| 摘要 |
PURPOSE:To prevent the temporary change of the supply quantity of gas upon switching burners by providing within a gas passage a passage control type proportional control valve, a branch pipe which distributes gas and an electromagnetic valve which opens and closes the gas passage. CONSTITUTION:Within gas passage, are provided a flow quantity control type proportional control valve PV, and a branch pipe Pr which distributes gas to a plurality of burners B1 and B2 on the downstream side of the control valve PV. Electromagnetic valves which open or close the gass passage in correspondence to the plurality of the burners B1 and B2 in the intermediate of the branch pipe Pr after branching. The control valve PV is provided with a valve body 4 having a variable sectional area of the passage, electrically driven parts 6-8, a primary pressure chamber 9 on the upstream side of the valve body 4 and a secondary pressure chamber 10 on the downstream side. A back pressure chamber 11 is provided on the opposite side to the passage of a diaphragm 5 moving in linkage with the valve body 4, and a communication pipe 15, communicating the low pressure part of the passage more downstream than the secondary pressure chamber 10 with the back pressure chamber 11 is provided. By this arrangement, the change of the temporary gas supply quantity at the time of switching the burner can be prevented. |
