Hello,

I am looking for a flat sensor, but I want it to:

1. Be very cheap.
2. Be able to sense that the air (gas) pressure has fallen from about 2-4 atmospheres to NEAR 1 atmosphere. It only needs to be close, so it doesn't have to compare to actual atmospheric.
3. Be flat, or at most about 1 mm thick.

I would be great if it:
1. Had an indicator built in to indicate when atmospheric had been sensed. (It could be a 1-time-use unit.)
2. Required no battery or electric circuitry.

Any idea where to get this more "mechanical" type of sense, rather than an electric one?

If not, do you know of any CHEAP (<$1 or so) electric sensors that are flat enough? It could be WILDLY inaccurate (>= 1 atmosphere) and would be FINE.

Thanks,

Mark

 

Mark

It's not clear to me what pressure you're looking to sense. If you're looking for a decay to atmospheric pressure try allelectronics.com. They have some cheap surplus pressure switches (also sub-atmos), but none less than 3-4 mm. Unfortunately, for a local indication you'll need a power source and led/bulb/annunciator.

Good Luck