LPG Properties

LPG physical properties include specific gravity (density), boiling point, pressure, vapour expansion, energy content, combustion facts, flame temperature, flash point & more.
This chart shows some of the physical properties of propane, butane and isobutane…

LPG Pressure Varies with Temperature

  • As previously mentioned, when LPG is stored in a gas bottle, it is under pressure.
  • The term “pressure” refers to the average force per unit of area that the gas exerts on the inside walls of the gas bottle.(LPG Pressure-Temperature Chart shown)
  • Pressure is measured in kilopascals (kPa) or pounds per square inch (psi).
  • LPG pressure can vary greatly based on temperature, as shown in the chart.
  • The level of fill in the gas bottle comes into play when the LPG is being used, as it affects the rate of vaporization.
  • As LPG is a liquefied gas, the pressure inside the cylinder will remain the same from full until the last of the liquid LPG is vaporized.
  • Then the pressure will fall quickly as the last of the LPG vapour is used, as well.

LPG is Heavier Than Air

  • In answer to the frequently asked question "Is LPG heavier than air", the answer is "YES".
  • For example, if the density of air is equal to 1.00, the density of propane is 1.53.
  • Butane is even heavier, at 2.00. Isobutane is heavier still, at 2.07.
  • On the other hand, natural gas - methane - is lighter than air, at about 60% of the density of air.