Sheet 4343-11 Page 2
FUEL TUBE INLETS For convenience in piping TwinBed II, fuel tubes have two gas inlets and one cooling air inlet. Only one gas inlet is used. The other inlet is plugged. The cooling air inlet is smaller in size than the two gas inlets. Cooling air must be supplied to TwinBed II's fuel tube at all times. Following is a table of gas and cooling air inlet pipe sizes.
Gas inlets
Burner
Gas inlet
Cooling
designation
air
Air inlet
4343-7
2" fpt 2" fpt 2" fpt 3" fpt 3" fpt 3" fpt 3" fpt
1 ¼ " fpt 1 ¼ " fpt 1 ¼ " fpt 1 ½ " fpt 1 ½ " fpt 1 ½ " fpt 1 ½ " fpt
4343-8-A 4343-8-B 4343-9 4343-10 4343-12-A 4343-12-B
FUEL TUBE GAS FLOW
12
These graphs can be used to determine maximum gas pressure required at the fuel tube for TwinBed ® II. Do not use the graphs for burner adjustment. An orifice or other flow meter is necessary to determine actual gas flow when making adjustments. Gas flow is dependent upon both inlet gas pressure and the position of the mixing rate adjustment plug in the case of the larger fuel tube (TwinBed II sizes -9 through -12-B.) The gas pressure drop is much higher when the mixing rate adjustment plug is full extended than when retracted. The pressure is somewhere between these extremes when the plug is in any other position.
4343 sizes -7 through -8-B
10
8
6
4
2
Note that the "Y" axis is different for each graph.
0
0
2000
4000
6000 8000
10000 12000 14000 16000 18000
Natural Gas Flow, scfh
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