Problem with Air compressor control valve.

[Movin/on]

I've got a IR Rand 4000 5HP compressor setup that's been running great for 15 years I leave it on full time and use it daily. About 2 weeks ago woke up about 2 AM from noise coming from my shop about 125 ft. away and it sounded like someone with a hit and miss engine in my shop. Ran up and found the compressor running at almost full 175 psi but the control valve hadn't tripped.

The noise was the blow off safety valve opening with a pop and reducing the pressure but the compressor still ran. Flipped the breaker and went to bed. Next day it did the same but I hit the little plastic button on the control valve switch and the compressor stopped. Sprayed some silicone spray on the switch and it worked ok for a week. Then it started over pressuring again but did stop after about 15 seconds. It does have a pressure relief feature on my control valve. The control valve is only 12 years old and cost around $100 so it should be good quality

Now 3 questions: could the pop off switch be weak and open before 175 PSI?

Could the control valve have gone out of adjustment? 90 on 175 off.

What is a good control valve that will last for 5HP?

I am switching my setup to a Lincoln/Quincy similar to the QR25 size and may run it in tandem with the IR. If the pressure drops below 80 the IR will kick in and shutoff at 160.
I will have 2 pressure control valves. Otherwise the Lincoln will be the primary.


Movin/on

 

[The Cobbler]

for a 5hp motor you need a pressure switch that controls a magnetic starter.
is this what you have?

 

[pcmeiners]

"for a 5hp motor you need a pressure switch that controls a magnetic starter.
is this what you have? "
5 hp is the limit for only using a pressure switch, above 5 HP you need a magnetic starter, that said even a 5 hp unit benefits from a magnetic starter..

Possible the pressure switch contacts are fusing together.

"Could the pop off switch be weak and open before 175 PSI?" Yes

"Could the control valve have gone out of adjustment? 90 on 175 off". Yes, 175 is pretty damn high, you would be better off 160 or below.

Square D on Ebay, heavy duty, or equivalent...

https://www.ebay.com/itm/USED-Squar...227325?hash=item25fe2e267d:g:YaoAAOSwzZFbYIXn

 

[Movin/on]

Well did some adjusting to the control valve by reducing the cutout pressure. The popoff/blowoff valve still opened. Because there are, for some reason, 2 on the compressor. Plugged the offending one and the compressor works fine. Shuts down at about 160#. The bad popoff is stamped 200 psig.
What would be a good source for the valve?

Movin/on

 

[DieselNut88]

Mcmaster carr or zoro should have one.

 

[bsaint]

Local hardware store too. Or Grainger. With a web account grainger is almost the same price as zoro without the shipping (but with the tax)

 

[The Cobbler]

Ebay has lots of options .

 

[Citation]

I'm a bit confused by the OP's comments.

First, this is a two stage compressor so it's common (required?) to have a blow-off valve for each stage and they should have different pressure settings.

Second, it sounds like the pressure switch is bad (it's not a valve). If this compressor has no magnetic starter then the fill motor current is going through the pressure switch. Perhaps your line voltage is a bit high or who knows but if the switch is stuck on, replace it. If this is your second time replacing it, get a magnetic starter when you replace it. With a mag starter the current through the switch will be minor and it should last a long time.

 

[MacMcMacmac]

Well did some adjusting to the control valve by reducing the cutout pressure. The popoff/blowoff valve still opened. Because there are, for some reason, 2 on the compressor. Plugged the offending one and the compressor works fine. Shuts down at about 160#. The bad popoff is stamped 200 psig.
What would be a good source for the valve?

Movin/on

If this is your interstage safety valve you have valve problems.

 

[Movin/on]

Well it over pressured today again while I was sand blasting in my cabinet. I was watching it and it went to 200# and I hit the Breaker. So a new control shutoff switch is needed.
Which one is recommended? Square D seems OK but not the best. Current is a Forney. I'm ordering new pressure control valves also both 175 and 200 psi.
Everything else on the Rand compressor is as purchased so I hope I don't need to change the 5 HP motor. I did buy it used.

Citation, Cobbler and MacMcMacmac -- thanks.
Movin/on

 

[bsaint]

175# if its two stage.

 

[Citation]

Well it over pressured today again while I was sand blasting in my cabinet. I was watching it and it went to 200# and I hit the Breaker. So a new control shutoff switch is needed.
Which one is recommended? Square D seems OK but not the best. Current is a Forney. I'm ordering new pressure control valves also both 175 and 200 psi.
Everything else on the Rand compressor is as purchased so I hope I don't need to change the 5 HP motor. I did buy it used.

Citation, Cobbler and MacMcMacmac -- thanks.
Movin/on

I don't think you need new blow off valves. You just need a new pressure switch and ideally a pressure switch plus magnetic starter.
No idea if this is a good one but one of these plus a new pressure switch
https://www.amazon.com/dp/B00Y1OZTFM/?tag=atomicindus08-20

The pressure switch doesn't have to be fancy since it would be longer have to deal with motor current.

https://www.amazon.com/dp/B008JVM45G/?tag=atomicindus08-20
This is a decent pressure switch but I don't know if the present pressure range is what you want. They are adjustable so not the right range isn't a big deal.