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Old 12-18-2008, 12:00 PM   #1
IllNastyImpreza
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Default anyone rig 2 air compressors together ?

I have a 15 gallon craftsman. And it just doesn't put out enough air long enough. I need a bigger compressor! but the large ones are BIG money. I have searched craigslist and can find some AWESOME deals on 15 gallon 4hp and less compressors...

Now my question is, has anyone rigged these together to equal a bigger compressor??

I need more air output to use my paintgun... would this work ?

how would I go about rigging them together ??
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Old 12-18-2008, 02:44 PM   #2
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Don't see why it wouldn't. Just hook the outputs together.

http://www.autobody101.com/forums/vi...ght=compressor

The only thing I would worry about is if you hoooked them up past the regulator if the regulator would withstand the back pressure.
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Old 12-18-2008, 02:45 PM   #3
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couldn't you find a coupler and couple the two together to one output and then regulate the airflow of each compressor to be half of normal output?

so set the output on each to be 45psi?
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Old 12-18-2008, 02:54 PM   #4
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Originally Posted by 640k View Post
so set the output on each to be 45psi?
He probably wants 30 psi at a huge volume at his gun. If you hook the outputs together the regulator with the higher setting will supply all the air. It is impossable to set them exactly the same. What he prbably wants to do is set them both fairly high and regulate the air at the gun.
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Old 12-18-2008, 03:09 PM   #5
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And don't do what is shown in the first YouTube

http://www.autobody101.com/forums/viewtopic.php?t=8199
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Old 12-18-2008, 04:21 PM   #6
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you have to do this BEFORE the regulator. Most regulators will handle higher pressure on the demand side by venting it overboard. End result would be one compressor doing most of the work, and tossing out the air produced by the other one.

one thing to consider, do you have the power capability to power 2 running compressors? Take a look at the electrical plate on the one you have and see what it draws, and if you have enough electrical headroom for a second. Most mid size and up compressors are 220v for a reason. A TRUE 4 horsepower compressor will draw at least 3000 watts at 100% efficiency. Take into account that no motor is 100% efficient, and you are looking at 4000 watts. (36 amps at 110v) Obviously the 4hp compressors you see advertised are not a true 4hp, it is the amount of power it might draw for an instant during startup. The LARGEST compressor you can run on a 110v line is 2hp, and only under ideal conditions.

(take a read over here for some good info about compressors
http://www.truetex.com/aircompressors.htm)


(disclaimer, yes, I do this all the time. Another option for the OP is to just get a big air tank or multiple tanks. Might take a while to fill but once they are all full you can supply the paintgun air for a lot longer at least.)

Last edited by rkramer; 12-18-2008 at 04:35 PM.
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Old 12-18-2008, 04:22 PM   #7
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Quote:
Originally Posted by rkramer View Post
you have to do this BEFORE the regulator. Most regulators will handle higher pressure on the demand side by venting it overboard. End result would be one compressor doing most of the work, and tossing out the air produced by the other one.

one thing to consider, do you have the power capability to power 2 running compressors? Take a look at the electrical plate on the one you have and see what it draws, and if you have enough electrical headroom for a second. Most mid size and up compressors are 220v for a reason.

(disclaimer, yes, I do this all the time. Another option for the OP is to just get a big air tank or multiple tanks. Might take a while to fill but once they are all full you can supply the paintgun air for a lot longer at least.)
good point. the 220v compressors are more efficient for a reason too.
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Old 12-18-2008, 07:30 PM   #8
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using 2 tanks to store 30gal of air with one compressor or just running one until it is out and switching while the other charges would work

i dont see any issue doing it a couple ways....but doing it WRONG would be easy if ya got rocks in ya head
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Old 12-18-2008, 10:27 PM   #9
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ok so where can I get a nice BIG air tank ??

I'm thinking diesel truck salvage yard ??
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Old 12-18-2008, 11:39 PM   #10
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ok so where can I get a nice BIG air tank ??

I'm thinking diesel truck salvage yard ??
Why do you need a big air tank?
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Old 12-19-2008, 09:58 AM   #11
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Why do you need a big air tank?
see posts above... he can't supply enough air to run the spraygun. A nice big tank will let him store up enough air to possibly run at whatever psi for long enough to spray whatever he needs. Yes the compressor CFM still isn't high enough, but if the spray is over before the tank is empty it doesn't matter.
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Old 12-19-2008, 10:56 AM   #12
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Quote:
Originally Posted by IllNastyImpreza View Post
ok so where can I get a nice BIG air tank ??

I'm thinking diesel truck salvage yard ??
Do what I did, buy a garage with a nice 50 gal plumbed in already (it happened to have a house on the property as well)
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Old 12-19-2008, 12:53 PM   #13
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see posts above... he can't supply enough air to run the spraygun. A nice big tank will let him store up enough air to possibly run at whatever psi for long enough to spray whatever he needs. Yes the compressor CFM still isn't high enough, but if the spray is over before the tank is empty it doesn't matter.
To paint a car you will need about two hours of continuous air. How big a tank will that be? I thought he wanted two compressors to meet the CFM requirement of his gun.

Now lets talk about cooling the air and getting the water out.
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Old 12-19-2008, 01:00 PM   #14
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Quote:
Originally Posted by rick-l View Post
To paint a car you will need about two hours of continuous air. How big a tank will that be? I thought he wanted two compressors to meet the CFM requirement of his gun.

Now lets talk about cooling the air and getting the water out.
Two hours?

I've painted a couple cars, I can usually lay down a coat in 10-15 minutes.
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Old 12-19-2008, 01:17 PM   #15
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Originally Posted by rick-l View Post
To paint a car you will need about two hours of continuous air. How big a tank will that be? I thought he wanted two compressors to meet the CFM requirement of his gun.

Now lets talk about cooling the air and getting the water out.
and that is if you do it all in one shot. What I know about painting a car comes in a spray can, but i'm assuming you don't need to do everything in one shot. Spray one panel, wait, spray one panel... He obviously isn't going into business doing this.

Cooling it won't be an issue. Let the compressor fill the tanks, walk away, come back later in the day and your air is cool.

I've got 2 - 10 gallon tanks I will parallel for doing this exact same thing. They are connected to a compressor that has a VERY small tank (4 gallon or so), but fairly decent CFM for a 120v unit. It fills up insanely quick if I just need to do something quick, and I can open the valves to the storage tanks if I need to do something bigger.
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Old 12-19-2008, 02:56 PM   #16
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Someone tell me if I am doing this right. I have a cheap gun that needs 8.4 CFM @ 40 psi. Note: some expensive guns need 12-15. I am assuming that 8.4 is volume at 1 atm, is that correct?

Looking at the example in the link above; http://www.truetex.com/aircompressors.htm
25 gallons = 3.342245989 cu ft

At 14.7 psi 1 cu. ft. in the tank contains 1 cu. ft. of air @ 14.7 psi so the tank in the example contains 3.34

At 40 psi 1 cu. ft. in the tank contains 2.72 cu. ft. of air @ 14.7 psi so the tank in the example contains 9.09

At 85 psi 1 cu. ft. in the tank contains 5.78 cu. ft. of air @ 14.7 psi so the tank in the example contains 19.33

At 102 psi 1 cu. ft. in the tank contains 6.94 cu. ft. of air @ 14.7 psi so the tank in the example contains 23.19


So I start at 102 psi the tank contains 23.19 cu. ft. (of air @ 14.7 psi) and I use up the air at a rate of 8.42 cu ft per minute down to a pressure of 40 psi where the tank contains 9.09 cu ft.

So 23.19 - 9.09 = 14.1 cu ft and using it at 8.4 CFM it would last 1 minute and 40 seconds so this compressor is inadequate?
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Old 12-19-2008, 03:35 PM   #17
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does it matter if I set the preasure @ the tank or @ the gun ? I have 2 regulators... right now its set @ 90 @ the tank, and 30 @ the gun. would I use less air setting it @ 30 at both ??
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Old 12-19-2008, 04:05 PM   #18
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Quote:
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does it matter if I set the preasure @ the tank or @ the gun ? I have 2 regulators... right now its set @ 90 @ the tank, and 30 @ the gun. would I use less air setting it @ 30 at both ??
I think you want to expand it as much as pracrtical (acct for line losses etc) at the source and then run it through 50 feet of iron pipe to cool it and condense out the water before the seperator.
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Old 12-19-2008, 04:08 PM   #19
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I think you want to expand it as much as pracrtical (acct for line losses etc) at the source and then run it through 50 feet of iron pipe to cool it and condense out the water before the seperator.
so set both to 30 correct ??
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Old 12-19-2008, 04:16 PM   #20
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Does your gun have a guage?
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Old 12-19-2008, 11:11 PM   #21
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yes it does
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