Table 3.
Gas pipe size
Nomin
al Iron
Pipe
Size
Inch
Inch
Intern
al
Diame
ter
Inch
Length of Pipe, Feet (meters)
10
(3.0)
20
(6.1)
30
(9.1)
40
(12.2)
50
(15.2)
60
(18.3)
70
(21.3)
80
(24.4)
90
(27.4)
100
(30.5)
125
(38.1)
150
(45.7)
175
(53.3)
200
(61.0)
1/2
0.622
175
(4.96)
120
(3.40)
97
(2.75)
82
(2.32)
73
(2.07)
66
(1.87)
61
(1.73)
57
(1.61)
53
(1.50)
50
(1.42)
44
(1.25)
40
(1.13)
37
(1.05)
35
(0.99)
3/4
0.824
360
(10.2)
250
(7.08)
200
(5.66)
170
(4.81)
151
(4.28)
138
(3.91)
125
(3.54)
118
(3.34)
110
(3.11)
103
(2.92)
93
(2.63)
84
(2.38)
77
(2.18)
72
(2.04)
1
1.049
680
(19.3)
465
(13.2)
375
(10.6)
320
(9.06)
285
(8.07)
260
(7.36)
240
(6.80)
220
(6.23)
205
(5.80)
195
(5.52)
175
(4.96)
160
(4.53)
145
(4.11)
135
(3.82)
1 1/4
1.380
1400
(39.6)
950
(26.9)
770
(21.8)
660
(18.7)
580
(16.4)
530
(15.0)
490
(13.9)
460
(13.0)
430
(12.2)
400
(11.3)
360
(10.2)
325
(9.20)
300
(8.50)
280
(7.93)
1 1/2
1.610
2100
(59.5)
1460
(41.3)
1180
(33.4)
990
(28.0)
900
(25.5)
810
(22.9)
750
(21.2)
690
(19.5)
650
(18.4)
620
(17.6)
550
(15.6)
500
(14.2)
460
(13.0)
430
(12.2)
2
2.067
3950
(112)
2750
(77.9)
2200
(62.3)
1900
(53.8)
1680
(47.6)
1520
(43.0)
1400
(39.6)
1300
(36.8)
1220
(34.5)
1150
(32.6)
1020
(28.9)
950
(26.9)
850
(24.1)
800
(22.7)
2 1/2
2.469
6300
(178)
4350
(123)
3520
(99.7)
3000
(85.0)
2650
(75.0)
2400
(68.0)
2250
(63.7)
2050
(58.0)
1950
(55.2)
1850
(52.4)
1650
(46.7)
1500
(42.5)
1370
(38.8)
1280
(36.2)
3
3.068
11000
(311)
7700
(218)
6250
(177)
5300
(150)
4750
(135)
4300
(122)
3900
(110)
3700
(105)
3450
(97.7)
3250
(92.0)
2950
(83.5)
2650
(75.0)
2450
(69.4)
2280
(64.6)
4
4.026
23000
(651)
15800
(447)
12800
(362)
10900
(309)
9700
(275)
8800
(249)
8100
(229)
7500
(212)
7200
(204)
6700
(190)
6000
(170)
5500
(156)
5000
(142)
4600
(130)
Installation
14
GKNE-SVX001B-EN
1. 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) Determine the required Cu. Ft./Hr. by dividing the input by 1000. For SI/Metric measurements: Convert
BTU/Hr. to kilowatts. Multiply the units inputs (kW) by 0.0965 to determine Cu. Meters./Hr.
2. For NATURAL GAS: Select pipe size directly from the table.
3. For PROPANE GAS: Multiply the Cu. Ft./Hr. value by 0.633; then, use the table.
4. Refer to the metric conversion factors listed in the General Safety section for SI Unit measurement conversions.
Pipe Installation
1. Install the gas piping in accordance with applicable
local codes.
2. Check gas supply pressure. Each unit heater must be
connected to a manifold pressure and a gas supply
capable of supplying its full rated capacity as specified
in Table 4. A field LP tank regulator must be used to
limit the supply pressure to a maximum of 14 inches
W.C. (3.5 kPa). All piping should be sized in accordance
with the latest edition of ANSI Standard Z223.1 (NFPA
54), National Fuel Gas Code; in Canada, according to
CSA B149. See
and
for correct gas
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.
3. Adequately support the piping to prevent strain on the
gas manifold and controls.
4. To prevent the mixing of moisture with gas, run the
takeoff piping from the top, or side, of the main.
5. Standard Unit Heaters, optional two-stage units are
supplied with a combination valve which includes:
a. Manual "A" valve
b. Manual "B" valve
c. Solenoid valve
d. Pressure regulator Pipe directly into the
6. Gas valve has a pressure test post requiring a 3/32 inch
hex head wrench to read gas supply and manifold
pressures. Open 1/4 turn counterclockwise to read,
turn clockwise to close and reseat. A 5/16 inch ID hose
fits the pressure post.
7. Provide a drip leg in the gas piping near the gas unit
heater. A ground joint union and a manual gas shutoff
valve should be installed ahead of the unit heater
controls to permit servicing. The manual shutoff valve
must be located external to the jacket (See
).
8. Make certain that all connections have been
adequately doped and tightened.
CAUTION
Do not over tighten the inlet gas piping into the valve.
This may cause stresses that will crack the valve!
NOTICE
Use pipe joint sealant resistant to the action of
liquefied petroleum gases regardless of gas conducted.
