| 摘要 |
PROBLEM TO BE SOLVED: To eliminate a measuring error generated due to the residue of moisture in the air in the peripheral part of a plunger by a method wherein a solenoid valve for gas-line changeover is equipped with a diaphragm and the creeping of a gas to the peripheral part of the plunger is prevented. SOLUTION: In a solenoid valve 9, for gas-line changeover, which is installed in the halfway part of a gas line 7 which guides a burning gas to a detector, a plunger 12 which is operated by an electromagnetic coil 11 is built in a valve body 10. The valve body 10 is divided into a plunger built-in part 10a and a flow-passage constitution part 10b. then, a diaphragm 13 which is used to isolate a narrow space P in the peripheral part of the plunger 12 from the gas line 7 [a communication flow passage (c)] is installed between them. When the diaphragm is pressed to a valve seat (d) by the plunger 12, the communication flow passage (c) is cut off. Consequently, a gas in the communication flow passage (c) flows smoothly. In addition, it is possible to prevent the air, the burning gas and the like creeping into a furnace from flowing into the space P. As a result, it is possible to prevent moisture in the air from being left in the space P, and a measuring error by the adsorption of a gas due to the residue of moisture in conventional cases is not generated at all.
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