Briggs & Stratton 202826GS system manual Fuel Consumption, Natural Gas LP Vapor, Fuel Pipe Sizing

Fuel Consumption

Estimated fuel supply requirements at half and full load for natural gas and LP vapor fuels are shown below.

	Natural Gas		LP Vapor
	1/2 Load	Full Load	1/2 Load	Full Load
18kW	160 C	293 C	N/A	N/A
	160,000 B	293,000 B	N/A	N/A
20kW	N/A	N/A	70.4 C	141.5	C
	N/A	N/A	176,825 B	353,650 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.

Physical Properties	LP Vapor	Natural
		Gas
Normal Atmospheric State	Gas	Gas
Boiling Point (in °F):
Initial	-44	-259
End	-44	-259
Heating Value:	83,340	63,310
BTU per gallon (Net LHV*)
BTU per gallon (gross**)	91,547
Cubic feet (gas)	2,500	1,000
Density***	36.39	57.75
Weight†	4.24	2.65
Octane Number:
Research	110+	110+
Motor	97

* 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
3/4”	346	293	240	192	163	145	132	120	113	106	99
1”	653	549	446	360	307	274	250	230	211	197	187
Natural Gas Pipe Size - Gas Flow chart, in cubic feet per hour, specific gravity=0.65
NPT	10ft	15ft	20ft	30ft	40ft	50ft	60ft	70ft	80ft	90ft	100ft
3/4”	277	192	158	126	107	95	87	79	74	69	65
1”	428	360	293	236	202	180	164	151	139	129	123

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	32° F	20° F	10° F	0° F	-10° F	-30° F	-40° F
50 CFH	115	115	115	250	250	400	600
100 CFH	250	250	250	400	500	1000	1500
150 CFH	300	400	500	500	1000	1500	2500
200 CFH	400	500	750	1000	1200	2000	2500
300 CFH	750	1000	1500	2000	2500	4000	5000

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