Small prv fluttering.

by dave
(las vegas)

I have a BIG craftsman compressor. The 80 gallon one. Has a 2 cyl, Cast iron V twin style pump.


Just a few days ago the little 70 psi prv on the head began going crazy. It pretty much pops off every or every other stroke.

Its on the 2nd piston in line, the way its setup. Its not the primary piston, its the smaller of the 2.

So i figured that valve was bad, as it seems awful soft. So i grabbed a new 70 psi prv at my fav tool place. Put it on, same deal.
What could be the issue?
Thanks for any help. Dave
bluepanel@gmail.com

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Bill says...

Dave, I can't my head around why you have a PRV set for 70 PSI on the second of what sounds like a two stage compressor.

Normally the second stage (pump) accepts already compressed air from the first piston, and this enables the unit to increase compression speed and pressure levels in the tank.

I sure would like to know the how of it too. Anyone help us?

Thanks,

Bill

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Feb 17, 2013
80 gallon Sears 2 stage prv on head
by: Anonymous

Bill I am having the exact same issue with my 80 gallon Sears compressor, the small prv on the HP head has 70 engraved into it but once the compressor hits 105psi it pops out every stroke after that. I can't figure out why
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It is either popping off because it has failed, or, more likely, because you have an air flow problem in the HP head that is causing pressure spikes when the tank pressure reaches 105 PSI. Common issues are valve problems. Before tearing it down, dump all the air and make sure the check valve is working properly.

B.

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Relief valve blows at 100 lbs

I have a Speedaire 80 gal 7.5 Compressor. The releif valve on the head blows at 100 lbs while compressor is running trying to make pressure. Is this a switch problem or is there a leak in the head causing pressure to develope too early. I have replaced the relief valve but that did not remedy the problem.I'm not sure what to do next....switch or replace gaskets

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Bill says...

Maybe you could take a second and read the page on PRV's, if you haven't done so?

http://www.about-air-compressors.com/PRV.html

If the PRV is letting go, it's normally nothing to do with the pressure switch.

Maybe also read the page on pressure switches if you haven't?

http://www.about-air-compressors.com/pressure-switch.html

I don't know what the normal PRV blow off pressure is of your Speedaire. It should be normally quite a bit higher than 100 PSI, as the normal high pressure cut out will be higher than 100 PSI.

The PRV is reading the system pressure, so if it's blowing off at 100 PSI and it's not supposed to, then as far as I'm concerned, you've got a PRV issue.

You can test your PRV if you have some simple air fittings and a pressure gauge. If it's blowing off at 100 PSI and it's not on your compressor, that reinforces that there is something wrong with it.

Good luck.

Bill



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Position of safety air valve.

by Ronald Norris
(Altoona, Pa.)

I added a 11 gal. air tank to my 10 gal. compressor.

I added a shut off valve and a water/oil seperator with the addition.

Now it leaks air at the new addition and I think that I know why. I really can't get 1 of the new fittings as tight as it should be.

Question is basically is on the pressure release valve I have it sitting straight up, the way it was before was it was horizontal. To get this valve tight I would almost have to have the pressure release valve upside down, will that hurt with the reading. If I can put it upside down I can tighten it up and it won't leak anymore. I was just not sure about water settling down inside it. Also can my oil/water seperator be a a very slight angle? As usual any help appreciated, keep up your good advice.
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Ronald, if by safety air valve you are referring to what I would call the PRV, or pressure relief valve, typically they are installed in a horizontal fashion.

You say "I would almost have to have the pressure release valve upside down, will that hurt with the reading." There is no gauge to read on a PRV, so this comment confuses me.

I also do not believe that a PRV must be perfectly horizontal to work, and I would have no problem installing mine at an angle. Do get in the habit of pulling on the ring periodically to make sure that the PRV moves easily. Just push the ring back in to shut off the air.

If, in your questions, you are referring to what I would call the pressure regulator (it does have a gauge) it can be installed in any plane to make it easier to install and to position the gauge for convenient viewing.

The air filter (air water separator) should be installed so that the bowl is at the bottom, so that debris and water collected can drip to the bottom of the bowl for periodic removal. The filter will work with the bowl at an angle, but the water / debris collection will be negatively affected if the bowl isn't vertical.

Cheers,

Bill



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1995 smith screw type compressor with diesel motor pop off valve releases when cold

by lee robichaux
(conroe Tx)

compressor when cool in the morning the pop off valve releases and motor will not idel down. 200 cmf 1995 smith screw type compressor with diesel motor

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Jan 19, 2014
Seperator
by: Carl

Hi,
Im guessing the pop off release valve youre talking about is the one on top of the seperator vessel (where you put the oil in)
In that case, it sounds like your oil seperator is blocked and needs replacing. As it is always in the morning, the oil is cold and wont let the air pass through it causing excess pressure in the vessel and popping the valve. Replace the oil seperator, that should sort out the problem

Hope that helps
Carl

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