PressureSwitch, 135-175, 1Port, Unload, Sw

• Air Compressor

Square D is not the name it used to be with their pressure switches, but this one still fills the bill for lighter duty equipment.

Yes, the control is lighter throughout than those of earlier times. This one actually has a non-adjustable pressure differential of 35 PSI, while its cutoff can be adjusted as low as 100 PSi or as high as 200 PSI. The factory cutoff setting is 175 PSI, so the cut-in is actually 140 at this setting.

The amperage is listed by horsepower as 1.5Hp@115 volts and 2Hp@230 in single phase power by Schneider Electric. Why they chose this oddball rating method is inane, but the actual amperage rating is going to be roughly 8-10 running amps the figure you will find and need to use from your electric motor plate. Excessive electrical draw under load? Don't go there, but momentary starter amps shouldn't cause concern unless the motor or compressor is in poor condition. This switch is not heavy duty, so I recommend dropping the factory pressure setting to decrease your compressor motor load. A cutoff setting of 150 PSI will help this switch last longer along with your compressor. Of course, this means the cut-in pressure will also drop to 115 PSI. That shouldn't be a problem as most air tools have a recommended maximum of about 90 PSI. If you're using a single stage compressor, you'll want to set this pressure lower anyway and your tank may not be rated for pressure settings over 130 PSI. This would still give you a cut-in pressure of 95 PSI which is where many 1-2 Hp compressor are set at the factory for safety concerns. The factory rated safety valve on your compressor will actually determine how high you should set this switch, but higher isn't better for any compressor use.

I have a 2-stage 2 HP compressor and this switch was just what I needed, but I would not recommend it for larger units unless used in conjunction with a higher amperage magnetic switch. The pressure differential at 35 PSI is adequate and my unit performs well with this switch. I actually purchased it for the lever switch incorporated into it, as my OEM switch did not have this feature. The included pressure unloader has a standard 1/4-inch NPSF fitting.

Buy PressureSwitch, 135-175, 1Port, Unload, Sw Now

I thought my 50 year old compressor was down with.

This was a perfect replacement for my old pressure switch. Works great!