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MACH® Gas-Fired Boiler
Page 24
Install a sediment trap (drip leg) and a union connection upstream of the primary manual shutoff valve on the boiler.
Gas piping should be installed in accordance with National Fuel Gas Code, ANSI Z223.1, latest edition, and any other
local codes which may apply. In Canada, please refer to CSA-B.149. In the Commonwealth of Massachusetts, the
gas cock must be a “T-handle type.”
See Pipe Capacity for Natural Gas chart (below) for required pipe size, based on overall length of pipe from meter
plus equivalent length of all fittings. Approximate sizing may be based on 1 cubic foot of natural gas per 1,000 Btu per
hour input, i.e., 1,500,000 Btu per hour requires about 1,500 cubic feet per hour. (See "Typical Boiler Operating
Conditions," Section 4.3, for more information.)
Pipe Capacity for Natural Gas
Nominal
Iron Pipe
Size
(Inches)
Internal
Diameter
(Inches)
Equivalent Pipe Length
Maximum Capacity in Cubic Feet of Natural Gas per Hour
Pressure Drop of 0.5 inch Water Column/Equivalent Length of Pipe
(in feet)
90º Ell
(Feet)
Tee
(Feet)
20
40
60
80
100
150
200
1/2
0.622
1.55
3.1
120
82
66
57
50
40
35
3/4
0.824
2.06
4.12
250
170
138
118
103
84
72
1
1.049
2.62
5.24
465
320
260
220
195
160
135
1- 1/4
1.380
3.45
6.9
950
660
530
460
400
325
280
1- 1/2
1.610
4.02
8.04
1460
990
810
690
620
500
430
2
2.067
5.17
10.3
2750
1900
1520
1300
1150
950
800
2- 1/2
2.469
6.16
12.3
4350
3000
2400
2050
1850
1500
1280
3
3.068
7.67
15.3
7700
5300
4300
3700
3250
2650
2280
4
4.026
10.1
20.2
15800
10900
8800
7500
6700
5500
4600
3.6.1 Gas Supply Piping by Installer
The boiler and all gas piping connections should be pressure-tested and must be checked for leaks before being
placed into service. Test with compressed air or inert gas if possible.
The boiler must be
disconnected
at the boiler manual shut-off valve (located at the end of the supplied gas train)
from the gas supply piping system during any pressure testing of the system at pressures in excess of 1/2 psig (14"
W.C.).
Boiler Main Gas
Valve
Gas
Supply
Union
Drip Leg
Remote Gas
Shutoff
Meter
Field Gas Piping