Abstract:
A water supply failure protection valve is connected to hot and cold water supplies. The failure protection valve is responsive to the loss of cold water supply pressure to shut off all water flow. The failure protection valve is responsive to the loss of hot water supply pressure to permit cold water flow through both a cold water flow path and a hot water flow path so as to ensure a substantial flow of water to a downstream fixture. The supply failure protection valve may be integrated with a thermal mixing valve to provide water at a preselected temperature.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates generally to a fluid supply failure protection valve and more particularly to a protection valve which safely accommodates failure of either a hot or a cold water supply to a tempering valve. 
   Tempered fluid mixing systems are used in a variety of commercial and/or industrial applications, for example, in emergency fixtures such as drench shower stations and/or safety eyewash stations, which are used to rinse hazardous chemicals from a person&#39;s skin and clothing or to extinguish burning clothing on a person. A typical system includes a thermostatic mixing valve or tempering valve which automatically blends hot and cold water supply streams to produce a mixed, tempered water output stream having a selected temperature, for example about 27 degrees C. (80 degrees F.). 
   A known problem with such tempered water mixing systems is that either the hot or cold water supplies may fail. If the cold water supply fails, the mixing valve will supply potentially scalding hot water to the user, causing the risk of burns and further injury. If the hot water supply fails, it is possible to continue using the emergency fixture. However, in this case, only cold water will be supplied to the thermostatic mixing valve, which will cause it to restrict the water flow to a level that is inadequate for proper rinsing or fire extinguishing. Attempts have been made in the prior art to provide for the cut-off of hot water flow in case of a cold water failure, and to provide a bypass flow of cold water should the hot water supply fail. However, these prior art systems require either that the tempering valve be replaced with a tempering valve of an entirely different design, for both tempering the water and accommodating the supply failure, or they require that a separate cold water bypass circuit be plumbed into the system. Accordingly, there is a need for fluid supply failure protection valve which protects a fluid system from failure of both hot and cold water supplies, and which may be integrated into existing systems. 
   BRIEF SUMMARY OF THE INVENTION 
   Therefore, it is an object of the invention to provide a fluid supply failure protection valve which provides an adequate flow under all possible conditions. 
   It is another object of the invention to provide a fluid supply failure protection valve which may be simply retrofitted into existing tempered fluid supply systems. 
   It is another object of the invention to provide a fluid supply failure protection valve which is responsive to a loss of cold fluid supply pressure to shut off all fluid flow. 
   It is another object of the invention to provide a fluid supply failure protection valve which is responsive to a loss of hot fluid supply pressure to provide a substantial flow of cold fluid through both hot and cold fluid flow paths. 
   These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing a supply failure protection valve which includes a housing defining a first fluid inlet in fluid communication with a spaced-apart first fluid port, and a second fluid inlet in fluid communication with a spaced-apart second fluid port. First valve means permit flow communication between the first fluid inlet and the first fluid port in the presence of fluid pressure in the second fluid inlet, and prevent communication between the first fluid inlet and the first fluid port in response to an absence of fluid pressure in the second fluid inlet. Second valve means for preventing the flow of fluid from the second fluid inlet to the first fluid port in the presence of fluid pressure in the first fluid inlet, and for permitting flow communication from the second fluid inlet to both of the first and second fluid ports in response to the absence of supply pressure in the first fluid inlet. 
   In another embodiment of the present invention, the first valve means includes a hollow, open-ended valve sleeve disposed in a bore formed in the housing, the bore being in fluid communication with the first and second fluid inlets. The valve sleeve is movable between a first position wherein flow from the first fluid inlet to the first fluid port is permitted, and a second position wherein flow from the first fluid inlet to the first fluid port is blocked. 
   In another embodiment of the present invention, the second valve means includes a piston disposed inside the valve sleeve. The piston is movable between a closed position wherein flow from the second fluid inlet to the first fluid port is blocked, and an open position wherein flow from the first fluid inlet to the second fluid port is permitted. 
   In another embodiment of the present invention, the supply failure protection valve includes first biasing means for urging the valve sleeve towards the first position. 
   In another embodiment of the present invention, the supply failure protection valve includes second biasing means for urging the piston towards the closed position. 
   In another embodiment of the present invention, the supply failure protection valve includes a first check valve disposed in the first fluid inlet. The first check valve allows flow from the first fluid inlet to the bore but prevents flow in the opposite direction. 
   In another embodiment of the present invention, the supply failure protection valve includes a second check valve disposed in the second fluid port. The second check valve allows flow from the bore to the second fluid port but prevents flow in the opposite direction. 
   In another embodiment of the present invention, a fluid supply failure protection valve includes: a housing having a bore with upper and lower portions formed therein; a cold fluid inlet for receiving a fluid at a first temperature, and a hot fluid inlet for receiving a fluid at a second temperature greater than the first temperature. The hot fluid inlet has a hot fluid check valve disposed therein which allows flow from the hot fluid inlet to the bore but prevents flow in the opposite direction. A hot fluid port is spaced-apart from the hot fluid inlet and connected in flow communication with the hot fluid inlet. A cold fluid port is spaced-apart from the cold fluid inlet and connected in flow communication with the cold fluid inlet. A hollow sleeve disposed in the bore, the sleeve having open upper and lower ends, and a plurality of side ports formed through the lateral surfaces thereof, the side ports forming a transverse flow path through the sleeve. The sleeve is movable between a first position which permits flow communication between the hot fluid inlet and the hot fluid port, and a second position in which flow communication between the hot fluid inlet and the hot fluid port is blocked;
         an upper biasing means is disposed in the bore above the sleeve, so as to urge the sleeve towards the first position. A piston is disposed in the sleeve, and is movable between a closed position in which the flow of fluid from the cold fluid inlet to the hot fluid port is blocked, and an open position in which flow communication is permitted from the cold fluid inlet to both of the hot and cold fluid ports. A lower biasing means is disposed in the sleeve between the lower end of the sleeve and the lower face of the piston, and urges the piston towards the open position.       

   The sleeve moves to the first position in the presence of fluid pressure in the cold fluid inlet, and moves to the second position in absence of fluid pressure in the cold fluid inlet, and the piston moves to the closed position in the presence of fluid pressure in the hot fluid inlet, and moves to the open position in response to the absence of fluid pressure in the hot fluid inlet. 
   In another embodiment of the present invention, the supply failure protection valve includes a cold fluid check valve disposed in the cold fluid port which allows flow from the bore to the cold fluid port but prevents flow in the opposite direction. 
   In another embodiment of the present invention, the supply failure protection valve has an upper face carrying an upper seal, a lower face carrying a lower seal, and a narrow central member connecting the upper and lower faces. 
   In another embodiment of the present invention, the upper biasing means includes a coil spring. 
   In another embodiment of the present invention, the lower biasing means includes a coil spring. 
   In another embodiment of the present invention, the upper biasing means comprises a surface area at the upper end of the sleeve which is greater than an opposing surface area at the lower end of the sleeve. 
   In another embodiment of the present invention, the supply failure protection valve includes a bypass passage providing flow communication between the hot fluid inlet upstream of the hot fluid check valve and the lower portion of the bore. 
   In another embodiment of the present invention, a valve assembly for receiving hot and cold water streams and providing a mixed output stream at a preselected temperature includes a tempering valve, having: a housing defining a cold fluid port, a hot fluid port, an outlet port, a cold fluid inlet for receiving a fluid at a first temperature, a hot fluid inlet for receiving a fluid at a second temperature greater than the first temperature, a first bore and a second bore having upper and lower portions, wherein the hot fluid inlet has a hot fluid check valve disposed therein which allows flow from the hot fluid inlet to the second bore but prevents flow in the opposite direction. A cylinder is disposed in the first bore in fluid communication with the cold fluid port, the hot fluid port, and the outlet port, the cylinder having upper and lower sealing edges and a cylinder seal which prevents fluid communication between the hot and cold water ports. 
   A temperature-responsive element is connected to the cylinder and is operative to move the cylinder so as to control the relative proportions of flow from the hot and cold water ports to the outlet port for maintaining a preselected fluid temperature. A fluid supply failure protection valve includes: a hollow sleeve disposed in the second bore, the sleeve having open upper and lower ends, and a plurality of side ports formed through the lateral surfaces thereof, the side ports forming a transverse flow path through the sleeve, the sleeve movable between a first position which permits flow communication between the hot fluid inlet and the hot fluid port, and a second position in which flow communication between the hot fluid inlet and the hot fluid port is blocked. 
   An upper biasing means is disposed in the bore above the sleeve, so as to urge the sleeve towards the first position. A piston is disposed in the sleeve, the piston movable between a closed position in which the flow of fluid from the cold fluid inlet to the hot fluid port is blocked and an open position in which flow communication is permitted from the cold fluid inlet to both of the hot and cold fluid ports. A lower biasing means is disposed in the sleeve between the lower end of the sleeve and the lower face of the piston, the spring urging the piston towards the open position. 
   The sleeve moves to the first position in the presence of fluid pressure in the cold fluid inlet, and moves to the second position in absence of fluid pressure in the cold fluid inlet, and the piston moves to the closed position in the presence of fluid pressure in the hot fluid inlet, and moves to the open position in response to the absence of fluid pressure in the hot fluid inlet. 
   In another embodiment of the present invention, the valve assembly includes a cold fluid check valve disposed in the cold fluid port which allows flow from the bore to the cold fluid port but prevents flow in the opposite direction. 
   In another embodiment of the present invention, the valve assembly includes a movable adjusting stem disposed in the housing which contacts the temperature-responsive element at a preselected position. 
   In another embodiment of the present invention, the piston has an upper face carrying an upper seal, a lower face carrying a lower seal, and a narrow central member connecting the upper and lower faces. 
   The present invention and its advantages over the prior art will become apparent upon reading the following detailed description and the appended claims with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which: 
       FIG. 1  is a cross-sectional view of an exemplary tempering valve including a supply failure protection valve constructed in accordance with the present invention, during a normal operating condition; 
       FIG. 2  is a view of the valve of  FIG. 1 , during a condition in which the hot fluid supply has failed; 
       FIG. 3  is a view of the valve of  FIG. 1 , during a condition in which the cold fluid supply has failed; and 
       FIG. 4  is a cross-sectional view of an alternative embodiment of the supply failure protection valve. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views,  FIG. 1  illustrates an exemplary fluid supply failure protection valve  10  constructed in accordance with the present invention. It should be noted that the present invention is equally applicable to systems which handle fluids other than water, and therefore the terms “water” and “fluid” are used interchangeably herein when describing the invention. In this embodiment, the supply failure protection valve  10  is combined with a known type of tempering valve  12  in a common housing  14 . The tempering valve  12  includes a hot fluid port  16 , a cold fluid port  18 , and an outlet port  20 . A hollow cylinder  22  with circumferential upper and lower sealing edges  24  and  26  is disposed in a first bore  28  in fluid communication with the hot water, cold water, and outlet ports  16 ,  18 , and  20 . A cylinder seal  30  prevents leakage between the hot and cold water ports  16  and  18 . A temperature-responsive element  32  is located inside the cylinder  22  and connected to the cylinder  22  by a circumferential array of struts  34 . For illustrative clarity only one such strut  34  is shown in  FIGS. 1 ,  2 , and  3 . In this example the temperature-responsive element  32  is a known type of thermomechanical unit such as a sealed, wax-filled capsule having upper and lower ends  36  and  38 . However, any other type of device capable of moving the cylinder  22  in response to a temperature change may be used. A return spring  40  is disposed between the lower end  38  of the temperature-responsive element  32  and a seat  42  located at the bottom of the first bore  28 . A threaded adjusting stem  44  is mounted in the housing  14 , for example in a removable adjuster cap  46 . The adjusting stem  44  is hollow and has an overtravel spring  48  disposed therein. The overtravel spring  48  is held in by a flat disk  50  and a retaining ring  52  at its lower end. 
   The tempering valve  12  operates as follows: Water flows into the tempering valve  12  through both the hot and cold ports  16  and  18 . It flows past the upper and lower sealing edges  24  and  26  of the cylinder  22 , past the temperature-responsive element  32 , and through the outlet port  20 . At temperatures below a selected metering range, the cylinder  22  is urged upward by the return spring  40  so that the upper sealing edge  24  contacts an upper sealing surface  54 . Therefore, most of the flow of water will be from the hot fluid port  16 , past the lower sealing edge  26 , and into the outlet port  20 . As the temperature increases, the temperature-responsive element  32  expands upward until a pin  56  protruding from the upper end  36  of the temperature-responsive element  32  contacts the disk  50 . Further expansion of the temperature-responsive element  32  causes it to displace the cylinder  22  downward, opening a flow path between the upper sealing edge  24  and the upper sealing surface  54 , simultaneously reducing the size of the flow path beneath the lower sealing edge  26 . As the temperature further increases, the cylinder is finally moved all the way to its lowest position in which the lower sealing edge  26  contacts a lower sealing surface  58 , thus cutting off all hot water flow. The temperature of the mixed water can be selected by moving the adjusting screw  44  up or down, which changes the distance the pin  56  must move before it contacts the disk  50 . Under normal operation, the disk  50  does not move, However, if the tempering valve  12  should be heated beyond its intended operating range, the excess force generated by the temperature-responsive element  32  will displace the disk  50  and compress the overtravel spring  48 . This prevents damage to the temperature-responsive element  32 . 
   The failure protection valve  10  includes a second bore  60  formed in the housing  14 . The upper portion  62  of the second bore  60  is in fluid communication with the cold fluid port  18  and a cold fluid inlet  64 , while the lower portion  66  of the second bore  60  is in fluid communication with the hot fluid port  16  and a hot fluid inlet  68 . A cold fluid check valve  70  is disposed in the cold fluid port  18  and allows flow to pass from the second bore  60  to the cold fluid port  18 , but prevents flow in the opposite direction. A hot fluid check valve  72  is disposed in the hot fluid inlet  68  and allows flow to pass from the hot fluid inlet  68  to the second bore  60  but prevents flow in the opposite direction. 
   A cylindrical, hollow valve sleeve  74  having open upper and lower ends  76  and  78  slides in the second bore  60 , sealed by first and second sleeve seals  80  and  82 , such as O-rings of a known type. A circumferential array of side ports  84  are formed in the lateral surfaces of the valve sleeve  74  near its upper end  76  and define a transverse flow path through the valve sleeve  74 . The valve sleeve  74  is biased downward by an upper bias means  86 , which in this case is shown as a spring which is retained by a threaded spring cap  88 . The upper bias means  86  may also take the form of an unbalanced surface area incorporated into the sleeve  74 , as described more fully below with respect to the alternative embodiment shown in  FIG. 4A  piston  90  is disposed in the interior of the valve sleeve  74 . The piston  90  has an upper face  92  with an upper seal  94 , and a lower face  96  with a lower seal  98 . The upper and lower faces  92  and  96  are connected by a narrow central member  100 . A lower bias spring  102  is disposed in the valve sleeve  74  and extends between the lower face  96  of the piston  90  and a retainer  104  having an opening  106  formed therein. The piston  90  is urged upwards by the lower bias spring  102  so that the upper seal  94  seals against a ledge  108  in the valve sleeve  74 . 
     FIG. 1  depicts the operation of the supply failure protection valve  10  during normal operation, that is, when both the hot and cold water supplies (denoted “H” and “C” respectively in  FIG. 1 ) are operating. Cold water from the cold water supply C passes through the cold fluid inlet  64 , passes through the second bore  60 , into the cold fluid port  18 , thorough the cold fluid check valve  70 , and finally into the tempering valve  12 . Hot water from the hot water supply H passes through the hot fluid inlet  68 . Some of the hot water flow passes through the hot fluid check valve  72 , through the side ports  84 , around the central member  100  of the piston  90 , through the hot fluid port  16 , and into the tempering valve  12 . Optionally, some of the hot water flow from the hot fluid inlet  68  is diverted, before it passes through the hot fluid check valve  72 , into a bypass passage  110 . This bypass flow acts on the bottom end  78  of the valve sleeve  74  and on the lower face  96  of the piston  90 . Alternatively, if the bypass passage  110  is not used, a flow path from the hot water inlet  68  to the bottom end  78  of the valve sleeve  74  and the lower face  96  of the piston  90  may be created by eliminating the lower seal  98  and the second sleeve seal  82 . In either arrangement, because the supply pressures of the hot and cold water are approximately equal, the pressure of the hot water plus the preload of the lower bias spring  102  will keep the piston  90  sealed in its upper (or closed) position and prevent the leakage of cold water into the hot water flow path, while the pressure of the cold water plus the load of the upper bias means  86  will keep the sleeve  74  seated in its lower position, where it permits hot water to flow from the hot fluid inlet  68  to the hot fluid port  16 . 
     FIG. 2  shows the operation of the supply failure protection valve  10  in a condition where the hot water supply H has failed. In the absence of the supply failure protection valve  10 , tempering valve  12  would still be supplied with cold water through the normal cold water flowpath when the hot water supply fails. However, the cold water would be substantially below the temperature set point of the tempering valve  12 , and this would cause the tempering valve to greatly restrict the flow of cold water, to a level insufficient to provide adequate flow for a downstream fixture. 
   In contrast, in the supply failure protection valve  10 , when the hot water supply H fails, the pressure on the lower face  96  of the piston  90  is relieved. The pressure on the upper face  92  of the piston  90  is sufficient to compress the lower bias spring  102  and push the piston  90  down to an open position so that the upper seal  94  is unseated and a flowpath is open from the cold fluid inlet  64 , downwards through the second bore  60 , and through the hot fluid port  16  into the tempering valve  12 . If the bypass passage  110  is present, it provides a flowpath from the interior of the valve sleeve  74  to the hot fluid inlet  68  (now at zero pressure) upstream of the hot fluid check valve  72 . This allows any residual hot water which may be contained in the lower end  78  of the valve sleeve  74  to be expelled so the piston  90  can move down as intended. In the absence of the bypass passage  110 , the lower seal  98  and the second sleeve seal  82  may be eliminated as described above, which allows any residual hot water to simply flow out between the sleeve  74  and the second bore  60 , in turn permitting the piston  90  to move down. 
   In this position, cold water flows to the tempering valve  12  through both the hot fluid port  16  and the cold fluid port  18 . The hot fluid check valve  72  prevents cold water from backing up into the hot water inlet  68 . Thus, no matter what the position of the tempering valve cylinder  22 , an adequate flow of cold water will flow out of the outlet port  20 . 
     FIG. 3  shows the operation of the supply failure protection valve  10  in a condition where the cold water supply C has failed. In this case, the pressure on the upper face  92  of the piston  90  and the upper end  76  of the valve sleeve  74  falls to zero. The hot water pressure acting on the lower face  96  of the piston  90  and the lower end  78  of the valve sleeve  74  will force the valve sleeve  74  upward, overcoming the upper bias means  86 . In this position, the side ports  84  are no longer exposed, and the valve sleeve  74  blocks off flow from the hot fluid inlet  68  to the hot fluid port  16 . The cold fluid check valve  70  keeps any residual hot water pressure from backing up through the cold water port into the cold water supply C before the hot water flow is fully shut off. In this position, no water can flow through the tempering valve  12 . Therefore, any chance of scalding is prevented. 
     FIG. 4  shows an alternative embodiment  210  of the supply failure protection valve. The supply failure protection valve  210  is substantially similar to the supply failure protection valve  10  described above. It differs in that the supply failure protection valve  210  is contained in its own individual housing  214 , and is not combined with a tempering valve. A central bore  260  is formed in the housing  214 . The upper portion  262  of the central bore  260  is in fluid communication with a cold fluid port  218  and a cold fluid inlet  264 , and is closed off by a cap  288 , while the lower portion  266  of the central bore  260  is in fluid communication with a hot fluid port  216  and a hot fluid inlet  268 . A cold fluid check valve  270  is disposed in the cold fluid port  218  and allows flow to pass from the central bore  260  to the cold fluid port  218 , but prevents flow in the opposite direction. A hot fluid check valve  272  is disposed in the hot fluid inlet  268  and allows flow to pass from the hot fluid inlet  268  to the central bore  260  but prevents flow in the opposite direction. 
   A hollow cylindrical valve sleeve  274  having open upper and lower ends  276  and  278  slides in the central bore  260 , sealed by upper and lower sleeve seals  280  and  282 , such as the illustrated O-rings. A plurality of side ports  284  are formed in the lateral surfaces of the valve sleeve  274  near its center. The valve sleeve  274  is biased downward by upper bias means  286 . In the illustrated embodiment, the upper bias means are implemented by providing an increased surface area at the upper end  276  of the sleeve  274  relative to the opposing surface area at the lower end  278  of the sleeve  274 . This ensures that here is a net downward force on the sleeve  274  when the hot and cold water supplies are at the same pressure. A spring such as that illustrated in  FIG. 1  (not shown in  FIG. 4 ) could also be used to provide an upper biasing means  286 . A piston  290  is disposed in the interior of the valve sleeve  274 . The piston  290  has an upper face  292  with an upper seal  294 , and a lower face  296  with a lower seal  298 , connected by a narrow central member  300 . A lower bias spring  302  is disposed in the valve sleeve  274  and extends between the lower face  296  of the piston  290  and a retainer  304  having an opening  306  formed therein. The piston  290  is urged upwards by the lower bias spring  302  so that the upper seal  294  seals against a ledge  308  in the valve sleeve  274 . A bypass passage  310  may be used to connect the lower portion  266  of the bore  260  to the hot fluid inlet  268  upstream of the hot fluid check valve  272 . Alternatively, if the bypass passage  310  is not present, the lower seal  298  and the lower sleeve seal  282  may be eliminated to provide a flow path between the hot fluid inlet  268  and the lower portion of the bore  266 . 
   The operation of the supply failure protection valve  210  is substantially the same as that of the supply failure protection valve  10  described above. It is installed into a water supply system by connecting the hot and cold fluid inlets  268  and  264  to hot and cold water supplies “H” and “C” respectively. The hot and cold water ports  216  and  218  are then connected to the hot and cold water inlets of a tempering valve (not shown) such as that described above. Thus, it may be retrofitted into an existing system to provide protection in the event either supply fails. Alternatively, the supply failure protection valve  210  may by connected to a system having a manual mixing valve, or separate hot and cold water faucets. 
   The foregoing has described a water supply failure protection valve. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation, the invention being defined by the claims.