| 摘要 |
The draught unit consists of first and second truncated conical surfaces (11,12) with fixing members (18) to hold them together and define an annular space (20) between them, leading to an inner duct (21) which has a partial shutter (22) at the top on a support (23). The fixing members (18) and shutter supports (23) are in the form of inverted L-shaped components with fixings (31,34) to attach them to the two truncated cones and a third fixing (39) for the shutter. Additional fixing members (40) are used to connect the lower cone to the chimney (3), e.g. by a strap (45). The fixings (31,34,39) can be in the form of rivets.
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