Kenmore 505 User Manual
Page 12
Attention! The text in this document has been recognized automatically. To view the original document, you can use the "Original mode".
![background image](/manuals/666183/12/background.png)
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,
NFPA54, 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.
Gas Input of the water heater (BTU / HR)
Cubic Feet per Hour (CFH) =
----------------------------------------------------------
Heating Value of Gas (BTU / FT 3 )
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 natural gas for your location is 1020 BTU/FP
The gas input is 199,000 BTU/HR. Additional appliances at the location require 75,000 BTU/HR.
Therefore the cubic feet per hour = (199,000 + 75,000) / 1020 = 268.6 FP/HR.
If the pipe length is 100 ft then the 1 % inch pipe size capable of supplying 304 FP/HR of natural gas will
be adequate.
TABLE 2: Pipe Sizing Table - Natural Gas
cubic feet per hour Schedule 40 Metallic Pipe
Inlet Pressure: less than 2 psi (55 inches W.C.)
Pressure Drop: 0.3 inches W.C.
Specific Gravity: 0.60
Length
Pipe Size (inches)
3/4
1
1 1/4
1 1/2
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
90
83
157
322
482
100
79
148
304
455
125
70
131
269
403
150
63
119
244
366
175
58
109
224
336
200
54
102
209
313
TABLE 3: Pipe Sizing Table - Propane Gas
cubic feet per hour Schedule 40 Metallic Pipe
Inlet Pressure: 11 inches W.C.
Pressure Drop: 0.5 inches W.C.
Specific Gravity: 1.50
Length
Pipe Size (inches)
1/2
3/4
1
1 1/4
10
291
608
1150
2350
20
200
418
787
1620
30
160
336
632
1300
40
137
287
541
1110
50
122
255
480
985
60
110
231
434
892
80
101
212
400
821
100
94
197
372
763
125
89
185
349
716
150
84
175
330
677
175
74
155
292
600
200
67
140
265
543
12
305 & 505 Indoor Manual