Why does propane require different fittings than natural gas?

The correct choice highlights the differing chemical properties of propane and natural gas, which necessitate the use of different fittings for each gas type. Propane is a hydrocarbon that exists as a liquid under pressure but can easily vaporize into a gas when released, while natural gas is primarily composed of methane and is a gas at ambient temperatures and pressures.

The distinct chemical behaviors of these gases affect how they interact with materials and fittings. For instance, propane's liquid state can lead to specific considerations regarding the strength and compatibility of materials used in fittings, as they need to withstand the properties of both liquid and gas phases. Additionally, the combustion characteristics of each gas differ, which can influence joint types and sealing methods required for safety.

Using fittings not designed for the unique properties of each gas can lead to unsafe situations, such as leaks or improper combustion, making it critical for fitters to be aware of the chemical differences when selecting materials for installation.