Form I-X, P/N 150491 R7, Page 8
All piping must be in accordance with requirements outlined in the National Fuel Gas
Code ANSI/Z223.1a (latest edition) or CAN/CGA-B149.1 and B149.2 (See Paragraph
1.4). Gas supply piping installation should conform with good practice and with local
codes.
Duct furnaces for natural gas are oriced for operation with gas having a heating value
of 1000 (±50) BTU per cubic ft. If the gas at the installation does not meet this specica-
tion, consult the factory for proper oricing.
Pipe joint compounds (pipe dope) shall be resistant to the action of liqueed
petroleum gas or any other chemical constituents of the gas being supplied.
Install a ground joint union and manual shutoff valve upstream of the unit control sys-
tem, as shown in FIGURE 8. The 1/8" plugged tapping in the shutoff valve provides
connection for supply line pressure test gauge. The National Fuel Gas Code requires
the installation of a trap with a minimum 3" (76mm) drip leg. Local codes may require a
minimum drip leg longer than 3" (76mm) -- typically 6" (152mm).
Gas connection sizes are listed in FIGURE 8. After all connections are made, discon-
nect the pilot supply at the control valve and bleed the system of air. Reconnect the
pilot line and leak-test all connections by brushing on a soap solution.
FIGURE 8 - Supply Piping Connection
FIGURE 9 - Gas and Electric Connections
Gas Connection to
Single-Stage Valve
(Not Gas Supply Line Size)
Unit Size 75-250 300-400
Natural Gas 1/2" 3/4"
Propane 1/2" 1/2"
Sizing a Gas Supply
Lines
Capacity of Piping
Cubic Feet per Hour based on 0.3" w.c. Pressure Drop
Specic Gravity for Natural Gas -- 0.6 (Natural Gas -- 1000 BTU/Cubic Ft)
Specic Gravity for Propane Gas -- 1.6 (Propane Gas -- 2550 BTU/Cubic Ft)
Length Diameter of Pipe
of 1/2" 3/4" 1" 1-1/4" 1-1/2" 2"
Pipe Natural Propane Natural Propane Natural Propane Natural Propane Natural Propane Natural Propane
20' 92 56 190 116 350 214 730 445 1100 671 2100 1281
30' 73 45 152 93 285 174 590 360 890 543 1650 1007
40' 63 38 130 79 245 149 500 305 760 464 1450 885
50' 56 34 115 70 215 131 440 268 670 409 1270 775
60' 50 31 105 64 195 119 400 244 610 372 1105 674
70' 46 28 96 59 180 110 370 226 560 342 1050 641
80' 43 26 90 55 170 104 350 214 530 323 990 604
90' 40 24 84 51 160 98 320 195 490 299 930 567
100' 38 23 79 48 150 92 305 186 460 281 870 531
125' 34 21 72 44 130 79 275 168 410 250 780 476
150' 31 19 64 39 120 73 250 153 380 232 710 433
175' 28 17 59 36 110 67 225 137 350 214 650 397
200' 26 16 55 34 100 61 210 128 320 195 610 372
Note: When sizing supply lines, consider possibilities of future expansion and increased requirements.
Refer to National Fuel Gas Code for additional information on line sizing.
6.0 Mechanical
(cont'd)
6.1 Gas Piping
and Pressures
(cont'd)
WARNING: All components of a gas supply system must be leak tested prior to
placing equipment in service. NEVER TEST FOR LEAKS WITH AN OPEN FLAME.
Failure to comply could result in personal injury, property damage or death.
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