1315.6 Variable Gas Pressures

Where the supply gas pressure exceeds 5 psi (34 kPa) for natural gas and 10 psi (69 kPa) for undiluted propane or is less than 6 inches (1.5 kPa) of water column, or where diversity demand factors are used, the design, pipe, sizing, materials, location, and use of such systems first shall be approved by the Authority Having Jurisdiction. Piping systems designed for pressures exceeding the serving gas supplier's standard delivery pressure shall have prior verification from the gas supplier of the availability of the design pressure.

Solution:

1. Maximum gas demand of Outlet A —

   32 cubic feet per hour (0.91 m³/h) (from Table 1308.4.1).

   Maximum gas demand of Outlet B —

   3 cubic feet per hour (0.08 m³/h) (from Table 1308.4.1).

   Maximum gas demand of Outlet C —

   59 cubic feet per hour (1.67 m³/h) (from Table 1308.4.1).

   Maximum gas demand of Outlet D —

   136 cubic feet per hour (3.85 m³/h) [150 000 Btu/hour (44 kW)] divided by 1100 Btu per cubic foot (0.0114 kW•h/L)

2. The length of pipe from the gas meter to the most remote outlet (Outlet A) is 60 feet (18 288 mm).
3. Using the length in feet column row marked 60 feet (18 288 mm) in Table 1315.2(1):

   Outlet A, supplying 32 cubic feet per hour (0.91 m³/h), requires ¹/₂ of an inch (15 mm) pipe.

   Section 1, supplying Outlets A and B, or 35 cubic feet per hour (0.99 m³/h) requires ¹/₂ of an inch (15 mm) pipe.

   Section 2, supplying Outlets A, B, and C, or 94 cubic feet per hour (2.66 m³/h) requires ³/₄ of an inch (20 mm) pipe.

   Section 3, supplying Outlets A, B, C, and D, or 230 cubic feet per hour (6.51 m³/h), requires 1 inch (25 mm) pipe.

4. Using the column marked 60 feet (18 288 mm) in Table 1315.2(1) [no column for actual length of 55 feet (16 764 mm)]:

   Outlet B supplying 3 cubic feet per hour (0.08 m³/h), requires ¹/₂ of an inch (15 mm) pipe.

   Outlet C, supplying 59 cubic feet per hour (1.67 m³/h), requires ¹/₂ of an inch (15 mm) pipe.

   Using the column marked 60 feet (18 288 mm) in Table 1315.2(1):

   Outlet D, supplying 136 cubic feet per hour (3.85 m³/h), requires ³/₄ of an inch (20 mm) pipe.