| 摘要 |
This invention relates to valve assemblies and particularly to valve assemblies adapted to prevent backflow which also incorporate an atmospheric vacuum breaker. The most basic arrangement involves a vacuum breaker device (16, 28) which comprises an integral non-return valve located upstream of a user operable valve control means (21) wherein the non-return valve of the vacuum breaker device is biased to close against the flow of fluid from the supply (Fig. 14). The second of these variations shows a vacuum breaker device comprising an integral non-return valve located upstream of the valve assembly outlet wherein the non-return valve is biased closed but which is limited in its movement to allow flow of fluid through the valve assembly by a user operable valve control means (Fig. 7). The third of these variations comprises the addition of a second non-return valve (17) upstream of the vacuum breaker device (Fig. 13). The fourth of these arrangements is conceptually identical to the third arrangement but offers an alternative construction (Fig. 12). The fifth of these arrangements shows a vacuum breaker device upstream of the valve assembly outlet and a second non-return valve further downstream wherein the second non-return valve is biased closed to allow flow through the valve assembly by a user operable valve control means (Fig. 16). Other arrangements for a ball valve (Fig. 22) and various bib-cocks (Figs. 23-34) are also described. |
