Abstract:
A fully draining valve including an upper valve portion and a lower valve portion. The lower valve body has an integral weir, which in conjunction with a resilient diaphragm, defines a fluid passage. The weir axis is sloped from a horizontal plane. A first duct axis is sloped downwardly away from the weir and sloped from the horizontal plane. A second duct axis is sloped downwardly away from the weir and sloped from the horizontal plane. A third duct axis is oriented downwardly away from the weir and substantially parallel to a vertical axis such that substantially all liquid from within the fluid passage drains from the valve by gravity.

Description:
CLAIM TO PRIORITY 
     This application claims priority to U.S. Provisional Patent Application ser. No. 60/365,492 filed on Mar. 18, 2002 entitled FULLY DRAINABLE WEIR VALVE which is incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to valves, and more particularly, to plastic diaphragm valves having a weir-type seating surface. 
     BACKGROUND OF THE INVENTION 
     Diaphragm valves provide excellent sealing and isolation characteristics to contain fluid being controlled and prevent migration of the controlled fluid. into the valve mechanisms or out of the valve. Diaphragm valves utilize a resilient diaphragm and a valve shoulder to engage a valve seat and prevent the flow of fluid past the valve seat. A weir-type diaphragm valve is a valve utilizing a resilient diaphragm that engages a weir to control flow of fluid over the weir. The diaphragm may be controllably lifted and sealed against the weir to selectively permit flow though the valve. 
     Weir-type diaphragm valves are often employed in the biotechnological, pharmaceutical, chemical, food processing, beverage, cosmetic, and semiconductor industries. These industries require valves that protect against product contamination and leakage within the valve, workplace and atmosphere. Weir-type diaphragm valves are well suited to meet these requirements because the mechanical valve parts are isolated from fluid flowing through the valve. 
     Weir-type diaphragm valves are commonly used to control the flow through a branch in a fluid distribution system or to deliver a sample of a fluid from a process. Each of U.S. Pat. No&#39;s 5,065,980, 5,227,401, 5,222,523, 5,327,937 and 6,289,933 disclose diaphragm valves suitable for branch control and sampling. Often, it is desirable to mount such valves in a horizontal position, wherein the weir extends in a horizontal direction. 
     These prior art valve design do not allow for complete draining of the fluid passageways due to surfaces that are not configured for drainage. U.S. Pat. No. 6,289,933, for example, has a plurality of horizontal surfaces that may retain fluids. Such stagnant or retained fluids may be a source for contamination in a process. For fluids used in industrial processes, such as the pharmaceutical, sanitary, and semiconductor industries, the process fluids generally must be kept ultra pure. Contamination of these processes may represent significant monetary losses. Therefore, separate cleaning steps must be employed to cleanse any stagnant or trapped fluids from the prior art valve designs. This extra step increases processing time and cost. 
     Traditionally, diaphragm valves were made of metal alloys. Such metal valves provide good durability and service life in basic fluid control applications. However, metal alloys are not well suited to some process environments, such as pharmaceutical and semiconductor manufacturing. In those applications, the fluids often used are highly corrosive or caustic and also must be kept ultra pure. These corrosive fluids can erode the metal from the valve body and contaminate the ultra pure process fluids. Also, some metal alloys may act as catalysts causing the process fluids to undergo chemical reactions, thereby compromising end products, and potentially, worker safety. 
     Specialized high strength alloys and stainless steels have been developed to minimize reactivity and erosion in the valve bodies. However, such specialized alloys are very difficult to cast or machine into valve components. The resulting valves are very costly to purchase relative to traditional metal valves. Moreover, stainless steel is not suitable in particular applications such as the semiconductor processing industry. 
     Plastic lined metal valves were developed to allow traditional metal valve bodies to handle caustic fluids in specialized process applications. The metal valve body is first formed by casting or machining. Then, a plastic or fluoropolymer is molded in the interior of the valve body where process fluids contact the body. U.S. Pat. No. 4,538,638 discloses a plastic lined metal bodied diaphragm valve. 
     Although, the plastic lined metal valves and plastic lined plastic valves may provide the desired resistance to degradation by-process fluids, manufacturing costs are high. High costs are attributable to the complicated multi-step manufacturing process of molding a plastic lining in a support body. The plastic lining may be subject to creep with respect to its surface underneath. Creep reduces the useful life of the expensive plastic lined valve. 
     Through advances in plastics and manufacturing technologies, valves made entirely or almost entirely of fluoropolymers have become commercially viable. Such plastic valves are capable of providing a cost effective valve having desirable non-reactive and corrosive resistant properties ideally suited for use in pharmaceutical and semiconductor manufacturing applications. U.S. Pat. Nos. 5,279,328 and 4,977,929 disclose plastic diaphragm valves. In certain applications, plastic bodied valves may also be provided with a plastic lining. U.S. Pat. No. 4,538,638 discloses a plastic lined diaphragm valve. These three patents are incorporated by reference herein. 
     While fluoropolymer valves and plastic valves having fluoropolymer liners are well suited to withstanding caustic fluids, they are susceptible to dimensional degradation such as warpage and creep. Fluids used in industrial processes, such as the pharmaceutical, sanitary, and semiconductor industries, generally require the process fluids to be kept ultra pure. Components used in fluid delivery systems, such as valves, are routinely cleansed to ensure that contaminants do not become trapped in such components and thereby introduced into the process system. 
     The cleansing processes may involve exposure to high temperature steam for a sufficient amount of time to sterilize the component. Particularly when repeated numerous times, this sterilization process can cause the plastic in the valve to change dimension slightly, resulting in warpage. Creeping results when plastic is subject to stress over a period of time. The plastic component&#39;s dimensions can change from the stress. Due to such warpage and creep, tolerances, especially at the weir, are affected and leakage may result. 
     Therefore, a need exists to provide a plastic lined weir-type diaphragm valve that has improved dimensional stability when exposed to repeated cleansing operations or exposure to conditions normally conducive to warpage or creep. Further, there is a continuing need to provide for a fully drainable valve suitable to branch control and sampling applications. 
     SUMMARY OF THE INVENTION 
     A fully draining valve apparatus in a preferred embodiment comprises an upper valve portion and a lower valve portion. The upper valve portion preferably includes an upper valve housing or body, a resilient diaphragm and a valve actuator. The lower valve portion comprises a lower valve housing or body that is preferably configured to mate with the upper valve housing to define a valve interior. The lower valve body preferably has an integral weir, which in conjunction with the resilient diaphragm, defines a fluid passage. The diaphragm is configured to sealingly engage and disengage with the weir as effected by the valve actuator. The weir defines an upper surface that is angled slightly with respect to the horizon to provide an interior passage slope. Said slope causes fluid to flow back into passage instead of remaining in the passage. Additionally, a slope is also formed on a lower portion of the flow passage defined by the valve body to cause fluid to drain into the third duct of the valve. The invention also includes the method of manufacturing a valve, preferably including the step of angling the horizontal surfaces within the fluid passages of the valve to promote full drainage of fluids that may otherwise accumulate. 
     A weir support member is disposable within the lower housing to support the weir. In preferred embodiments, an exoskeletal framework configured as the support collar extends circumferentially around the valve and supports the weir support member. In particular embodiments, the valve body components may also comprise a plastic fluoropolymer lining for contacting fluids. The invention also includes the method of manufacturing a reinforced plastic valve preferably including the step of providing a rigid support member to the weir of a lower valve housing. 
     An object and advantage of particular embodiments of the present invention is to provide for a fully drainable weir-type diaphragm valve. 
     An object and advantage of particular embodiments of the present invention is to provide a diaphragm valve wherein the weir is angled slightly above the horizontal to create a sloping surface. 
     An object and advantage of particular embodiments of the present invention is to provide a valve design that reduces the occurrence of retained fluids. 
     An object and advantage of particular embodiments of the present invention is to provide a valve design that reduces contamination of sterile or aseptic processes. 
     Another object, and advantage of particular embodiments of the present invention is to provide for a fluoropolymer diaphragm valve that is dimensionally tolerant to repeated sterilization processes. 
     Another object and advantage of particular embodiments of the present invention is to provide for a valve that is able to withstand repeated sterilization processes and that is also suitable to use in the pharmaceutical, biotechnological, chemical, and/or semiconductor industries. 
     Another object and advantage of particular embodiments of the present invention is to provide a means for reinforcing a plastic valve. 
     Another object and advantage of particular embodiments of the present invention is to provide for a method of reinforcing a plastic valve, thereby having improved resistance to warpage and creapage. 
     Another object and advantage of particular embodiments of the present invention is to provide a support for the weir of a plastic valve. 
     Further features, objects and advantages of the present invention will become apparent to those skilled in the art in the detailed description below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded parts view of a diaphragm valve according to an embodiment of the present invention. 
         FIG. 2  is a perspective view of the assembled diaphragm valve of FIG.  1 . 
         FIG. 3  is another perspective view of the assembled diaphragm valve of FIG.  1 . 
         FIG. 4  is a side view of the lower portion of a diaphragm valve according to an embodiment of the present invention. 
         FIG. 5  is a side view of an assembled diaphragm valve according to an embodiment of the present invention. 
         FIG. 6  is an end view of an assembled diaphragm valve according to an embodiment of the present invention. 
         FIG. 7  is a partial cross sectional view of an assembled diaphragm valve according to an embodiment of the present invention taken along line A—A of FIG.  6 . 
         FIG. 8  is an exploded perspective view of a diaphragm valve according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A weir-type diaphragm valve  20  in accordance with the invention is illustrated in  FIGS. 1 ,  2  and  3 . Such valve generally includes an upper valve portion  22 , a lower valve portion  24 , a bracket support framework  26  and a mounting bracket  28 . A plurality of fasteners  30  are used to fasten the upper portion  12 , lower portion  14  bracket  28  and bracket mount  26  as shown in the assembly drawing of FIG.  1 . Additionally, an endoskeletal support member  32  may be used to add rigidity to the valve, which is often comprised of plastic. It should be understood that the terms upper valve portion  22  and lower valve portion  24  are used for convenience of description and that the valve of the present invention is not limited to the valve  20  being positioned such that the upper valve portion  22  must be vertically above lower valve portion  24  relative to the earth. In fact, a preferred operating position for the valve may include the upper valve portion  22  being positioned substantially to the side of the lower valve portion  24 . 
     The upper portion  22  includes a resilient diaphragm  38  and an actuator for controllably sealing against the valve seat  42  provided in the lower housing  24 . The lower housing  24 , shown in  FIGS. 1 and 4 , comprises a central flow passage  44 , a first flow duct  46 , a second flow duct  48 , a third flow duct  50  and a valve seat  42  therein. The valve seat  42  includes a weir  52  for isolating the third duct  50  from the first  46  and second  48  ducts when mated with the diaphragm  38 . 
     Referring to  FIG. 5 , the valve  20  is shown assembled and in position for mounting to an overhead surface with the attached bracket  28 . An axis  56  is shown to indicate the normal horizontal H and vertical V orientation of the valve  20 . A centerline C 1  drawn through the third duct  50  is parallel to the vertical axis V. The horizontal axis H is normal to the vertical V. A centerline C 2  through the upper valve portion  22  is not parallel to the horizontal H; rather, it is parallel to the line indicated as H′. V′ is defined as normal to H′. H′ is tilted at angle X to the horizontal H. Angle X is preferably 5 degrees. However, those skilled in the art will recognize that X could include the following range 0°&lt;×&lt;90° without departing from the spirit and scope of the present invention. 
       FIG. 7  indicates a partial sectional view of valve  20  taken along line A—A of FIG.  6 . The central passage  44  includes a first inwardly facing surface  58  defined by the weir  52 . The centerline C 2  of the weir  52  (which, in some embodiments, may also be the same as centerline C 2  of the upper housing  22 ) is offset from the horizontal H by X degrees. This produces a slope on the first surface  58 . The first sloped surface  58  ensures that all fluids drain into the central passage  44  between the first  46  and second  48  ducts. 
     A second inwardly facing surface  60  is provided to the inside of the passage  44  defined by the lower housing  24 . This slope X may be the same as for the first surface  58 , although it may be more of less depending on the application. Second sloped surface  60  causes fluids in the central passage  44  to drain into the third duct  50 . The presence of these two sloped surfaces  58  and  60  allows all fluids to be fully drained from the valve  20 , thereby addressing the retained fluid problems of the prior art. 
     The valve may be reinforced, or supported, by the provision of the endoskeletal support member  32  as depicted in FIG.  8 . Endoskeletal support member  32  is configured as a weir support member  62  and exoskeletal framework  64  configured as support collar  66 . The weir support member  62 , as shown in  FIG. 8 , is preferably rod shaped having a first end  68 , a second end  70 , a longitudinal surface  72  and notches  74  in the longitudinal surface  72  at both first end  68  and second end  70 . The weir support member  62  may be any suitably shaped elongated member. Those skilled in the art will recognize that many alternative embodiments of weir support member shape, such as polygonal, will provide the envisioned support without departing from the scope of the present invention. 
     The support collar  66 , shown in  FIG. 8  includes an upper bracket  76  and a lower bracket  78 . The upper bracket  76  and lower bracket  78  are preferably approximately U-shaped and overlap when placed on the valve housing. There are a plurality of collar mounting holes  80  and slotted mount holes  82  in the upper bracket  76  that correspond to respective upper mounting holes  84 , lower mounting holes  86  and mounting slots  88 . The slotted mount holes  82  aide in joining the upper bracket  76  to the lower bracket  78  and the valve upper portion  22  and lower portion  24  during assembly. 
     The lower bracket  78  may be provided with two mounting posts  90  that cooperate with the mounting slots  88  and upper mounting holes  84  of the valve upper portion  22  and lower portion  24  and slotted mount holes  97  of the upper bracket  76  for enabling the joining of the valve upper portion  22  and lower portion  24 . The mounting posts  90  have a threaded portion  92  and a smooth portion  94  to provide a means for fastening the valve upper portion  22  and lower portion  24  together. The lower bracket  78  also has two collar mounting holes  80  that communicate with respective collar mount holes  80  of the upper bracket  76 , the upper mounting holes  84  of the valve upper portion  22  and the lower mounting holes  64  of the valve lower portion  24 . 
     When assembled upper bracket  76  supports weir support member  62  at notches  74  thereby transferring force from weir  52  to weir support member  62  and thence to upper bracket  76  and lower bracket  78 . This support prevents or reduces creep induced by pressure on weir  52  and other valve components. Thus, warpage and creep of the weir, the flanges and generally the valve body is inhibited. 
     The valve upper portion  22  and lower portion  24  are preferably formed of fluoropolymers, including but not limited to perfluoroalkoxy resin (PFA), polyvinylidene fluoride (PVDF) or other fluoropolymers. In certain applications, other plastics may be suitable, such as polyvinyl chloride (PVC), or polypropylene (PP). The body components are preferably injection molded, although they may be machined. The wetted portion of the diaphragm  38  may be formed of polytetrafluoroethylene (PTFE). The diaphragm may be composite with a layer adjacent the PTFE layer formed of EPDM. The weir support member  62  and the support collar  66  are preferably constructed of stainless steel. Stainless steel provides the desirable amount of rigidity and durability to provide the plastic valve with the desired amount of dimensional integrity. In certain instances, other rigid materials such as carbon fiber filled PEEK or other polymers may be utilized. Those skilled in the art will recognize that the above structures may be constructed from other materials without departing from the scope of the invention. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize changes may be made in form and detail without departing from the spirit and scope of the invention.