Abstract:
A valve manifold box that can be opened and closed easily and repeatedly while maintaining a sealed environment around the valves when closed by means of a latch system and a prong and groove gasket seal.

Description:
FIELD OF THE INVENTION 
     The present invention relates, in general, to a valve manifold box that can be opened and closed easily and repeatedly while maintaining a sealed environment around the valves when closed. 
     BACKGROUND OF THE INVENTION 
     Semi-conductor chip manufacture requires the use of high purity chemicals and a distribution piping network. Many of the chemicals are hazardous and include volatile organic components. The piping network is subject to strict State and Federal requirements such as the Federal Clean Air Act of 1990. Every connection in the piping network poses a potential leak. While joints and connections in the piping can be welded or otherwise sealed as strongly as the pipe material itself, valves pose a particular area of vulnerability to leaks because of the moving parts contained in valves. In order to protect workers from leaks at the valves, valves for controlling and operating the piping network are contained in a multi-point of use chemical distribution box, known as a valve manifold box. Any number of pipes or lines can be connected to the box in the same manner as other joints in the line where the connection is at least as strong as the pipe or line material itself. The valves are the connected to the pipes and lines inside the valve manifold box The essential feature of the box is that it can be sealed so that in the event of leak the chemicals will be contained. However, the box must be capable of being opened for access to the valves and then closed again with a tight seal. The box must be capable of being opened and closed repeatedly with a tight and reliable seal each time. By sealing the area around the valves, even minor leakage of chemicals will accumulate in sufficient quantity to set of an alarm such as a fiber optic alarm inside the container. The use of a valve manifold box protects employees from exposure to the chemicals and also saves the company money in the event of a leak due to the high cost of these concentrated chemicals. 
     The valve manifold boxes in use today obtain a seal by using a box with a lid that is secured by a large number of thumbscews. The thumbscrews must be tightened initially by hand and then tightened down with a screwdriver thus requiring at least two manual operations per screw. In some cases the number of thumbscrews can be as high as one hundred or more requiring a large number of manual operations. The labor time involved in undoing such large number of thumbscrews for access and then replacing and seating the thumbscrews for re-sealing is significant. When power driven screw drivers are used to speed up the process the incidence of stripped screws goes up significantly, with a concomitant potential loss of seal effectiveness. Moreover, the monotonous and repetitious task tempts workers to skip thumbscrews or to properly seat only some thumbscrews thereby compromising the integrity of the seal. When access is needed in an emergency or in a very short time span for process control, the access time can be excessive. Therefore, a need exists for a valve manifold box that can be opened and closed quickly while ensuring a strong seal. 
     The prior art focuses on apparatus and methods for controlling the transfer and flow of chemicals from one container such as a holding container to another such as a process system container. However, the prior art does not address the problem of enclosing a valve manifold system within a sealed container where the valves can be accessed and re-sealed with relative ease. For example, U.S. Pat. No. 5,607,000 to Cripe et. al., discloses a non-venting hazardous material dispensing system which does not address the problem of protecting the control valves in the piping network. U.S. Pat. No. 4,601,409 to DiRegolo discloses a system for dispensing liquid chemicals such as photoresist including a valve to govern the flow from the containers. Once again, the disclosure is directed to solving problems in the flow and process control and does not address the problem of protecting valves in the piping network. Therefore, while valve manifold boxes in various forms are in use the semi-conductor manufacturing industry, there is a need for valve manifold boxes that solve the problem of providing a sealed environment around the valves and that are also capable of being opened and closed repeatedly while maintaining the quality and integrity of the seal. 
     Therefore, a need exists for a container that can be opened and closed easily and routinely with a minimum number of manual operations while ensuring a seal which will prevent the escape of any possible leaked chemicals. 
     SUMMARY OF THE INVENTION 
     The present invention meeting the needs described above consists of a container with a lid and a box which fit together to form a tight seal by the closing of the latches located in the lid and the box. The seal is ensured by a lid having a continuous prong containing a gasket so that when the lid is placed on the box, the prong and gasket enter into a corresponding continuous groove in the box. The gasket first seats in the groove and then deforms to provide an expansive seal when pressure is created by a latch system using a hook and an anchor to pull a latch top and latch bottom together. Alternatively, the box can be constructed with a lid having a continuous blister and a box with a gasket placed over a corresponding continuous blister so that when the lid is pulled down onto the box by means of the latch system, the gasket is squeezed between the two continuous blisters to form a seal. The box can be used in any variety of ways by adapting the sealed environment to different processes. Any number of inlet pipes, outlet pipes, tubes or lines can be connected to the box and sealed. The container meets the need for a container that can be opened and closed numerous times while maintaining a consistent seal. The container also meets the need for a container in which the seal can be achieved without the necessity for a large number of manual operations such as seating of multiple thumbscrews. 
     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawing wherein like reference numbers represent like parts of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a perspective view of the container. 
     FIG. 2 shows an exploded view of the container with the lid raised. 
     FIG. 3 shows a cross section a section of the sealing system. 
     FIG. 4 shows a cross section of the sealing system with the gasket deformed. 
     FIG. 5 shows an alternative embodiment of the sealing system. 
     FIG. 6 shows a side view of a latch top. 
     FIG. 7 shows a side view of a latch top with the hook retracting. 
     FIG. 8 shows an interior view of the latch top and latch bottom. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows container  10  assembled with lid element  100  affixed to box element  200 . In FIG. 1 container  10  is assembled and closed. Lid  100  has first lid rails  110 , second lid rails  112 , top  120  and window  170 . First lid rails  110  are shown with latch wrench holes  150  and latch top hex screw holes  140 . Second lid side  112  also has wrench holes  150  and latch top hex screw holes  140 . Lid  100  has two handles  180  affixed to second lid rails  112 . Box element  200  has base  210 , first box walls  220 , second box walls  222 , first box rails  230 , and second box rails  232 . Container  10  can be used in any position. In the preferred embodiment container  10  is mounted on the wall of a room or building by affixing base  210  to a wall where base  210  is oriented so that first lid rails  110 , first box walls  220  and first box rails  230  are parallel to a level floor (not shown). In the preferred embodiment container  10  is a rectangular box with two long it(sides and two shorter sides; however container  10  could be made in any shape to accommodate the process supported by container  10 . 
     The structural components of lid  100 , first lid rails  110 , second lid rails  112 , top  120  and handles  180  are made from polyvinyl chloride. Polyvinyl chloride is used in lid  100  because of its strength and rigidity which provides a strong frame for window  170  made from ⅜ inch clear polyvinyl chloride. Polyvinyl chloride is further used in order to eliminate deformation of box  200  which is made of polypropylene, a less rigid material. In the preferred embodiment, the polyvinyl chloride used has a specific gravity of 1.30 to 1.58 and a tensile strength of 6000 PSI. Another suitable material is Polyvinylidene Chloride (CPVC). The structural components of box  200 , base  210 , first box walls  220 , second box walls  222 , first box rails  230 , and second box rails  232  are made from polypropylene. The box is made from polypropylene for several reasons. First, in order to introduce the piping network into the box access holes (not shown) must be cut in box and polypropylene is easier to cut. Second, use of polypropylene keeps the cost of the box down. While the polypropylene is not as rigid as the polyvinyl chloride, rigidity is imparted to container  10  by lid  100  when it is properly seated and affixed to box  200 . In the preferred embodiment, polypropylene with a specific gravity of 0.905 and a tensile strength of 5000 PSI is used. The specific gravity is important because the chemical resistance of the polypropylene improves with increasing molecular weight. 
     In an alternative embodiment first lid rails  110 , second lid rails  112 , top  120  handles  180 , base  210 , first box walls  220 , second box walls  222 , first box rails  230 , and second box rails  232  are made from stainless steel. 
     FIG. 2 shows container  10  in a exploded view with lid  100  raised above box  200 . Lid  100  has latch top cavities  160  for receiving latch tops  300 . Box element  200  has latch bottom cavities  260  for receiving latch bottoms  400 . Container  10  may be any size depending on the needs and the limitations imposed by the necessity of manually lifting lid element  100  on and off box element  200 . In the preferred embodiment, Latch top  300  and latch bottom  400  remain the same size for all variations of container  10 . Therefore, for larger versions of container  10  additional latch top cavities  160  and latch bottom cavities  260  may be necessary. Smaller versions of container  10  will require fewer latch top cavities  160  and latch bottom cavities  260 . To insure proper sealing of container  10  latch tops  300  and latch bottoms  400  should be positioned so that there is no more than 12 inches from center to center of adjacent latch tops  300  and adjacent latch bottoms  400 . Additionally, there should be no more than six inches from the center of latch tops  300  and latch bottoms  400  and the ends of first lid rails  110 , second lid rails  112 , first box rails  230  and second box rails  232 , respectively. 
     Latch top cavities  160  are cut from first lid rails  110  and second lid rails  112 . In the preferred embodiment latch wrench holes  150  are drilled 0.56 inches through the outer surface of first lid rails  110  and second lid rails  112  into latch top cavities  160  but do not extend into the rear walls of latch top cavities  160 . Latch top hex screw holes  140  are drilled and countersunk for ½-20 flat head screws for receiving hex screws (not shown) to secure top latch  300 . The rear wall of latch top cavities  160  are drilled and tapped ¼-20×½. Latch bottom cavities  260  are cut from first box rails  230  and second box rails  232 . Latch bottom hex screw holes  240  are drilled and countersunk for ½-20 flat head screws for receiving screws to secure top bottom  400 . The rear wall of latch bottom cavities  260  are drilled and tapped ¼-20×½. Additional fasteners are within the knowledge of persons skilled in the art. 
     Box element  200  has box rail top  270 , box rail ridge  280  and box rail groove  282 . Box rail ridge  280  extends continuously along box rail roof  270  parallel to first walls  220  and second walls  222  so that box rail ridge  280  extends continuously around the inside perimeter of box rail top  270 . In the preferred embodiment, when box rail ridge  270  extends from first rails  230  to second rails  232  the junction is curved. Box rail ridge  280  has box rail groove  282  extending continuously within box rail ridge  280 . Box rail groove wedge  284  extends continuously within box rail groove  282  and is centered in box rail groove  282 . 
     FIG. 3 shows a cross sectional view of that portion of lid  100  and box  200  which contain latch tops  300  and latch bottoms  400 . Top  120  is joined to first lid rail  110 . The same view would apply to top  120  joined to second lid rail  112 . The preferred method for bonding top  120  to first rails  110  and second rails  112  is by triple bead weld  132 . A triangular bead weld can be substituted for triple bead weld wherever a triple bead weld is called for. Top latch  300  is shown affixed within top latch cavity  160 . Prong  122  is molded into the bottom surface of top  120 . Prong  122  has prong outside wall  124 , prong inside wall  126  and prong wedge  128 . Gasket  190  is wedged between prong outside wall  124  and prong inside wall  126  so that it is held in place by friction and the force exerted by the compression of prong  190  against prong outside wall  124  and prong inside wall  126 . The preferred material for prong  190  is ethylene propylene rubber with a durometer rating of 60. Gasket  190  will not function with a durometer rating of less than 40 or greater than 70. Ethylene Propylene Rubber is used because it is especially suitable for environments with exposure to aggressive chemicals and because of its ability to deform and regain its shape when container  10  is closed and opened repeatedly. Butyl rubber is another appropriate material. Top latch  300  has casing  302 , hex nut  320 , inside hook  380 , outside hook  382  and trigger  370 . 
     The lower half of FIG.  3 . depicts a cross sectional view of box rail ridge  280  affixed to box rail  230 , and box wall  220 . The view of box rail ridge  280  affixed to box rail  232  and box wall  222  would be the same. Latch bottom  400  is shown affixed within latch bottom cavity  260 . Latch bottom  400  has latch bottom casing  402  and latch bottom bar  420 . Box rail ridge  280  is joined to box wall  220  with triple bead welds. A triangular bead weld can be substituted for triple bead weld wherever a triple bead weld is called for. Box rail groove  282  is rectangular in shape and has groove wedge  284 . 
     FIG.  4 . shows the same cross section as FIG. 3 when lid  100  is closed onto box  200 . Inside hook  380 , outside hook  382  and trigger  370  of latch top  300  have engaged latch bottom bar  420  and prong  122  and gasket  190  have entered box rail groove  282 . As top  120  approaches box rail ridge  280  gasket  190  deforms from pressure exerted by prong wedge  128  and groove wedge  284  so that the portion of gasket  190  extending beyond outside wall  126  and inside wall  124  spreads beneath outside wall  126  and inside wall  124  toward the sides of groove  282  forming a tight seal between top  120  and box rail ridge  280 . The optimum distance between the tip of prong wedge  126  and groove wedge  284  when lid  100  is closed onto box  200  is 0.110 inches with an allowable tolerance from 0.100 to 0.120 inches. 
     FIG. 5 depicts a cross sectional view of the stainless steel embodiment of container  10  in which top  120  has top blister  128 , box rail  280  has box rail blister  129  and rectangular gasket  192  is affixed over box rail blister  129 . Gasket  192  can be affixed to box rail  280  by screws inserted into gasket  192  and box rail  280 . Top blister  128  and box rail blister  129  run continuously around the perimeters formed by first lid rails  110 , second lid rails  112 , first box rails  230  and second box rails  232  respectively, and have square corners rather than rounded corners as in the polypropylene and polyvinyl chloride versions. 
     FIG. 6 depicts top latch  300  with casing  302 , first securement hole  310  and second securement hole  312 , indent  304 , hex nut  320  and outside hook  382 . Intermediate position  383  of outside hook  382  is shown by broken lines. In FIG. 7 top latch  300  is shown with outside hook  382  in its closed position. The start position  384  for outside hook  382  is shown by a broken line. When hex nut  320  is turned by means of a hex wrench (not shown) outside hook  382 , inside hook  380  and trigger  370  (see FIG. 8) will draw upward into casing  302 . Inside hook  380  and trigger  370  (see FIG. 8) are hidden by outside hook  382 . 
     FIG. 8 depicts an interior view of top latch  300  and bottom latch  400 . Outside hook  382  is removed so that trigger  370  and offset cam  340  can be seen. Trigger  370  rotates around pin  360  which is engaged to outside hook  382  and inside hook  380 . The fully retracted position  381  for inside hook  380  is shown by a broken line. When hex nut  320  is turned by means of a hex wrench (not shown) inside hook  380  and trigger  370  (outside hook  382  not shown) will rotate downward around the axis of hex nut  320  until trigger  370  strikes latch bottom bar  420 . When trigger  370  strikes latch bottom bar  420  further rotation of hex nut  320  will cause offset cam  340  to engage trigger  370  at which time further turning of hex nut  320  will cause the offset cam to lift inside hook  380  and outside hook  382  (not shown) upward into casing  302  pulling latch bottom bar  420  upward as well. Second cam  342  ensures a positive stop so that hex nut  320  cannot be over torqued and excessive pressure be brought to bear on latch bottom bar  420 . Therefore, when lid  100  is pulled together with box  200  by means of latch tops  300  and latch bottoms  400 , the positive stop feature prevents damage to container  10  and gasket  190 . In the preferred embodiment, latch top  300  is Southco, Inc. part number R5-0074-08 and latch bottom  400  is Southco, Inc. part number R5-0079-08 which are depicted as prior art in FIG.  8 . 
     It will be understood from the foregoing description that various modifications and changes may be made in the preferred embodiment of the present invention without departing from its true spirit. It is intended that this description is for purposes of illustration only and should not be construed in a limiting sense. The scope of this invention should be limited only by the language of the following claims.