Re: [a/s] Propane tanks

[bjacobs <bjacobs@xxxxxxxxxxxxxxxxxxx>]

Hello All:

	The pressure in a propane tank is dependent upon the temperature, not
the amount of propane in the tank.  

	If we assume there is a little liquid, the pressure will be 

psi      temperature

 38.2          0
124.0         70
187.0         100
240.0         120 
661           202   critical temperature

	This is true unless the tank is absolutely full with no expansion
room.  
	
	The coefficient of expansion for propane is about .0007.  This means
that one gallon of propane will be 1.0007 gallons if heated 1 degree F. 
Your 30 pound tank which contains about 7 gallons of fuel will expand
about .49 gallons if warmed from 0 to 100.  (7 x .0007 x 100)  This is
about 1/2 gallon.  In a 12 inch diameter tank, this is almost 1 inch.

	This space in the top of the tank is necessary to keep the liquid from
entering the pipeline downstream of the regulator.  At the appliance, we
want "dry" gas with no liquid.  You may have seen a propane torch flair
up when it is  held upside down.  The liquid gets into the pipeline in
this case.

bill
25 ft Land Yacht in WV