Propane is delivered and stored as a liquid. However, propane boils at a temperature of -44°F, so inside the truck and tank that liquid is boiling and turning to vapor (or gas). Propane gas has a greater volume than propane liquid and so requires more space to contain it. Because of this, a propane tank is never filled to 100% – there must always be space into which the liquid propane can evaporate, creating a pocket of gas at the top of the tank. This is the gas that will be used when you open a valve on an appliance in your home. As the gas is drawn off, so the liquid within the tank boils faster and more gas is produced to replace the old.
On top of a propane tank you will see a fill pipe, a shut-off valve, an emergency vent, a gauge showing how much liquid propane is in the tank, and possibly a regulator valve (if it is not on top of the tank itself it will be located next to the tank and will be connected to the valve via a copper, iron or special plastic pipe).
The tank gauge shows what percentage of the tank’s capacity is full. (Remember it will never read 100% – full will be 80%.) Thus, if you have a 1000-gallon tank and the gauge reads:
80% (full), you have 800 gallons of propane
50% you have 500 gallons of propane
30% you have 300 gallons of propane and should order more
10% you have 100 gallons of propane
If you have a 500-gallon tank and the gauge reads:
80% (full), you have 400 gallons of propane
50% you have 250 gallons of propane
30% you have 150 gallons of propane and should order more
10% you have 50 gallons of propane
If you have a 120-gallon tank and the gauge reads:
80%, you have 96 gallons of propane
50% you have 60 gallons of propane
30% you have 36 gallons of propane and should order more
10% you have 12 gallons of propane
If you’re not on automatic delivery, it’s time to reorder when your gauge reads 30% of less. And even if you are on automatic delivery, it’s good to know where your gauge is and how to read it – perhaps you’ve switched on a pool heater and haven’t told us, or maybe you ran your propane-fired generator for a few days…whatever the reason, if there’s a spike in your consumption caused by anything more than just a drop in outdoor temperature, check your gauge and give us a call at 603.964.6703 if you’re at 30% or less.