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: freezing gas tanks and gas safety

updated wed 1 mar 00


iandol on tue 29 feb 00

----------------------------Original message----------------------------

It seems kind of an accepted general rule that when firing with =
they =22freeze up=22 but does anybody know why? Do the tanks lose pressure =
they're emptying or is that just a consequence of another phenomenon? =
shaking the tank and pouring hot water over it, are there any other ways of
deterring it? Thanks for any help.

LPG tanks appear to freeze up because they cool down as the LPG evaporates. =
causes the temperature of the bottle to fall. Water condenses on the outside=
the tank and will eventually freeze to ice. I doubt if the liquid inside
freezes. The freezing point of Propane is minus 187.7 Celsius, of Butane =
138.4 Celsius, very chilly. Heat from the environment keeps the stuff
evaporating even under pressure. As you evaporate gas more quickly to supply=
greed of the kiln for more heat as its temperature increases, more heat is
needed by the bottle to keep the pressure up because cold liquids do not
evaporate as quickly as warm liquids. The faster you pull out the gas, the
colder the tank gets.

How to overcome this.

1 Just keep a cold hose going over the tank. 2 Put a blower heater to warm =
tank. 3 Gang two or more portable bottles together on one manifold and run =
open. 4 Install a big capacity tank, like 1000 or 5000kg.5 Stand the bottle
where it gets radiation from the kiln, but be sure you have no leaks in your

Just as a matter of interest, how many Clayarters who use gas check their =
when they connect a fresh bottle to find out if they have a perfect seal? =
Even a
few bubbles can lead to an explosive mixture at floor level over a period of

Ivor. Still inquisitive