For a natural gas piping system with a 250,000 BTU furnace and a longest run of 93', what is the minimum diameter of schedule 40 metallic pipe required?

To determine the minimum diameter of schedule 40 metallic pipe required for a natural gas piping system with a 250,000 BTU furnace and a longest run of 93 feet, factors such as the BTU input, the distance of the run, and the allowable pressure drop within the system must be considered.

A 250,000 BTU furnace requires sufficient gas flow to operate efficiently, and the longest horizontal run of 93 feet indicates the need to maintain proper gas pressure at the appliance. According to the National Fuel Gas Code (NFPA 54 or ANSI Z223.1), when sizing gas piping, it's important to reference tables that specify the pipe diameters based on BTU input and length.

In this case, when you cross-reference the gas input with the distance using appropriate gas piping sizing tables, a 1 1/4-inch schedule 40 pipe is often indicated as the minimum diameter to provide adequate gas flow without experiencing excessive pressure drop.

This diameter ensures that the furnace will receive enough gas for combustion while maintaining efficiency and safety standards. Choosing a smaller diameter could result in an insufficient gas supply, potential operational issues, or even hazards due to inadequate flow.

Therefore, the minimum diameter of schedule 40 metallic pipe