Abstract:
A flow shut off valve for residential water line pressure includes a self cleaning valve element held in a housing having an inlet, an outlet section and an outlet adapter with a fluid passage connecting the inlet and the outlet adapter. The inlet and the outlet adapter include exterior threads for connection to a further item. The valve element is slidably mounted within a passage in a poppet guide and metering slot insert having one or more metering slots that allow variable fluid flow between the inlet and outlet adapter. A spring biases the valve element toward the inlet. Reduced back pressure at the outlet adapter drives the valve element into a closed position with a sealing surface against the valve seat to terminate flow. The flow shutoff valves are contemplated for integration with stop valves supplying water to employment with household appliances, sinks, toilets and the like.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of pending application Ser. No. 11/535,194, which was filed on Sep. 26, 2006, entitled Self Cleaning Flow Shutoff Valve. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The field of the present invention is generally flow shutoff valves for residential water line pressure and, more specifically, the use of such valves which are self cleaning and which may be used with stop valves for sinks, toilets, and the like. 
   2. Description of Related Art 
   Shutoff valves to prevent excess flow, such as when a sudden leak occurs downstream of the valve, are well known in the art. Such valves are found in high pressure hydraulic systems, fueling systems and critical gas systems. Such valves are relatively expensive because of complicated housings and/or valve elements, the materials, and their precision machining requirements. 
   Household water supplies to appliances, sinks and toilets; for example, water supplies to washing machines, sinks and toilets are most often connected to manual shutoff valves which are installed in the water line. The conventional means for connecting the manual shutoff valves to an appliance, or the like, are typically through flexible hoses. Personal experience and insurance statistics suggest that a great many such manual shutoff valves are not closed when appliances are not in use. Consequently, the integrity of the flexible hoses remains the only means of containing a household system water pressure to an appliance. Insurance companies in North America report payments amounting to hundreds of millions of dollars annually which solely result from broken household appliance hoses. Other statistics for sinks and toilet systems, not using flexible hoses, but which are subject to leaking or other problems are similar. 
   The shutoff valves used for hydraulics, fuels and gasses are out of practical range for use with home appliances. However, other solutions have been applied to the problem of residential flooding from appliance hoses in a number of ways. Electrical sensors, timers and valve drives have been devised. Mechanical devices have also been employed which are complicated, expensive and/or limited in their use. 
   One problem which must be addressed by shutoff devices for residential use is the presence of particles and hardness in the water supply which can accumulate to disable such valves. The utility of most shutoff valves is as an emergency device with very infrequent actuation. Consequently, interfering deposits can be built up with continued flow through the valve without actuation and result in malfunction of the valve when needed. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a flow shutoff valve for residential water line pressure and includes a housing, a valve element slidably mounted in the housing and a spring biasing the valve element. The housing includes a passage therethrough with at least a first cylindrical section. The valve element includes a sealing surface which is engageable with a valve seat about the passage in the housing. A flow restrictive passage is located between the inlet and the outlet with communication therethrough controlled by the valve element. 
   In a first separate aspect of the present invention, the valve element includes a cylindrical wall slidably engaging the first cylindrical section of the passage through the housing. Communication through the flow restrictive passage is closed with the valve element at the inlet end of its slidable mounting. Under this condition, the valve element operates as a piston through a distance responsive to the water pressure each time water begins to flow through the valve, performing a forced physical cleaning. 
   In a second separate aspect of the present invention, the valve element includes a cavity open to the inlet. The flow restrictive passage includes at least one restrictive orifice extending from the cavity to the periphery of the valve element. The restrictive orifice(s) is closed by the first cylindrical section with the valve element at the inlet end of its slidable mounting. 
   In a third separate aspect of the present invention, back pressure at the outlet dropping to near zero gauge pressure results in a force on the valve element greater than and opposed to the force of the spring. Further, the spring has a spring force with the valve element in the no-flow position which is less than the total force of the water line pressure on the valve element with the back pressure of the outlet at near zero gauge pressure. 
   In a fourth separate aspect of the present invention, the flow shutoff valve includes a motion damper operatively coupled between the housing and the valve element. This damper may include damping which is progressive with displacement. The motion damper may include a cavity and a plunger. The plunger can have an increasing cross-sectional area with increasing distance from the free end of the plunger for a first length of the plunger. 
   In a fifth separate aspect of the present invention, the flow shutoff valve includes a flexible hose having a proximal end attached to the outlet and a distal end, a line filter adjacent the distal end of the flexible hose and no line filter adjacent the proximal end of the hose or the flow shutoff valve. 
   In a sixth separate aspect of the present invention, any of the foregoing aspects are contemplated to be employed in combination to greater utility. 
   In a seventh separate aspect of the present invention, the flow shutoff valve for residential water line pressure is adapted to be used with or made integral with a stop valve for use with sinks, toilets and the like. 
   In an eighth separate aspect of the present invention, the flow shutoff valve is made more compact and smaller so as to be integrated with known stop valves and includes a poppet guide and metering slot insert with one or more metering slots therein for flow control therethrough. 
   Accordingly, it is an object of the present invention to provide an improved combination flow shutoff valve and stop valve. Other and further objects and advantages will appear hereinafter. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view taken along the centerline of a flow shutoff valve in a position with no flow therethrough. 
       FIG. 2  is a cross-sectional view taken along the centerline of the flow shutoff valve in an intermediate position with flow therethrough. 
       FIG. 3  is a cross-sectional view taken along the centerline of a flow shutoff valve in a shutoff position. 
       FIG. 4  is a bottom view of a second embodiment of a flow shutoff valve. 
       FIG. 5  is a cross-sectional view taken along lines  5 - 5  of  FIG. 4 . 
       FIG. 6  is a perspective exploded assembly view of flow shutoff valves with an appliance. 
       FIG. 7  is a perspective view of a flow shutoff valve with a sprinkler system. 
       FIG. 8  is a cross-sectional view taken along the centerline of a third embodiment of a flow shutoff valve, in a position with no flow therethrough, for use with a stop valve. 
       FIG. 9  is a cross-sectional view of the flow shutoff valve of  FIG. 8 , in an intermediate position with flow therethrough. 
       FIG. 10  is a cross-sectional view of the flow shutoff valve of  FIG. 8 , in a shutoff position. 
       FIG. 11  is a perspective view of a poppet guide having a plurality of metering slots therein held in the housing of the flow shutoff valve of  FIG. 8 . 
       FIG. 12  is a cross-sectional view of the combination flow shutoff valve of  FIG. 8  and a stop valve, with the flow shutoff valve, in a position with no flow therethrough. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Turning in detail to  FIGS. 1 through 3 , a self cleaning flow shutoff valve for residential water line pressure is disclosed. The flow shutoff valve, generally designated  10 , includes a housing  12 . The housing  12  is constructed of an inlet section  14 , and an outlet section  16 . These sections may conveniently be of inexpensive plastic molding material. Such materials include polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), acrylonitrile butadiene styrene (ABS) and other plastics. Brass or bronze may alternatively be employed. The sections  14 ,  16  are generally cylindrical. “Cylindrical” is used herein in the broader mathematical sense without necessarily being limited to a circular cylinder. 
   The inlet section  14  includes an inlet  18 . The outlet section  16  includes an outlet  20 . The inlet  18  and outlet  20  sections are shown to be threaded with female and male threads, respectively. The entire body of the housing  12  is preferably cylindrical at any cross section and the two sections  14 ,  16  include male and female engaged pilot diameters. The two sections  14 ,  16  may be bonded together or threaded together with an o-ring seal  40 . 
   The resulting housing  12  defined by the two sections  14 ,  16  includes a passage  21  therethrough extending from the inlet  18  to the outlet  20 . The passage  21  includes a washer  22  arranged at the inlet to prevent flow from backing out through the inlet  18 . 
   The passage  21  further includes a cylindrical section  24  found inwardly of the inlet  18  and washer  22 . This section  24  extends to a central section  26  of enlarged cross section also forming part of the passage  21 . At one end of the central section  26 , an annular spring seat  28  is arranged to accommodate a spring inwardly displaced from the wall of the passage  21  at the central section  26 . A valve seat  30  is also located in the central section  26  at the annular spring seat  28 . The valve seat  30  extends around the passage  21  as it defines an outlet channel  32 . 
   A valve element  34  includes a cylindrical wall about its periphery which slidably engages the cylindrical section  24 . The body  36  of the valve element  34  is of sufficient length and fit so that it will not bind with the cylindrical bore  24  in movement within the passage  21  and yet precludes any substantial flow between the cylindrical wall and the cylindrical section  24 . The clearance between the body  36  and the cylindrical bore  24  is small but does not require that all fluid flow therebetween be prevented. A retaining ring  38  fits within a groove in the passage  21  at the first section  24 . A spring clip may be employed for this ring  38 . This limits the travel of the valve element  34  toward the inlet  18 . A nose  42  of smaller diameter than the body  36  extends downwardly below the cylindrical wall of the body  36 . 
   A flow restrictive passage is located between the inlet and the outlet with communication therethrough controlled by the valve element  34 . In the preferred embodiment, the flow restrictive passage is defined by a central cavity  44  extending into the body of the valve element  34  from the inlet end. The cavity  44  does not extend fully through the valve element  34 . Rather, several orifices  46  extend from the cavity  44  in a radial direction to the periphery of the valve element  34  for communication between the inlet and the outlet. Further the central section  26  can provide communication from the orifices  46  to the valve seat  30 . A sealing surface  48  is arranged on the end of the nose  42  to cooperate with the valve seat  30  for closure of the passage  21 . 
   A spring  50  is positioned in the annular spring seat  28  and is placed in compression against the shoulder created by the diameter change in the valve element  34 . The spring  50  biases the valve element  34  toward the inlet and against the retaining ring  38 . 
   In comparing  FIGS. 1 ,  2  and  3 , it may be noted that the valve element  34  is shown in three functional positions. A first position, as illustrated in  FIG. 1 , is with the valve element  34  positioned fully toward the inlet  18 . A second position, as illustrated in  FIG. 2 , is an intermediate position with the orifices  46  in communication with the central section  26  and the valve  10  open. The second position actually spans a range of locations for the valve element  34 . A third position, as illustrated in  FIG. 3 , is with the sealing surface  48  pressed against the valve seat  30 . In the first position, the orifices  46  are closed by the cylindrical section  24  which closely surrounds the cylindrical periphery of the valve element  34 . In this way, communication through the flow restrictive passage is closed. With no open passage, pressure builds up on the top of the valve element  34  which in turn acts as a piston and is forced downwardly by the water pressure every time the valve is opened. With the added force of the piston, the valve element  34  is cleared of any accumulation of particles and hardness on a regular basis. Further, the valve remains open with the sealing surface  48  displaced from the valve seat  30 . 
   In the second position, flow proceeds relatively unimpeded by the mechanism with the exception of the design of the orifices  46 . Under normal flow conditions, the valve element  34  remains in this intermediate position. 
   In the third position, the sealing surface  48  is on the valve seat  30  and there is no flow. It is through this range of positions that the flow shutoff valve  10  operates. 
   The spring  50  and the orifices  46  are empirically selected to accommodate residential water line pressure and household appliance flow rates. At normal flow, there is some pressure drop across the valve element  34 . This pressure drop is due to flow resistance through the orifices  46  and general drag on the valve element  34 . This pressure drop along with pressure imbalances resulting from velocity variations around the valve element  34  provides differential forces on the valve element  34 . However, the orifices  46  and the spring  50  are selected to allow a certain range of flow through the flow shutoff valve  10  at a range of line pressures with the spring  50  retaining the valve element  34  in the intermediate zone of positions. This is accomplished by having the spring maintain a range of force on the valve element  34  that the hydraulic forces do not move the valve element  34  fully to the third position against the valve seat  30 . Naturally, the spring  50  cannot resist the piston action of the valve element  34  as it moves from the first position to expose the orifices  46 . As the residential water line pressure is reasonably stable during such flow, the back pressure at the outlet  20  significantly determines flow rate. This back pressure is developed at an appliance or other device in fluid communication with the outlet  20 . 
   When the back pressure at the outlet  20  drops significantly, the differential pressure between the inlet  18  and the outlet  20  becomes substantially greater. In response, flow through the flow shutoff valve  10  increases. As the flow increases, greater resistance is provided by the orifices  46 . Resulting hydraulic forces acting in the direction of flow increase. At a flow rate between 150% and 200% of anticipated normal flow, the resulting hydraulic force on the valve element  44  exceeds the opposing spring force from the compressed spring  50 . Preferably the spring  50  is arranged such that the distance between the first and third positions does not greatly increase the spring force. This is accomplished with some precompression of the spring  50  in the first position and a small spring constant. With the resulting hydraulic force exceeding the spring force, the valve element  34  will move to the third position with the sealing surface  48  against the annular valve seat  30 . As the sealing surface  48  engages the valve seat  30 , flow is terminated. 
   Once there is no flow, the pressure about the valve element  34  equalizes at the line pressure. At this point, the only forces on the valve element  34  are the spring  50  and the imbalance between the line pressure and the lower pressure at the outlet channel  32  operating on the valve element  34  inwardly of the valve seat  30 . With the outlet  20  being near zero gauge pressure, the differential pressure across the area of the outlet channel  32  retains the valve element  34  in the third position. Reinstating the flow shutoff  10  to the first or second positions is accomplished by reducing the line pressure sufficiently so that the spring  50  may force the valve element  34  back toward the inlet  18 . 
   The second embodiment illustrated in  FIGS. 4 and 5  includes the reference numbers applied to the first embodiment where functions are substantially to identical. This second embodiment of the flow shutoff valve, generally designated  51  principally differs in the provision of a motion damper, generally designated  52 . The motion damper includes a cavity  54  associated with the housing  12  and a plunger  56  associated with the valve element  34 . The first position of the valve element  34 , as seen in  FIG. 5 , has the plunger  56  just entering the cavity  54 . In the intermediate position the plunger  56  has more fully entered into the cavity  54  but has not bottomed out. 
   For a first distance, the plunger  56  increases in cross-sectional area by means of the chamfer  58 . With this device, the damping resistance is progressive with displacement of the valve element  34  from the intermediate position toward the valve closed position. 
   To accommodate the motion damper  52 , the housing  12  includes an insert  60 , centrally defining the cavity  54 , with multiple ports  62  thereabout. The ports are substantially larger in cumulative cross-section than the orifices  46 . This allows a rapid drop in pressure below the valve element  34  with resulting closure of the shutoff valve  51  when pressure at the outlet  20  drops to near zero gauge. The insert  60  may be press fit or retained by bonding. A further variation from the first embodiment may be the employment of slip sockets, as the shutoff valve  51  is depicted in  FIG. 7 , particularly adaptable with PVC, CPVC and ABS type piping systems for bonding of the system components to the valve  51 . 
     FIG. 6  illustrates the use of flow shutoff valves  10  with a home appliance such as a washing machine  66 . Flexible hoses  68 ,  70  are coupled with the flow shutoff valves  10  which are in turn coupled with the standard manual valves  64 ,  72 . In the circumstance that a flexible hose  68 ,  70  breaks, water pressure within the hose and correspondingly at the outlet  20  would drop to near zero gauge pressure. Under this circumstance, the flow shutoff valve  10  would close by having the valve element  34  moved to the third position. The corresponding valve  64 ,  72  must then be closed before flow is restored through the flow shutoff valve  10 . 
   The hoses  68  and  70  have proximal ends adjacent the shutoff valve  10  and distal ends at the appliance  66  or other device. A line filter  74  may be located adjacent the distal end of each of the hoses  68  and  70 , where they connect to the appliance solenoid valves,  75  and  76 , and no line filter is located adjacent the proximal end of the hoses  68  and  70  or the flow shutoff valve  10 . As indicated above, particles and hardness accumulate from a domestic water line. If there is a filter before the flow shutoff valve  10 , there is the danger of sufficiently clogging the line filter enough that flow would never reach the shutoff velocity through the flow shutoff valve  10  to properly actuate with a break in the hose. By placing line filters after the hoses, the increased flow from a break would not be reduced by an upstream clogged line filter. 
     FIG. 7  illustrates a sprinkler system including sprinklers  74 , an anti-siphon valve  76  and sprinkler pipes  78 . The motion damper  52  of the second embodiment has particular utility in the sprinkler system of  FIG. 7 . When the anti-siphon valve  76  is closed, the anti-siphon operates to release pressure and drain some of the sprinkler pipe  78 . Therefore, when the anti-siphon valve is again opened, there is the possibility that the sprinkler piping  78 , and correspondingly the outlet  20 , will be at near zero gauge pressure until filled by line water. Without slowing the closure of the valve, this condition could prematurely close the shutoff valve. 
   Turning now to the third embodiment of the invention shown in  FIGS. 8 through 11 , a self cleaning flow shutoff valve for residential water line pressures and for connection to or use with a stop valve is disclosed. This flow shutoff valve is a miniaturized version for use in specific situations and is generally designated  110 . A currently preferred version of this miniaturized flow shutoff valve is approximately ¾″ in diameter by about 1.4″ long. This flow shutoff valve  110  includes a housing  112 , preferably constructed from metal and having an inlet section  114 , an outlet section  116 , sealed with an o-ring  126 , and an outlet adapter  118 . An o-ring seal  150  is used between the outlet section  116  and the outlet adapter  118 . The sections  114 ,  116 , and  118  are generally cylindrical. “Cylindrical” is used herein in the broader mathematical sense without necessarily being limited to a circular cylinder. 
   The inlet section  114  includes an inlet  120 . The outlet adapter  118  includes an outlet  122 . The inlet section  114  and the outlet adapter  118  are shown to be threaded with exterior male treads. The exterior threads on inlet section  114  provide for integration of the valve  110  into or with a standard commercial stop valve, such as  123  (see  FIG. 12 ). The threads on outlet adapter  118  are varied to match a broad range of plumbing requirements. The entire housing  112  is preferably cylindrical at any cross section and the two sections  114 ,  116  may be bonded or threaded together. A poppet guide and metering slot insert  124  (best shown in  FIG. 11 ) is fitted into the smooth bore of the inlet section  114 , and is sealed with two o-rings  126 . This poppet guide and metering slot insert  124  is preferably made from a ceramic or a glass filled polypropylene. 
   The resulting housing  112  defined by the three sections  114 ,  116 , and  118  includes a passage  121  therethrough extending from the inlet  120  to the outlet  122 . The passage  121  further includes a series of metering slots  128  formed in the poppet guide and metering slot insert  124 . 
   The passage  121  further includes a cylindrical section  130  found inwardly of the inlet  120 . This section  130  is preferably formed in the poppet guide and metering slot insert  124  and extends to a central section  132  also forming part of the passage  121 . At one end of the central section  132  an annular spring seat  134  is arranged to accommodate a spring  136  inwardly displaced from the wall of passage  121  at the central section  132 . A valve seat  138  is also located in the central section  132  at an end of the annular spring seat  134 . The valve seat  138  extends around the passage  121  as it defines an outlet channel  140 . 
   A cylindrical poppet type valve element  142  slidably engages the cylindrical section  130  of the poppet guide and metering slot insert  124 . The body  144  of valve element  142  is of sufficient length and fit so that it will not bind with the cylindrical bore  130  in movement within the passage  121  and yet precludes any substantial flow between the body  144  and the cylindrical section  130 . The clearance between the body  144  and the cylindrical section  130  of the poppet guide and metering slot insert  124  does not require that all fluid flow therebetween be prevented. 
   A nose  146  of smaller diameter than the body  144  of the valve element  142  extends downwardly, below the cylindrical housing  112 . A valve o-ring sealing surface  148  is fitted to the nose  146  of the valve element  142 . 
   A flow restrictive passage is located between the inlet  120  and the outlet  122  with communication therethrough controlled by the width and number of metering slots  128  in the poppet guide and metering slot insert  124 . In the preferred embodiment, the flow restrictive passage is defined as the metering slots  128  which are cut into, or otherwise formed in the insert  124 . 
   The number and width of slots  128  determine the amount of flow restriction. Further, the central section  132  can provide communication from the metering slots  128  to the valve seat  138 . The sealing surface  148  is arranged on the end of the nose  146  to cooperate with the valve seat  138  for closure of the passage  121 . 
   The spring  136  is positioned in the annular spring seat  134  and is placed in compression against the shoulder created by the diameter change in the body  144  of the valve element  142 . The spring  136  biases the valve element  142  toward the inlet  120 . 
   In comparing  FIGS. 8 ,  9 , and  10 , it may be noted that the valve element  142  is shown in three functional positions. A first position, as illustrated in  FIG. 8 , is with the valve element  142  positioned fully toward the inlet  120 , defining a valve closed position. A second position, as illustrated in  FIG. 9 , is an intermediate position with the metering slots  128  in communication with the inlet  120  and central section  132 , defining a valve open position. The second position actually spans a range of locations for the valve element  142 . A third position, as illustrated in  FIG. 10 , is with the sealing surface o-ring  148  pressed against the valve seat  138 , defining a further valve closed position. In the first position, the metering slots  128  are closed by the upper portion of the cylindrical section  144  of the valve element  142 . In this way, communication through the flow restrictive passage is closed. With no open passage, pressure builds up on the top of the valve element  142  which in turn acts as a piston and is forced downwardly by the water pressure every time the supply valve is opened. With the added force of the piston, the valve element  142  is cleared of any accumulation of particles and hardness on a regular basis. Further, the valve remains open with the sealing surface  148  displaced from the valve seat  138 . 
   In the second position, flow proceeds relatively unimpeded by the mechanism with the exception of the design of the metering slots  128 . Under normal flow conditions, the valve element  142  remains in this intermediate position. 
   In the third position, the sealing surface  148  is on the valve seat  138  and there is no flow. It is through this range of positions that the valve  110  operates. 
   The spring  136  and the metering slots  128  are empirically selected to accommodate residential water line pressure and household appliance, sink, and toilet flow rates. At normal flow, there is some pressure drop across the valve element  142 . This pressure drop is due to flow resistance through the metering slots  128  and general drag of the valve element  142 . This pressure drop, along with pressure imbalance resulting from velocity variations around the valve element  142 , provides differential forces on the valve element  142 . However, the metering slots  128  and the spring  136  are selected to allow a certain range of flow through the flow shutoff valve  110  at a range of line pressures with the spring  136  retaining the valve element  142  in the intermediate zone of positions. This is accomplished by having the spring  136  maintain a range of force on the valve element  142  that the hydraulic forces do not move the valve element  142  fully to the third position against the valve seat  138 . Naturally, the spring  136  cannot resist the piston action of the valve element  142  as it moves from the first position to expose the metering slots  128 , thus providing the self-cleaning action. As the residential water line pressure is reasonably stable during such flow, the back pressure at outlet  122  significantly determines flow rate. This pressure is developed at an appliance, toilet valve, sink valve, or other device in fluid communication with outlet  122 . 
   When the back pressure at the outlet  122  drops significantly, the differential pressure between the inlet  120  and the outlet  122  becomes substantially greater. In response, flow through the flow shutoff valve  10  increases. As the flow increases, greater resistance is provided by the metering slots  128 . Resulting hydraulic forces acting in the direction of flow increase. At a flow rate between 150% and 200% of anticipated normal flow, the resulting hydraulic force on the valve element  142  exceeds the opposing spring force from the compressed spring  136 . This is accomplished with some precompression of the spring  136  in the first position and a small spring constant. With the resulting hydraulic force exceeding the spring force, the valve element  142  will move to the third position with the sealing surface  148  against the annular valve seat  138 . As the sealing surface  148  engages the valve seat  138 , flow is terminated. 
   Once there is no flow, the pressure about the valve element  142  equalizes at the line pressure. At this point, the only forces on the valve element  142  are the spring  136  and the imbalance between the line pressure at the inlet  120  and the lower pressure at the outlet  122  operating the valve element  142  inwardly of the valve seat  138 . With the outlet  122  being near zero gauge pressure, the differential pressure across the area of the outlet channel  140  retains the valve element  142  in the third position. Reinstating the flow shutoff valve to the first or second position is accomplished by reducing the line pressure sufficiently so that the spring  136  may force the valve element  142  back toward the inlet  120 . 
     FIG. 12  illustrates the connection or integration of flow shutoff valves  110  with stop valves  123 . The exterior threads of the inlet section  114  are coupled to or inserted within female or internal threads formed on an outlet  125  of the stop valves  123  and retain a ball valve and O-ring or similar seal in place. The stop valves  123  may take any known configuration, such as ¼ turn stop valve, and are coupled to a water line (not shown), feeding water to the shutoff valve for delivery elsewhere. If water pressure downstream of the shutoff valve  110  drops to near zero gauge pressure, the flow shutoff valve  110  would close to cut off water flow, without the need to close the stop valves  123 , except to reset the flow shutoff valve. 
   Thus, relatively simple, inexpensive and reliably responsive and self cleaning flow shutoff valves that may be used alone or integrated with stop valve have been disclosed. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the appended claims.