| 摘要 |
PROBLEM TO BE SOLVED: To provide a heating device which prevents continuous supply of a fire extinguishing gas, while ensuring to prevent flashback at the time of service interruption. SOLUTION: At normal use, contacts 48 and 49 cause terminals T3 and T7, and terminals T4 and T8, respectively, to become conducting state by the action of a relay 50 which is operated by the application of a voltage, and a conduction in which a direct-current voltage is not applied to a normally closed solenoid valve 38 is maintained. In such a condition, a capacitor 47 is charged with predetermined power by the supplied power. When service interruption occurs, the relay 50 goes to a non-operative state. Also, the contacts 48 and 49 are changed, so that the power that has been charged in the capacitor 47 is applied to the solenoid valve 38. As a result, the solenoid valve 38 is maintained in an 'open' condition, until the electrical discharge of the capacitor 47 is completed, and N2 gas is discharged as a result.
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