can find is almost $1000, a little out of my price range. Would it be possible to drop to maybe a 7.5 or maybe a quality 5 hp? The compressor is a Speed Air but not sure on the specs on it.

 

[strutaeng]

You need to find the model number of the pump. Many pumps are rated 7.5-10 hp, or 10-20 hp. A few are rated 5-10 hp. If it is a SpeedAire, try Grainger: they have all of the specifications on their website.

By the size of the pump I think 7.5 hp will be the minimum. You will also need a properly sized pulley for the motor to run the pump at the correct RPM, given the horsepower.

Finally, you will need a magnetic starter with correct overloads (heaters) for the motor.

Good luck

 

[theoldwizard1]

By the size of the pump I think 7.5 hp will be the minimum. You will also need a properly sized pulley for the motor to run the pump at the correct RPM, given the horsepower.

You could go down to a 5hp IF you can get the correct size pulley.

Check with the compressor manufacturer, but quick rule of thumb says for a 5hp motor the motor pulley should 1/2 the size of the 10hp motor pulley.

This will cut your CFM in 1/2.


BTW, do a little clean up on the old motor and it should pay for a brand new single phase motor !

 

[strutaeng]

You could go down to a 5hp IF you can get the correct size pulley.

Check with the compressor manufacturer, but quick rule of thumb says for a 5hp motor the motor pulley should 1/2 the size of the 10hp motor pulley.

I would check with the manufacturer first. If it a 5-10Hp pump, then yes it will work, but not if it is a 7.5-10 Hp pump. Besides, you can't slow a pump too much as this will prevent proper lubrication. Most will require a 550 RPM or so.

I ran a 7.5-10 hp pump with a 5hp motor at the min. RPM and the 5hp motor heaters kept tripping. It checked the current with an ammeter and it was much higher than the AMP times S.F. of the motor. Lesson learned: go with the manufacturers' recommendation. I had to go with a larger motor.

 

[CNGsaves]

OP, you'll need to post specific details like Model #, etc if you want best advice from guru's on GJ.

Also, those tiny pictures aren't any help. Even with Photobucket, the pics are tiny.

You'll also want to take out bung-hole plugs in the tank (after air pressure released) so you can look in there for condition of tank. Be careful and don't trust a rusty tank. If water was drained while this was in use, likely will be fine, but still need to check for damage.

Nice score with monster FREE compressor. Good luck with rebuild.

 

[larry_g]

Do you have a shop with multiple employees? That is a lot of compressor and tank for a single shop running full time and if a home shop questionable. You might be money ahead to sell that and get something smaller.

That said, and as others have asked, we need the numbers off the pump head so that the input can be sussed out. If we get the numbers then maybe we can link you to something like this, http://www.aircompeq.com/ka.htm Or if you know the bore &stroke then you can interpolate some information from the link.

Remember, Free is not always a good price.

lg
no neat sig line