TM 5-3895-374-24-2
GAS SUPPLY PIPING
Gas piping should be sized to provide required pressure
at the burner train inlet manual shutoff cock, when
operating at the maximum desired fuel input.
All gas piping should be appropriately pressure tested to
ensure leak free operation. It is recommended that a dirt
pocket or trap be piped into the gas supply system just
ahead of the burner train inlet manual shutoff cock.
When testing with pressures higher than the maximum
pressure ratings of the gas train components, be sure to
isolate these components and test their piping for gas
maximum main gas train and/or pilot gas train components
pressure is 1/2 psig. (14" W.C.).
Refer to Table 3 for information relating to the sizing of gas
supply piping. These charts are based on the general flow
characteristics of commercially produced black wrought iron
pipe. If in doubt regarding flow capabilities of a chosen line
size, the next largest size is recommended.
Refer to page 9, Figs. 8 and 9 for typical gas piping
schematics to meet U.L. requirements in the C burner firing
ranges.
Table 3
Capacity of Pipe · Natural Gas (CFH)
With Pressure Drop of 0.3" w.c. and Specific Gravity of 0.60
Pipe Length
Pipe Size - Inches (IPS)
In Feet
1
1¼
1½
2
2½
3
4
10
520
1050
1600
3050
4800
8500
17500
20
350
730
1100
2100
3300
5900
12000
30
285
590
890
1650
2700
4700
9700
40
245
500
760
1450
2300
4100
8300
50
215
440
670
1270
2000
3600
7400
60
195
400
610
1150
1850
3250
6800
70
180
370
560
1050
1700
3000
6200
80
170
350
530
990
1600
2800
5800
90
160
320
490
930
1500
2600
5400
100
150
305
460
870
1400
2500
5100
125
130
275
410
780
1250
2200
4500
150
120
250
380
710
1130
2000
4100
175
110
225
350
650
1050
1850
3800
200
100
210
320
610
980
1700
3500
Table 3A
Correction Factors
Specific Gravity
Pressure Drop
Other Than 0.60
Other Than 0.3
Specific
Multiplier
Pressure
Multiplier
Gravity
Drop
0.50
1.10
0.1
0.577
0.60
1.00
0.2
0.815
0.70
0.926
0.3
1.00
0.80
0.867
0.4
1.16
0.90
0.817
0.6
1.42
1.00
0.775
0.8
1.64
Propane
-
Air
1.0
1.83
1.10
0.740
2.0
2.58
Propane
3.0
3.16
1.55
0.622
4.0
3.65
Butane
6.0
4.47
2.00
0.547
8.0
5.15
Note: Use multiplier at right for other specific gravities and pressure drops.
Table 4
Equivalent Length of Fittings in Feet
Pipe Size (IPS)
1
1.25
1.5
2
2.5
3
4
Std. Tee through Side
5.5
7.5
9.0
12.0
14.0
17.0
22.0
Std. E11
2.7
3.7
4.3
5.5
6.5
8.0
12.0
45 E11
1.2
1.6
2.0
2.5
3.0
3.7
5.0
Plug Cock
3.0
4.0
5.5
7.5
9.0
12.0
16.0
Table 5
Gas Train Components Supplied for Standard U.L. Burner Requirements
See Gas Flow Schematics Fig. 8 and 9 for additional information.
Fuel Air Control Modes of Operation
On/Off
Low/High/Off
Low/High/Low
Modulating
Main Gas Cock
XU
XU
XU
XU
Main Gas Pressure Regulator
XU*
XU
XU
XU
High and Low Gas Pressure Switches
OU
X1U
X1U
X1U
Automatic Main Gas Valve
XU*
X
X
XU
Automatic Main Gas Valve with Proof of Closure
O
X1
X1
X1
Main Auxiliary Gas Valve
O
X2
X2
X2
Leak Test Gas Cock
XU
X
X
XU
Pilot Cock Pressure Regulator & Solenoid Valve
X
X
X
X
Modulating Butterfly Valve
N/A
N/A
N/A
X
Side Tee Orifice Assembly
X
X
X
N/A
Main and/or Pilot Gas Pressure Gauge
O
O
O
O
(page 3 - 960)
