Francesca Knowles wrote:
Dunno what exactly you mean by "physically hold", or where your other numbers come from but:....
From your link... the capacity of a 20# bottle is 47.6 lbs of water. The bottle can "physically hold" 47.6 lbs of water.
Water is essentially incompressible and weighs something on the order of 8.2 lbs per gallon. (77 deg)
47.6 lbs of water is 5.8 Gallons.
The density of liquid Propane is approximately 4.11 lbs per gallon. (77 deg)
5.8 X 4.11 = 23.85 Lbs
Not references, but anecdotal support"
"The bottle filling station will generally have a cylinder filling chart that converts water capacity (WC) to pounds of propane that the filler will refer to before filling the bottle. The chart will show that 47.6 pounds of water converts to 20 pounds of propane. In other words, a propane bottle that will hold 47.6 pounds of water will hold 20 pounds of propane. This indicates that the scale needs to be set a little over 38 pounds (20 lbs + 18 lbs = 38 lbs) to obtain the weight of the bottle when it reaches its allowable capacity."
http://www.propane101.com/propanecylinderfilling.htm
http://www.propanetankstore.com/dot-5-lb-100-lb/
http://www.orangecoat.com/the-truth-about-filling-20-lb-bbq-grill-propane-tanks
http://www.missiongas.com/lpgascylinders.htm
PS From YOUR link the capacity of the 20# bottle is 4.7 gallons of propane - 4.7gal X 4.11 lbs/gal = 19.3 lbs.
