My nice civilised Hydrovane 15 (well I think that it's a 15 but never found a model number on it!) was cutting in a 85 psi and out at 125 psi which has been fine until I got my CNC Plasma Table - the Hypertherm PM45 plasma cutter on it specifies it at 90 psi (although it regulates it lower internally).
So a job yesterday was to tweak the pressure switch on the compressor up just a tad so that it never falls below 90 psi. Often compressor pressure switches - or at least the better ones - have settings for maximum pressure and hysteresis or dead band, thus setting the range from 'cut in' to 'cut out. But not this one - it's a cheapy generic one with only the maximum pressure settable. No problem, increase it from the 125 psi upper limit to a bit nearer the 150 psi that the compressor is rated at. I checked the test pressure of the tank and there was loads of margin, so 'one flat at a time', I tweaked the adjusting nut and cycled the compressor noting where it switched off.
I got it up to about 140 psi when suddenly the Hydrovane would not raise the pressure one iota. I thought I'd done massive internal damage to it, so a bit miffed I left the Portakabin where the compressor is housed, to go in the main workshop to google for technical diagrams of the beast.
As I got to the door, a chap that I have at the moment lowering a massive Laurel hedge called over saying he was glad I was ok as he'd heard the 'loud explosion', and come knocking on the locked workshop door to check I was ok
What explosion - I'd heard nothing ! So I went hunting along the considerable length of my air distribution system and eventually found the culprit. There was a three way Tee joint, where one branch is for future expansion, and the blanking plug had decided it was no longer going to stay put