Sure, if you can find one that can be set to minus 45 psi…
I think what you want is a pressure switch that acts as a double-throw (SPDT or DPDT) switch; this will allow you to wire it either way (normally closed or normally open). A quick google search for “SPDT pressure switch” returned a number of results (example), though I have no idea if these meet your other requirements (cost, size, environment, etc).
A closed switch means it is allowing power through.
An open switch means it does not allow power through.
On a regular pressure switch when it drops below a set pressure the switch closes and powers the compressor till it hits the top set point which it then opens cutting power to the compressor.
I haven’t run into any commonly available switches for Napier’s purpose.
With his goal however you could easily wire up what you want with a contacter and a standard pressure switch. The combined cost will likely be less then a specialized switch.
The pressure switch will work to protect from loss of inlet air, but a flow switch is better, as the heater may overheat if the outlet is blocked, (dead ended) which will not trip the pressure switch on the input. Flow switches are more expensive than pressure switches so I’ve never won this argument, but maybe you will have better luck!
No. It’s further downstream where accuracy matters.
This makes control harder, but I wrote a program to fit FOLDP models to step response studies and try a variety of tuning rules for PID parameters, and have a pretty good control loop now. There’s another component with a much longer lag time, so this particular loop does not set the time before settling anyway.
It would have been nicer to cascade two loops, but this is good enough.
Exactly the company I was about to link to and suggest you search. They’re one of my favorite companies for finding and buying odd stuff like this. Bookmark their home page for future searches of this “oddity level”.
Yeah. Actually, I tried them first, and then Grainger and a few others, before I posted. I don’t know what I did wrong, but I didn’t find ANYTHING.
I actually order from McMaster-Carr several times a week and have a personal account as well!
By the way, the switch I would up ordering from them just arrived and it looks perfect, very nice. I find that they occasionally fill orders later on the day I requisition them, meaning I process it, then the PA processes it, then McM-C processes it, then UPS (or whoever) processes it, then our receiving department processes it, and finally I get an email and run downstairs and pick the thing up. It’s amazing.