Gas Piping
Pipe Sizing Procedure - Example
The gas supply must be capable of handling the entire gas load at the location. Gas line sizing is based on gas type, the pressure drop in the system, the gas pressure supplied, and gas line type. For gas pipe sizing in the United States, refer to the National Fuel Gas Code, NFPA 54. For Canadian gas pipe sizing, refer to the Natural Gas and Propane Installation Code CAN/CSA B149.1. The below information is provided as an example. The appropriate table from the applicable code must be used.
1.For some tables, you will need to determine the cubic feet per hour of gas required by dividing the gas input by the heating value of the gas (available from the local gas company). The gas input needs to include all gas products at the location and the maximum BTU usage at full load when all gas products are in use.
Gas Input of all gas products (BTU / HR)
Cubic Feet per Hour (CFH) =
Heating Value of Gas (BTU / FT 3 )
2.Use the table for your gas type and pipe type to find the pipe size required. The pipe size must be able to provide the required cubic feet per hour of gas or the required BTU/hour.
Example: The heating value of natural gas for your location is 1000 BTU/FT3. The gas input of the RC98i is 199,000 BTU/HR. Additional appliances at the location require 65,000 BTU/hr. Therefore the cubic feet per hour = (199,000 + 65,000) / 1000 = 264 FT3/HR. If the pipe length is 10 feet then the 3/4 inch pipe size is capable of supplying 264 FT3/HR of natural gas.
Length |
| Pipe Size (inches) |
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3/4 | 1 | 1 1/4 | 1 1/2 | ||
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10 | 273 | 514 | 1060 | 1580 | |
20 | 188 | 353 | 726 | 1090 | |
30 | 151 | 284 | 583 | 873 | |
40 | 129 | 243 | 499 | 747 | |
50 | 114 | 215 | 442 | 662 | |
60 | 104 | 195 | 400 | 600 | |
70 | 95 | 179 | 368 | 552 | |
80 | 89 | 167 | 343 | 514 | |
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90 | 83 | 157 | 322 | 482 | |
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100 | 79 | 148 | 304 | 455 | |
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125 | 70 | 131 | 269 | 403 | |
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150 | 63 | 119 | 244 | 366 | |
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175 | 58 | 109 | 224 | 336 | |
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200 | 54 | 102 | 209 | 313 | |
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Length |
| Pipe Size (inches) |
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1/2 | 3/4 | 1 | 1 1/4 | ||
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10 | 291 | 608 | 1150 | 2350 | |
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20 | 200 | 418 | 787 | 1620 | |
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30 | 160 | 336 | 632 | 1300 | |
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40 | 137 | 287 | 541 | 1110 | |
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50 | 122 | 255 | 480 | 985 | |
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60 | 110 | 231 | 434 | 892 | |
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80 | 101 | 212 | 400 | 821 | |
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100 | 94 | 197 | 372 | 763 | |
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125 | 89 | 185 | 349 | 716 | |
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150 | 84 | 175 | 330 | 677 | |
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175 | 74 | 155 | 292 | 600 | |
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200 | 67 | 140 | 265 | 543 | |
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Manual - Rinnai Condensing Water Heaters | 19 |
