Cut in pressure

[colinh]

I've just set up a blast cabinet and my compressor was struggling to keep up with the demand. I've just bought another similar sized compressor (200lt 3hp 14cfm) and set it up in parallel with my original. I adjusted the cut off pressure so there is about 10 psi difference hoping it would stagger the switching of the electric motors. That has worked well but the cut in pressure on one of the machines is significantly lower than the other. This means that (especially now I've 400 lts of storage) the one compressor is running for way too long before the second compressor cuts in. They are both fitted with the single spring pressure control switch. From my research it looks like you cannot independently control the cut in pressure on these, is that correct? I'm wondering what my options are? I guess I could match my control switches but the replacements (cheap) don't seem to state the cut in values. I could buy one with independent adjustments (sounds expensive!). Or perhaps lower the cut out pressure on one until the cut in pressures match? Any thoughts would be appreciated.

 

[mike 109444]

A pic of the pressure switches (with there lids removed) should get you better responses.
There is usually a 2nd screw inside on the few I have looked at for restart pressure.

 

[m_c]

Basic pressure switches often have a fixed differential pressure adjustment.

Some pressure switches, you can buy a differential adjustment kit, but basic pressure switches aren't that expensive - https://www.duncanrogers.com/pneuma...ondor-mdr1-compressor-pressure-switch/S020122

 

[brightspark]

up the p;ressure back up then just sufficient to make them slightly different they only need a few seconds difference on starting load