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"Basic" air compressor question

Old Sep 11, 2006 | 12:56 PM
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Default "Basic" air compressor question

So, a few months ago I bought a nice 60gal (7hp) Campbell-Hausfeld air compressor. Nothing fancy. It was a good deal so I figured - why not?

I finally got it all hooked up (220v), got a filter for it, pressure regulator, etc.. I set the pressure regulator to 90psi. Works great.

The "problem" - is there supposed to be some sort of auto-shutoff? The power switch only has 2 settings - Off and Auto. When I turn it on Auto, it just runs forever. Once it hits 90psi, the pressure regulator starts bleeding off air to maintain the pressure. But it just keeps going forever. This seems pretty wasteful (not to mention, annoyingly loud for hours and hours).

Is there any way I can make it turn off at a certain pressure, and then back on when it gets too low? A friend of mine has a small air compressor (like 25gal) and it only turns on when it needs to.

Finally, when I'm done with air tools should I drain the air out of the tank, or just leave it? If I do, how do I release the air safely/easily?

Never had an air compressor, please bear with me

Dope
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Old Sep 11, 2006 | 01:05 PM
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Sounds like the limit switch isn't working properly.

The compressor should kick on at a minimum pressure, and off at a maximum pressure. A lot of times, these are adjustable with a set screw and/or set nut.

On a standard single-stage compressor, "minimum" would be ~80-90 PSI, "maximum" would be ~125-130 psi. The compressor should turn off when it hits max pressure.

You do not need to empty the tank after each use. A waste of electricity. All you need to do is empty the drain at the bottom of the tank occasionally (depending on use). There's a petcock on the bottom of the tank to drain water. IMO it's better to stick an elbow, a small pipe extension, and a small ball valve on there so you can drain it easier. But anyhow, all you need to do is to crack that open until water stops sputtering out (doesn't take long), and then close it back up again.

Sounds like the compressor limit switch isn't set up right tho.
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Old Sep 11, 2006 | 01:10 PM
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Originally Posted by Dope
So, a few months ago I bought a nice 60gal (7hp) Campbell-Hausfeld air compressor. Nothing fancy. It was a good deal so I figured - why not?

I finally got it all hooked up (220v), got a filter for it, pressure regulator, etc.. I set the pressure regulator to 90psi. Works great.

The "problem" - is there supposed to be some sort of auto-shutoff? The power switch only has 2 settings - Off and Auto. When I turn it on Auto, it just runs forever. Once it hits 90psi, the pressure regulator starts bleeding off air to maintain the pressure. But it just keeps going forever. This seems pretty wasteful (not to mention, annoyingly loud for hours and hours).

Is there any way I can make it turn off at a certain pressure, and then back on when it gets too low? A friend of mine has a small air compressor (like 25gal) and it only turns on when it needs to.

Finally, when I'm done with air tools should I drain the air out of the tank, or just leave it? If I do, how do I release the air safely/easily?

Never had an air compressor, please bear with me

Dope
I'll answer your 2nd question first: You should drain your compressor out periodically. I do mine about once a week or so. It depends on how much you use it and how much humidity is in the air while using. Mine has a bottom draincock and I usually bleed the air down to about 30 PSI or so with the little pin bleed valve and then open up the drain **** and let it drain into a plastic cup. You'll probably find the moisture comes out rusty colored.

Now the auto shutoff: I have a Craftsman 33 Gal 6.5HP 120V and mine shuts off automatically at the max PSI of 140PSI. It is then set to turn back on automatically at around 100 PSI or so. If there are no leaks in the system, it will run to 140 PSI, turnoff and stay there indefinitely until I start using it again. I, however, usually turn my compressor on and off manually whenever I 'm ready to use it or am finished using it. I work nights and one time I must have had a small leak in the system and it kicked on at about 3:00AM and scared the **** out of my wife!!

Bryan
parbreak
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Old Sep 11, 2006 | 01:11 PM
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Guess I didn't type fast enough ^^^^ What he said
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Old Sep 11, 2006 | 02:33 PM
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Where are you bleeding air? On the factory, built-in regulator or on the one that you installed in-line yourself?

To test I'd close the main valve on the compressor and then flip on the power. It should not bleed air until it hits it's max capacity (usually 130-150 psi) and then it should auto shut off. You should then be able to operate tools until the pressure drops below 90psi and then the compressor should kick back on and refill itself.
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Old Sep 11, 2006 | 02:54 PM
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Ahhh I see what you guys are saying. I set the pressure on the external pressure regulator (the one I bought). It is bleeding off air once it hits the pressure I set it to. I guess I don't even need it. I will try removing it (or just set the max to 150+ psi) and see if the compressor turns itself off around 130-140psi.

I guess I don't see the point of the external pressure regulator? Maybe if I were using something that needed a specific pressure to run? Painting maybe?

Like I said, I'm new to this. I was reading that automotive air tools use 90-100psi so I assumed that's what I needed a pressure regulator for.

Thanks for the tips, I'll give it a whirl.

Dope
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Old Sep 11, 2006 | 03:26 PM
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If your external pressure regulator is messed up, it will leak out the regulator. I have one on my portable compressor that - if I don't hit it just right it'll leak (it's 10 years old, and was a cheapie when I bought it). You may have to tighten/loosen/adjust something on the regulator. And double check that it's pressure rated for the max pressure of your compressor.

The way my compressor is set up (a 60 gallon tank) is that I have a ball valve on the output of the compressor, and after that is where the pressure is regulated. The ball valve allows me to cut off pressure from the rest of my air system, while still leaving air in the tank. The rest of my system has a very slow leak somewhere, but the tank itself keeps pressure without any noticeable leakdown.

The regulator does indeed need to be there. Air tools are happiest between 90-100 psi, but your compressor (assuming a single stage) would likely go to 125-130 psi. Two stage compressors go to ~150 psi (that's what I have).

You can get as crazy as you want with compressed air setup. Here's mine:

https://ls1tech.com/forums/tools-fabrication/480039-plumbing-shop-air.html
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Old Sep 11, 2006 | 10:07 PM
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Originally Posted by Dope
I guess I don't see the point of the external pressure regulator? Maybe if I were using something that needed a specific pressure to run? Painting maybe?

Dope
The valve on the compressor isn't really a regulator. It's simply a pressure gauge and a check valve that will release excess air if the compressor should go above it's rated capacity.

I suppose you could try to regulate the pressure at the tank but the problem is that you don't have an accurate reading on the psi coming out of the air hose. This is where the external regulator you purchased comes in handy. You can just open the main valve on the compressor all the way and use the external regulator to control the flow to your tools. Most tools are going to be around 90psi but it always helps to check your instructions to make sure.

The external regulator should not bleed off excess air. Most regulators have a valve that you manually open to remove any water in the reservior. Check to make sure this is closed.
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