I'm running a Nitrous express system and I'm adding in a pressure switch to the mix and it is a 3 terminal safety switch Each. The terminals are marked with a C and a NO and a NC, can anyone tell me how to wire this into the system.

Fuel pressure safety switch? Most i see are just two terminal and are used on the ground side of the nitrous solenoid relay

NO is normally open
NC is normally closed.

C may be whatever you want to run off of it im not sure but you can test its functionality by hooking things up and using compressed air to see what does what

Double post

C is probably coil. Use a multimeter to measure resistance and you'll know one way or the other.

If the part number printed on the relay comes up at Mouser website, then you'll likely be able to download the schematic and tech specs.

C is common to both the NO (normally open) and NC (normally closed) contacts. All relay terminal markings are based on a shelf state, meaning no power or in this case no pressure applied to the switch.

When pressure increases past the set value, the contacts toggle, NC becomes open to C, NO becomes closed to C.

Wire to C and one of the two others as you need the contact to operate.

Oh, so it's really a switch and not a relay. Sorry, my bad.

Thanks everyone. Good help. I decided not to connect it to the Nitrous to automatically turn it off. Lots of responses about having trouble with it going on and off. So I will hook it to a safety light that I can stop the nitrous manually if it comes on and stays on. any thoughts