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Vii. gas Piping
Warning
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.
Size corrugated stainless steel tubing (CSST)
to ensure proper capacity and minimize flow
restrictions.
Use two wrenches when tightening gas
piping at boiler, using one wrench to
prevent the boiler gas valve from turning.
Failure to support the boiler gas valve to
prevent it from turning could damage gas
valve components.
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. Actual point of delivery pressure may be less;
inlet Pressure 0.5 PSi or less; 0.3 inch W.C. Pressure Drop
nominal Pipe
Size, in.
inside
Diameter, in.
Length of Pipe, Ft.
10
20
30
40
50
60
70
80
90
100
½
0.622
131
90
72
62
55
50
46
42
40
38
¾
0.824
273
188
151
129
114
104
95
89
83
79
1
1.049
514
353
284
243
215
195
179
167
157
148
1¼
1.380
1056
726
583
499
442
400
368
343
322
304
1½
1.610
1582
1087
873
747
662
600
552
514
482
455
2
2.067
3046
2094
1681
1439
1275
1156
1063
989
928
877
2½
2.469
4856
3337
2680
2294
2033
1842
1695
1576
1479
1397
3
3.068
8584
5900
4738
4055
3594
3256
2996
2787
2615
2470
Table 21a: Maximum Capacity of Schedule 40 Black Pipe in CFH* (natural gas) For gas Pressures
of 0.5 psig or Less
inlet Pressure 0.5 PSi or less; 0.5 inch W.C. Pressure Drop
nominal Pipe
Size, in.
inside
Diameter, in.
Length of Pipe, Ft.
10
20
30
40
50
60
70
80
90
100
½
0.622
172
118
95
81
72
65
60
56
52
50
¾
0.824
360
247
199
170
151
137
126
117
110
104
1
1.049
678
466
374
320
284
257
237
220
207
195
1¼
1.380
1392
957
768
657
583
528
486
452
424
400
1½
1.610
2085
1433
1151
985
873
791
728
677
635
600
2
2.067
4016
2760
2217
1897
1681
1523
1402
1304
1223
1156
2½
2.469
6401
4400
3533
3024
2680
2428
2234
2078
1950
1842
3
3.068
11316
7778
6246
5345
4738
4293
3949
3674
3447
3256
* 1 CFH of Natural Gas is approximately equal to 1 MBH; contact your gas supplier for the actual heating value of your
gas.
contact gas supplier for additional information.
Minimum gas valve inlet pressure is stamped 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 21A (natural gas) or 21B (LP gas) for
maximum capacity of Schedule 40 pipe. Table 22
lists equivalent pipe length for standard fittings.
4. Specific gravity of gas. Gas piping systems for gas
with a specific gravity of 0.60 or less can be sized
directly from Tables 21A or 21B, unless authority
having jurisdiction specifies a gravity factor be
applied. For specific gravity greater than 0.60,
apply gravity factor from Table 23. If exact specific
gravity is not shown choose next higher value.
For materials or conditions other than those listed
above, refer to
National Fuel Gas Code
, NFPA54/
ANSI Z223.1, and/or CAN/CSA B149.1
Natural Gas
and Propane Installation Code
. or size system using
standard engineering methods acceptable to authority
having jurisdiction.
Содержание ALP080B
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