Apologies if this is a stupid question!
I have been refurbishing a SIP compressor. It came to me basically as a tank with a compressor and motor mounted on it. Through SIP I have acquired and replaced the pressure switch, the outlet regulator, the pressure relief valve and the drain tap.
It is has a 50 litre tank and is a belt driven type. Amongst the parts I have replaced is the pressure switch (brand new from SIP). This has two pressure connections. Both direct to the tank. There were two pipes sticking up (of the right dimension!) that seemed to fit, so I used those
I am assuming that the two form the "high" and "low" pressure switches. Switching off at >120psi and turning back on