Wayne P250 - Page 11

64659-001 REV. A 07/06/18
11
It is recommended that Table 2, Table 3, and Table 4be used to determine the size pipe to use from the
meter to the burner. The building structure should not be weakened by installation for the gas piping.
The piping should not be supported by the other piping, but should be firmly supported with pipe hooks,
straps, bands or hangers. Butt or lap welded pipe should not be bent. Note: Each elbow, union, and tee
adds approximately 2.5 feet of pipe.
The gas piping should be so installed as to prevent an accumulation of condensation and must be
protected against freezing. A horizontal pipe should be pitched so that it grades toward the meter and
is free from sags. The pipe should not be run through or in an air duct. The appliance and its individual
shutoff valve must be disconnected from the gas supply piping system during any pressure testing of the
system at test pressure over 1/2 psig (3500 PaG). The appliance must be isolated from the gas supply
piping system by closing its individual manual shutoff valve during any pressure testing of the gas supply
piping system at test pressures equal to or less than 1/2 psig (3500 PaG).
Pipe Sizing Chart for Natural Gas (0-0.5 psi) with Straight Schedule 40 Metal Pipe
This table is based on 0-0.5 psi inlet pressure, specific gravity of 0.6, and a pressure loss of 0.5” w.c..
Maximum Capacity of Pipe Size in Btu per Hour
Length of
Pipe (ft)
1/2”
3/4”
1”
1 1/4”
1 1/2”
10
175,000
360,000
680,000
1,400,000
2,100,000
20
120,000
250,000
465,000
950,000
1,460,000
30
97,000
200,000
375,000
770,000
1,180,000
40
82,000
170,000
320,000
660,000
990,000
50
73,000
151,000
285,000
580,000
900,000
60
66,000
138,000
260,000
530,000
810,000
70
61,000
125,000
240,000
490,000
750,000
80
57,000
118,000
220,000
460,000
690,000
90
53,000
110,000
205,000
430,000
650,000
100
50,000
103,000
195,000
400,000
620,000
150
40,000
84,000
160,000
325,000
500,000
200
35,000
72,000
135,000
280,000
430,000
Table 2 - Natural Gas Pipe Capacity
Pipe Size
Inch (mm)
Effective Length of
Thread
Inch (mm)
Overall Length
of Thread
Inch (mm)
3/8 (9.5)
3/8 (9.525)
9/16 (14.29)
1/2 (12.7)
1/2 (12.7)
3/4 (19.05)
3/4 (19.0)
1/2 – 9/16 (14.29)
13/16 (20.64)
1 (25.4)
9/16 (14.29)
1 (25.4)
Table 1 - Pipe Thread Length
Figure 5 - Proper Piping Practice
Leave 2 end
threads bare
2 imperfect
threads