03-30-2014, 08:21 AM
Correcting some of the misinformation posted in this thread...
The standard steel propane bottle used in BBQs an the like is commonly referred to as a 5 gallon container. Its total water* capacity is stamped into the steel collar and typically is about 5.7 gallons.
They are also referred to as "20 pound" cans, but some brands of refills only contain as little as 15 pounds of propane, so buyer beware. There should be a DOT notice somewhere on the rack that says what the contents are, but they often tuck it away in an inconspicuous corner. When you get your own bottle filled at a propane dealer, rather than doing a swap at a hardware store, the fill is metered and you pay for what you get.
* Since so many propane explosions (est. 600/yr) were traced to over-pressurized tanks, as of 2002 all propane tanks must be equipped with an Overfill Protection Device (OPD) using a float valve that turns off the fill valve at about 80% capacity. Valves with the OPD device installed have triangle shaped handles. Tanks using valves with round or square handle cannot be refilled any longer.
By federal law propane container can only be used for 12 years after the date of manufacture unless they are retested for pressure, in which case they can be requalified for another 5. The date(s) are stamped into the steel collar. For a 100# portable bottle, like my neighbor uses to fire his pottery kiln, or the maybe 40-60# bottles that have many industrial uses such as powering fork lifts, retesting may be worth it to extend their use, but it's probably not practical for a 20#, which can simply be swapped for a refill at many places.
Light visible rust is not a safety issue, but heavy rust is. And dents are dangerous. Bottles that need to be retired are normally accepted for recycling by propane dealers. Typically they will remove any gas still in the bottle, remove the valve for recycling the brass, render the bottle unusable by punching a hole in the side, then sending on to a metal recycler.
The standard steel propane bottle used in BBQs an the like is commonly referred to as a 5 gallon container. Its total water* capacity is stamped into the steel collar and typically is about 5.7 gallons.
They are also referred to as "20 pound" cans, but some brands of refills only contain as little as 15 pounds of propane, so buyer beware. There should be a DOT notice somewhere on the rack that says what the contents are, but they often tuck it away in an inconspicuous corner. When you get your own bottle filled at a propane dealer, rather than doing a swap at a hardware store, the fill is metered and you pay for what you get.
* Since so many propane explosions (est. 600/yr) were traced to over-pressurized tanks, as of 2002 all propane tanks must be equipped with an Overfill Protection Device (OPD) using a float valve that turns off the fill valve at about 80% capacity. Valves with the OPD device installed have triangle shaped handles. Tanks using valves with round or square handle cannot be refilled any longer.
By federal law propane container can only be used for 12 years after the date of manufacture unless they are retested for pressure, in which case they can be requalified for another 5. The date(s) are stamped into the steel collar. For a 100# portable bottle, like my neighbor uses to fire his pottery kiln, or the maybe 40-60# bottles that have many industrial uses such as powering fork lifts, retesting may be worth it to extend their use, but it's probably not practical for a 20#, which can simply be swapped for a refill at many places.
Light visible rust is not a safety issue, but heavy rust is. And dents are dangerous. Bottles that need to be retired are normally accepted for recycling by propane dealers. Typically they will remove any gas still in the bottle, remove the valve for recycling the brass, render the bottle unusable by punching a hole in the side, then sending on to a metal recycler.