What is the maximum pressure drop allowed by codes for a natural gas piping system with a supply pressure of 5 psi?

In natural gas piping systems, the maximum allowable pressure drop is typically governed by codes and standards that ensure safe and efficient operation of the system. For a natural gas supply pressure of 5 psi, the permissible pressure drop is generally specified as a percentage of the supply pressure, which helps maintain system functionality while preventing conditions that could lead to inadequate pressure at the appliance or equipment fed by the gas system.

The specification of a maximum pressure drop of 2" NPS is relevant to the measurement of pressure drop in relation to the diameter of the piping. It indicates that the system can accommodate a substantial flow of gas while still maintaining the necessary pressure levels required for proper operation of appliances. Generally, larger diameters correspond to lower resistance to flow, thereby allowing greater flexibility in design and installation while still adhering to safety requirements.

In contrast, the option of 2 psi and other lower drop measurements do not align with typical systems designed for a 5 psi supply, as these represent a greater reduction than is generally allowed. Such significant drops could lead to operational issues. Furthermore, while 5 psi as a maximum drop corresponds to being equal to the supply pressure, it would be impractical and unsafe, as it would eliminate any available pressure for gas delivery to the system