Fuel Consumption
Estimated fuel supply requirements at half and full load for
natural gas and LP vapor fuels are shown below.
Natural Gas
1/2 Load
Full Load
84 C
162 C
84,000 B
162,000 B
C = Cubic feet per hour
B = BTU's per hour
Fuel Pipe Sizing
The tables below provide the maximum capacity of pipe in
cubic feet of gas per hour for gas pressures of 0.5 psi or
less and a pressure drop of 0.3 in. water column. Specific
gravity of gas is shown.
Listed values compensate for a nominal amount of
restriction from bends, fittings, etc. If an unusual number of
fittings, bends, or other restrictions are used, please refer to
federal and local codes.
NPT
10ft
15ft
3/4"
346
293
1"
653
549
Natural Gas Pipe Size - Gas Flow chart, in cubic feet per hour, specific gravity=0.65
NPT
10ft
15ft
3/4"
277
192
1"
428
360
Liquid Propane (LP) Gas Pipe Size - Gas Flow chart, in cubic feet per hour, specific gravity=1.50
Required Propane Tank Size
The required size of the propane tank at various
temperatures when kept at least half full is shown below
in the chart. Given the gas withdrawal rate and the lowest
average winter temperature, an installer can specify the
required LP storage tank size.
Withdrawal Rate
50 CFH
100 CFH
150 CFH
200 CFH
300 CFH
LP Vapor
1/2 Load
Full Load
35 C
65 C
87,000 B
164,000 B
20ft
30ft
40ft
240
192
163
446
360
307
20ft
30ft
40ft
158
126
107
293
236
202
32° F
20° F
115
115
250
250
300
400
400
500
750
1000
Physical Properties
Normal Atmospheric State
Boiling Point (in °F):
Initial
End
Heating Value:
BTU per gallon (Net LHV*)
BTU per gallon (gross**)
Cubic feet (gas)
Density***
Weight†
Octane Number:
Research
Motor
*
LHV (Low Heat Value) is the more realistic rating.
**
Gross heat value does not consider heat lost in the form of water
during combustion.
*** Density is given in "Cubic Feet of Gas per Gallon of Liquid".
†
Weight is given in "Pounds per Gallon of Liquid".
50ft
60ft
70ft
145
132
120
274
250
230
50ft
60ft
70ft
95
87
79
180
164
151
10° F
0° F
-10° F
115
250
250
400
500
500
750
1000
1500
2000
LP Vapor
Natural
Gas
Gas
Gas
-44
-259
-44
-259
83,340
63,310
91,547
2,500
1,000
36.39
57.75
4.24
2.65
110+
110+
97
80ft
90ft
113
106
211
197
80ft
90ft
74
69
139
129
-30° F
-40° F
250
400
500
1000
1000
1500
1200
2000
2500
4000
100ft
99
187
100ft
65
123
600
1500
2500
2500
5000
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