pluguglyinhere

Anyone know where I can get a 100 psi low air alarm for my air system? I do not want another guage but a light that went off if it drops below 100 would be nice.

HMX-1

I don't know if there is such a thing, but you could easily make one.

Get a 100 psi pressure sensor that you would normally use with a compressor (to turn it off and on) and just wire it up so that instead of turning on a pump it turns on a light.

pluguglyinhere

Not a bad idea, I have been scratching my head since I read your post. It would be easy say the sensor did 50-100 for a compressor it would light up in that range, but if my tank was less than the 50 (or whatever) it would not be lit. Unless I am missing something? I know that tractor trailers have them for their air brakes, but I can only find them for 60 psi.

MrLuckey

If you use a pressure switch (like for turning the compressor on/off) the contact would be ON (closed) below 50, and OFF (open) above 100. You could add a relay to it to fit your needs.

pluguglyinhere

I guess I would like to warn me if the psi dropped below 100 psi, so I am thinking that if the light came on from 100 psi down to 50 great. I am worried or not understanding from this possible set up is what happens from 50 through 0. Technically if overnite the tank dropped due to a leak to zero, I would not know because the light would not be on below 50.

The reason again is I want a gauge for each bag, so one dual guage. I do not want another for the tank, but want to know if the tank drops below 100 psi, so the compressor is not running all the time from a leak.

MrLuckey

Pretty sure that the switches used for turning the compressor on/off work like this. Say it's a 100/50 switch. Under 50 psi it turns ON, stays ON until it reaches 100 or above. Once it's above 100, it won't turn back on until it's under 50 again. They are more than a simple switch, having a latch and deadband between 50 and 100.

In your example your light would be ON in the morning (below 50) but OFF when dropping between 100 and 50. If it had dipped to 50 to turn ON, it would stay ON until getting to 100.

The purpose of the latch and deadband is so that your compressor isn't turning on and off as often.

Sounds like you really just want a simple pressure switch.

HMX-1

I know HornBlasters has an adjustable pressure valve .... dial it out to where you want it to turn off and on. Real simple, and they have it for all NPT sizes.

I'm getting most of my parts from them for my train horn install I'm doing this summer, and it was something I've seen them sell on there.