Hi

 

I'm building an ESP so have been looking at the same problem.. The cheapest and simplest I've found so far is to just put a cheap non sensitive altimeter in to read cabin pressure. (don't hook it up to the outside air) Otherwise Guardian has a carbon monoxide detector model 352 that also outputs in RS232 format the cabin pressure that you can run into what ever you have that will read it and display it.  I'm going to use the MVP-50 engine monitor which will do that and let me set an alarm for what ever level I choose.

 

Good luck.  If you come up with more alternatives let me know.

 

Thanks

 

Cliff Scheel