Determine the required CSST size for Section G (retrofit application) of the piping system shown in Figure A.6.4, with a designated pressure drop of 0.5-inch w.c. (125 Pa) using the branch length method. The gas to be used has 0.60 specific gravity and a heating value of 1,000 Btu/ft 3 (37.5 MJ/m3).
- The length of pipe and CSST from the point of delivery to the retrofit appliance (barbecue) at the end of Section G is 40 feet (12192 mm), A + B + G.
- Use this branch length to size Section G.
- Assume the CSST manufacturer has tubing sizes or EHDs of 13, 18, 23 and 30.
- Using the row marked 40 feet (12192 mm) in Table 402.4(15), Section G, supplying 40 cfh (1.13 m3/hr) for the barbecue requires EHD 18 CSST.
- The sizing of Sections A, B, F and E must be checked to ensure adequate gas carrying capacity since an appliance has been added to the piping system (see A.6.1 for details).