Help figuring out a high cfm low psi?

by Renee
(Denver, CO, USA)

I need help figuring out a high cfm low psi configuration please?

I have a sand carving system in my garage.

I have one air compressor that only puts out about 6 cfm. I have another compressor that puts out 24cfm.

I have tried running both of these air compressors to a 100lb sandblasting pot. The low cfm compressor has a 26 gallon tank. This thing is never going to keep up with the air demand but I just wait for it to get up to pressure and it’s ok for hobby use.

The 23cfm only has an 8 gallon tank. It’s a workhorse but I can’t figure out how to take full advantage of the air. I want all the cfm at around 40psi. The compressor is set to 90psi on the low end and 125psi at the high end. It never cuts off just cycles down.

I tried using the biggest blasting nozzle I had and had a cheap regulator in line but still way too much pressure.

Obviously I need a better regulator but I don’t want to waste air every time the pressure is too high which would be often.

I’ve thought of a few things.... bigger nozzle maybe 1/4 inch but i think that’s a band-aid because i’m just blasting 6” stones..... maybe an air tank but how big?

could i just use the 26 gallon from the other compressor or should i try to find a 60 or 80 gallon..... also would it make sense to change the cut in cut out pressure to lower settings.

This compressor gets up to full cfm/psi very quickly i’m just guessing but it seems like it only takes 20 seconds. how can i take full advantage. Again, I want consistent air with no hiccups.... mostly at 40psi but occasionally spurs 15psi up to 60psi. It doesn’t take much pressure, I’m blasting with silicon carbide.

I can’t figure it out:(

Any help is appreciated!!!!!



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Apr 10, 2018
High cfm low psi configuration air regulation
by: Bill

I am thinking you are confusing some of the issues.

Flow of air is measured in CFM.

Pressure of air is measured in PSI.

If you have a half decent air regulator in the line before your air tools, and that regulator is set for 40 PSI, then the air tool should (assuming the regulator is working) only get 40 PSI of air, regardless of what the air demand of the tool is.

If the CFM requirement of the air tool at 40 PSI is greater than what can be produced by either or both compressors, the air pressure to your air tool will drop since the air tool is using more air in CFM at that 40 PSI than either or both compressors can generate.

The size of the air tanks simply means that you have a "pre-pressurized" supply of air at whatever the cut out pressure setting of the pressure switches is.

If you do not have a working regulator in the line between the two air compressors and the air tool, then the pressure received the air air tool will be at whatever pressure is coming out of the air tanks.

If one compressor is generating higher pressure air than the other, air will flow from the high pressure to the low pressure tank until both are full and the compressors cut off.

What I am not seeing in your post is what is the demand of the air tool at 40 PSI? That's critical information in sizing an air supply.

Please see the pages on this site that are about CFM, PSI, sizing a compressor, improving air flow etc., as pretty much all of the answers to your questions are already here to be read.

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