| 摘要 |
<p>The reverse flow prevention valve has a frame (2) with seals (3) at its edge, fitting in a horizontal flue (1). The frame has an opening (5) for the flue gases, with sloping beams (11) to hold the valve flap (6). The flexible flap is held (7) at the top edge and rests on sloping support surfaces (4) with knobs (12) at intervals. The valve flap has two rearward projections (8) with mushroom heads (9) engaging in apertures (10) in a flat surface at the top of the frame.</p> |
