Husky H1503TP popping safety valve.

by Larry
(Florida, USA)

I have a Husky 3 gallon air compressor. Since I got the compressor, it will occasionally pop the safety valve instead of shutting off at 155#.


I got the manufacturer to send me two different replacement pressure switches under warranty, but the problem persists. It is now out of warranty, so need to figure this out on my own.

Should I try to find a pressure switch with a lower shut off pressure, or replace the safety valve as the next shot at fixing the problem?

I bought this as a reconditioned unit, and only use it occasionally.

When I pulled the first pressure switch, it had rust on it as the tank had some water in it.

Thanks for any help.

Comments for Husky H1503TP popping safety valve.

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Mar 07, 2015
FIX
by: Doug in s.d.ca

Hey, glad you got it working and thanks for reporting back, Larry.

Mar 06, 2015
Fixed
by: Larry

Got a new gauge and safety valve. The old gauge was reading about 10 to 12 pounds high. With new gauge, shut off is at about 160# instead of 170#. The problem was the safety valve blowing close to 160#, about where the shut off switch was working. Thanks for the help!

Feb 16, 2015
Thanks
by: Larry

I've ordered a new gauge and safety valve. I'll let you know what I find out when they arrive, After reading what you suggested and pulling the parts, I know the gauge is bad and feel quite confident the safety valve is the issue.

Feb 16, 2015
safety valve (PRV)
by: Doug in s.d.ca

Well, you may want to start with a new pressure gauge.

That aside, I know I referred to a tag on the tank, but it would more likely be stamped directly into the tank. Please take another look.

As to the valve at 175, yes. Turns out that particular rating can be pricey (see Grainger) or quite a bit cheaper (see McMaster). Or, you could do 165 (cheapish at both places. That should hold fine at your 155 cut out pressure.

BTW, it's probably 1/4" pipe size - see the fittings section on how to measure PIPE size, it's not straight up...

Good luck and have fun!

Feb 16, 2015
Replace the gauge
by: Bill

I second Doug's comments, but it were me, I'd first replace the gauge with one that works.

Only then can you get an accurate read on the situation.

It's odd that you appear to have a gauge that shows actual rather than gauge pressures, or, perhaps, the gauge really has failed.

I would not change the pressure switch to one that shuts down at 175. That's out of spec for your compressor, and leaves no margin between the high pressure cut out and the PRV letting go.

Bill

Feb 16, 2015
Tank Readings
by: Larry

The safety valve is rated at 170#. All three pressure switches are rated for on at 125# and off at 155#. I can't see a rating for the tank. The gauge shows shut off at about 170#, and on at about 135#. However, the gauge shows about 12# when the tank is completely empty, so I assume it reads about 12# high throughout the cycle. That would mean the shut off is about 155 to 158#. I think I should try to replace the safety valve, but would like your input. Also wonder if a 175# shut off is available and could be used.
Thanks for any help and suggestions.

Feb 15, 2015
safety valve (PRV)
by: Doug in s.d.ca

According to my source, the pressure switch is supposed to be 125-on / 155-off.

Have you actually seen the pressure rise above 155psi without cutting out? Even if it goes to 160 from time to time, the PRV should stay closed.

There may be a pressure rating on the current valve, so when you remove it (per Bill's suggestion) check that out. It may be rated at only 155, but should likely be 175 or so, depending on the tank rating. Look for a tag on the tank for rated and tested pressure.


Feb 15, 2015
Husky H1503TP safety valve
by: Bill

Larry, this is interesting. You say " When I pulled the first pressure switch, it had rust on it "

Air from the tank should not affect the operation of the pressure switch, nor should it impart rust to the innards. That's an indication of a ruptured diaphragm that is the barrier between tank air and the switch itself, and also the part that reacts to the changing tank pressure.

When you say " (the compressor )occasionally pops the safety valve instead of shutting off at 155# " is 155 PSI the normal cut out pressure setting?

If 155 PSI is the normal cut out, and the PRV lets go at that pressure or below that normal cut out pressure, I would suspect the PRV. With the tank empty and power off, pull the PRV, rinse it thoroughly in a solvent, let it dry completely, and reinstall it. Test it. If it now won't release at 155 PSI, that's good, but you want to operate it manually a few times to ensure that it moves freely when it is supposed to do so.

Bill

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