18
UGT Series Manual
Size the gas pipe
The gas supply must be capable of handling the entire
gas load at the location. Gas line sizing is based on
gas type, the pressure drop in the system, the gas
pressure supplied, and gas line type. For gas pipe siz-
ing in the United States, refer to the
National Fuel Gas
Code, NFPA 54
. The below information is provided as
an example. The appropriate table from the applica-
ble code must be used.
1. For some tables, you will need to determine the
cubic feet per hour of gas required by dividing the
gas input by the heating value of the gas
(available from the local gas company). The gas
input needs to include all gas products at the lo-
cation and the maximum BTU usage at full load
when all gas products are in use.
2. Use the table for your gas type and pipe type to
find the pipe size required. The pipe size must be
able to provide the required cubic feet per hour
of gas or the required BTU/hour.
Example:
The heating value of natural gas for your location is
1000 BTU/FT
3
. The gas input of the UGT-199N is
199,000 BTU/HR. Additional appliances at the loca-
tion require 65,000 BTU/hr. Therefore the cubic feet
per hour = (199,000 + 65,000) / 1000 = 264 FT
3
/HR. If
the pipe length is 10 feet then the 3/4 inch pipe size is
capable of supplying 264 FT
3
/HR of natural gas.
Gas Input of all gas products (BTU / HR)
Heating Value of Gas (BTU / FT
3
)
Cubic Feet
per Hour =
(CFH)
Any compound used on the threaded joint of the
gas piping shall be a type which resists the action
of liquefied petroleum gas (propane / LPG).
The gas supply line shall be gas tight, sized, and so
installed as to provide a supply of gas sufficient to
meet the maximum demand of the heater and all
other gas consuming appliances at the location
without loss of pressure.
INFORMATION
Refer to an approved pipe sizing chart if in doubt
about the size of the gas line.
Length
Pipe Size (inches)
3/4
1
1 1/4
1 1/2
10
273
514
1060
1580
20
188
353
726
1090
30
151
284
583
873
40
129
243
499
747
50
114
215
442
662
60
104
195
400
600
70
95
179
368
552
80
89
167
343
514
90
83
157
322
482
100
79
148
304
455
Pipe Sizing Table - Natural Gas
Inlet Pressure: less than 2 psi (55 inches W.C.)
Pressure Drop: 0.3 inches W.C.
Specific Gravity: 0.60
Schedule 40 Metallic Pipe
cubic feet per hour
Length
Pipe Size (inches)
1/2
3/4
1
1 1/4
10
291
608
1150
2350
20
200
418
787
1620
30
160
336
632
1300
40
137
287
541
1110
50
122
255
480
985
60
110
231
434
892
80
101
212
400
821
100
94
197
372
763
Pipe Sizing Table - Propane Gas
Inlet Pressure: 11.0 inches W.C.
Pressure Drop: 0.5 inches W.C.
Specific Gravity: 1.50
Schedule 40 Metallic Pipe
Capacity in Thousands of BTU per Hour
