| 摘要 |
A pivotal vane carrying member secured to the damper for a furnace flue normally maintains the damper by gravity in an open position. An electric motor driven air blower discharges air against the vanes of the pivotal member to pivot the latter and damper to a closed position when no fuel is supplied to the furnace. Otherwise power for the blower motor is shut off and the pivotal member returns by gravity to its normal flue-open position.
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