Pressure Sensor recommendation

[victorf]

In my Interfacing a DS18S20 topic I was pointed to Sensirions site and while sniffing around there I found their differential pressure devices which are also very interesting.

Reading the data sheet I got to thinking if perhaps I am letting myself into a lot of problems. The differential pressure I am looking to measure is across the fabric from inside to outside. The balloon is a manned gas balloon and the lifting gas could be hydrogen.

Does anyone know if these types of pressure sensors would be safe to use with one port plumbed directly into the hydrogen side of the balloon? I know; you all have visions of the Hindenburg.

Any enlightenment will be appreciated.

Vic

[GTBecker]

The sensor manufacturer might be able to tell you if the device will suffer from continuous exposure to hydrogen but, despite that answer, I think I would avoid allowing hydrogen access to the electronics.

You might put a liquid trap in the pressure line, much like a vanity sink U-trap, that would isolate one pressure side gas from the other, presumably air. I remember, also, that IBM used a membrane isolator in vacuum-column tape drives to prevent oil mist, I think, from reaching the tape. It was a disk of some flexible material between two mouth-to-mouth funnels, with a hose off each end. Equalized, somehow, that might work, too.

Actually, it is that membrane displacement that you might measure to determine differential pressure and, for that matter, the liquid U-trap is a manometer, too.


Tom

[GTBecker]

Vic, I had a thought in the middle of the night. Although this method does not use the Sensiron sensor, can you use the gas bag itself as a displacement diaphram?

Suppose you mounted the equivalent of an embroidery hoop in the side of the balloon, making a taught surface that is nearly flat when inflated at ground level. At altitude, the surface will bulge outward as the bag expands. Measure the bulge, calibrated for the material?


Tom