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Designs, materials, weights and performance ratings are approximate and subject to change without notice. Visit
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9
Table 9-2. Specific Gravity Conversion Factors
Natural Gas
Propane Gas
Specific Gravity
Factor
Specific Gravity
Factor
0.55
1.04
1.50
0.633
0.60
1.00
1.53
0.626
0.65
0.962
1.60
0.612
Table 9-1. Gas Pipe Capacities
Length
of Pipe
(Feet)
Gas Flow in Piping (Cu. Ft. per Hour)
Iron Pipe Size (NPT) Inches
1/2
3/4
1
1-1/4
1-1/2
10
132
278
520
1050
1600
20
92
190
350
730
1100
30
73
152
285
590
890
40
63
130
245
500
760
50
56
115
215
440
670
60
50
105
195
400
610
70
46
96
180
370
560
80
43
90
170
350
530
90
40
84
160
320
490
100
38
79
150
305
460
Plugged 1/8" NPT
Test Gauge Conn.
Gas Cock
Gas Supply Line
Note:
All piping and fittings
external to humidifier
supplied by others.
Drip Pocket
3" Min.
Ground Joint
Union
Humidifier Cabinet
Gas Cock
Supplied by
Armstrong International, Inc.
Figure 9-1
Allow at least 5 feet of piping between any high pressure regulator and unit pipe connection.
The physical location of the manual main shut-off valve external to the jacket when local codes require the
installation of such a valve.
Gas Leak Testing
When leak testing the gas supply piping system, the humidifier and its gas shut-off valve must be
disconnected during any pressure testing in excess of 14” WC (1/2 psi). The humidifier must
be isolated from the gas supply piping system by closing the field-installed manual shut-off valve
during any pressure testing equal to or less than 14” WC (1/2 psi).
Verify the gas supply pressure upstream of gas control unit is 7” WC on natural gas, or 11” WC on
LP Gas. Purging of gas should be performed as described in ANSI Z223.1 (latest edition) or, in
Canada, CAN/CGA-B149 codes.
Minimum Supply Pressure: 5” WC for Natural Gas and 10” WC for LP.
