leaking air out of shut off

pumps up shuts off but air leaks out of shut off


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Bill says...

Howdy. If by the shut off you are referring to the pressure switch, the air will probably be leaking out the little dooey (technical term) on one side of the switch.

If that is the case, check out the page on CHECK VALVE, as that is likely your problem.

Cheers,

Bill

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Gasket ~ for check valve

by Tom
(Moreno Valley, Calif.)


I found the source of my leak. It is the gasket for the check valve. Where can I find a replacement gasket as seen in the picture?

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Bill says...

Hi Tom. I vaguely remember your first post, but I'm not sure if you identified the compressor make in that one, and you don't here.

Where did you get the compressor you have now? If purchased from a store, go to them, and ask where they get their compressors fixed under warranty. Get the contact info for that shop. They should be able to help you with parts.

Good luck.

Bill

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Check valve installation

by Al
(Newark, Oh)

Hi,
I am installing a commercial compressor onto a new tank. My question applies to the check valve. Is it acceptable to install the 3/4 inch check valve into a 1" or 1.5" pipe or does it have to be installed directly into the tank?

My tank has 1.5" bungs so I could use a 1.5" to .75" bushing but I would rather bring a 1” pipe up and reduce it to .75 for the check valve. I am not sure if this would create too much back pressure on the compressor.

Thanks, Al

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Bill says...

Al, a check valve, or non-passing valve, will work in preventing compressed air back flow at the point it is installed. As long as where the check valve is installed is the point where you do not want back flow to occur, then installing it there is just fine; a the compressor discharge, in the line to the tank, or at the tank itself.

Do recognize that by introducing a .75" check valve into a 1" inch line, you are creating an air damn, which will reduce the flow of air downstream, through the tank, to the point of use.

If you can get enough air flow through a .75" line to the tank and ultimately to the equipment, no problem.

The check valve, in slowing the air, will not negatively affect the operation of your air compressor.

Cheers,

Bill


Comments for Check valve installation

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Dec 05, 2011
Check Valve
by: Al McDaniel

Thanks Bill, you have been very helpful.

Al McDaniel

________________

10-4. Glad to help.

B.


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Check Valve

by Paul Smith
(Valdese, NC, USA)

I am installing a 2nd air tank for reserve when I use air sanders. Will a check valve from the plumbing section of a local hardware work with air pressure? Thanks,

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Bill says....

Maybe. To check, blow into the downstream side as hard as you can without doing yourself a damage. If the check valve stops your breath from blowing back, it will likely work for your air system. Just make sure that it's rated for the pressure your air compressor generates.

Cheers,

Bill

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Check Valve


Is there a step by step procedure on how to remove and check the "check Valve?" I received your response on the problem with my leaking compressor and was extremely pleased.

I would highly recommend this site to my friends that experience problems with their compressors.

By the way, I have a Central Pneumatic Compressor.

Thanks, Tom.

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Bill says...

Hi Tom. Good thought on the how-to for re & re the check valve. I'll do a video and instruction on that shortly.

First, unplug the compressor. Then, open the tank drain valve and bleed off all the air. Leave the tank drain valve open.

Look at the top of the compressor pump, and find the line that exits the top and goes down to the tank.

Usually, where that line meets the tank, there is another line that goes off to the unloader valve, and the fitting that both lines are attached to contains the check valve.

Pull the lines, and unscrew, or remove, the check valve.

It is a one-way valve, so air should only go through it one way, and into the tank.

Check the valve seats, and make sure the flapper ( or whatever checks the air from coming back out) to make sure it works freely, and no debris is blocking the operation of the flap.

Once satisfied, re-assemble, close the tank drain, and plug the compressor back in.

Cheers,

Bill

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Check Valve Gasket

by Tom
(Moreno Valley, Calif.)

I povided you a photo of my check valve gasket that was leaking. You asked where did I purchase my compressor and the make of my compressor. I purchased by Central Pneumatic Compressor from Harbor Freight Tool. When I described my problem to the sales persons, they were unable to help me. They are in sales only. They couldn't even give me the phone number for Central Pneumatic!!!

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Bill says...

Their response is not surprising. A high school kid working part time isn't going to know anything about air compressors.

Tell you what. Go to your local big box store, or find one nearby, and ask them where they send their compressors for warranty repair. Go to see these folks with your check valve and gasket.

Or, find the local industrial compressor supply outfit and ask them.

Central Pneumatic is Harbor Freight's house brand. They will have that brand manufactured by the cheapest compressor builder in the world, I would think, and that location would be in the Orient.

Cheap price, cheap compressors, no reliability, no service. That's the cost of buying cheap. It's a price that we, in North America, are coming to pay more and more as we continue (I'm as guilty as anyone) to buy cheap imported product at the cost of our own standard of living.

Cheers,

Bill

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TANK CHECK VALVE

by DAVID
(WATERTOWN SD USA)

I PURCHASED A USED 1964 KARGARD MODEL 331TV, SERIAL N491906.
DOES THIS HAVE A CK VALVE AT TANK OR WOULD IT HAVE SOMETHING IN HEAD?
PUMPS GREAT , BUT AFTER SHUTDOWN WILL LEAK AIR BACK.
THANKS DAVE

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Bill says...

Dave, I don't know the compressor myself, though I expect that someone out there that does will comment too.

You say "BUT AFTER SHUTDOWN WILL LEAK AIR BACK." It would be good to know where that air is leaking from. If it is the unloader valve, then you either don't have a check valve (hardly reasonable) or the one you do have is not working.

Look where the fitting from the pump enters the tank. That's where the tank check valve is normally located. With the compressor off, and air drained completely from the tank, disassemble this fitting and clean the check valve, as I suspect that's all the problem is.

Cheers,

Bill



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Unloader valve - check valve - valve issues

I have a homemade air compressor my grandfather had for years. The problem was it leaked around the tube from the compressor to the tank.

Before I researched some similar problems I didn't know about unloader valves. I found that it had this valve and was actually installed incorrectly at some point leaving it stuck open, allowing pressure to build into the tank but when it reached max pressure it would shut off and slowly bleed out, cycle would obviously continue.

After I realized what was going on I installed it correctly because it was just a matter of reversing the fittings that someone must have messed with. So, now the valve is correctly positioned so the it opens when the compressor is running and shuts when it goes off, and, allows it to unload that short spurt of air off the compressor.

My problem is that while it is filling/running air shoots out of the little unloader valve hole only letting my pressure to build to a certain point and but never reach full capacity.

I can only assume that when that unloader valve is open allowing air to flow to the tank it somehow also shuts the little unloader hole on the side, leaving air to travel in one direction. If I am correct then I know that the valve is bad. If that is not how it works then I don't know what to do. Any advice?

Thanks,

Wayne

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Bill says...

Hi Wayne. The way I'm reading your post is making me wonder if you are using the terminology "unloader valve" for the CHECK VALVE that is usually installed where the air from the pump enters the tank.

Above the check valve is normally a line that shoots over to the pressure switch. This line is upstream from the check valve is it is the line that allows the pressure switch to "read" the tank pressure, so it knows when to trip and shut off the air compressor at cut out.

That same line also plumbs air to the UNLOADER VALVE, often located beside your pressure switch. The unloader valve is closed when the compressor is running, allowing air to be pumped into the tank, and open when the compressor stops, allowing air over the piston to escape, making start up easier.

If you have air bleeding out of the unloader valve all the time, your check valve is not working properly.

Cheers,

Bill

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valve to control air to a tank from a compressor

by bill wuttke
(cambs england)


i have a screw compressor with three air outlets, i have a 300 l tank which is connected to one outlet, i need a valve which is non return but lets the compressor know to increase revs to refill, its a diesel controlled screw compressor i have a valve will this work

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Bill says....

Good luck with this, Bill.

The non-return valve will ensure that the main pressure switch will not know what the pressure in the 300 L tank is.

The only way I can see it happening is if you put a pressure switch between the non-return valve and the tank, with a signal back to the throttle.

You can get pressure switches that work on, and signal, with air only.

I cannot tell from the photo what this valve is.

Anyone else?

Cheers,

Bill


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