Actual 120 PSI for Storage

[FrankJ]

Originally Posted by wilsonmw04

We tried that and out of 4 that we have we never got one to 120. only 115.

The little screw on the side is a locking screw. You adjust the switch by turning the barrel. Once you run out of range, the switch stops working. (which means adjusting to the high side the compressor will stay on.) The part number of the legal switch calls for a set pressure of 115 PSIg rising. So most switches will turn off close to 115 psi. They turn back on based on the hysteresis of the switch which isn't as precise. As Al said, they are nonadjustable by rule.

[Sperkowsky]

We also have the same issue. Ours usually says 112 PSI.

[zinthorne]

Ours only reaches 105 psi.

[FrankJ]

Originally Posted by Sperkowsky

We also have the same issue. Ours usually says 112 PSI.

Most of the ones I have seen turn off between 115 & 112 indicated. I suspect that Nason adjusts them to turn off before 115. Your pressure gauge is almost certainly a class B which are accurate to 2% of span in the middle. So assuming a 160 psi gauge that 112 +/- 3.2 psi.