| 摘要 |
A back flow prevention device and/or vacuum breaker device for mounting on a plumbing fixture. The device comprises a body having fluid entry means, fluid exit means and backflow prevention means. The backflow prevention means is located between the fluid entry means and the fluid exit means and the backflow prevention means comprises, a chamber having an entry port contiguous with the fluid entry means, an exit port contiguous with the fluid exit means and a back flow prevention port which is open to atmospheric pressure and a valve movably mounted between a first position sealing the entry port and a second position sealing the backflow prevention port. Fluid flowing into the chamber moves the valve out of the first position into the second position thereby allowing fluid to freely flow through the chamber, out the exit port and along the fluid exit means. The valve, in the absence of fluid flow along the fluid entry means, returns to its first position thereby leaving the backflow prevention port open to atmospheric pressure to prevent backflow and to permit vacuum breakage.
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