# Speedaire 3z322. Leaking valve won’t build pressure



## Freightwrench (Sep 5, 2020)

Help, my old speedaire 3z322 won’t build pressure the valve under the pressure switch is leaking. Anyone know where I can get a replacement? It has very little time in it and I can’t afford a replacement. Any help at all is very much appreciated! Thanks in advance!


----------



## Freightwrench (Sep 5, 2020)

I was wondering if I remove the pressure relief valve that’s under the silver cap on the right where it leaks. Could I put in a pressure relief valve?


----------



## iowagold (Jan 22, 2020)

here is a parts place
click here for speed air parts

the question is does the compressor work?
make sure the drain under the tank is closed.

does the compressor start and run??
how big is the leak?
the red buttons is a slide on off valve for the pressure out of the tank.
does it slide side to side??


----------



## stevon (Mar 5, 2019)

Freightwrench,

the valve under your pressure switch is probably fine, what is probably not fine is your check valve. They are a maintenance parts like a belt or oil in a compressor. the unloader valve under the pressure switch is supposed to be open to vent the pressure between the cylinders when set pressure is reached and switch cycles off. This feature is so that when the pump starts up, there is very little load for the motor to overcome starting to pump air. If check valve is broken or leaking you will hear a constant "hissing" sound until the tank runs out of air

Stephen



Freightwrench said:


> Help, my old speedaire 3z322 won’t build pressure the valve under the pressure switch is leaking. Anyone know where I can get a replacement? It has very little time in it and I can’t afford a replacement. Any help at all is very much appreciated! Thanks in advance!


----------



## stevon (Mar 5, 2019)

Freightwrench,

The check valve is one problem, if you can't build pressure something else is going on like broken reed valves or another issue. I would replace the check valve, they are relatively cheap to start.

Stephen



stevon said:


> Freightwrench,
> 
> the valve under your pressure switch is probably fine, what is probably not fine is your check valve. They are a maintenance parts like a belt or oil in a compressor. the unloader valve under the pressure switch is supposed to be open to vent the pressure between the cylinders and the tank, when set pressure is reached then switch cycles off. This feature is so that when the pump starts up, there is very little load for the motor to overcome starting to pump air. If check valve is broken or leaking you will hear a constant "hissing" sound until the tank runs out of air
> 
> Stephen


----------



## Freightwrench (Sep 5, 2020)

So there’s another valve in the tank under the pressure switch? It runs up to 90lds but I am not sure what it should shut off at.


----------



## stevon (Mar 5, 2019)

Freightwrench,

Yes, usually they are in the tank see: 




Stephen


----------



## stevon (Mar 5, 2019)

Freightwrench,

The pressure limit switch is adjustable on most compressors. The Speedaire you have is a single stage I'm guessing so the absolute limit is 150 PSI cutoff. Typical factory setting is 125 to 135 PSI there should be no leaking when compressor is first turned on and solenoid should close the unloader valve until set pressure is reached. Once it hits targeted pressure limit you should hear a click, motor power is disconnected and release valve is opened, a short hiss should be heard, that's all and it should stop after air in tube is discharged. the check valve is supposed to hold back the built up tank pressure, unloader valve stays open until the pressure switch is tripped by lower pressure and fill cycle begins again

Stephen



stevon said:


> Freightwrench,
> 
> Yes, usually they are in the tank see:
> 
> ...


----------



## Freightwrench (Sep 5, 2020)

Ok just to be clear. I know that the pump outlet line runs to the tank and through a check valve. So in the tank under the pressure switch is another check valve?


----------



## stevon (Mar 5, 2019)

Freightwrench,

There is only one check valve and one release or unloader valve. the fat tube from the pump goes into the check valve in the tank. a skinny line off of the check valve runs back to the pressure switch unloader valve. this valve is activated by a lever coming off of the pressure switch









Stephen


----------



## stevon (Mar 5, 2019)

Freightwrench,

under the pressure switch is a manifold for switch, gauge, shutoff valve to the outlet in your case. This manifold always sees tank pressure what ever it is. The discharge tube from the pump is what the unloader valve relieves to reduce the load on the motor when starting to pump air. There should be no air pressure in fill tube when switch is in "full" position (shut off pressure), little lever should be pushing relief valve open

Stephen


----------



## stevon (Mar 5, 2019)

Freightwrench,

Yes I see your question now, the pressure release valve is leaking. This also a maintenance part they are very cheap.

Stephen


stevon said:


> Freightwrench,
> 
> under the pressure switch is a manifold for switch, gauge, shutoff valve to the outlet in your case. This manifold always sees tank pressure what ever it is. The discharge tube from the pump is what the unloader valve relieves to reduce the load on the motor when starting to pump air. There should be no air pressure in fill tube when switch is in "full" position (shut off pressure), little lever should be pushing relief valve open
> 
> Stephen


----------



## Freightwrench (Sep 5, 2020)

Ok I understand now! Thank you!


----------



## stevon (Mar 5, 2019)

Freightwrench,

Pressure safety release valve:









Control Devices Air Safety Valve, 1/4 In Inlet, 150 psi ST25-1A150 | Zoro


Order Control Devices Air Safety Valve, 1/4 In Inlet, 150 psi, ST25-1A150 at Zoro.com. Great prices & free shipping on orders over $50 when you sign in or sign up for an account.




www.zoro.com










Stephen


----------



## Freightwrench (Sep 5, 2020)

1st question.
What would be the cut off pressure for this speedaire 3z322? 
2nd question
Would replaceing the pressure safety relief valve. With one like the one shown in the post above. By removing the cap spring and plunger on the unit. It’s the silver cap in the attached piv


----------



## stevon (Mar 5, 2019)

Freightwrench,

The cutoff pressure is a design target of the manufacturer. the tank is ASME rated (welded tag on tank) and the parts will not exceed this rating. the safety valve is to prevent going beyond the pressure the tank is certified for. Single stage compressors only can go up to 150 PSI because that's near the limit one can produce. It is very inefficient to run a single stage compressor at this pressure as it "runs out of wind" and CFM drops. The safety valve is not a usable part in everyday operation, it is just so if something happens like control contacts weld stuck on and do not cut off power to the motor and if pressure builds up beyond the tank rating so an explosion does not happen. "safe operation guarantee" the style is not critical but the pressure range is. Single stage safety valves are set to 150 PSI before they "vent" over pressure and protect the tank and you. Two stage safety valves are set to 200 PSI, don't get one of those. The goal is to never use the safety valve, so type does not matter. Looks like the one you have is the adjustable type, just replace it.
To adjust the cut off pressure on the control regulator there is a self locking nut with a large spring under it already set by the manufacturer. This should already be set and left alone unless somebody messed with it for some reason. you can lower the shut off pressure threshold by loosening this nut. The new safety valve would trip if the pressure regulator is set wrong, just run your compressor and see that it does not go over 150 PSI. The tank could still burst if there is excessive corrosion in the tank, check for that visually at least, hydro test (fill with water, and pressure just over limit) is also an option.

Stephen


----------



## stevon (Mar 5, 2019)

Freightwrench ,

Just remove the old safety valve and go to a Graingers with it. they should hook you up with a usable replacement with the same pipe thread size

If I had to adjust the pressure regulator, I would set it to 135 PSI with a single stage compressor. Thats' at the peak pressure at any usable CFM that can be delivered by a single stage pump anyways

Stephen


----------

