Compressor Pressure Switch Adjustment

[Danny]

Hello

Last year I bought a Wolf Air 2HP 24L compressor from Screwfix. It's not that good but I did only pay £80 for it in an offer. Anyway I have a small problem with it. It's crap with a nailer, the cut in pressure is 4.5 bar and its cut out pressure is 8 bar. I'm finding that I need at least 6 bar with 40mm brads.

So today I finally got around to adjusting the pressure switch. Few pictures are in order...

I tried adjusting the cut in pressure (down though, just in-case it was the cut out pressure) using the bolt on the top, turns out that it is the cut out pressure. however the cut in and out pressure seem to move together, so is this a fixed pressure switch? or am I missing another adjustment on it, I cant see one. I have set the compressor back to it's original factory settings for those concerned by the first picture :lol:

Any help on this would be appreciated.
Thanks
Danny

 

[JackL]

I may be wrong - I often am, but if memory serves me well, 8 bar is equivalent to about 116 pounds per square inch.
I believe that in order for the attached pressure vessel to pass as safe for work, it should be capable of containing twice the working pressure (in this case 232 l.p.s.i.)
That (even at 116) is an awful lot of pressure if things go wrong. Believe me, I have seen an air receiver blow apart at only 85 l.p.s.i. and the shrapnel that it generates is awesome.
My suggestion is that you leave well alone and get a compressor that is larger and capable of holding a larger volume of air.

 

[9fingers]

Hi Danny,

Normally the adjustments are the cut off pressure and the difference between the cut in and out pressure. So set the cut off first and then fiddle with the other adjustment to see if that helps.
The switches are pretty basic and I would expect a degree of interaction between the two adjustments. Playing with the settings and making a few notes should get you established with some sort of pattern but don't expect perfection.
I have a similar machine from Aldi badged as powercraft but I've not had the need to fiddle with it (yet) and not used it for nailing (yet)

HTH

Bob

 

[Gary M]

Hi Danny,
I may be completely wrong on this, but the pressure is adjusted by the black knob inbetween the two regulators.
I have never had to adjust anything else, i have a 24l and a 100l both of which work the same. 110 psi will drive a framing nailer on the 24l with ease,it may have to charge the tank regularly as its only 24l.
40mm brads should be easy for this compressor, you must have it set up wrong.
There should be a + and - on the black knob for increasing and decreasing the amount of pressure delivered to the tool.
I wouldnt take the top off as its been factory set and any adjustment would void your warranty.
Try turning the knob and watch the pressure gague.
HTH,
Gary.

 

[Danny]

I think people here are misunderstanding me a bit here. may be the way ive worded it.

JackL I'm not intending on altering the maximum cut out pressure to get more then 8 bar out of the compressor, the pump probably wouldn't cut it anyway.

9fingers That's what the problem is, I can only find that one bolt which allows adjustment, but its moving both the cut in and cut out pressure at the same time equally.

Gary M I want to alter the CUT IN pressure. That is, when I'm nailing and I have a full tank at 8 bar, as the air pressure decreases through usage, the compressor only kicks in at 4.5bar or lower. Which means it stops driving nails fully before the compressor kicks in. The black knob is just the regulated pressure (which I have at 7 bar)

Cheers, Danny

 

[9fingers]

Hi Danny,

I've just reached the same level of understanding having just been tinkering with my compressor. I see that unlike other compressor switches I've used, there is only one adjustment - sorry for my error.

On mine, if the adjustment is set to cut off at 8bar, it cuts in at 6bar. For some reason yours seems to have wider hysteresis and I can see no way of adjusting it.

The only approach I could suggest is to buy a different, dual adjustment switch. Such things are made by companies like Enots, Honeywell Ranco etc and should be available from professional compressor dealers.

Good Luck

Bob

 

[Travis]

Hey Danny

I had the same problem as you. Low cut in pressure was to low to run a framing nailer. I opened up the pressure box and I had 2 big springs with adjustments for each, one for high and one for low pressure. They operated independent of each other.
So yes, I think you have a single adjustment only, making high and low pressure parallel each other.


Sorry

Travis

 

[christoph clark]

The pressure switch is operated by the spring either opening or closing the switch. When the rising set pressure is reached ie 8 bar the spring will open the switch and stop the compressor. When the pressure falls the switch will open causing the compressure to start.
If you want the compressor to stop at a higher pressure you adjust the nut so the spring is in effect tighter. Getting to the point of if you adjust the rising point this will also adjust the falling point. They are joined and the difference is the hysteresis. Higher stopping pressure = higher starting pressure.
8 bar stop - 4.5 start = 3.5 hysteresis
This type of pressure switch is where the hysteresis is non adjustable.
There should be a over pressure safety valve so adjusting the max pressure higher is not a good idea.