High temperature proximity sensor

[paulengr]

The highest temperature proximity sensor I could find goes to just slightly under 500 F, sold by P+F. In the plant I work at, there are several places where we could easily use one that goes much higher. I was thinking it might be a worthwhile product to produce/sell. Anyone else have a need for such a thing or is this a severely niche product?

[gravitar]

I'm surprised there's even a prox that goes THAT high! There's a little PC board with solid-state electronics inside a prox, they don't like extreme heat. Maybe somebody has come up with a remote sensing coil that could be mounted away from the electronics.. I'm sure the coil is a lot less picky about environment.

[paulengr]

That is exactly how it's done. The only thing in the head is the coil. P+F uses teflon. I was thinking of going to pure nickel wire with mica insulation and a ceramic "can". This pushes the service temperature to 2000 F. You can "cheat" with mechanical linkages, push rods, etc., but that completely destroys the advantage of proximity switches over mechanical limit switches (no moving parts...longer lifespans). I could think of several places in lime and cement, and also in cast iron pipe plants where these would be really useful. The question is how many other plants have similar applications. If there's not much of a "market" then I'll home brew the dozen or so that we need and not even consider producing hundreds...I realize that it's definitely a specialty item anyways.

[BobLfoot]

We usually used an infared sensor which could read 1100 to 3000 degrees. If it had a reading our part was there if not then wither the part was cold or not there. In some cases we opened a shutter and brought a low temp standard prox into play once the infared gave a green light. Can't recall whose infared we were using.

[gravitar]

I gotta figure that if you could produce a reliable, practical product at a halfway-decent price (I'm thinking <$100-$150) then you would probably generate some comercial interest. My questions are can you ensure a long lifespan for the coil and connecting cable, and how long of a lead can you put on the coil?