| 摘要 |
<p>The invention relates to an automatic air valve device for sanitation waste pipes for preventing communication in the rooms between the waste pipes and atmosphere and to permit the introduction of fresh air into the pipes when a negative pressure occurs. It comprises a body formed by a vertical tube in communication with a waste pipe, the said body having at its upper part a constriction in the form of a Venturi cooperating with a cover so as to form a peripheral air inlet situated at the exterior of the constriction. The said air inlet is provided with an annular valve. Around the cover and the upper end of the cylindrical body there is an insulating covering in which there is formed a circular recess providing communication with the atmosphere (FIG. 1).</p> |
