Air leak at the on off switch on a Speedaire.

by Steve

I have a speedaire ml. #5z645c and after it pumps up to pressure it has developed a leak just under under the on off switch.


Once the tank pressure drops down to around 100lbs.it suddenly stops leaking. Can this part be replaced?






Bill answers...

Hello Steve. Thanks so much for visiting and taking the time to write in.

Since I can't see the ON/OFF switch (a photo sure would have helped) it's a bit difficult to diagnose for sure.

Speedaire and other manufacturers have had so many models of air compressors over the years, there's no way I can identify on from a model number.

Where is the air leaking from just under the switch? Is it a fitting? If so, you may solve the problem yourself by simply tightening the fitting nut 1/2 turn. If the fitting is almost tight, as the air pressure exceeds that 100 PSI mark, it forces open a thread slightly, and you develop a leak, perhaps.

Or, it might be that air is leaking from the unloader valve. That doesn't mean that the unloader valve itself is the problem, it might be the check valve.

Check out this page.

Cheers,

Bill









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Compressor unloading problem

I have a speedaire compressor model 3JR76.
After it runs for an hour it sometimes does not unload when it reaches its set pressure. When this happens the motor trips out. If I let it sit and it then starts fine again. I do not have a manual but would like one if you can help with this as well.

Thanks in advance for your help
Dick






Bill says...

It sounds as though you may have a pressure switch issue.

Here is info on pressure switches.

Regarding your manual, if you haven't contacted Grainger as yet, that's your best bet. Follow the guidelines on the Speedaire page on this site.

If you have and they cannot help then please post your request here.

Cheers,

Bill





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the tank fil up wen ful the motor turn of buty air leaks out from the botom of presure swith

by d vion
(springwood nsw austalia)

went and by a new swith and the same thing as before whit the old one

_______________________

Bill says....

I don't think it's your pressure switch. I think it's your check valve.

Check out this page.

Cheers,

Bill

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installed new pressure switch, leaks air at unloder valve.

by mprrpm
(covington ga)

when compressor shuts off,at required pressure,unloader does'nt go pssst and stop leaking . it goes psssssssssssssssssssssssssssssssssssssssssss until the compressor comes back on. it is a new switch , for 2 stage, it is new style, with knob on top instead of lever on side. air leaks at bottom of switch at unloader valve on switch.
__________________
Hi there... I don't think you have an unloader valve issue, I think your tank check valve may be leaking.

Remove that, clean it, replace it, and see if that works. If not, post a comment here.

Cheers,

Bill

Comments for installed new pressure switch, leaks air at unloder valve.

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Aug 12, 2012
air pressure
by: bill E.

I took off the check valve cleaned it out and solved my problem. Thanks.

Aug 09, 2012
pressure switch
by: bill E.

my pressure switch continues to release air from the bleeder valve. I have changed the check valve in the tank and double checked for leakage. No leaks from the check valve. What other possibilities would cause this to continue leaking air?
_________________
Bill, just to be sure we are talking about the same thing, when you say "bleeder valve" are you referring to what I would call the "unloader valve", the one that goes "pssssst" and dumps a bit of air when the compressor stops on cut out?

If it the unloader valve that you refer to, and it is leaking air continuously, the only source for that air is the compressed air tank. This means that a) your tank check valve is leaking b) the diaphragm in your pressure switch is leaking, allow air from the tank to exhaust via the pressure switch openings, and if just feels like it is coming out of the unloader valve

Bill

Jul 31, 2012
No external check valve
by: Michael

This sounds like my problem aswell, how ever i do not have an external check valve. It goes from the pump to tank. Any ideas? Can I install a check valve where there is not one?
_______________
Michael, this is difficult to answer without details of your compressor, make, model, HP etc.

Typically though, the check valve is installed where the line from the pump head enters the tank. That fitting often incorporates a check valve, as well as a line over to the pressure switch.

B.


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Reaches 125psi shuts off and blows air out of the valve attached to the tank

by Darin
(Seattle)

My compressor reaches pressure, kicks off and depresses a release valve in the LF 10-L4H switch that is attached to the tank by a tube. It gets down to 80psi and kicks back on again. I have to manually pull the plug and push down the adjustment bolt.

I replaced with a brand new switch and it worked for a year and a half. Started again doing the same thing, this time the new switch I installed has the same issues as the one I replaced.

When the cover is on, it has a push pull red button. If at anytime that button is pushed, it turns off the compressor and releases the pressure... it is the same valve that hisses when it turns off after reaching pressure of 125.

thanks

D

_____________________
Bill says...

Darin, from what you have described, I don't think your compressor has a pressure switch problem, so much as a check valve issues.

Please visit the site map page, and read the page on Unloader Valves, Check Valves, and Unloader Valve Leaking for more info.

If the information there doesn't help, please post a comment here telling me what you found, and we'll press on.

Cheers,

Bill

Comments for Reaches 125psi shuts off and blows air out of the valve attached to the tank

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Dec 31, 2011
Unloader valve
by: Darin

It is the unloader valve, that is draining the air all the way down to 85psi, at which point it kicks on and fills up to 125psi, at which point it kicks off and bleeds down to 85psi. On a Brand NEW pressure switch.

"First, What The Unloader Valve Does
The unloader valve is a needle valve which is linked to, and responds to the pressure switch as the switch reacts to the compressor tank pressure. The mechanical action which opens the contacts inside the switch to shut off the compressor motor, is linked too, and also opens, the unloader valve. This unloader valve then connects the compressed air trapped over the compressor piston to atmosphere, and allows that trapped air to escape, unloading the compressor.

You can hear this happen. When a compressor reaches the high pressure set point and stops, there is the characteristic "Psssssst" sound, the sound of air escaping. This is the sound of the compressor pump being unloaded. And it should be a brief burst of air, normally less than a second or two."

Dec 31, 2011
do not believe your compressor problem has anything to do with the pressure switch
by: Anonymous

"If air is bleeding out of the unloader valve when the compressor is running,
A bum or dirty check valve is a possibility,

I do not believe your compressor problem has anything to do with the pressure switch. I suspect your problem will be solved if you remove, clean and replace the tank check valve."

It is when the compressor is OFF, when it shuts OFF, when it reaches 125psi and the switch opens the contacts..at this time depressing that valve. My brand new non rusty, non dirty, completely clean brand new switch pushes down on that valve in the OFF position. IF I unplug the unit before it gets to 125psi, NOTHING leaks, Tight as a drum.

I've tried adjusting the cut in/cut out, on this switch, (brand spanking new switch, not dirty not fouled by grease oil or rust) it is a bolt inside a spring, turn it to the right and it increases the values, turn it to the left it decreases the values. It did not help any.

Dec 30, 2011
valves and compressor
by: Darin

Ps. there are 3 valves on my compressor... one is a safety valve on the tank, the other is in the pressure switch, maybe this is what you say is an unloader valve, the other is a stopcock at the bottom of the tank to drain the condensed water and oil occasionally... I'm not grasping your useage of the check valve.

This is my compressor, very similar to mine.
http://www.harborfreight.com/25-horsepower-21-gallon-125-psi-cast-iron-vertical-air-compressor-67847.html

________________

Darin, the valve beside the pressure switch is the unloader valve. Please read the unloader valve page to better understand its purpose.

If air is bleeding out of the unloader valve when the compressor is running, either the unloader valve isn't shutting off (stuck??) or the check valve inside the fitting where the air line from the pump head to the tank is plumbed, is not sealing properly, and air is bleeding back out the unloader valve.

A bum or dirty check valve is a possibility, even on a new compressor.

I do not believe your compressor problem has anything to do with the pressure switch. I suspect your problem will be solved if you remove, clean and replace the tank check valve.

B.

Dec 30, 2011
The switch is New it is an LF10-L4H
by: Darin

It is an LF10-L4H (http://www.toolmarts.com/interstate-pneumatics/IP-LF10-L4H.html)

It is 100 percent brand new and if you look at the link and the picture, that little brass compression nut, is a plunger like valve that gets pushed down and Open when my compressor reaches 125psi it shuts off which drops a lever that depresses that valve and lets the air out till it gets down to 80-85psi then it kicks back in again... cycling over and over if I don't go and pull the dang plug out of the wall. This happened a couple years ago, I got a new pressure switch, replaced it and it worked fine... now doing the same thing... so I got a NEW CLEAN UNUSED switch and replaced the one that leaks and it has the same problem.

Dec 28, 2011
valve or switch or switch valve
by: Darin

Hi
I probably did not describe well enough.

On the pressure switch, the thing that has electricity running to it and there are contacts that turn off and on the motor. There is a valve that can release air when I turn off (push the red button down), this valve has a tube attached to it with a compression nut, this tube goes into the tank.

There is a separate "safety release" valve on the tank that blows if the tank pressure goes over 125psi, this one does not leak, unless I pull up in the pin.

The compressor cycles on at 80 off at 125, it kicks on, reaches pressure of 125 then kicks off, and blows air out of the little plunger valve attached to the pressure switch, until it hits 80psi then kicks back on again. This is a new pressure switch, the LF10, it is just like the pressure switch I replaced a year and a half ago. It worked up until a week ago.

_________________________

"There is a valve that can release air when I turn off (push the red button down), this valve has a tube attached to it with a compression nut, this tube goes into the tank." I believe that this is your unloader valve, not a safety valve at all. I also believe that your pressure switch is a Condor, is that correct?

I believe your check valve is leaking. Pull it an clean it or replace it and this should solve the problem.

B.


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Leaking pressure switch.

by Marlin

I have a 5Z402B dayton compressor that has been leaking air at the pressure switch only when stopping. Is that right or do i have to adjust or replace switch?






Bill answers...

Hello Marlin. Thanks for visiting and writing in.

Nope, I don't think you need to replace the pressure switch.

I suspect that what you have is a leaky check valve.

Here is information about a leaking pressure switch.

Cheers,

Bill

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air pressure switch unloader valve connection

by Manuel Torres
(Guatemala)

I just purchased a new 2hp compressor but nneded the switch to have no more than 20psi difference range between stoping and starting. It will work at 120psi.

The pressure switch that came with the compressor had about 40 psi difference so I ordered from Grainger via internet a new switch CONDOR USA, model MDR3.

When I got it I noticed that the swith does not have a place where the small hose is connected. I guess it is the unloader valve.

Can I still use the new switch? Can I solve the problem by blocking the small hose? Or may I use two switches? : One the new one and use parallel another old switch that has an unloader valve?
___________________
Manuel, the compressor needs to unload when it reaches cut out pressure. The Condor switch has an internal unloader switch, and normally the unloader line is plugged into the bottom of the switch.

It appears as though the one you got offers the unloader as an option:

www.condor-benelux.nl/nederlands/documentatie/drukschakelaars/condor/mdr3_gb.pdf

Can you run two switches in parallel, with the unloader of one working that part, and the switch of the other turning the power on and off. I suppose you could rig it, seems like a lot of work to me, when a compressor switch of the right kind has an unloader mechanism built in. I'd get the optional unloader for the switch if it were me.

Cheers,

Bill

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Air leak from pressure switch

by ken
(california)

Hi I just purchased a used pro air II compressor 5hp 26 gallons tank. I noticed the air leaking from the pressure switch area. This is my first air compressor. But when the pressure dropped down to 35-45 psi. seem it hold air. and tips on setting cut in and out pressure.
thanks

_________________________
Bill says...

The air that is leaking out from or around your pressure switch is a symptom of a check valve leak.

More information on why pressure switches seem to leak on this page.

Cheers,

Bill


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