Want to adjust pressure switch down.

by Terryl Cozart
(Tupelo, MS)

I have a Dewalt D55168, 200 PSI 1.8 HP 15 Gallon tank I picked up used the other day. Everything seems to run just fine except it hasn't cut off on it's own. I got chicken and cut it off manually. It has reached 200PSI, but it won't cut off. This thing scares me a little. I would like to cut the pressure down to 175 or so. This seems a little more manageable to me, I just don't know how or if you can. Any help you can give me would be greatly appreciated.

Bill answers...

Hello Terryl, very nice to hear from Tupelo. Thank you for visiting this site and for writing in.

I suspect that your pressure switch has failed on the high pressure cut-out setting.

Yes, you can adjust the cut-in and cut-out pressure level yourself, but I think that with your switch you will be trying to adjust it in vain.

Have a look at this page for info on adjusting your pressure switch.

You are quite correct to be intimidated by the compressor. I don't know of any DIY type home compressors that exceed, say, 175 PSI at the high end.

Do yourself a favor too, and once the pressure gets up to 150 PSI or so, manually toggle the PRV by pulling on the ring to make sure that it's free. In the event that the pressure in your tank reaches the PRV threshold, it will open and vent the air to prevent pressure rupture. Manually toggling the PRV open and closed will satisfy you that it will actually work when you need it.

Change your pressure switch. I think that's your problem.


Comments for Want to adjust pressure switch down.

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Oct 17, 2017
Pressure D55168
by: Bill

The specs on the D 15568 DeWalt compressor show that it's set up to fill the tank to 200 PSI.

That the rebuild resulting in an "O" ring letting go under 200 PSI suggests that the replacement parts either weren't rated for the pressure, or there was a problem with the installation.

The "O" ring you refer to is the one on the tube? That wasn't clear.

Yes, 200 PSI is high, but the compressor is built for it.

Oct 17, 2017
D55168 pressure in
by: Ron

I have the same compressor. After putting in a new belt, piston and sleeve it was pumping up and I let it get to almost 200psi and it blew the oring and out let tube out of the tank. This thing is almost scary. What say you to fix this thing. Thanks Ron

Oct 14, 2009
Incorrect Advice (I think)
by: Anonymous

This compressor is a 200psi model and thus runs up too 200 psi. This is why it is so expensive. Just read the description of the compressor.

Aug 16, 2009
by: Terryl

Thanks Bill,
I appreciate the response. You said just what I was thinking. Nice to be backed up.

You are very welcome, Terryl.


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Pressure Switch chatters at end of cycle/ shut-off

by Valentino Mitchell
(San Francisco, ca)

I have installed several different shut-off switches from square D to Furnas and now I am trying an Ashcroft with a Ray Pressure Snubber.

My problem is repeated for each switch I install.

They work initially and then fail by loosing there adjust ability and chatter at the contacts.

I have 2 - 5HP control air compressors in series going through an air dryer into a 200gal receiving tank.

My kick in pressure is 75psi and my kick out pressure is 110psi. I have new check valves and my compressors have been maintained quarterly since being put on line.

The Ashcroft (installed 9/12/09) is now starting to chatter at the end of the cycle, causing the alternator to cycle the off-line compressor briefly then back to the currently running compressor; so I get chattering at the starter.

I am using the switching the starters coil voltage only that runs through an alternator. The alternator is new and mechanically latches the contactor alternately as the coil control voltage drops.

I also have a second low air switch installed (with a snubber) as a low air switch which comes on at 70psi and off at 95psi. The low air is not active when the Ashcroft switch chatters at the end of the cycle.

Very frustrating because they work initially then stop. The Ashcroft is 5x the cost but is rated for greater differential adjustment and has much higher tollerances including vibration. On the note of vibration, I have the Aschcroft mounted securely with uni-strut.

I have contacted Furnas and they could only suggest a snubber, which I have installed.

Please help if you can.

Bill answers...

hello Valentino. Nice to hear from San Fran, and thanks very much for visiting my site.

It's my opinion that the pressure switch chatters normally when the points are wearing out. Have you examined the points in your pressure switch to see if that's the case?

If so, then I'm wondering about their voltage and amperage rating? Check that out too.

Anyone else have any advice on this issue for Valentino?



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