What is a critical factor for determining the proper size of LP gas piping?

The length of the gas run is a critical factor for determining the proper size of LP gas piping because it directly impacts the pressure drop that occurs as gas travels through the pipes. The longer the gas run, the more resistance there is to the flow of gas, which can lead to a significant drop in pressure. This pressure drop must be accounted for to ensure that the appliances being supplied receive an adequate and consistent flow of gas. If the piping is not appropriately sized considering the length of the gas run, it can result in inadequate performance of the appliances, risk of incomplete combustion, or even safety hazards.

In addition, other factors such as the location of gas appliances, elevation of the property, and type of propane, while important in their own right, do not specifically relate to the flow and pressure dynamics in the same way that the length of the gas run does. Proper sizing based on the gas run length provides the foundational assurance that the overall gas delivery system functions safely and efficiently.