On Sep 16, 5:29*pm, "Tom Gardner" wrote:
I want to sense pressure in a line that feeds part clamps and turn on a
green light and/or have a red light go out so the operator will try to
remember to clamp the parts. *(don't laugh) *I could use a compressor switch
for about $30 and a search finds sensors for about $80. *Can I use an
automotive oil pressure idiot light switch or something like those? *They
are only $5-$10. *Any other ideas?

I'm fond of Nason pressure switches. I needed a SPDT oil pressure
switch for my car that operated at 15psi but didn't want to pay an arm
and a leg for one. A standard oil pressure switch operates at 3-5
psi, which for me is way too late. The 15 psi gave me the warning I
needed, and on the engines I've used them on, the light would barely
flicker when the engine was really hot. Got it from my local Carquest
that ordered it for me. I think I paid in the $25 range, retail. The
thing is solid as a rock and very well built. I was never worried
about the stem breaking off from the vibration.

Anyway, the price was really good as well. A buddy of mine repeated
what I did, and they sampled him the one he wanted. Link is
http://www.nasonptc.com/pressure_switches.html You pick out the
pressure range, connection type, etc, rather than figuring out how to
make what's on the market wire up to your existing system. They also
have adjustable ones, too.