my psi cuttoff varies

Main Train Horns
1

hi i have a 5 gal tank with a az ob2 comp i also have a adjustable pressure switch set to cut off at 160 psi
why does it vary sometimes it will cut off at 162ish sometimes 159 and then you mostly always see that needle drop slowly a few psi until stablized

would u say i am to gain a few psi ? when it is warmer outside ? or does the expansion of the air in the tank take awhile to build up to see a few gain of psi.
just tryin to understand why sometimes my tank will fill up to 160 psi dead even and then drop a few psi…and other times it will vary a few psi maybe like today when i went to work it filled it up to about 158 ish
i know during the day when it is HOT out it will go from like 160 to 170 just because of the heat … so my question is
would you get higher psi cutoffs due to it being HOT or would it just still cut off when the pressure is the pressure? hope this makes sense … kinda hard to get what i had on my mind out into words… lol

2

Pressure switches aren’t perfect

3

AC’s typically are pumping hot air. When the compressor cuts off - air stops flowing, and the air in the system begins to cool, dropping the pressure a bit.

You switch should cut out at essentially the same pressure (160) regardless of temperature. If the system is filled when it is hot, then it cools… your pressure will decrease. If the system is filled when it is cold, then it warms up, the pressure will increase.

Take a balloon… fill it up, tie it off, and stick it in the freezer. It will shrink quite drastically. :slight_smile:

4

x2.

5

Most pressure switches have a 3-5% + or -.