Get Ps 86b

Gas piping systems with supply pressures: less than 7″ w.c. (1.75 kPa) must be designed so the pressure drop does not exceed 0.5″ w.c. (125 Pa). 7″ w.c. to 14″ w.c. (1.75 kPa to 3.5 kPa) must be designed so that the pressure drop does not exceed 1″ w.c. (250 Pa).

While transmission pipelines may operate at pressures over 1000 psi, distribution systems operate at much lower pressures. Some gas mains (2 to 24 inches in diameter) in a distribution system may operate up to 200 psi, but the small service lines that deliver gas to individual homes are typically well under 10 psi.

The pressure drop for a 2 Psig (14 kPa) system operating on natural gas can be either 1.5 Psig (10 kPa) or 1 Psig (7 kPa) depending on what pressure is required at the end of the system.

The pressure drop in the pipe is affected by items such as the internal roughness of the pipe material, internal pipe diameter, length of pipe, gas flow rate, pressure at the start of the pipe, and gas density at the entry condition.

A standard residential pressure test may include pumping the line with 20 psi and requiring that the line hold pressure for 4 hours with less than a 2 psi drop.

Standard gas line inspections usually require that lines hold 1.5 times the maximum operating pressure or 50 psi, whichever is greater. Typically, if the gas line loses 2 psi from a test of 20 psi on the line, the lines are considered acceptable. If the line loses more than 10% of the pressure, it may have a leak.

It is common for standard gas line inspections to require lines hold three times their working pressure load for at least 30 minutes. Typically, if the gas line loses approximately 2 psi from a test of 20 psi on the line, the lines are acceptable.

The pressure (P) should be taken as the maximum allowable pressure drop ing to the relevant standard. In the case of EN ISO 4126, this would be 10% of the set pressure, and it is at this pressure we determine ρ.