| 摘要 |
<p>A pressure relief valve through which flow can take place in one direction or the other, partic. to adjust automatically either overpressure or underpressure within a vessel to which the valve is connected. The valve comprises a cylindrical chamber contg. two discs which are axially movable and are pressed against annular seals to sub-divide the chamber into a central and two side, cylindrical compartments. The vessel space in which pressure is to be controlled is connected into the central compartment. Both side compartments are vented to atmos. Overpressure in the central compartment presses the first disc harder on its seal and lifts the second disc so that gas may flow from the central compartment into the compartment behind the second disc and hence to atmos. Underpressure in the central comp. allows an adjustably loaded spring to lift the first disc from its seal. Air from the compartment behind the first disc passes into the central compartment and hence to the vessel space. The second disc is adjustably spring-loaded to resist lifting from its seal. The valve is esp. suitable for fitting to digesters which produce methane by fermentation of manure etc. The valve prevents digester vessel dropping below atmos. which might result in impulsion. The valve can be preset to prevent explosion by relieving pressure build up. The valve is inexpensive, compact and simple and serves a dual purpose.</p> |
