Abstract:
A surge reliever relief valve is provided in which a flexible membrane is maintained in a peripherally sealed relationship across a rigid grid. The grid bounds the laterally adjacent intake and output regions of the valve. Intake pressure extends the membrane allowing flow between intake and output. Extension of the membrane is limited by a retainer. Extension may be elastic or inelastic.

Description:
FIELD OF THE INVENTION 
     This invention pertains to liquid surge relief valves and more particularly to a relief valve having a peripherally supported membrane-like seal interposed between a rigid grid plate and a retainer. 
     BACKGROUND OF THE INVENTION 
     Pressure surges or water hammer phenomena are caused by liquid deceleration or flow variations in pipes. The resulting destructive energy can cause ruptures in piping and piping components, pipe vibrations and noise. Surge arresters or relief valves, if properly used, provide relief to increases in fluid pressure associated with unsteady flow conditions. While other relief means or desurgers are known, the present invention is designed to operate reliably and economically. 
     SUMMARY OF THE INVENTION 
     The benefits and improvements of the present invention are provided by a valve having separate laterally adjacent intake and output regions bounded by a grid and sealable from one another by a membrane supported by the grid. The membrane is interposed between the grid and a retainer which defines the arched interior of a flow chamber. Pressure surges deflect or distend the membrane against pressure communicated from a pressure chamber to the flow chamber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows in cross section, a surge relief valve of the present invention; 
     FIG. 2 shows in plan view the grid plate utilized in the valve of FIG. 1; 
     FIG. 3 shows the grid plate of FIG. 2 in cross section; 
     FIGS. 4-6 show in sequential schematic diagrams, the operation of the valve illustrated in FIG. 1; 
     FIG. 7 shows another embodiment of the relief valve of the present invention; and 
     FIGS. 8-10 show in sequential schematic diagrams, the operation of the valve illustrated in FIG. 7. 
    
    
     DETAILED DESCRIPTION 
     As shown in FIG. 1, the surge reliever relief valve 10 of the present invention comprises a &#34;T&#34; shaped section of pipe 11 defining a valve body having an intake flange 12, an output flange 13 and a third flange 14, onto which the mechanically active components of the invention are mounted. The &#34;T&#34; section or valve body 11 further includes a barrier 15 which transects the valve body and separates the intake portion 16 from the output portion 17 of the valve. The intake region 16 includes an effluent end 61 where fluid flow traverses the opening defined by the third flange. The output region 17 includes an affluent end 62 where fluid enters the region 17 from the opening defined by the third flange. Together, the affluent of the output and effluent end of the intake comprise a divided or transected opening. It should be understood that in operation, the valve described herein is functionally symmetrical and that the intake and output designations used herein are made for convenience, and may be determined by the direction of flow. Deflectors 18, 19 are positioned within the intake and output portions to improve the efficiency of flow. Through passages 20 are provided around the edges of the deflectors so that a pressure differential across the deflector is prevented. 
     The third flange 14 supports a gasket 21, a grid (in this instance a grid plate) 22 and the flange 41 of a cap 23. A flat elastomeric membrane 24 is interposed between the grid and the cap flange. The cap 23 is divided by an arched retainer 25 into a flow chamber 26 and a pressure chamber 27. The pressure chamber includes upstanding side walls 29, one ore more pressure ports 30 and a dome 31. Vents 28 extend between the pressure chamber and the flow chamber allowing pressure in the chamber to bear on the membrane. In this instance, the retainer 25 and flat grid plate 22 define a hemispherical flow region 26. 
     As illustrated in FIGS. 2 and 3, the grid plate 22 may comprise a peripheral flange 32 having a pattern of bolt holes 33 which accommodate the fasteners 34 which attach the cap 23 to the third flange 14 of the &#34;T&#34; 11. In the alternative, the grid can be incorporated integrally into the valve body, as by welding. A recessed landing 35 accommodates the membrane 24 and bears a second pattern for bolt holes 36 which are used in the securing of the grid 22 to the third flange 14. A central portion of the grid includes a series of ribs 37 extending from a central pier 38 to the landing area 35, thus defining laterally adjacent input and output matrices, each having through passages 39. The central pier 38 has bolt holes 40 which are used to affix the pier to the barrier 15 in the valve body. Thus, passages 39 in the intake matrix cover and accept flow from the intake effluent, while passages in the output matrix admit flow to the output affluent. 
     When assembled, as seen in FIG. 1, the grid 22 is sandwiched between the cap flange 41 and the third flange 14. The gasket 21 seals between the grid and the flange 14. The elastomeric membrane 24 seals between the cap flange 41 and the grid 22. The membrane 24 is sealed about its periphery or circumference by the clamping action of the flanges 41, 14. The membrane is said to cover the opening to the flow chamber. 
     Thus, it can be appreciated that when the cap 23 is pressurized with dry air or nitrogen through the ports 30, that the membrane 24 acts as a closure which resists the flow of liquid in the valve from the intake section 16 to the output section 17. Generally, a fixed pressure of at least 10 p.s.i. in excess of line pressure is maintained in the pressure chamber. However, the pressure in the pressure chamber may be modulated in accordance with variations in line pressure which are not considered surges. As shown in FIGS. 4, 5 and 6, when the pressure of fluid in the intake section 16 exceeds the pressure in the cap 23 the membrane 24 will expand or extend, gradually increasing the effective volume of the intake 16 by allowing fluid to expand into the opening of the flow chamber 26 (FIG. 4), eventually communicating the intake 16 and output 17 (FIG. 5), and finally allowing full flow between intake 16 and output 17 (FIG. 6). As shown in FIG. 6, in the fully extended position, the membrane is in full contact with the retainer and is prevented from further expansion by the generally hemispherical retainer 25. 
     A second embodiment of the invention is illustrated in FIGS. 7-10. This embodiment of the invention is well suited to higher pressure applications because the sealing membrane is inelastic, i.e., not extensible to any appreciable degree. Rather than a flat grid plate, a grid 50 having a gentle curvature is provided. The curvature of the arched retainer 60 is similar to that of the grid. The radius 51 of the curvature of the grid is preferably greater than the radius 52 of the divided opening. Thus, the similar curvatures of the grid 50 and arched retainer 56 define a lenticular flow chamber 53. Rather than a flat extensible membrane, a reinforced polymeric membrane 54 is provided, whose rest shape matches the curvature of the grid 50. The reinforcement of the polymeric membrane can be by way of loosely woven nylon or rayon cloth that renders the membrane flexible but inelastic. 
     Under fluid pressure which exceeds the relief pressure in the cap 55, the reinforced membrane rolls or folds, as shown in FIG. 8. Membrane stretching in this instance is minimal. Continued membrane deflection admits partial flow into the output affluent as shown in FIG. 9, eventually contacting the retainer in full as shown in FIG. 10. The curvature of the arched portion 56 of the cap matches the curvature of the grid 50, so that even in the full flow position, as shown in FIG. 10, the membrane 54 is not significantly deformed. 
     While the principles of the instant disclosure are provided by way of specific examples, it will be understood that these examples should not operate as limitations to the scope of the invention as set forth in the following claims.