What do you think is wrong with my air compressor

My air compressor is a 220V, 6.5HP, 175 PSI unit with 80 gal tank.

We lost power last week for four days. I turned off the breaker
to my air compressor before firing up the generator so it was not
run on generator power at all.

When the power came back on, I turned the breaker back on and
the compressor ran until it tripped the breaker on it's own.

I decided to see if it had built any pressure at all so I plugged a
300 PSI gauge into the air line and slowly turned on the air valve.
I shut the valve back off when it showed 275 PSI. Way above 175.

I haven't tested the pressure switch yet, but I assume it is fused.
What do you think? What else could it be?

mine has done that the pressure switch had corroded and stuck closed

Pressure switch, or something between the pressure switch and air supply[plugged port?] Ice?

Sounds like you don't have a safety valve, or it's not working.

Why didnt the safety valve blow off on the compressor???? Thats not safe at all

I agree, both your safety pressure relief valve and your pressure control switch are now working right. I would try cleaning and lubing them, then test both before buying replacements.

Post some pix of the unit and the switch/switches... I would hope it has a motor starter with fuses... Every air compressor I have ever owned had a pop off pressure relief valve my oldest goes back to 1941/42...

Now working right should have said Not working right.

Ice in the pressure line to the pressure switch and a pop off frozen shut? Sounds way far off and not probable but it possibly could happen.

I wish it could be ice, but it never got cold enough to freeze where the compressor is.

I'm with everyone else, why didn't the safety valve blow?

1. The compressor doesn't have a safety valve or it's the wrong pressure or defective?

2. The safety valve and the pressure switch are on the same line, and somehow they are not reading pressure?

Once you determine pressure is getting to the switch, even if it doesn't appear to be welded, I still would not trust it. Could have an unseen mechanical problem.

And for sure address the problem with the relief valve!

Let me put it simply. You are damn lucky to still have a shop standing!!!! The
pressure switch and the high pressure release should both be at a high point so
no frozen lines or such should screw them up. Personally I would change both of
them cause you can get good ones on Ebay and they are not that expensive. You
are so lucky your shop is not scattered over half the county. Look on Ebay.
First look up air pressure saftey release. There are several thread sizes and
pressures. Get the correct one for you. Next look up this number 281910242142.
This is a Square D switch. Very high quantity. Do Not Try to set them. Get the
correct pressure and just hook it up. You said 175lbs. and that is what this
one is set for. DON'T mess around. Just replace 40 bucks worth of stuff and you
are safe.

Number one thing, your relief is bad, do NOT run that compressor until it is replaced.

The pressure switch stuck, you are really lucky the breaker tripped before it exploded.

Here is the Square D switch. The video is a Small compressor.
Blown tank.

Try the picture again.

Just to repeat, there are two devices, the first is a pressure switch that should open the circuit when pressure setting is met, then there is a secondary mechanical pressure relief that will relieve it the first failed.

Both failed, replace both.

(quoted from post at 19:44:07 02/14/19) I wish it could be ice, but it never got cold enough to freeze where the compressor is.

Click to expand...

Well that throws my theory out the window. LOL a relief valve is brass, or should be brass and usually doesn’t stick.

Two things you KNOW failed in this case: 1) The popoff valve (relief valve), and 2) The pressure control valve/switch.

Replace both.

I would trade problems. Mine has a hole in the tank.

At least you know your tank is in good shape! I wouldn't want to be near one that ruptured at 275! Change the pressure
switch and relief valve.

Finally had a chance to get to the repairs today.
I can't see anything wrong with the old pressure switch. It opens
and closes correctly with the manual lever. No stuck contacts.
But it got replaced anyways. Along with the safety release.
Pumps up to the correct pressure, shuts off, turns on when the
pressure drops to 145 PSI just like it always has in the past.
About $30 between the switch and safety valve.

When the weather warms up, the whole unit will likely get replaced.
I don't trust it anymore. The circuit breaker is shut off until I need it.

Anyone else here ever pop the relief valve on their compressor to make sure it's not stuck. My compressor is right inside the door to my shop. Every once in a while, I give a tug on the little metal ring on the relief valve to pop it open. My dad did that on his compressor and told me it was a good safety check so I've continued.

Someone once told me that it was not good for the valve to do that. My compressor is ~35 years old now and the original valve still works with no leaks or other evidence of trouble so I'm doubting that it is bad for the valve to pop it once in a while

Sounds like you got lucky, most air compressor tanks are only rated for 240 psi max., since that one has been stressed past it's design limits I'd be replacing it soon.
I've readjusted the pressure switches on my two stage compressors to shut off at 150 psi instead of 175.
Seldom do I need the extra pressure, yes during heavy use the compressor cycles more but it doesn't work as hard building that extra 25 psi.
My Quincy compressor as a safety pop off valve in the discharge side of head and another in the tank, both are 200 psi pop offs.
I have seen and had pressure switches stick before but the pop off valve worked on each occasion.

A funny story about pop off valves.

Big trucks have a air governors that regulates air pressure to 120 psi. I was nearing Fort Collins, Co around 10 pm one night, the air governor on the truck I was driving vibrated loose and I didn't notice the air pressure increasing, the air tanks on that truck where mounted to the cab under the floor board. Suddenly the pop off valve on the air tank directly under my seat poped off at 175 psi.
I nearly baled out of the truck at 55 mph, although a change of under clothes was not required, it was close.

Nuttin wrong with two pop offs for the tank... One of my compressors has a 75PSI pop off on the first stage I dunno why, it has gave issues I adjusted it for a higher pop off... I brought a new one it did not fit and have not brought another...

I have never got into the habit of pulling the pop off but think I will... After burning up several electric motors thru the years I run thermal starters on my compression's.

(quoted from post at 21:21:00 02/14/19) Pressure switch, or something between the pressure switch and air supply[plugged port?] Ice?

Sounds like you don't have a safety valve, or it's not working.

Click to expand...

I was getting worried regarding the same issues. The relief valve is on there to save property and lives in these circumstances.

I have both my compressors set up with a motor starter I had been lead this is the way to go to keep the motor form killing itself to the point it was not repairable...








This allows the pressure regulator to be a low amperage switch to work the high amperage relay this takes the hard work off the pressure switch contacts...

On my other for giggles I pulled the pop off its stuck so I need to replace it are take it apart and free it up...




This a pix of the pop off on the first stage I dunno why it there it has one in the tank..




Back in October getting ready for a hurricane I turnd the compressors on let them build up so I would have air if the power went out. I went about my businesses about 15 min later it dawned on me one was still running. It goes from 0 to 175 fast about a min are so when I got to it, it was steaming hot the pressure was at 90 WTF... I turned it off it was leaking air around the head gasket when I went to turn it back on the compressor was locked up....

I just walked away from it knowing the compressor had burnt up a few weeks later for the ell of it turned it on it fired up but would only build up to 90... I pulled the head a reed valve had broke probably got on top of a piston that's what locked it up... Part of a reed had the check valve in the take stuck open... Low bidder got the contract... A new head and a new check valve its back up and running like new other than I think the new check valve has a small leak I cleaned out the old one just have not got around to checking it out...

I still would like to see a pix of yours...

I would not be skeered of your old one on shop talk forums I read some states require the tank to be tested once a year... I think they are tested to 600PSI... I know its at least twice the rated pressure... 275 did not hurt the tank...

"I still would like to see a pix of yours... "

I don't think I have any pics of it Hobo.
It's an older Delta (no longer made) unit.
It is buried in a small, enclosed room in the corner of my shop.
That room is insulated and deadens the sound.
It also houses my floor heating system, which is why it hasn't froze.

Since it's buried in that room, it is out of sight, out of mind.
I never checked the pop-off valve. In fact, I installed an automatic,
timer controlled drain valve because I would always forget to drain
the moisture out of the tank otherwise.

Here's a pic of that little room and where I park my truck in comparison.
Thankfully it didn't blow. No one was hurt, including my truck.
That room is 8 ft wide, 8 ft tall and 5 ft deep. The door you see is 4 ft wide.

Since it will be getting replaced, anyone have suggestions on brands?
I see Ingersol Rand has one in my consumption requirements.
So does Sandborn. I don't really need 175 PSI, but I do need to
stick in the 17-25 CFM @ 90 PSI rating or better.

It will probably be the last compressor I ever buy, so I don't mind paying
for quality, but I don't want to spend extra money just for the name brand.

P.S. If I had it to over again, that room would be outside.

I would be looking used those big ones go cheap compared to new prices... Homeowners are looking for something cheap and look over a quality compressor... I gave $750 for the Westward it was almost new the guy was moving... Its a air making machine to get 27 cfm they turn it fast that equals water and heat it makes plenty of water ... The head has reed valves (PLATE VALVES) in it but a new head was $275 I guess that's cheap the reed valves are not replaceable they are staked, pined and branded in no way to get them out... I would think a split V-twin cylinder would run cooler... I like the ones with mechanical valves they are built to last forever when I say mechanical they are of the disc type.

I have rebuild sever old compressors they are EZ as pie to rebuild...The only older style valves that gave me issues were from a American Air that was made in 1942 the valves were no longer available

The older Kellogg units were built to last forever... If you search YT I have built several use keywords Kellogg and Emglo...

https://forums.yesterdaystractors.c...torder=asc&highlight=kellogg&start=15

I just bought a Champion (which is a Gardner Denver product). I bought a 5 horse 2stage 17.3 cfm@175lbs pressure, so at 90lbs pressure it would be in the area you are looking for. I bought this same model in 2008 from tptools.com They are made in Princeton. Il and are shipped free. The reason I bought again is that I moved and sold my old shop and the new owner wanted the compressor. I used the 2008 a lot and never had a problem and it is about the most quiet one of this size I have ever seen and heard. The number for TP tools is 1-800-321-9260. They are in Ohio and the guy I talked to was Carmen, a very helpful and knowledgeable guy.
FWD

(quoted from post at 21:17:13 02/18/19) I just bought a Champion (which is a Gardner Denver product). I bought a 5 horse 2stage 17.3 cfm@175lbs pressure, so at 90lbs pressure it would be in the area you are looking for. I bought this same model in 2008 from tptools.com They are made in Princeton. Il and are shipped free. The reason I bought again is that I moved and sold my old shop and the new owner wanted the compressor. I used the 2008 a lot and never had a problem and it is about the most quiet one of this size I have ever seen and heard. The number for TP tools is 1-800-321-9260. They are in Ohio and the guy I talked to was Carmen, a very helpful and knowledgeable guy.
FWD

Click to expand...

Thank you for the tip. I'll look into them too.
I still have my old Puma I could put back in there.
It was trouble free for the 12 years I used it. I upgraded for a bigger
tank and higher pressure. The Puma is 60 gallon, 125 PSI, 6HP, single stage.