Compressor questions

[TAftw]

I'm looking at a Speedaire 60 gal. compressor on CL for $250.

The specs:
125 psi max
11.2 scfm @ 90 psi
9.3 scfm @ 90 psi

The 125 psi and 11.2 cfm look a little low to me for a 60 gal. tank. But based off this, I would be able to run a SO MG725 1/2" impact with no problems. I'm just using that for numbers purposes, I doubt whatever I get will require that much air.

I'm also looking at random orbital sanders, and they take upwards of 15 cfm to operate. Why can I use a 1/2" impact but not a sander? What tools require the most air?

Should I pass on this compressor and wait for something better?

 

[Charles (in GA)]

Impacts are very low on the air consumption list, motors such as sanders, drills and grinders are the high consumption items.

Charles

 

[930dreamer]

Impacts work good, sander & grinders only about a minute then you have to wait for air to catch up.

 

[Torque1st]

It all depends on whether you are working in your own shop where "breaks" are acceptable or in a production environment.

 

[onewaydave]

It all depends on whether you are working in your own shop where "breaks" are acceptable or in a production environment.

Sorry, around my shop you have that backwards

 

[TAftw]

Well it would just be for my home shop. But I would be using grinders, not so much sanders. Is there any way to increase the CFM of a pump by modifying it or anything?

 

[Gary S]

Is there any way to increase the CFM of a pump by modifying it or anything?

Sure, you put on a larger motor and a larger compressor...................or, just buy a bigger compressor to begin with and save yourself some money.


At 11cfm, that would be about a 3hp motor. If you need more, look at a 5hp compressor instead. A 5hp would give you around 18 cfm.
And, don't worry about tank size. CFM is what counts.

 

[TAftw]

So just a bigger motor would up the CFM? I can deal with that. Would there be any extra strain on the pump since there is a bigger motor, i.e. is a pump only designed to work with a 3 hp motor verses one that is made to work with a 5 hp motor?

 

[geko29]

No, Gary said you need a larger motor AND a larger compressor (ie pump). If you put a 20hp motor on a 3hp pump, the motor will draw the same amount of current as the 3hp did, and the pump will produce the same volume of air (assuming rpm stays constant).

 

[wearetheromans85]

$250 for an air comp with those specs is actually pretty good. the CH 60 gallon has the same specs and is $200 more.

 

[Torque1st]

You can always add another compressor unit in the future.

 

[Kev442]

I think it's a great deal at $250. Grinders are air hawgs, but a 60 gallon tank gives you some reserve. I purposely pounded on my used 70's 20 gallon Craftsman I bought to make sure it would stay in one piece. Kept it running steady for 15 minutes while using a 3" cutoff. I would only need to stop for about a minute to let things fill and it is only 7.8 at 90. I was amazed today that the compressor would catch up and shut off running a needle scaler. It's weird to let go of the scaler and have silence!