| 摘要 |
PURPOSE: A back draft damper having a multi guide vane is provided to prevent the floating or shaking of a vane caused by air current and the inflow of noise from a vertical pipe to an indoor place. CONSTITUTION: A back draft damper comprises a guide vane and a leaf spring type control plate. The guide vane comprises a vane pipe formed with a guide rib having a plurality of guide vanes to accelerate the speed of air current according to section. The leaf spring type control plate has a free end(520) which is coupled by a fixing piece on a support and opens and closes the discharge end of the vane pipe.
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