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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. Refer to the National Fuel
Gas Code, NFPA 54, for proper gas line sizing. The below information is provided as an example.
1. Determine the cubic feet per hour of gas required by dividing the gas input (on the rating plate) 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.
Cubic Feet per Hour (CFH) =
2. Use the table for your gas type to find the pipe size required for your cubic feet per hour of gas and your pipe
length.
Example: The heating value of propane gas for your location is 2516 BTU / FT
The gas input is 190,000 BTU/HR. Additional appliances at the location require 75,000 BTU/HR.
Therefore the cubic feet per hour = (190,000+75,000) / 2516 = 105.3 FT
If the pipe length is 100 ft then the 3/4 inch pipe size capable of supplying 197 FT
will be adequate.
Pipe Sizing Table - Natural Gas
cubic feet per hour
Inlet Pressure:
less than 2 psi (55 inches W.C.)
Pressure Drop: 0.3 inches W.C.
Specific Gravity: 0.60
Length
3/4
10
273
188
20
30
151
40
129
50
114
60
104
70
95
80
89
90
83
100
79
70
125
150
63
175
58
200
54
16
Gas Input of the water heater (BTU / HR)
Schedule 40 Metallic Pipe
Pipe Size (inches)
1
1 1/4
514
1060
353
726
284
583
243
499
215
442
195
400
179
368
167
343
157
322
148
304
131
269
119
244
109
224
102
209
305, 505, 705 Indoor Manual
Heating Value of Gas (BTU / FT
Pipe Sizing Table - Propane Gas
cubic feet per hour
Inlet Pressure:
Pressure Drop: 0.5 inches W.C.
Specific Gravity: 1.50
Length
1 1/2
1580
10
1090
20
873
30
747
40
662
50
600
60
552
80
514
100
482
125
455
150
403
175
366
200
336
313
3
)
3
.
3
/ HR.
3
/ HR of propane gas
Schedule 40 Metallic Pipe
11.0 inches W.C.
Pipe Size (inches)
1/2
3/4
291
608
1150
200
418
787
160
336
632
137
287
541
122
255
480
110
231
434
101
212
400
94
197
372
89
185
349
84
175
330
74
155
292
67
140
265
1
1 1/4
2350
1620
1300
1110
985
892
821
763
716
677
600
543
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