So, what you are probably re â¦ ferring to is 'energy'. The SI unit of energy is the joule (J). An alternative unit, used by electricity utility companies for the purpose of billing its consumers, is the kilowatt hour (kW.h).
a typical steel 30 pound liquid propane tank weighs about 25-28 pounds empty. propane tank markings (on collar) propane weighs about 4.125 pounds per gallon and a 30 po â¦ und tank will hold about 7.5 gallons so a full tank will weigh about 55 pounds or so. /source: wiki.answers.com/.
The most commonly used propane tank, the 20 lb tank is the standard size tank for barbecue grills, mosquito magnet, turkey fryer, small space heaters. However, the 20 lb tank can be used on several more propane applications. A 20 lb propane tank holds 4.5 gallons of propane and weighs 37 pounds full.