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Discussion Starter · #1 · (Edited)
Hello All,


I'm in the process of setting up my shop for building hotrods. I have a 7hp 80 gallon 15 CFM @ 90 PSI 175 max PSI compressor, and was not sure what size pipe to run. I looked at the Devilbiss desiccant air filter system and it has 3/4" fittings. I also looked at the Eastwood Companies system which has 1/2" fittings and is also a couple hundred bucks cheaper. In the Eastwood Companies how to videos, the guys says uses 3/4" pipe but the filter system he shows has 1/2" fittings. My question is, is 1/2 lines more than enough to supply a 10 CFM Devilbiss Finishline spray gun as well as DAs and other air tools used in a body shop, or should run all 3/4" ??? There will only be one person working at a time, mainly me, a weekend warrior. They also recommended running 50 feet of pipe between the compressor and filter system to allow the air to cool before filtering which I planned on doing. Thanks for any advice on what's the best set-up ~ Len
 

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Brian Martin,Freelance adviser
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You want the 3/4" pipe, VOLUME is very important with HVLP guns, the HV is "High Volume" right?


Brian
 

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The main lines in my shop are 3/4" black pipe. All of the drops are 1/2" black pipe. I have a big regulator plumbed into the system with 3/8" Quick Disconnect fittings and 1/2" hose out to the guns. I have no problems feeding any of my HVLP guns with this set-up.
Mark
 

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The Penny Pincher
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The half inch will work fine as long as you run high pressure
(like 90 psi or higher) through them and regulate down at the gun.
 

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Brian Martin,Freelance adviser
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Pressure and volume are two different things.

You could run a quarter inch line and have 100 lbs PSI at the gun right?

Brian
 

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Pressure and volume are two different things.

You could run a quarter inch line and have 100 lbs PSI at the gun right?

Brian
Right! And no volume...
 

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Gotta love a turbo!
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I'm pretty sure he won't have any problem getting 15 cfm thru a 1/2" pipe system...

Russ
 

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Brian Martin,Freelance adviser
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"Getting" 15cfm through 3/4" would be easier. It does matter what tools are going to be used. An 8" hog needs a lot of air volume, an HVLP gun (depending on the gun, Sharpe Platinum is my favorite because it needs so little) needs a lot of volume of air to perform propertly.

If you go to paint gun manufacturers they all recommend 3/4" or larger because of this. That goes for the hoses too, the larger hoses are recommended, the low restriction couplers are recommended, all because volume is so important.

I have done tests with hoses for instance using a pressure gauge at the air cap on the gun that shows a drop in pressure by a few pounds (volume lost) when the hose length or diameter is changed.

Let me put it this way, outside of the slightly higher cost, is there a downside to having the larger pipe? Nope is the answer, it's all good, why not go with it?

Brian
 

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I ran 1" copper tubing. You want/need the volume. Do it right the first time and wont have to do it again. A 1" garden hose with 60psi water pressure will move much more than 1/2" will at same psi. Setting up a shop - so some blasting will be involved too. 3/4 or 1" is what you will need. And with blasting, that 15cfm may not be enough either. It is going to run often and depending on what you are doing, a long time.


I can sand blast with my 7hp 80 gallon 23-24cfm and the pump will shut off while blasting. I like my compressor.
 
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