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Re: Gas Level Indicator



kyle forinash wrote:

I picked up a little $3 thing the other day, flexible plastic about 8x6 cm
and a few mm thick (looks like a refrigerater magnet) which magnetically
sticks to a propane tank and indicates when the gas in the tank is low. A
vertical color bar changes color at the level of the gas. Says it only
works when the tank is on (for 2-5 minuites) and gas is going out. Anyone
have any idea how this is suppose to work? The only thing I can think of is
if the vapor in the tank cools faster than the liquid so there is a
temperature gradient at the liquid/gas interface and the plastic is
actually temperature sensitive....?

As propane tanks operate the liquid turning to vapor cools the liquid.
Put one of these thermally sensitive liquid crystal strips on the tank
and the line on the strip corresponds to the liquid level in the tank.
Quite often you will find a frost level on the outside of the tank which
corresponds to the liquid level.
--
Jerry Hester Email: jhester@mtu.edu
Dept. of Physics Phone: (906) 487-2273
Michigan Technological University Fax: (906) 487-2933
1400 Townsend Drive
Houghton, Michigan 49931-1295