Abstract:
Valve assembly comprising a valve base, a valve bonnet attached thereto, a rotatable valve stem extending coaxially through the valve bonnet, a rotatable valve handle attached to the valve stem and having a plane of rotation which is generally perpendicular to the axis of the valve stem, and an indicator tab attached to the valve base or the valve bonnet and extending outward from the valve body or valve bonnet in a direction generally parallel to the plane of rotation of the valve handle. The rotatable valve handle can be disposed in at least a first position and a second position, wherein the rotatable handle when disposed in the first position renders the indicator tab invisible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle, and wherein the rotatable handle when disposed in the second position renders the indicator tab visible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle.

Description:
BACKGROUND OF THE INVENTION 
     Gas manifolds having multiple valves for directing different gases to various destinations are widely used in analytical instrumentation, specialty gas blending, microelectronic component manufacture, and selected process industries. In some applications, gas manifold systems are highly automated and are operated by sophisticated computer control systems. In other applications, because of cost, safety, and/or reliability considerations, some or all of the valves in a gas manifold system are designed for manual or hand operation. In the manual operation of these manifolds, an operator must set the position of a plurality of valves correctly so that various gases flow to the proper end user, analytical instrument, or apparatus. Processes using these hand-operated manifolds typically are batch processes requiring a number of cyclically repeated steps, each of which requires a different set of manifold valve positions. Because operator error in some of these systems can cause significant economic losses and may result in serious safety hazards, careful attention to valve positions during critical operating steps is extremely important. 
     Various types of valve position indicators for gas manifold valves are widely available and usually indicate whether a valve is open or closed. Many of these are integrated with electric or pneumatic drive mechanisms and display the valve position by means of electrical or mechanical readout mechanisms which are integral parts of the valves. 
     In certain applications in which an operator requires valve position information for manual manifold valves, it is desirable to have simple valve position indicators that are not electrically or mechanically driven. It is also desirable to have valve position indicators that can be easily installed on and removed from standard valves not originally designed or manufactured with position indicators. The present invention, which is described below and defined by the claims that follow, provides a simple valve position indicator that can be attached to standard valves to serve as visual operator reminders of required valve positions. The invention also includes the use of multiple valve position indicators installed on a manifold system to remind operators of a plurality of required valve settings, in both open and closed positions, for critical process steps in multiple-step manufacturing operations. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention includes a detachable valve position indicator comprising an elongate tab having a first end and a second end, a first flexible member having a first and a second end, a second flexible member having a first and a second end, wherein the first end of the first flexible member and the first end of the second flexible member are attached to the first end of the elongate tab, a first connecting means attached to the second end of the first flexible member, and a second connecting means attached to the second end of the second flexible member. The first and second flexible members can be placed around a valve body, the first connecting means can be engaged with the second connecting means to attach the elongate tab to the valve body, and the first connecting means can be disengaged from the second connecting means to remove the elongate tab from the valve body. 
     The first and second flexible members may have a semicircular shape and may be generally coplanar with the elongate tab. The first and second connecting means may comprise opposing ratchet-toothed connection members each having ratchet teeth of opposite pitch angles which can be engaged by sliding the connection members circumferentially about the valve body, thereby attaching the elongate tab to the valve body, and which can be disengaged by sliding the ratchet teeth apart in directions perpendicular to the plane formed by the first and second flexible members and the elongate tab, thereby removing the elongate tab from the valve body. 
     The elongate tab typically has a first surface and a second surface, and one of the surfaces may include an area having a different color than the color of the first and second flexible members and the color of the first and second connecting means. The detachable valve position indicator may be made of material selected from the group consisting of a polymeric material, a metallic material, and combinations thereof. 
     The invention also includes a valve assembly comprising a valve base, a valve bonnet attached thereto, a rotatable valve stem extending coaxially through the valve bonnet, a rotatable valve handle attached to the valve stem and having a plane of rotation which is generally perpendicular to the axis of the valve stem, and an indicator tab attached to the valve base or the valve bonnet and extending outward from the valve body or valve bonnet in a direction generally parallel to the plane of rotation of the valve handle. The rotatable valve handle can be disposed in at least a first position and a second position, wherein the rotatable handle when disposed in the first position may render the indicator tab invisible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle, and wherein the rotatable handle when disposed in the second position may render the indicator tab visible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle. 
     The rotatable valve handle when disposed in the first position may allow the flow of a fluid through the valve base and when disposed in the second position may prohibit the flow of a fluid through the valve base. Alternatively, the rotatable valve handle when disposed in the first position may prohibit the flow of a fluid through the valve base and when disposed in the second position may allow the flow of a fluid through the valve base. The valve assembly may be characterized by a valve type selected from the group consisting of a ball valve, a butterfly valve, and a diaphragm valve. The first position and the second position of the rotatable valve handle may define a one-quarter turn of the valve stem. 
     In another embodiment, the invention is a method for determining a desired position of a handle of a valve comprising 
     (a) providing a valve assembly comprising a valve base, a valve bonnet attached thereto, a rotatable valve stem extending coaxially through the valve bonnet, a rotatable valve handle attached to the valve stem and having a plane of rotation which is generally perpendicular to the axis of the valve stem, and a moveable indicator tab attached to the valve base or the valve bonnet and extending outward from the valve body or valve bonnet in a direction generally parallel to the plane of rotation of the valve handle, wherein the rotatable valve handle can be disposed in at least a desired first position and an undesired second position; 
     (b) fixing the indicator tab in a circumferential position such that the rotatable handle when disposed in the desired first position renders the indicator tab invisible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle, and such that the rotatable handle when disposed in the undesired second position renders the indicator tab visible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle; and 
     (c) viewing the valve assembly in a direction generally perpendicular to the plane of rotation of the valve handle to determine whether the indicator tab is visible or invisible, thereby determining whether the valve handle is in the desired first position or the undesired second position. 
     The first position of the rotatable handle may prohibit the flow of a fluid through the valve base and the undesired second position of the rotatable handle may allow the flow of a fluid through the valve base. Alternatively, the desired first position of the rotatable handle may allow the flow of a fluid through the valve base and the undesired second position of the rotatable handle may prohibit the flow of a fluid through the valve base. 
     The invention includes a fluid manifold system comprising 
     (a) a plurality of valve assemblies, each valve assembly comprising a valve base, a valve bonnet attached thereto, a rotatable valve stem extending coaxially through the valve bonnet, a rotatable valve handle attached to the valve stem and having a plane of rotation which is generally perpendicular to the axis of the valve stem, and an indicator tab attached to the valve base or the valve bonnet and extending outward from the valve base or the valve bonnet in a direction generally parallel to the plane of rotation of the valve handle, wherein the rotatable valve handle can be disposed in at least a first position and a second position, wherein the rotatable handle when disposed in the first position renders the indicator tab invisible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle, and wherein the rotatable handle when disposed in the second position renders the indicator tab visible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle; and 
     (b) manifold piping means which interconnect the valve assemblies such that flow of fluid through the valve assemblies and manifold can be controlled by setting the positions of the rotatable handles of the valve assemblies. 
     The positions of the rotatable handles on a portion of the valve assemblies may be located such that some of the indicator tabs are visible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle. The positions of the rotatable handles on a portion of the valve assemblies may be located such that at least some of the indicator tabs are visible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle. The positions of the rotatable handles on all of the valve assemblies may be set such that none of the indicator tabs are visible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle. 
     The invention includes a method of operating a fluid manifold system comprising 
     (a) providing a fluid manifold system which includes 
     (1) a plurality of valve assemblies, each valve assembly comprising a valve base, a valve bonnet attached thereto, a rotatable valve stem extending coaxially through the valve bonnet, a rotatable valve handle attached to the valve stem and having a plane of rotation which is generally perpendicular to the axis of the valve stem, and an indicator tab attached to the valve base or the valve bonnet and extending outward from the valve base or valve bonnet in a direction generally parallel to the plane of rotation of the valve handle, wherein the rotatable valve handle can be disposed in at least a first position and a second position, and 
     (2) manifold piping means which interconnect the valve assemblies such that flow of fluid through the valve assemblies and manifold can be controlled by setting the positions of the rotatable handles on the valve assemblies; 
     (b) locating the indicator tab on each valve assembly such that the rotatable handle on each valve assembly when disposed in either the first position or in the second position renders the indicator tab invisible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle; 
     (c) moving valve handles on the valve assemblies such that the indicator tabs on at least a portion of the valve assemblies are visible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle; and 
     (d) identifying the valve assemblies which have visible indicator tabs when viewed in a direction generally perpendicular to the plane of rotation of the valve handle and moving the valve handles on the valve assemblies so identified such that all indicator tabs on all valve assemblies are invisible when viewed in a direction generally perpendicular to the plane of rotation of the valve handle. 
    
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
     FIGS. 1A and 1B show views of a valve in an open position with an exemplary valve position indicator of the present invention. 
     FIGS. 2A and 2B show views of the valve in FIGS. 1A and 1B in a closed position. 
     FIG. 3 is an exemplary removable valve position indicator of the present invention. 
     FIG. 4 is a schematic flow diagram of an exemplary gas manifold system. 
     FIG. 5 is a schematic view of a gas manifold control panel showing valves in various positions for an exemplary process step using valve position indicators of the present invention. 
     FIG. 6 is a schematic view of the gas manifold control panel showing valves in various positions for an alternative exemplary process step using valve position indicators of the present invention. 
     FIG. 7 is a schematic view of the gas manifold control panel showing valves in various positions for another alternative exemplary process step using valve position indicators of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to valve position indicators and the use of these valve position indicators to assist operators in setting the proper valve positions on fluid manifolds during critical process steps. The invention provides simple valve position indicators that can be attached to standard valves to serve as a visual operator reminder of required valve positions. The invention also includes the use of multiple valve position indicators installed on a manifold system to alert operators to a plurality of required valve settings, in both open and closed positions, for critical process steps in multiple-step manufacturing operations. Embodiments of the invention may be for directing the flow of gases or liquids. 
     An exemplary valve assembly is illustrated in top and side views in FIGS. 1A and 1B respectively. Valve assembly  1  includes valve base  3 , threaded bonnet section  5 , bonnet base  6 , bonnet or packing nut  7 , valve stem  9 , and handle  11 . The exemplary valve as illustrated is a two-way, quarter-turn shutoff valve shown in the open position which allows fluid (gas or liquid) to flow from valve inlet  13  to valve outlet  15 . 
     The valve is defined by the valve base  3 , threaded bonnet section  5 , bonnet base  6 , bonnet or packing nut  7 , valve stem  9 , and handle  11 . The valve body is defined by non-movable parts including valve base  3 , threaded bonnet section  5 , bonnet base  6 , and bonnet or packing nut  7 . The interior of valve base  3  includes inlet and outlet ports and a valve seat (not shown). The valve bonnet is defined by threaded bonnet section  5 , bonnet base  6 , and bonnet or packing nut  7 . 
     Removable position indicator  17  fits tightly around threaded bonnet section  5  and has elongate tab or position indicator tab  19  that generally extends beyond the outer edge of valve base  3  and is visible in top view when valve handle  11  is in the open position. The top view is a view in a direction parallel to the axis of the valve stem and generally perpendicular to the plane of rotation of the valve handle. Position indicator tab  19  is generally parallel to the plane of rotation of handle  11 . 
     FIGS. 2A and 2B shows the valve and position indicator of FIGS. 1A and 1B when the valve is in the closed position. It is seen that handle  11  covers elongate tab or indicator tab  19  of removable position indicator  17  such that indicator tab  19  is not visible when viewed in a direction generally parallel to the axis of the valve stem or generally perpendicular to the plane of rotation of the valve handle. 
     Position indicator  17  is installed on the valve so that indicator tab  19  indicates a preferred handle position and gives a person operating the valve a quick visual check on the preferred position of the valve handle. If the operator can see indicator tab  19 , valve handle  11  is not in the preferred position. In FIGS. 1A,  1 B,  2 A, and  2 B, the preferred position of the handle is the off position wherein no fluid can flow through the valve. As explained later, the preferred position is defined by critical process steps in which the valve must be in the correct position to eliminate costly process errors or potential hazards to personnel at a downstream location. Some or all of the upper surface of indicator tab  19  may be coated with a bright color, such as fluorescent orange, to assist an operator in a quick visual check of the valve handle position. If the operator sees the tab when a critical process step is about to begin, it becomes a quick reminder to move the valve handle to the closed or off position. During non-critical process steps, the valve may be in the correct position when open, and in this case the tab would be visible. 
     FIGS. 1A,  1 B,  2 A, and  2 B show the preferred valve position as the closed position. Alternatively, the preferred valve position may be the open position. In this alternative, position indicator  17  is installed on the valve so that indicator tab  19  is parallel (not shown) to outlet line  15  and is not visible when the valve is open. If the operator sees the tab when a critical process step is about to begin, it becomes a quick reminder to open the valve. During non-critical process steps, the valve may be in the correct position when closed. 
     Position indicator  17  may be readily installed or removed as needed and is not necessarily a permanent part of the valve. It may be installed on any fixed part of the valve, such as the threaded bonnet section  5  as illustrated in FIGS. 1A,  1 B,  2 A, and  2 B. Alternatively, it could be installed on bonnet base  6 , bonnet nut  7 , or even on valve base  3 . It is generally preferred that the position indicator be installed as close as possible to handle  11  while allowing an appropriate gap for an operator to turn the handle without contacting indicator tab  19 . As described later, it is desirable that the installation of the position indicator be simple and require standard tools. 
     The position indicator may be installed on any type of valve which is operated with a rotary handle in one of at least two fixed positions. The valve illustrated in FIGS. 1A,  1 B,  2 A, and  2 B, for example, is an on/off quarter turn valve and can be any type of commercially available valve. Valves used in this service may include ball, butterfly, or diaphragm type valves. 
     Use of the position indicator is not limited to the two-way on/off valve described above and may be used to indicate a preferred handle position for any type of flow diversion or shutoff valve which uses multiple handle positions. For example, three-way port valves are available having three inlet/outlet ports in which one handle position allows flow between a first port and a second port while blocking a third port, another handle position directs flow between the second port and the third port while blocking the first port, and another handle position which blocks all three ports. In this example, any one of the three handle positions could be the preferred handle position designated by a position indicator of the type disclosed herein. 
     An exemplary type of position indicator as used in FIGS. 1A,  1 B,  2 A, and  2 B is illustrated by the position indicator tab assembly of FIG.  3 . Elongate tab or indicator tab  19  is connected to first flexible member  21  and second flexible member  23 . First flexible member  21  in turn is connected to ratchet-toothed connection member  25  having ratchet member  26  with ratchet teeth  27  and flexible spring member  29 . Second flexible member  23  is connected to ratchet-toothed connection member  31  having ratchet member  32  and ratchet teeth  33  and flexible spring member  35 . 
     Spring members  29  and  35  press ratchet teeth  27  and  33  together in a radial direction while the ratchet teeth are engaged by pressing and moving ratchet-toothed connection members  25  and  31  together in a circumferential direction. The ratchet teeth  27  and  33  have opposite pitch angles and lock together as ratchet-toothed connection members  25  and  31  are moved together circumferentially. Flexible members  21  and  23  along with flexible spring member  35  firmly grasp the valve bonnet as illustrated in FIGS. 1A,  1 B,  2 A, and  2 B. The engaged ratchet teeth can be readily disengaged by pulling ratchet member  26  in an upward axial direction while bending flexible member  21  and pushing ratchet member  32  in a downward axial direction while bending flexible member  23 . The position indicator can be reused as desired. 
     The actual dimensions of the various parts of the position indicator of FIG. 3 may be varied and are determined by the dimensions of the valve upon which the position indicator is installed. The position indicator parts may be fabricated of any appropriate material and preferably are made of flexible material, particularly flexible members  21  and  23 . The entire position indicator may be fabricated from a polymeric material, such as, for example, nylon, polypropylene, or high density polyethylene. Alternatively, metal of the appropriate flexibility may be used, and combinations of polymeric material and metal may be used if desired. 
     While the ratchet mechanism illustrated in FIG. 3 is a simple and preferred connecting means for connecting the ends of flexible members  21  and  23 , any other connecting means may be used. For example, snap mechanisms, worm clamps, screw clamps, lever-type locking mechanisms, or mating pieces of Velcro® could be attached to the ends of flexible members  21  and  23  and engaged to install the position indicator on a valve. 
     Alternatives to the use of the position indicator tab assembly of FIG. 3 are possible for attaching an indicator tab to a valve. For example, an indicator tab could be attached to a closed ring sized to fit over threaded bonnet  5  (FIG. 1B) wherein the ring has a set screw to fix the position of the ring on the bonnet. Alternatively, the closed ring could be hexagonally-shaped and sized to fit over bonnet nut  7  (FIG. 1B) wherein the ring has a set screw to fix the position of the ring on the bonnet nut. Installation of these alternative assemblies would require removing and reinstalling valve handle  11 . 
     In the above embodiments, the various types of position indicator tab assemblies are designed to be attachable to and detachable from standard valves which are not equipped with any position indicators. If desired, however, a moveable indicator tab could be designed as an integral part of a valve such that the position of the indicator tab could be changed as required. This tab would be used in the same manner as the removable indicator tabs described above. 
     The use of the valve position indicators is illustrated with reference to the schematic flow diagram of a gas cabinet and manifold shown in FIG.  4 . In this example, gas cabinet  401  encloses gas cylinders  403  and  405  equipped with shutoff valves  407  and  409 , respectively, and with pressure regulators  411  and  413 , respectively. The manifold system includes line  415 , valve assembly  417 , line  419 , valve assembly  421 , and line  423  through which contents of cylinder  403  can be delivered to user  1 . The manifold system also includes line  425 , valve assembly  427 , line  429 , valve assembly  431 , and line  433  through which contents of cylinder  405  can be delivered to user  3 . Lines  419  and  429  are connected by crossover line  435  with valve assembly  437 . Line  439 , valve assembly  441 , and line  443  deliver gas to user  2 . The manifold system can be evacuated via line  445  and valve assembly  447 . Purge gas can be introduced into the manifold system via line  449 , valve assembly  451 , and line  453 . Valve assemblies  417 ,  421 ,  427 ,  431 ,  437 ,  441 ,  447 , and  451  are two-way quarter-turn valves fitted with position indicators as described above with reference to FIGS. 1A,  1 B,  2 A, and  2 B. 
     The manifold system in this example may be operated in three modes. In a first mode, the manifold is evacuated via line  445  and open valve assembly  447 . In this first mode, valve assembly  437  is open and valve assemblies  417 ,  421 ,  427 ,  431 , and  457  are closed. In a second mode, the manifold and lines  423 ,  433 , and  443  to downstream users  1 ,  2 , and  3  are purged with purge gas supplied via line  449 , valve assembly  451 , and line  453 . In this second mode, valve assemblies  421 ,  431 ,  437 ,  441 , and  451  are open while valve assemblies  417 ,  427 , and  447  are closed. In a third mode, gas from cylinder  403  is delivered to users  1  and  2  while gas from cylinder  405  is delivered to user  3 . In this third mode, valve assemblies  417 ,  421 ,  427 ,  431 , and  441  are open while valve assemblies  437 ,  447 , and  451  are closed. 
     The first and second modes of operation may be described as non-critical operating modes wherein an operator error in placing the valves in the prescribed open and closed positions will not cause serious process or safety problems for downstream users  1 ,  2 , and  3 . The third mode of operation may be described as a critical operating mode wherein an operator error in placing the valves in the prescribed open and closed positions will cause serious process or safety problems for downstream users  1 ,  2 , and  3 . Thus the positions of the valves in the third mode of operation are critical and the valve position indicators are located on the valves such that the operator can tell immediately by a visual check whether any of the valves are in the wrong position. 
     A schematic sketch of the manifold, valves, and valve position indicators for the first non-critical mode of operation is shown in FIG.  5 . This manifold is mounted vertically or near vertically such that the operator views the manifold as it appears in FIG. 5, that is, from the front. The operator&#39;s view of each valve assembly is in a direction generally parallel to the axis of the valve stem and generally perpendicular to the plane of rotation of the valve handle. The term “generally perpendicular to the plane of rotation of the valve handle” means that the operator may view any given valve and valve position indicator in a direction perpendicular to the plane of rotation of the valve handle or at an angle of less than about 45 degrees from a direction perpendicular to the plane of rotation of the valve handle. The location of the valves and lines in FIG. 5 correspond to those of FIG.  4 . It is seen that valve assemblies  437  and  447  are open while the other valves are closed, and that valve position indicator tabs  418 ,  422 ,  428 ,  432 ,  438 ,  442 , and  448  are visible. The valve position indicator tab on valve assembly  451  is hidden by handle  454  and therefore is not visible to the operator. Since this mode of operation is non-critical, the operator will not be concerned that many of the valve position indicator tabs are visible. 
     A schematic sketch of the manifold, valves, and valve position indicators for the second non-critical mode of operation is shown in FIG.  6 . As in FIG. 5, the manifold is mounted vertically and the location of the valve assemblies and lines correspond to those of FIG. 5; the operator views the manifold as it is seen in FIG.  6 . It is seen that valve assemblies  421 ,  431 ,  437 ,  441 , and  451  are open while the other valves are closed. Valve position indicator tabs  418 ,  428 ,  438 , and  452  are visible in this mode of operation. The valve position indicator tabs on valve assemblies  421 ,  431 ,  441 , and  447  are hidden by handles  424 ,  434 ,  444 , and  450 , respectively, and therefore are not visible to the operator. Since this mode of operation is non-critical, the operator will not be concerned that many of the valve position indicator tabs are visible. 
     A schematic sketch of the manifold, valves, and valve position indicators for the critical mode of operation is shown in FIG.  7 . As in FIG. 6, the manifold is mounted vertically and the location of the valve assemblies and lines correspond to those of FIG.  6 ; the operator views the manifold as seen in FIG.  7 . It is seen that valve assemblies  417 ,  421 ,  427 ,  431 , and  441  are open while the other valves are closed. No valve position indicator tabs are visible to the operator in this mode of operation because the valve position indicator tabs on all valves are hidden by the respective valve handles. Since this mode of operation is critical, the operator will be concerned if any of the valve position indicator tabs are visible. A quick visual check will remind the operator immediately if any of the valve handles are in the wrong positions. This visual check does not require the operator to consider whether specific valves are open or closed, but simply to consider if any valve handle is in the wrong position and should be moved to the correct position. 
     The method of the present invention is a valuable tool and guide for an operator of a group of fluid manifolds, each of which utilizes multiple manually-operated valves and proceeds through multiple process steps with multiple valve positions. The invention provides a simple, quick, visual guide for the operator to ensure that all valves are in the proper positions (e.g., open or closed) for critical process steps. The method is especially useful for operators who are responsible for a large number of manifold systems in a manufacturing environment where errors in valve settings could cause economic damage to products or equipment, or hazards to persons associated with these products or equipment. The method is applicable, for example, in a semiconductor fabrication facility in which a large number of multi-valve gas manifolds with manually-operated valves are utilized to supply hazardous reactant gases to numerous process tools.