Our team is using pneumatics on our robot, the only thing that we are unsure of is if the compressor should be running continuously or if it should only be running when we are short on air. I saw on the manual that we should calibrate the relief valve by shorting the pressure switch, but we have no idea how to do that. Any suggestions?
If the system is set up correctly with the pressure switch wired into the PCM, the compressor will automatically shut off when pressure reaches ~120psi. Also, I’d recommend you buy the McMaster relief valve (48435K714) as it’s precalibrated.
You short the pressure switch by temporarily connecting across the two terminals.
A wire with alligator clips on both ends, for instance.
That causes the compressor to run continuously, and you adjust the pressure relief value so that the pressure doesn’t build up past 125psi.
In general operation, when you have the system pressurized to ~120 and the compressor is shut off by the pressure switch, it won’t come back on until your pressure gets down around 110. If you’re having trouble getting to the pressure where the system is shut off by the pressure switch, or if it doesn’t stay pressurized when you aren’t actuating anything, you have one or more leaks.
Be very careful when you do the relief valve calibration. At no point should you let the pressure get over around 130. The process requires you to disable the primary safety feature (by shorting the pressure switch) in order to calibrate the backup safety feature. If you have trouble with it, it’s ok to have your inspector walk you through the process at your first event.