at a given temperature? My grill runs on propane and I understand that when the tank is "empty" there is still some propane in it, there is just not enough pressure to allow it to escape. In a standard 20 lb tank what is this amount of propane left in an empty tank when the tank is at room temperature. When the tank is in a cold outdoor environment, there will be more propane left in the tank when it is "empty" than in a warm environment. How do i determine the amount of propane left in the tank at different temperatures? I know this is thermodynamic related and I just need some one to get me started moving in the right direction with an equation or something...

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Pv= Mrt .p Pressure .v Volumem Gas Mass Expressed In Gm Molecular Weight .r Gas Constant T Temprature In Deg. K.putting Numerical Values You Will Be Able To Find Gfas Wight At Any Temperature .

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PV=nRT can be used to approximate the value, the thing to remember is that propane is not flowing because the pressure in the tank is equal to atmospheric pressure. So you know your P (atmospheric), your V is the volume of 20lbs liquid propane (about 15.6 liters, assuming you have a standard 20lb tank), R is constant, and T is your ambient temp. Solve for n at various T's to tell you how many mols of propane you have left, and you can easily convert that to weight.

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The above is true, but don't forget pressure losses at the valve.

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