KBD Series Manual 43
Size the gas pipe
The gas supply must be capable of handling the enre
gas load required at the locaon. 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 Naonal
Fuel Gas Code, NFPA 54. The below informaon 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 heang value of the gas
(available from the local gas company). The gas
input needs to include all gas products at the lo-
caon and the maximum BTU usage at full load
when all gas products are in use.
2. Use the table for your gas type and pipe type to
nd 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 heang value of natural gas for your locaon is
1000 BTU/FT
3
. The gas input of the RUC98i is 199,000
BTU/HR. Addional appliances at the locaon require
65,000 BTU/hr. Therefore the cubic feet per hour =
(199,000 + 65,000) / 1000 = 264 FT
3
/HR. If the pipe
length is 10 feet then the 3/4 inch pipe size is capable
of supplying 264 FT
3
/HR of natural gas.
Gas Input of all gas products (BTU / HR)
Heang Value of Gas (BTU / FT
3
)
Cubic Feet
per Hour =
(CFH)
Any compound used on the threaded joint of the
gas piping shall be a type that resists the acon of
liqueed petroleum gas (propane / LPG).
The gas supply line shall be gas ght, sized, and so
installed as to provide a supply of gas sucient to
meet the maximum demand of the heater and all
other gas consuming appliances at the locaon
without loss of pressure.
If in doubt about the size of the gas line, refer to an
approved pipe sizing chart
273 514 1060 1580
188 353 726 1090
151 284 583 873
129 243 499 747
114 215 442 662
104 195 400 600
95 179 368 552
89 167 343 514
83 157 322 482
79 148 304 455
-
Inlet Pressure: less than 2 psi (55 inches W.C.)
Pressure Drop: 0.3 inches W.C.
Specic Gravity: 0.60
Schedule 40 Metallic Pipe
cubic feet per hour
291 608 1150 2350
200 418 787 1620
160 336 632 1300
137 287 541 1110
122 255 480 985
110 231 434 892
101 212 400 821
94 197 372 763
-
Inlet Pressure: 11.0 inches W.C.
Pressure Drop: 0.5 inches W.C.
Specic Gravity: 1.50
Schedule 40 Metallic Pipe
Capacity in Thousands of BTU per Hour
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