Natural Gas & Propane Gas Composition
Natural gas (NG) and propane gas (LPG) are currently the predominant residential and commercial gas fuels. They are relatively consistent, predictable fuels. Both NG and LPG have no color, have no odor (without additives), and are not toxic. The differences in composition and characteristics between the two gases, however, are significant in their bearing on safety and performance factors. Propane gas is made up of larger molecules that contain more hydrogen and carbon atom bonds to release energy as they break.
The Natural Gas molecule consists of 1 carbon atom and 4 hydrogen atoms. The Liquid Propane Gas molecule consists of 3 carbon atoms and 8 hydrogyn atoms.
This difference in molecular makeup results in important differences in the characteristics of the two gases. Because natural gas is lighter than air, it rises when released into the atmosphere. Propane gas is heavier than air, so it tends to sink and seek the lowest areas in the product or room.
Consequently, dissipation of propane gas or removal time is longer than for than for natural gas, which rises on release.
Gas & Air Combustion Ratio
Own its own, natural gas and propane gas IS NOT flamable. Three requirements must be present for combustion to take place: fuel, oxygen & heat. If any one of the three is missing, combustion will not occur.
1 cubic foot of Natural Gas requires 10 cubic feet of air to ignite. 1 cubic foot of Propane Gas requires 24 cubic feet of air to ignite.
So we see that propane gas needs nearly 3 times the amount of air as natural gas. Since natural gas is lighter than air, air mixture typically takes place at the base of the flame. Since propane gas is heavier than air, air mixture must take place before the propane/air mixture gets to the burner, typically after the valve but before the burner.