Air Compressor Cutoff Switch Assembly
- Thread starter SKFishing
- Start date
Given the propensity of pressure switches to fail after a rebuild, specifically due to that diaphragm, have you considered just buying a new one? I use a Square-D 135-175 on my QT-7.5, lightly modified with a manual toggle switch added so I can break the circuit as a 'soft' safety disconnect at the pump when I don't want it running.
I'm sure you can order a new diaphragm and/or contacts, but by the time you've gone that far (both via time and trouble), you may eclipse the cost of just ordering a new unit. At a minimum, you could clean the contacts and that diaphragm and see if it holds. What could possibly go wrong here?
There is nothing wrong with the contacts or the diaphragm. It had water behind the diaphragm, so I took it apart to check it out. When I was taking the screws out, I had an uh oh moment when the springs popped everything out of place. I can see how it goes back together, but can't get it back in the case and the screws in. I saw a reference on another site to a trick to get it back together but they didn't say what it was.
But, yes I have considered buying new just because I can't put it back together. I thought I would swallow my pride and ask for help first. It wouldn't be the first (nor last) time I took something apart and it hit me in the pocketbook.
But, yes I have considered buying new just because I can't put it back together. I thought I would swallow my pride and ask for help first. It wouldn't be the first (nor last) time I took something apart and it hit me in the pocketbook.
Guilty as charged, I am. I did the same thing on another one. That's why I strongly advocate new ones, ha! If I had a third hand with better fine motor control than the first two, I could have done it - I remain convinced.
On that note, the Square-D I'm using now works fantastic and once I put the small toggle switch in, does everything I need it to. I combined mine with a 7.5A contactor, but that's just so it wouldn't tear up the contacts in the pressure switch trying to run 32+ FLA. I'd say it's one of the higher quality pressure switches I've run across in the 'consumer' market.. I paid ~$35 shipped for it.
brawls43
Well-known member
Polar, where'd you get this pressure switch, and how did wiring in the toggle go? I'd like to do something similar. I'd got an old Square D pressure switch that I think is dead.
Try this one!
I mounted the toggle into the bottom side of it, though you could easily drill a hole in a knockout or KO plug and put it there. All you need to do is interrupt one leg. I interrupted the one on the cold side of the pressure-activated contact. Be advised, if you're not running a magnetic contactor, you should use a toggle that's rated for the voltage/current your system uses. Mine is only used to trigger a magnetic contactor, so it was of no concern to me as there's little current going through it.
brawls43
Well-known member
I'm running a contactor, so the load shouldn't be an issue for the toggle. Thanks.