Air compressor from PTO... need CFM for sand blasting

digger doug · Feb 7, 2017

First thing, look on google for an air usage chart.
All the sandblasting outfits have them, Empire comes to mind.

Then work from that chart to figure out what compressor size you need.

I built one that ran off the PTO like pictured above, I get 200 CFM.

I then purchased a work truck with a engine drive one on the back, it is
a grimmer Schmidt 1/2 engine affair, put's out 150 cfm, and runs great
Who would think a ford 302 v-8 could run so smoothly on 4 cylinders ?

BukitCase · Feb 7, 2017

"Who would think a ford 302 v-8 could run so smoothly on 4 cylinders ?"

As long as it's the RIGHT 4 cylinders - might "lope" a bit if you were to make one that used all 4 firing cylinders in order, then all 4 compressor cylinders

My local tire guys have their ag/industrial trucks fitted with those small-block Ford compressors - when they came out and replaced all the tires on my 580B I found out how LOUD they are, but they sure make my 5 horse 23cfm look like a wimp... Steve

RNeumann · Feb 7, 2017

The CFM required is in direct relation to the media and orifice size and pressure used. If you have a small orifice and fine media 9 CFM MAY work.
Now to the second part of the question. The easiest way to deal with the constant pressure build-up is to dump it with a pressure sensitive valve. That way the pump and tractor can just keep going. The second idea would be an electric clutch between the PTO and pump (like the AC on you car or truck). I'm guessing the clutch solution would be more expensive.

digger doug · Feb 15, 2017

Bukitcase,
Odd that they were so loud.
Mine has a normal muffler, and it kind of just hums along nicely.

BukitCase · Feb 15, 2017

Doug, when I think back it seems like theirs was only loud when the compressor half kicked in - maybe it didn't have a breather on the compressor inlet?

Dunno, too long ago and at the time I'd just got my 580B and was more concerned with gettin' enough traction to do the push-out below my shop ('bout 800-900 yds of material moved with 3ph and Gannon box on the back)... Steve