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7
Gas Piping
!
WARNING
Explosion Hazard.
Failure to properly pipe gas supply to boiler may
result in improper operation and damage to the
boiler or structure. Always assure gas piping is
absolutely leak free and of the proper size and
type for the connected load.
An additional gas pressure regulator may be
needed. Consult gas supplier.
NOTICE: Size corrugated stainless steel tubing
(CSST) to ensure proper capacity and minimize
flow restrictions.
A. Size gas piping. Design system to
provide adequate gas supply to boiler.
Consider these factors:
1. Allowable pressure drop from point of delivery
to boiler. Maximum allowable system pressure
is ½ psig (3.4 kPa). Actual point of delivery
Table 7-1: Maximum Capacity of Schedule 40 Black Pipe in CFH* (Natural Gas) For Gas Pressures of 1/2 psi
(3.4 kPa) or Less
Inlet Pressure 14.0 in wc (3.4 kPa)or less; 0.3 in wc (0.07 kPa) Pressure Drop
Nominal
Inside
Pipe Size, In.
Diameter, In.
½
0.622
¾
0.824
1
1.049
1¼
1.380
1½
1.610
2
2.067
2½
2.469
3
3.068
Inlet Pressure 14.0 in wc (3.4 kPa)or less; 0.5 in wc (0.12 kPa) Pressure Drop
Nominal
Inside
Pipe Size, In.
Diameter, In.
½
0.622
¾
0.824
1
1.049
1¼
1.380
1½
1.610
2
2.067
2½
2.469
3
3.068
* 1 CFH of Natural Gas is approximately equal to 1 MBH; contact your gas supplier for the actual heating value of your gas.
106308-05 - 3/23
10
20
30
131
90
72
273
188
151
514
353
284
1060
726
583
1580
1090
873
3050
2090
1680
4860
3340
2680
8580
5900
4740
10
20
30
172
118
95
360
247
199
678
466
374
1390
957
768
2090
1430
1150
4020
2760
2220
6400
4400
3530
11300
7780
6250
APEX
Installation, Operating, & Service Instructions
pressure may be less; contact gas supplier for
additional information. Minimum gas valve inlet
pressure is printed on the rating label located
in the boiler's vestibule compartment.
2. Maximum gas demand. Refer to the boiler's
input as printed on its rating label. Also
consider existing and expected future gas
utilization equipment (i.e. water heater, cooking
equipment).
3. Length of piping and number of fittings. Refer
to Tables 7-1 (natural gas) or 30 (LP gas) for
maximum capacity of Schedule 40 pipe. Table
7-3 lists equivalent pipe length for standard
fittings.
4. Specific gravity of gas. Gas piping systems for
gas with a specific gravity of 0.60 can be sized
directly from Table 7-1 and gas with a specific
gravity of 1.5 can be sized from Table 7-2,
unless authority having jurisdiction specifies
a gravity factor be applied. For other specific
gravity, apply gravity factor from Table 7-4. If
exact specific gravity is not shown choose next
higher value.
Length of Pipe, Ft.
40
50
60
62
55
50
129
114
104
243
215
195
499
442
400
747
662
600
1440
1280
1160
2290
2030
1840
4050
3590
3260
Length of Pipe, ft.
40
50
60
81
72
65
170
151
137
320
284
257
657
583
528
985
873
791
1900
1680
1520
3020
2680
2430
5350
4740
4290
70
80
90
46
42
40
95
89
83
179
167
157
368
343
322
552
514
482
1060
989
928
1690
1580
1480
3000
2790
2610
70
80
90
60
56
52
126
117
110
237
220
207
486
452
424
728
677
635
1400
1300
1220
2230
2080
1950
3950
3674
3450
100
38
79
148
304
455
877
1400
2470
100
50
104
195
400
600
1160
1840
3260
53
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