Propane, like almost all other materials, is affected by cold temperatures. It contracts as temperature declines, and that reduced level of materials in the tank is reflected by the tank level gauge. This often comes into play when a homeowner checks the tank level gauge before and after a delivery during cold weather. The percentage of the tank may not rise as much as anticipated.
Propane Tank Level Gauge
The gauge on a propane tank reflects what percentage of the tank is full. Normally, tanks are not filled above 80 percent to allow for the propane to expand on hot days. For a 500-gallon tank, for example, a reading of 80 percent at normal temperatures amounts to about 400 gallons of propane in the tank; this is about as much as can typically be stored.
According to the website Propane101, operated by the propane gas industry, an exterior temperature of 60 degrees is considered baseline or reference point. If the gauge reads, for example, 50 percent of capacity on a day where the temperature is near 60 degrees, a 500-gallon propane tank should contain close to 250 gallons of propane. If the temperature is well above 60 degrees, the gauge will read higher because of the expansion of the gas. If the temperature is well below 60 degrees, the gauge will read lower.
Effect of Expansion and Contraction
According to the propane industry website, the amount of energy contained in the tank does not change as the gas contracts or expands. The amount of propane has not changed, only the density of the gas has.
Propane is measured by the pound as it is dispensed from a truck or other delivery vehicle. Propane weighs 4.24 pounds per gallon. During cold conditions, a smaller, denser physical volume weighs 4.24 pounds. When the temperature rises the volume increases, but the weight does not change.
If a homeowner orders 100 gallons of propane, she will receive 424 pounds of propane. If, for example, she has a 1,000-gallon propane tank, she may expect the gauge to go up by 10 percent with the delivery of 100 gallons of propane. This would be true if temperatures were near 60 degrees at the time of delivery. Colder temperatures would result in a smaller increase on the propane gauge. The amount of difference will vary with the temperature.