Spray gun and air compressor size?

by jan
(nc)

Paint spray gun - http://www.about-air-compressors.com

Paint spray gun - http://www.about-air-compressors.com

I got a spray gun and its rated at for 30psi inlet 10 psi at 13 cfm, will a 3hp compressor with a 30gal tank handle this

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Well Jan, since you can get about 4 CFM of compressed air at 90 PSI for each horsepower of electric motor size on the compressor, your compressor should, theoretically, give you about 12 CFM at 90 PSI.

However, if you are running your 3 HP compressor on a 120 volt supply line, then you sure are not getting that 12 CFM at 90 PSI, since, in my opinion, there isn't enough power in a 120 volt line to power your compressor motor enough to give you that flow and pressure.

Why not have a look at some of the pages linked under CFM / SCFM / Flow / Pressure Issues on the sitemap page for much more info?

Anyway, depending on what you are doing with your spray gun (besides painting that is), I mean, if it is air brush work with intermittent use, and you have dialed your regulator down to the minimum operating pressure for the gun that gives you the spray you want, you will be able to work with your 3HP compressor. You will, depending on how much spraying you want to do at one time, likely have to stop periodically and let the compressor catch up.

Cheers,

Bill

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Average Air Tool SCFM

by James Toland
(Cincinnati, OH)

How is the Average SCFM for an air tool calculated? Is there a formula?
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James, not to my knowledge.

It's like asking if there is an average motor size in all the cars in the world.

Each manufacturer of air tools builds their tools to provide a certain amount of force to do the job that tool is supposed to do.

Another manufacturer of that same type of tool will make a DIY model with less force and lower cost components.

Another manufacturer will make the same type of tool, but in industrial strength size.

Each will use different levels of flow.

On the Sizing page on this site is more info. It provides a guide of some air tool usage. Yet, the only thing you can do for sure is to pick the tool, read the manual and or specification plate, and see what that air tool requires in flow and pressure.

Then, if you give it that, the tool will work properly. If you don't, it's like feeding the carb (my, that does date me doesn't it) with too little fuel when you step on the gas in the car. The car will not run properly.

Neither will your air tool.

Cheers,

Bill

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Air keeps blowing out of air gun?

by Steve T.
(Bronx NY)

Duralast air tank (Photo: www.autozone.com)

Duralast air tank (Photo: www.autozone.com)

converting an air tank to blow compressed air with a blow gun

I bought a Duralast 7 gallon airtank hoping to use it with a blow gun, but after filling it up and opening the on/off air valve, the air just started coming out the air gun nozzle by itself. Do i need a different valve on the tank or is the blow nozzle bad? Thanks for any help u can give me. Steve T. Bronx NY
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Hello Steve. From what you have written, your blow gun needs work.

Typically, a blow gun comes with a stud or trigger that needs to pushed or pulled for air to travel out the nozzle. These studs or triggers are the manual operator for an internal 2/2 air valve inside the gun. Pushing or pulling on them shifts the valve, and opens an air path from the hose to the gun nozzle. Let go of the trigger or stud, and the air should stop.

Time for a new blow gun I think.

Bill

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Dec 04, 2012
Fixed!
by: Steve T.

Problem solved!
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Yay... the good guess wins one! :-)

B.

Dec 03, 2012
thanks!
by: Steve

Awesome! Thank you Bill. I'll replace it tommorow and see what happens.

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Using my nail gun my air compressor won't shut-off.

by Bo
(La Mesa, CA USA)

Framing nail gun in action (Photo: www.datapowertools.co.uk)

Framing nail gun in action (Photo: www.datapowertools.co.uk)

My compressor shuts off when the pressure reaches 135psi but turns back on after just a few nails which drops the pressure to around 100-105 psi. I have to slow down and wait for the pressure to build again or my nails won't properly sink. What is my problem?
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Bo, I have to tell you, that a nail gun often does a good job at lower pressures that 135 PSI. But, I cannot second guess your nail gun as I don't have any details. When you got it, did you happen to keep the user guide? Does it give you a recommended pressure to run the gun at?

In any case, a nail gun is normally a good air tool to run with a small air compressor, as the nail gun shoots a nail, then does not consume any more air until you pull the trigger to fire another nail. Then it uses another short burst of air.

You indicated that you are using Bostitch air compressor. It is not unusual for them to have a cut out pressure of 125-135 PSI, and a cut in pressure in the 90-100 PSI range. You don't indicate your Bostitch air compressor model yours is, so I'm going to assume yours has a cut in and cut out pressure in that range.

This means that the compressor shuts off at, in your case, 135 PSI. It doesn't take too many shots of a nail gun (more for a framing nail gun versus a brad nailer) before the pressure in the tank starts to drop.

The tank pressure will drop until it reaches the cut in pressure setting of the compressor pressure switch, and in this case, I'm surmising that cut in is around 100 PSI.

So, your air compressor seems to be operating normally, based on the info you provided.

The issue is that your nail gun evidently needs 135 PSI to shoot a nail.

If the manual says that you need a minimum of 135 PSI to run your nail gun, then you have the wrong air compressor.

You need one with an upper PSI limit well over your 135 PSI, and with a cut in pressure at 135 PSI minimum, if that is what your nail gun really needs.

Cheers,

Bill


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Dec 29, 2012
More info
by: Bo

Bill,

The model No. for my Bostitch air compressor is CAP2000P-OF. The working pressure is 0 - 150 psi, the working pressure on my Senco coil nail gun is 70 - 120 psi. For the best results should the regulated pressure be set at 120 psi?
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Bo, I always say start using the air tool at the minimum operating pressure, and dial up the pressure only if the min op pressure is insufficient. Saves money on energy use and your air compressor and air tool will last longer between maintenance.

If you are needed 120 PSI to seat the nail, I wonder if your air nailer needs adjustment?

B.

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