Compressor pressure switch- this CAN'T be factory???

[MatBirch]

Some of you may remember, I picked up a newer Devilbiss 60 gal and grafted an old Craftsman pump to it. After a very short working life... Like the first day I had to really use the compressor for anything... The pump started to howl like a banshee and screeched to nearly stopping as I ran to shut it down.
Enter- Rebuild #2. Off to Harbor Freight for a 3hp replacement pump. Had to pick up a few bits like a new pulley as the old was flat polyrib style and new is V. A few more plumbing parts and we're back up and running. I'm VERY pleased with it so far. It appears that the air cleaner problems some folks mentioned has been handled, as mine has a real nice paper element w/foam sleeve. Anyway, it is even again MUCH quieter than the Craftsman. I'm running a link belt with it too.

The whole point of this post though, is the pressure switch. I looked up the part# and it is a 95-125 fixed differential w/ 40-150 range. It is currently set at 105-135. I want to lower it, a LOT. I have no use for 135psi, and it just puts undo load on everything, more heat, more moisture, and more cost to run. When I went to adjust it, this is what I found-

That weld can't possibly be factory, can it?? I have googled as much as I can, and I can't find a match. Previous owner had a problem?
I guess I'm screwed to try to adjust it?? I think even the expense of a new switch would pay for itself it other ways??? I read somewhere on here that you can use a well pump switch and they are much cheaper? How does the head unloader work with that?


Here's how it all sits now with my double franzinator set-up. All in all, I'm really quite happy with it, and the total cost now sits at $278

 

[ishiboo]

There is essentially "no more cost to run", and very little additional "load". Those extra PSIs are not "lost", they are made up in CFM as the pressure is reduced. So the higher tank PSI = the longer time between when the pump runs to replenish.

I wouldn't touch it. You're definitely going to need a new pressure switch fi you wanted to adjust it. I'm not familiar enough with looking at them to know if the weld was how the factory prevented you from raising the pressure right up near the relief valve pressure, or if another owner did it… I can't imagine a nylock backing off in that application though.

 

[Trey T]

are your franizator in series?

 

[daparrothead]

Some of you may remember, I picked up a newer Devilbiss 60 gal and grafted an old Craftsman pump to it. After a very short working life... Like the first day I had to really use the compressor for anything... The pump started to howl like a banshee and screeched to nearly stopping as I ran to shut it down.
Enter- Rebuild #2. Off to Harbor Freight for a 3hp replacement pump. Had to pick up a few bits like a new pulley as the old was flat polyrib style and new is V. A few more plumbing parts and we're back up and running. I'm VERY pleased with it so far. It appears that the air cleaner problems some folks mentioned has been handled, as mine has a real nice paper element w/foam sleeve. Anyway, it is even again MUCH quieter than the Craftsman. I'm running a link belt with it too.

The whole point of this post though, is the pressure switch. I looked up the part# and it is a 95-125 fixed differential w/ 40-150 range. It is currently set at 105-135. I want to lower it, a LOT. I have no use for 135psi, and it just puts undo load on everything, more heat, more moisture, and more cost to run. When I went to adjust it, this is what I found-

That weld can't possibly be factory, can it?? I have googled as much as I can, and I can't find a match. Previous owner had a problem?
I guess I'm screwed to try to adjust it?? I think even the expense of a new switch would pay for itself it other ways??? I read somewhere on here that you can use a well pump switch and they are much cheaper? How does the head unloader work with that?


Here's how it all sits now with my double franzinator set-up. All in all, I'm really quite happy with it, and the total cost now sits at $278

So what is this double franzinator set-up you speak of ? And what is it's purpose ?

 

[larry_g]

I have no use for 135psi, and it just puts undo load on everything, more heat, more moisture, and more cost to run. When I went to adjust it, this is what I found-

I read somewhere on here that you can use a well pump switch and they are much cheaper? How does the head unloader work with that?

I'm not sure what your doing with this compressor that you need to operate it at much lower pressures, but I guess you know your business, obviously not much running of automotive repair tools.

If the compressor head has a built in unloader then a water pressure control will probably work. If your running 40-60 psi in the tank you probably could get away without an unloader if you have a motor that is on the larger size of the compressor head requirements.

All that said I wish you good luck as your going against most conventions in the compressor world. Nothing here that I would recommend or do.

lg
no neat sig line

 

[Charles (in GA)]

Put a regulator on it. Let it run at its standard pressures. If you lower it to near your operating range, it will run virtually all the time. That simply isn't the way to operate a compressor.

Charles

 

[MatBirch]

Thanks guys-
Maybe I overstated when I said "a lot", but there is no reason for me to run a single stage, home shop compressor at 135psi. The cfm drops off dramatically, the recovery time increases, the heat on the head increases, the load on the motor goes up... Maybe all these are pretty small losses, but added together over a lifetime of the machine, I would like to improve my odds. No tool I own or operate needs to be over about 95 lbs so going over the original stock setting of 125, seems to only to shorten the life of the machine. 10 psi may not seem like much, but it takes well over a minute to get from 125 to 135. That's the toughest minute the compressor has to spend. I don't know if someone messed with it, but the web shows the pressure switch should operate from 95-125, not 105-135.

 

[MatBirch]

Oh, and I have one franzinator between the head and the tank, and one between the tank and the regulator/ hose coupling. The first one fills with white froth, the second is dry

 

[Charles (in GA)]

I read somewhere on here that you can use a well pump switch and they are much cheaper? How does the head unloader work with that?]

It doesn't, thats the problem with a well pump switch. Use the correct switch with an unloader.

I did not realize you only wanted to lower the pressure from 135 to 125. That makes sense, esp if the specs call for 125.

Charles

 

[kams1973]

New pressure switches are cheap. Buy a new one and be done with it.

 

[G_P]

Im running a well pump switch on my compressor. It was set 30/50 from the factory but with some adjusting I have it set around 90/120.

Just make sure to get a switch that can handle the HP of your motor.

 

[larry_g]

Im running a well pump switch on my compressor. It was set 30/50 from the factory but with some adjusting I have it set around 90/120.

Just make sure to get a switch that can handle the HP of your motor.

How are you handling the unloader operation?

lg
no neat sig line

 

[EOC_Jason]

They are less than $50 at Northern Tool.... Plus you could use a coupon code...

http://www.northerntool.com/shop/tools/product_22938_22938

I'm sure Grainger and other places have them too... Maybe check eBay first, probably cheapest.

Previous owner probably welded it because the vibration was causing it to change?

 

[ishiboo]

LeFoo brand for $16!

I wonder how many of the other compressor switches are Chinese to begin with and simply rebranded

 

[EOC_Jason]

I wonder how many of the other compressor switches are Chinese to begin with and simply rebranded

My guess would be.... ALL OF THEM.

 

[signcrafter]

Northern tools has nice square D compressor pressure switches for not a lot of money. It's where I got mine.

 

[zkling]

New pressure switches are cheap. Buy a new one and be done with it.

This, with that small of a motor you really don't even need a starter. Check out surplus center.com for some cheap options.

Or if you are really ambitious, grind off that weld (take the switch out of circuit first) , chase the threads, thoroughly clean all contacts of abrasive dust and reassemble. Adjust as needed.

I'd probably shoot for something in the ~85-130psi range. At least it isn't one of the new 155 psi jobs. IIRC mine is ~80on-105off, in end use you really aren't going to lose much power on the low end at ~80 vs 90psi.

 

[G_P]

How are you handling the unloader operation?

lg
no neat sig line

I replaced the original check valve with a combination check/unloader. Once the switch shuts off the motor and the pump stops the valve automatically unloads.

Cant remember the brand but its almost exactly like these.

http://www.airtekltd.com/valves.htm#UNLOADER