When the initial test runs are completed, the manometer is removed and the port is plugged. A typical final fuel connection assembly is shown here, where (A) is the fuel supply and (B) goes to the home generator.
A
B
Fuel Consumption
Estimated fuel supply requirements at half and full load for natural gas and LP vapor fuels are shown below.
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| 1/2 Load | Full Load | 1/2 Load | Full Load | |
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18kW | 160 C | 293 C | N/A | N/A |
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| 160,000 B | 293,000 B | N/A | N/A |
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20kW | N/A | N/A | 70.4 C | 141.5 | C |
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| N/A | N/A | 176,825 B | 353,650 B | |
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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.
Physical Properties | LP Vapor | Natural |
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Normal Atmospheric State | Gas | Gas |
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Boiling Point (in °F): |
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Initial | ||
End | ||
Heating Value: |
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BTU per gallon (Net LHV*) | 83,340 | 63,310 |
BTU per gallon (gross**) | 91,547 |
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Cubic feet (gas) | 2,500 | 1,000 |
Density*** | 36.39 | 57.75 |
Weight† | 4.24 | 2.65 |
Octane Number: |
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Research | 110+ | 110+ |
Motor | 97 |
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* 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”.
NPT | 10ft | 15ft | 20ft | 30ft | 40ft | 50ft | 60ft | 70ft | 80ft | 90ft | 100ft |
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3/4” | 346 | 293 | 240 | 192 | 163 | 145 | 132 | 120 | 113 | 106 | 99 |
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1” | 653 | 549 | 446 | 360 | 307 | 274 | 250 | 230 | 211 | 197 | 187 |
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Natural Gas Pipe Size - Gas Flow chart, in cubic feet per hour, specific gravity=0.65 |
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NPT | 10ft | 15ft | 20ft | 30ft | 40ft | 50ft | 60ft | 70ft | 80ft | 90ft | 100ft |
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3/4” | 277 | 192 | 158 | 126 | 107 | 95 | 87 | 79 | 74 | 69 | 65 |
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1” | 428 | 360 | 293 | 236 | 202 | 180 | 164 | 151 | 139 | 129 | 123 |
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Liquid Propane (LP) Gas Pipe Size - Gas Flow chart, in cubic feet per hour, specific gravity=1.50
10 | BRIGGSandSTRATTON.COM |
