| 摘要 |
The device includes a tubular body, an annular flap cooperating with the tubular body, and a cover cooperating with the tubular body to form a channel or peripheral air inlet beneath the annular flap, which channel is closed by the latter. When a partial vacuum occurs in the conduit connected to the device, the annular flap is raised by the incoming ambient air upwardly and into the internal space defined by the inner periphery of the cover. The annular flap is provided with external guiding lugs oriented downwardly and which cooperate with ribs integrally formed on the outside of the tubular body.
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