If the distance between the first stage regulator and a second stage regulator is 60 feet with a total propane load of 520,000 btu/hr, what is the minimum size Type L copper tubing that may be used?

The minimum size Type L copper tubing required in this scenario is determined by considering the total propane load and the distance between the regulators. For a load of 520,000 BTU/hr over a distance of 60 feet, the sizing must accommodate both the capacity needed to transport that volume of gas effectively and the pressure drop over the distance.

To ensure safety and efficiency, the NFPA 58 code provides guidelines for sizing gas piping systems, factoring in parameters such as load and length of run. The calculations involve the gas flow capacity of different tubing sizes when transporting propane. Each tubing diameter has an associated capacity for delivering a certain amount of BTUs over a specified distance without excessive pressure drop.

In this case, the 5/8" Type L copper tubing meets the necessary requirements for both the 520,000 BTU/hr load at a length of 60 feet. This size is adequate to prevent significant pressure loss while maintaining the ability to deliver the required volume of propane efficiently. Larger diameters, while they would also work, are not necessary for this load and distance, and smaller diameters would result in inadequate flow and potential safety issues.

Thus, selecting 5/8" tubing ensures compliance with the NFPA 58 code's stip