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(a)
Table 4.
Gas pipe size
Nominal
Internal
10
Iron Pipe
Diameter,
Size, in.
in. (mm)
(3.0)
1/2
0.622
175
(16)
(4.96)
3/4
0.824
360
(21)
(10.2)
1
1.049
680
(27)
(19.3)
1-1/4
1.380
1400
(35)
(39.6)
1-1/2
1.610
2100
(41)
(59.5)
2
2.067
3950
(53)
(112)
2-1/2
2.469
6300
(63)
(178)
3
3.068
11000
(78)
(311)
4
4.026
23000
(102)
(651)
Notes:
3
1. Determine the required ft
/h by dividing the rated heater input by 1000. For SI / Metric measurements: Convert unit Btu/h to kilowatts. Multiply the
unit input (kW) by 0.0965 to determine m
2. FOR NATURAL GAS: Select the pipe size directly from the table.
3. FOR PROPANE GAS: Multiply the ft
4. Refer to the metric conversion factors listed in
(a) Maximum capacity of pipe in cubic feet of gas per hour (cubic meters per hour) for gas pressures of 0.5 psig (3.5 kPa) or less, and a pressure drop of
0.5 inch water column (124.4 Pa) (based on a 0.60 specific gravity gas).
Pipe Installation
1. Install the gas piping in accordance with applicable
local codes.
2. Check gas supply pressure. Each duct furnace must be
connected to a gas supply capable of supplying its full
rated capacity as specified in
tank regulator must be used to limit the supply
pressure to maximum of 14 in. wc (3.5 kPa). All piping
should be sized in accordance with the latest edition of
ANSI Standard Z223.1 National Fuel Gas Code; in
Canada, according to CGA-B149. See
p. 10Table 4, p.
17, and
piping size.
If gas pressure is excessive on natural gas applications,
install a pressure regulating valve in the line upstream
from the main shutoff valve.
GMND-SVX01B-EN
20
30
40
(6.1)
(9.1) (12.2) (15.2) (18.3) (21.3) (24.4) (27.4) (30.5) (38.1) (45.7) (53.3) (61.0)
120
97
82
73
(3.40)
(2.75)
(2.32) (2.07) (1.87) (1.73) (1.61) (1.50) (1.42)
250
200
170
151
(7.08)
(5.66)
(4.81) (4.28) (3.91) (3.54) (3.34) (3.11) (2.92)
465
375
320
285
(13.2)
(10.6)
(9.06) (8.07) (7.36) (6.80) (6.23) (5.80) (5.52)
950
770
660
580
(26.9)
(21.8)
(18.7) (16.4) (15.0) (13.9) (13.0) (12.2) (11.3)
1460
1180
990
900
(41.3)
(33.4)
(28.0) (25.5) (22.9) (21.2) (19.5) (18.4) (17.6)
2750
2200
1900
1680
(77.9)
(62.3)
(53.8) (47.6) (43.0) (39.6) (36.8) (34.5) (32.6)
4350
3520
3000
2650
(123)
(99.7)
(85.0) (75.0) (68.0) (63.7) (58.0) (55.2) (52.4)
7700
6250
5300
4750
(218)
(177)
(150)
(135)
15800
12800
10900 9700
(447)
(362)
(309)
(275)
3
/h.
3
3
/h (m
/h) value by 0.633; then use the table.
"General Safety Information," p. 7
Table 5, p.
18. A field LP
Table 1,
Table 5, p. 18
for correct gas
Length of Pipe, ft (m)
50
60
70
80
66
61
57
138
125
118
260
240
220
530
490
460
810
750
690
1520
1400
1300
2400
2250
2050
4300
3900
3700
(122)
(110)
(105)
8800
8100
7500
(249)
(229)
(212)
for more SI unit measurements/conversions.
Hazard of Explosion!
Adequately support the piping to prevent strain on the
gas manifold and controls. To prevent explosion, fire, or
gas leaks, support piping so that piping does not sag or
put pressure on the burners internal to the unit. Failure
to follow these recommendations could result in death
or serious injury or equipment or property-only-
damage.
3. To prevent the mixing of moisture with gas, run the
take-off piping from the top, or side, of the main.
4. Duct furnaces are shipped with a combination valve
which includes:
a. Manual "A" valve
b. Manual "B" valve
c. Solenoid valve
d. Pilot safety
e. Pressure regulator
Installation: Piping
90
100
125
150
53
50
44
40
(1.25)
(1.13)
110
103
93
84
(2.63)
(2.38)
205
195
175
160
(4.96)
(4.53)
430
400
360
325
(10.2)
(9.20)
650
620
550
500
(15.6)
(14.2)
1220
1150
1020
950
(28.9)
(26.9)
1950
1850
1650
1500
(46.7)
(42.5)
3450
3250
2950
2650
(97.7) (92.0)
(83.5)
(75.0)
7200
6700
6000
5500
(204)
(190)
(170)
(156)
WARNING
175
200
37
35
(1.05)
(0.99)
77
72
(2.18)
(2.04)
145
135
(4.11)
(3.82)
300
280
(8.50)
(7.93)
460
430
(13.0)
(12.2)
850
800
(24.1)
(22.7)
1370
1280
(38.8)
(36.2)
2450
2280
(69.4)
(64.6)
5000
4600
(142)
(130)
17
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