compressor cfm

[amac70]

compressor cfm and pic of new rehabed compressor

So was trying to figure out my true cfm of my compressor that i just build and it seems to be coming out more then what I thought was possible. So what i have is a 80 gallon tank cut in at 94 cut out at 142. Takes 64 seconds to between cut in and cut out. From my calcs 80/7.48 =10.7 tank cubic feet 48/14.7 =3.27 atmosperic psi 10.7*3.27=34.9 cubic feet added 34.9/64 64secs to fill up =.55 .55*60 = 32.7 cfm is this actually possible out of a true 7.5 hp compressor.

here is a pic of the compressor head for ref.

http://www.garagejournal.com/forum/showthread.php?t=215488

well after a bunch of research i guess it is out of the better compressors. just used to cheap compressors i guess.

 

[DekeT]

That is putting out some air. Glad you got it running and not sending it to the recycle.

 

[amac70]

heres a pic of it almost finished, going to add an after cooler and redue the input power when it gets stuck in place. kind of dusty right now also.

 

[zkling]

I came up with the same numbers using my little equation. I may have missed it in the other thread, but what RPM are you running on the pump? Good job on the rebuild, I like that color scheme. Just has a vintage, quality look to it.

 

[amac70]

its spinning about 780 rpms.

 

[zkling]

That sounds about right. It might be a bit towards the high side for that pump. Do you know the jug volume by chance? Between that and the RPM you could do a sanity check on the CFM calculation, but it sounds very reasonable for that setup. That ain't exactly your hardware store style DIY garage compressor.

 

[amac70]

don't know jug volume, needed a bigger compressor for shop this fits the bill. I paint a car a year this will make a vast improvement in that area. my da's are going to love this. as are my spray guns i think i was at the very limit of my old compressor.

 

[b-body-bob]

FWIW here is an on-line calculator if you want to sanity check yourself
http://aircompeq.com/formulas.htm