compressors in parallel

prkaye · #1 10-06-2009, 01:54 PM

For painting, I've heard of people linking two or more small compressors in parallel to get the required cfm.
I was told that I would need 13cfm (for Stewart Systems paint). My question is, is this 13cfm at the gun pressure of 23psi, or is it 13cfm at the tank pressure of 100psi? Big difference there... my current compressor is rated 7.2cfm @ 40psi and 5.4 cfm @ 90psi. Would two of these compressors be suitable for painting?

noelf · #2 10-06-2009, 02:11 PM

...and don't forget the electrical power requirements. Depending on the power required, you may need two separate ac power sources and not two power outlets on the same circuit.

Rick S. · #3 10-06-2009, 02:22 PM

I rigged two of them together to paint my -10...I saved major money doing it myself, enough money to justify buying a nice big powerful compressor if I had it to do all over again. A good supply of air with adequate volumn and pressure clear of moisture and oil is PRICELESS when doing paint. I own a turbine system but wasn't super happy with it so I just used my HVLP rig on two compressors. It worked OK but I would buy an adequate compressor, you won't be sorry.

longranger · #4 10-07-2009, 12:14 AM

Quote:

Originally Posted by Rivethead

...I'm going to predict that a jury rigged system is going to shoot well for about 30 seconds before it begins to drop off to a point that you'll begin to start noticing a change...

It would take a VERY jury rigged system (no or POS regulator) to get that result. Yes, the tank pressure will begin to fall immediately, but a decent regulator should hold the line pressure steady. You'll know whether your compressor(s) is (are) adequate by noting whether or not it (they) can maintain the tank(s) above the reg setpoint.

Steve Barnes · #5 10-07-2009, 10:17 AM

The pneumatic cutter uses so much air that I could only cut 6" to 1' of canopy before I had to wait for a recharge. I borrowed a second compressor and with a T fitting I was able to quickly able to put them on the same supply line. WOW what a difference, I hardly had to slow down at all. Remember, each compressor on its own circuit.

Steve Barnes, The Builders Coach

MrNomad · #6 10-07-2009, 01:53 PM

I did this and I've painted about a dozen cars and one airplane.

If you have a good regulator at the gun, NOT an $8 Harbor Freight regulator, a big enough tank 60++, and you work in short segments like most jobs require, you're smaller compressor may carry the load. If not, just flip on # 2. The key is a good regulator at the gun.

Equally important, the only worse than an engine that quits in flight is a compressor that dies in the middle of a shoot. With two compressors, you've got a safety net and the job may go more slowly, but at least you can complete it.

I ONLY work with an HVLP gun.

lufthans.nl · #7 10-07-2009, 03:19 PM

Just recently painted a BIG wing that way. Works very well, with no pressure drops at all. Just a lot of noise from those two buggers humming away.

We're blessed with 240 volts here, so I could easily run both compressors plus all my lighting off one 16 Amp circuit.

Hans

(Ever tried running a media blasting cabinet on just one small compressor? Talk about frustrating!)

prkaye · #8 10-08-2009, 10:03 AM

So would two small compressors of this size work?

5.9 SCFM @ 90 PSI, 20 Gallon, 150 max PSI

http://www.deltaportercable.com/Prod...roductID=22864

For the paint, I apparently need 13CFM, but I think this means air delivery at the gun pressure of 23psi? The above unit can provide 7.2 CFM at 40psi, so two of them would be 14.4cfm at 40psi, which should be greater than the requirement?

aero_tango · #9 10-08-2009, 10:40 AM

Phil,
Instead of 2x 20 gal compressors, why don't you buy a used 60 gal compressor. Assuming you have a 20gal already, this will give you 80 gal of capacity. This is exactly what my set-up was.

Look on Kijiji, you might find good deal.
I've found this unit in Gloucester....
http://ottawa.kijiji.ca/c-buy-and-se...AdIdZ157301601

Michel R.

prkaye · #10 10-08-2009, 10:48 AM

Quote:

Instead of 2x 20 gal compressors, why don't you buy a used 60 gal compressor

Power and space constraints mainly. I have no need for a compressor that large other than for painting. I also don't have a 240V circuit in my shop or my hangar, and don't want that monstrosity taking up space in my garage after the project is done.

I'm leaning heavily towards a turbine with an extra hose for cooling. Busy bee in ottawa has the 4-stage mini-mite regularly 975, on sale for 769. If this works, would be MUCH more convenient that plumbing together compressors and all the required filters and water separators, which together would cost almost as much as the turbine. This little turbine is very portable. My only fear is investing that much money in it and then discovering I can't get a good finish with it...