|
In a message dated 3/11/2010 6:43:48 A.M. Pacific Standard Time,
jonw@psubs.org writes:
Also, is the depth indication (graduations) as shown by The variations will gradually get smaller as the pressure increases. With
the availability of inexpensive pressure gages it seems like building your own
isn't worth the effort. A nice big gage is what, about $60 ?
But.......
Jens design could be used as an internal cabin pressure gage. The
differential isn't that great so a very heavy piece of glass wouldn't be
required.
It wouldn't however detect negative pressure. Again, a simple barometer
could work, or a "U" tube gage called a manometer. We used these in air ducts
while testing. Really simple.
It's a plastic/clear vinyl tube in a "U" shape with a small amount of
colored oil in the bottom. To sense room air, you simply plug one end and hang
it up. Any increase or decrease in pressure moves the oil in the tube giving you
"inches of water column". Works for increases or decreases.
Like the "water level" Jon spoke of, simple, reliable, easy to read,
and cheap.
Frank D.
|