Re: Pneumatics Code
 

You'll lose the same amount of pressure each time, down to 60 psi, so that part's consistent.

Restoring the pressure is a function of how much pressure is already in the system. The compressor takes longer the more it has to work against higher pressure. So, for example, pumping 5psi back into a system already at 110 psi will take longer than pumping 5 psi into a system at 60 psi.

What you're suggesting will probably work for your purposes though. You don't have to be too exact. You can probably go with the time you measure when the overall system is down to 90 psi and you'd be fine. Then you could still check the pressure sensor for "1" and keep the compressor running as long as it doesn't turn back to "0".

Re: Pneumatics Code
 

Cool, I wasn't too far off! :D

Looks like I have some system-of-equations to write tomorrow!