Newer Quincy compressor has a relief valve problem.

swatkins · Jun 20, 2017

This is almost a new compressor that only sees light duty. Today while using the sandblast cabinet the relief valve on top of the head started popping off when almost to the end of a tank filling cycle.

The compressor seems to be running fine, pressures and volume are good, relief valve is closed up until the tank is almost full and the relief valve closes when the motor stops.

Wondering if there is a bad valve or something is going on in the head.. I like to know more than the repair men do so I ask here

Danny VanVoorn · Jun 20, 2017

I built a compressor with a new pump, motor and tank. Some of the parts were a deal and others off set it enough I could have bought a ready built unit like yours for the same money? I have a pressure relief valve in the head on that newer Curtis pump, don't really understand it being there unless to protect the line from a stuck mechanical unloader valve? On that Curtis compressor it has a relief valve in the tank also but the unloader valve is screwed into the tank with the line running to it. I think the Quincy pumps have an unloader built into them closing after getting oil pressure built up, totally different than the Curtis. The valve in the head was popping like you explain so I adjusted the shutoff pressure about 5 PSI lower and left it at that. I could have replaced it with a new pop off valve but left it as is and haven't had any other issues since, near ten years or so? Maybe the heat or vibration works against them when in the head like that?
Dan

rons · Jun 20, 2017

Does your relief valve have a number printed on it for the set PSI?

swatkins · Jun 20, 2017

I will have to look...

Played with it a little and was able to to get it where it only made a few pops before the motor shut down with a full tank. Once the motor is off there is no pressure at that relief valve.

When it is running and that relief valve is opening it does not seem like there is a lot of pressure being released either.

WHHJR · Jun 20, 2017

The relief valve should protect the tank. If it is behind the compressor check valve it isn't possible to work properly.

4¢

guest · Jun 20, 2017

I keep a couple extra popoff valves on hand, it's a $10 item. Not a bad idea to replace them every few years anyway.

CONTROL DEVICES Brass Air Safety Valve with Soft Seat Valve Type - 5A71'|'ST25-1A2 - Grainger

swatkins · Jun 20, 2017

WHHJR said:
The relief valve should protect the tank. If it is behind the compressor check valve it isn't possible to work properly.

4¢

This is on the head of the compressor. The tank has it's own relief valve.

WHHJR · Jun 20, 2017

swatkins said:
This is on the head of the compressor. The tank has it's own relief valve.

Sounds like a good place for a pipe plug.

FWIW I just purchased a 1952 package compressor with a Quincy pump. Back in those days the only relief was on the tank. I reworked a few threaded joints, changed the oil a few times, and replaced the pressure switch and it works like new.

Tony Quiring · Jun 20, 2017

Exactly where is it?

Our champion has one in the intra - stage line between stages.

If the second stage gets stuck valve or other issue the valve pops off.

Running pressure there usually 60 psi or so once tank pressure above that point.

Do not change anything yet...Locate a t connector and add a pressure gage to that spot and see what is going on.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

swatkins · Jun 20, 2017

Tony Quiring said:
Exactly where is it?

Our champion has one in the intra - stage line between stages.

If the second stage gets stuck valve or other issue the valve pops off.

Running pressure there usually 60 psi or so once tank pressure above that point.

Do not change anything yet...Locate a t connector and add a pressure gage to that spot and see what is going on.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

There is a picture of it in the video.

This valve looks to be next to the exit port of the first stage. When the pump is not running there is no pressure released when I pull the valve open. I'm hesitant to mess with it as it's not very old and still under warranty but that is a good idea on the T and extra guage...

dkmc · Jun 20, 2017

The spring may have broke in that saftey valve.
Get a replacement from Quincy, or the equivalent from Granger, etc.
If it's not defective, then there is some other restriction between it and the tank.
It's there for a reason, only an idiot would replace it with a pipe plug.
An Abrasive Blast cabinet is far from 'light duty', it's about as severe duty as you can
place on any air compressor.

swatkins · Jun 20, 2017

dkmc said:
The spring may have broke in that saftey valve.
Get a replacement from Quincy, or the equivalent from Granger, etc.
If it's not defective, then there is some other restriction between it and the tank.
It's there for a reason, only an idiot would replace it with a pipe plug.
An Abrasive Blast cabinet is far from 'light duty', it's about as severe duty as you can
place on any air compressor.

I can pull on the valve ring and feel lots of resistance so the spring might have weakened but I don't think it's broken. While the pump is running it is closed and only pops off when the tank is almost full.

I could change out the valve easily but its a new compressor and I was just looking for some information before I did so..

This valve is not on the tank, it's inline between the two stages of the compressor.

I happened to have a client that did not believe in relief valves when he built a compressor.. He spent the last 6 years of his life sitting in a chair watching TV because that was all he could do after the tank exploded and they put a plate in his head

No plugs for me!

This compressor has an easy life... An hour or two running a cabinet once every two or three weeks...

Lakeside53 · Jun 20, 2017

Your high pressure inlet valve may be sticking or faulty. As above -> put a pressure gauge where that relief valve is and see what is really happening. Better still call Quincy... they will help you figure it out especially as it's under warranty.

dkmc · Jun 20, 2017

swatkins said:
I can pull on the valve ring and feel lots of resistance so the spring might have weakened but I don't think it's broken.

I happened to have a client that did not believe in relief valves when he built a compressor.. He spent the last 6 years of his life sitting in a chair watching TV because that was all he could do after the tank exploded and they put a plate in his head

No plugs for me!

This compressor has an easy life... An hour or two running a cabinet once every two or three weeks..

It's possible just one or two coils broke. You'd still feel resistance, but it's exerting less force.
As cheap as they are, you can just read the pressure specs on the valve and get a new one to try.

Compressor tanks don't explode! That's just interweb hype.
(Not)

Your compressor has an easy life......before and after you run your blast cabinet with it...but not during.

DDoug · Jun 21, 2017

WHHJR said:
The relief valve should protect the tank. If it is behind the compressor check valve it isn't possible to work properly.

4¢

It's a 2 stage compressor I bet.

IIRC it's the interstage releife valve, and this was discussed a few years ago here.

Also IIRC the second stage valve is leaking back to cause this.

dkmc · Jun 21, 2017

Very possibly the problem

digger doug said:
It's a 2 stage compressor I bet.

IIRC it's the interstage releife valve, and this was discussed a few years ago here.

Also IIRC the second stage valve is leaking back to cause this.

msimard · Jun 21, 2017

This behavior of the inter stage relief valve chaterring or making multiple little pops is typical when there are issues with the valves in the heads. That is more likely than the valve itself.
EDIT "more likely" should have been "it is absolutely the valves in the head"

swatkins · Jun 21, 2017

Just got off the phone with Quincy.

One of two problems possible according to them.

First the head gasket might have slipped. Suppose to retorque the heads after the first hour of running.. I must have missed that part in the manual

Second cause is more likely a problem with the valves. Guy said that I'm not running the compressor hard enough and need to get it up to temperature for an hour or two every couple of weeks...

They are sending me the parts to fix either problem and should be here next week.

Turning me into their repair man! Which in this case I don't mind as I don't have to wait around for someone to show up and I figure I'll learn a little something by repairing it.

rons · Jun 21, 2017

swatkins said:
Just got off the phone with Quincy.

Second cause is more likely a problem with the valves. Guy said that I'm not running the compressor hard enough and need to get it up to temperature for an hour or two every couple of weeks...

How many times has that guy used this line?

Lakeside53 · Jun 21, 2017

Probably not "a line". I have four Quincy's, one of which I just rebuilt. Operating these compressors in short bursts is never a good idea. The output valves and head inter-stage chambers will rust unless run up to temperature regularly. With maintenance they (model dependent) will run 50-80,000 hours between major rebuild.

Bead blast cabinet is a good way to get you compressor working to temperature though.

Yours is not a QR - Same lower end but "economy" reed valve type head.

Lighty used QR310 HP inlet valve.

QR340 HP Output valve. This was actually working, but just leaking slightly. Machine was not looked after and run in short cycles.

Why spend $150 on new valve - Valve above after evaporust and a little machining on the seat. I did buy a new spring and disk for $25.

Newer Quincy compressor has a relief valve problem.

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