ning
Elite Member
That's super useful!First, the size of tank has nothing to do with the internal pressure of the tank. The pressure is solely dependent on the ambient temperature and can be upwards of 200 psi. The pressure is controlled by a regulator and depending on the distances involved there may be more than one regulator. In my case the regulator at the tank steps it down to 10 psi (which is considered hi pressure - for propane) at the house is further stepped down to an 11 inch water column (somewhere around 1/2 psi) The size of distribution pipe matters as well on providing enough gas to meet the BTU requirements.
You will need to add up all your gas appliances to get a total BTU count - this is an important number! You will also need to know the coldest temperature you expect to see. You can then use the tank size you want to use with the ambient temperature to see if it will vaporize enough gas to meet that total BTU count. (Propane gas is in the form of a liquid in the tank with the propane gas above the liquid.)
Vaporization rate
There are charts for the different tanks. Vaporization depends on the surface area and temperature of the liquid propane, so a horizontal tank will have it's highest rate when half full because it has the greatest surface area at that point.
Curious why the vaporization rate goes down as the amount of propane in the cylinder reduces - is it because there's less thermal mass and so the the entire mass cools down more rapidly from heat loss of vaporization?