After much searching, I found a reasonably priced pressure sensor for my project. It’s a Danfoss AKS 32R, which has 0-300psi range (20.68 bar). It takes a 5V supply, and the output is analogue ratiometric, ranging between 0.5V and 4.5V DC.
No prizes for guessing where I plan to install this sensor!
This is an ebay special, so the first challenge was to track down some more detail on the sensor. The male thread is about 16mm long, and has 8 tracks in 11.4mm which is about 18 TPI. It clearly tapers, and the thread OD is about 13.3~13.8mm, so it looks like a 1/4-18 NPT thread.
I was keen to see if the sensor worked, so I tried hooking up a meter and blowing into the end. This produced a miniscule change in output voltage. After a bit of research, it seems that maximum lung pressure during exhalation is only about 2.1psi for an adult male, which is less than 1% of the sensor’s measurement range. Hmm… that explains why it didn’t give much of a reading then!
Quite a bit of work will be needed to plumb this in. I might need to fit a pulse snubber to protect the sensor. To be continued…