Abstract:
A pressure reducing valve for coupling to a pressurized water supply line includes a valve body with an inlet for coupling to the pressurized water supply line, an outlet, a passage extending between the inlet and the outlet, and a valve seat in the passage. A valve stem extends into the passage, which has a sealing member. An automatic pressure reducing system is provided for urging the sealing member toward the valve seat for throttling the valve to thereby reduce the pressure at the outlet. The automatic pressure reducing system includes parallel springs that occupy less space than conventional springs for a given spring load.

Description:
[0001]     This application incorporates by reference herein application entitled PRESSURE REDUCING VALVE, filed Nov. 30, 2004, U.S. Ser. No. 10/999,789 (Attorney Docket ELK01 P-314). 
     
    
     TECHNICAL FIELD AND BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to a field adjustable pressure reducing valve that is particularly useful, for example, in a high-rise building application in a fixed fire protection system.  
         [0003]     In high-rise buildings, the riser pipe of the fire protection system, which is typically located in a stairwell of the building, operates with a relatively high pressure in order to have a sufficient operating pressure at the highest elevation of the building. When firefighters need to access the water in these fire protection systems, for example in the riser pipe, the pressure in the system typically exceeds the maximum pressure ratings for the fire protection components. In addition, at the lower elevations, the pressure may exceed pressure ratings for the sprinkler piping components.  
         [0004]     In order to reduce the pressure, fire protection systems have incorporated pressure reducing valves, which reduce the pressure at the valve and are located at intermediate elevations along the riser so that the water pressure is reduced at these locations to acceptable levels for firefighting equipment and for the sprinkler piping. To reduce the pressure, pressure reducing valves incorporate springs that counteract the pressure exerted on the valve piston generated, for example, in the riser pipe.  
         [0005]     Because pressure reducing valves used in fire suppression applications deal with relatively high pressures (greater than 175 psi), the force required by these springs may often be quite large, for example, on the order of up to 2000 to 3000 lbs. To generate these large spring forces, however, the springs are relatively large in height. The larger height equates to more coils to distribute stress load. For example, in some applications, the spring may be 6 inches or taller.  
         [0006]     However, the large height of the spring creates multiple problems. For example, with the taller springs, the size of the valve, which encloses the spring, is necessarily increased. Hence, the weight of the valve can be significant. Also, with increased size comes increased material cost. In addition, pressure reducing valves for the fire suppression industry are constructed of brass, which is cast. Hence, in addition to the material cost increase, the cost for the casting process and casting equipment will increase. The added weight and bulk of the valve also results in the valve being more difficult to handle and, therefore, also increases the shipping and handling costs. The large size of the valve also makes it impractical to use in a tight area—therefore, its use may be limited in some applications or locales. As a result, many contractors will not use field adjustable pressure reducing valves because of these size/weight issues.  
         [0007]     Consequently, there is a need for a pressure reducing valve with a more compact configuration, without comprising the function of the pressure reducing valve.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention relates to a pressure reducing valve that has a more compact configuration while still providing the reduction in pressure for application in a high rise protection system.  
         [0009]     In one form of the invention, a pressure reducing valve for coupling to a pressurized water supply line includes a valve body with an inlet for coupling to the pressurized water supply line, an outlet, a passage extending between the inlet and the outlet, and a valve seat in the passage. A valve stem extends into the passage, which has a sealing member. An automatic pressure reducing system is provided for urging the sealing member toward the valve seat for throttling the valve to thereby reduce the pressure at the outlet and includes a spring assembly and a piston mounted to the valve stem. The valve is configured so that the water pressure at the inlet is directed to a chamber in the valve where the piston is located to apply pressure on the piston. The pressure on the piston applies a load on the valve stem to urge the sealing member toward the valve seat to thereby automatically adjust the pressure at the outlet. The spring assembly, which includes parallel first and second springs, is coupled to the valve stem and generates a spring force opposed to the pressure on the piston to adjust the load on the piston and to thereby adjust the pressure at the outlet.  
         [0010]     In one aspect, one of said springs comprises a left-hand coiled spring and another of said springs comprises a right-hand coiled spring.  
         [0011]     In further aspects, the springs are preferably nested. For example, the inner spring may comprise the left-hand coiled spring, and the outer spring may comprise the right-hand coiled spring. For example, each spring may have 4 to 7 coils, depending on the diameter of the spring&#39;s wires. Each spring may have an overall height in a range of about 2 inches to 5 inches, more typically, in a range of about 3 to 4 inches, and, most typically for a spring assembly generating a spring force in a range of 1700 to 2300 lbs., each of the spring heights is preferably in a range of about 3.2 to 3.8 inches.  
         [0012]     The diameter of the spring wires may vary as well. For example, the diameters may vary from about 0.2 to 0.6 inches. In addition, the inner spring&#39;s wire may vary from the outer spring&#39;s wire diameter. For example, the inner spring wire diameter may fall in a range of about 0.2 to 0.4 inches, more typically about 0.3 to 0.4 inches and, most typically for spring compression loads of about 1700 to 2300 lbs., in a range of about 0.28 to 0.35 inches. The outer diameter spring wire diameter may fall in a range of about 0.3 to 0.6 inches, more typically about 0.4 to 0.5 inches and, most typically for resulting spring compression loads of about 1700 to 2300 lbs., in a range of about 0.4 to 0.5 inches.  
         [0013]     According to another form of the invention, a pressure reducing valve for coupling to a pressurized water supply line includes a valve body with an inlet for coupling to the pressurized water supply line, an outlet, a passage extending between the inlet and the outlet, and a valve seat in the passage. The valve also includes a valve stem that extends into the passage and a sealing member coupled to the valve stem. An automatic pressure reducing system is provided for urging the valve stem and the sealing member toward the valve seat for throttling the valve to thereby automatically reduce the pressure at the outlet. The automatic pressure reducing system includes a piston mounted to valve stem and nested springs. The water pressure at the inlet is directed to the chamber where the piston is located and applies pressure on the piston to apply a load on the valve stem to urge the sealing member toward the valve seat to adjust the pressure at the outlet. The springs are coupled to the valve stem and generate a spring force opposed to the pressure on the piston to adjust the load on the valve stem and to thereby adjust the pressure at the outlet.  
         [0014]     In any of the above pressure reducing valves, the valve may include a manual override system to move the valve stem and urge the sealing member toward or away from the valve seat. The manual override system may comprise a manual override system that is decoupled from the automatic pressure reducing system. In one form, the manual override system includes a hand operable member, which is coupled to the valve stem and is movable to urge the sealing member toward the valve seat but with the movement of the hand operable member decoupled from the pressure on the piston and the spring force of the spring assembly.  
         [0015]     In one form, the valve stem may include a first valve stem portion, which coupled to the piston and the spring assembly, and a second valve stem portion, which coupled to the hand operable member. In addition, the second valve stem portion may be guided by the first valve stem portion and movable relative to the first valve stem portion. For example, the first valve stem portion may comprise an outer valve stem portion, with the second valve stem portion comprising an inner valve stem portion guided in the outer valve stem portion.  
         [0016]     According to yet another form of the invention, a method of closing a pressure reducing valve, which includes a valve body, a valve stem with a sealing member, and an automatic pressure reducing system in the valve body for urging the sealing member toward the valve seat for throttling the valve to thereby reduce the pressure at the outlet, includes providing the automatic pressure reducing system with a spring assembly that includes two or more parallel springs to reduce overall size of the valve body and, optionally, the stress level on the springs.  
         [0017]     In one form, the springs are nested, with each spring coupled to the valve stem.  
         [0018]     Accordingly, the pressure reducing valve of the present invention offers a more compact valve arrangement while achieving the same or similar spring loads associated with conventional pressure reducing valves. In addition, with the spring assembly configuration of the present invention, the stress in the springs may be lower than conventional spring designs with comparable spring loads.  
         [0019]     These and other objects, advantages, purposes, and features of the invention will become more apparent from the study of the following description taken in conjunction with the drawings.  
     
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
       [0020]      FIG. 1  is an elevation view of the pressure reducing valve of the present invention;  
         [0021]      FIG. 2  is a side view of the pressure reducing valve of  FIG. 1 ; and  
         [0022]      FIG. 3  is a cross-section view taken along line III-III of  FIG. 1 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     Referring to  FIGS. 1-3 , the numeral  10  generally designates a field adjustment pressure reducing valve of the present invention. Pressure reducing valve  10  is adapted to reduce the pressure in a pipe that is subject to high pressures, for example a riser pipe in a fire protection system. In riser pipes, the water pressure is often high in order to deliver water at a suitable operating pressure at higher elevations but is too high to permit firefighting equipment to be directly coupled to the riser pipe at the lower elevations. As will be more fully described below, valve  10  is configured to have a more compact arrangement than conventional valves and may be configured to facilitate opening of the valve such as described in copending application entitled PRESSURE REDUCING VALVE, filed Nov. 30, 2004, Ser. No. 10/999,789 (Attorney Docket No. ELK01 P-314), which is incorporated by reference herein in its entirety and commonly owned by Elkhart Brass Manufacturing of Elkhart, Ind.  
         [0024]     As best seen in  FIG. 3 , valve  10  includes a valve body  12  with an inlet  14  and an outlet  16  and a housing  28 . Inlet  14  and outlet  16  are in selective communication by way of a passageway  15  that extends through body  12 . In the illustrated embodiment, inlet  14  is internally threaded for coupling to a pipe, such as a water supply pipe of a fire protection system, while outlet  16  is externally threaded for coupling to a fire hose or may be internally threaded for coupling to a pipe, such as sprinkler piping. Positioned in body  12  and in passageway  15  is a valve stem  18  and a valve member  20 , which is mounted to the distal end of valve stem  18  and aligned over a valve seat  22  formed or otherwise provided in body  12 . As will be more fully described below, valve  10  includes a compact automatic pressure reducing system and a manual override system for opening or closing the valve, which is optionally decoupled from the automatic pressure reducing system as described in the referenced patent.  
         [0025]     Valve member  20  includes an annular body  23 , which is mounted to the distal end of valve stem  18  by a push rod guide  23   a  and a fastener  23   b,  and a gasket  24 , such as an annular rubber gasket, for selectively sealing inlet  14  when valve stem  18  urges valve member  20  to seal against seat  22 . Gasket  24  is mounted in annular body  23  in an annular groove  23   c  by a washer  24   a  and a nut  24   b,  which are mounted on stem  20   a  of valve member  20 .  
         [0026]     Valve stem  18  extends from body  12  and into housing  28  for coupling to a hand wheel  29 , described more fully below. Housing  28  includes a lower housing portion  28   a,  which defines a chamber  30 , and an upper portion  28   b,  which includes a passageway  32  and houses the upper portion of valve stem  18 , a spring assembly  34 , and an adjustment member  36 . Upper housing portion  28   a  is mounted to lower housing portion  28   b  by a collar  28   c  that is mounted to upper housing portion  28   a  on threads onto lower housing portion  28   b.  As will be more fully described below, spring assembly  34  is configured to have a more compact configuration than springs of comparable stiffness or spring loads so that housing  28  and, hence, valve  10  may have a more compact configuration.  
         [0027]     In the illustrated embodiment, lower portion  28   a  of housing  28 , which forms cavity or chamber  30 , is threaded onto body  12 . Positioned between lower portion  28   a  of housing  28  and body  12  is an annular member  38 , which separates passage  15  from chamber  30  and includes a central opening  38   a  through which valve stem  18  extends into body  12  to provide a guide for valve stem  18 . To seal opening  38   a,  a seal  40   a,  such as an O-ring seal, is mounted in member  38  at opening  38   a.  A second seal  40   b  is provided in member  38  at its interface with body  12 .  
         [0028]     Positioned in chamber  30  and secured to valve stem  18  is a piston  42 , which includes an annular seal  44  at its perimeter, such as an O-seal, and is coupled to stem  18  by an annular shoulder  18   b  formed or otherwise provided on stem  18 . In addition, piston  42  includes a threaded portion  42   a  for engaging a corresponding threaded portion  19  provided on stem  18 . Further, to limit rotation of piston  42 , and in turn stem  18  about axis  10   a  ( FIG. 3 ), piston  42  is rotationally coupled to annular member  38 , for example, by one or more pins  45 . By rotationally coupling stem  18  to member  38 , and in turn valve body  12 , adjustment of the preload on the spring assembly  34  can be achieved with minimal, if any, rotation of the valve stem. While this rotation may not be significant in some valves, valves that generate spring loads on the order of 2000 to 3000 lbs. can have significant rotation of their valve stems when adjusting the spring load, which hampers the ability to provide field adjustment of the valve.  
         [0029]     Stem  18  also includes an annular seal  18   c  to seal piston  42  against stem  18  and a seal  18   d  for sealing stem  18  in the bottom wall of upper housing  28   b.  Piston  42  and, hence, stem  18  are movable so that piston  42  moves between an upper position (not shown) and a lower position (shown in  FIG. 3 ) in which piston  42  is adjacent annular member  38  and valve stem  18  is urged downward to seal valve member  20  against seat  22 . As would be understood, the position of piston  42  is controlled by the pressure of fluid flowing into inlet  14 , which is directed into cavity  30  above piston  42  through valve stem  18 , and by spring assembly  34 , which varies the load on the piston to adjust the pressure at outlet  16 . As will understood by those skilled in the art, the position of valve stem  18  and, hence, valve member  20  is controlled at least in part by the input pressure from the water entering inlet  14  that is directed above piston  42 , which tends to close the valve in response to the inlet pressure and, therefore, throttles the valve. Spring assembly  34 , however, is used to vary the load on the piston to adjust the pressure at outlet  16 .  
         [0030]     In the illustrated embodiment, spring assembly  34  includes at least two parallel springs  34   a,    34   b  and, more preferably, at least two nested, parallel springs such that their spring constants are additive. It should be understood that spring assembly  34  may include more than two parallel springs. Further, springs  34   a,    34   b  are arranged so that one of the springs (outer or inner) is a left-hand coiled spring while the other spring is a right-hand coiled spring. In the illustrated embodiment, inner spring  34   b  is the left-hand coiled spring, with outer spring  34   a  as the right-hand coiled spring.  
         [0031]     For example, the springs may each have 4 to 7 coils, depending on the diameter of the spring&#39;s wire. The overall height of each spring falls in a range of about 2 to 5 inches and, more typically, in a range of about 3 to 4 inches. Most typically for springs generating a spring rate in a range of about 1700 to 2300 lbs., each of the spring heights is preferably in a range of about 3.2 to 3.8 inches. However, it should be understood that the number of coils and these dimensions may vary, especially when smaller or larger spring loads are desired. In addition, with the spring assembly configuration of the present invention, the stress in the springs may be lower than conventional spring designs with comparable spring loads. For example, for a spring assembly of the present invention with two nested springs, with the inner spring having 5 coils and a wire thickness of about 0.31 inches and the outer spring with 4 coils having a wire thickness of about 0.45 inches and with the spring assembly having an overall height of about 3.4 inches, the maximum stress in each of the springs is about 50 percent of ultimate tensile stress, as compared to a stress level of about 60-65 percent of ultimate tensile stress in a conventional 6″ spring with 8 coils.  
         [0032]     Further, the spring assembly of the present invention has a greater ratio of allowable deflection to overall spring height before reaching the shut height (the fully compressed height of the spring where the spring no long acts like a spring in the compression direction) than conventional spring designs currently being used. For example, for a spring assembly of the present invention with two nested springs, with the inner spring having 5 coils and a wire thickness of about 0.31 inches and the outer spring with 4 coils with a wire thickness of about 0.45 inches, and with the spring assembly having an overall height of about 3.4 inches, the ratio of allowable deflection to overall spring height before reaching the shut height is about 50 percent. While the ratio for a conventional 6″ spring with 8 coils is on the order of about 33 percent.  
         [0033]     The diameter of the spring wires may vary as well. For example, the diameters may vary from about 0.2 to 0.6 inches. In addition, the inner spring&#39;s wire may vary from the outer spring&#39;s wire diameter. For example, the inner spring wire diameter may fall in a range of about 0.2 to 0.4 inches, more typically about 0.3 to 0.4 inches and, most typically for resulting spring compression load of about 1700 to 2300 lbs., in a range of about 0.28 to 0.35 inches. The outer diameter spring wire diameter may fall in a range of about 0.3 to 0.6 inches, more typically about 0.4 to 0.5 inches and, most typically for resulting spring compression load of about 1700 to 2300 lbs., in a range of about 0.4 to 0.5 inches.  
         [0034]     As noted above, the inlet pressure is directed into chamber  30  above piston  42  by valve stem  18 . In the illustrated embodiment, valve stem  18  includes a passageway  46 , which is in fluid communication with passageway  15  by way of opening  48  and in fluid communication with chamber  30  above piston  42  by way of opening  50 . In this manner, when inlet  14  is opened, water will flow into chamber  15  and into valve stem  18  and then into chamber  30  above piston  42 . This water pressure then urges piston  42  downward (as viewed in  FIG. 3 ) and tends to throttle or close the valve. However, as noted above, spring assembly  34  generates a spring force that counteracts the pressure on piston  42 . In the illustrated embodiment, springs  34   a,    34   b  are compressed between adjustment member  36  and lower end  28   c  of upper portion  28   b  of housing  28 . Adjusting member  36  is mounted on valve stem  18  and includes a pair of washers  36   a  and a threaded annular nut  36   b  that threads onto stem  18  and compresses washers  36   a  against the ends of springs  34   a,    34   b  to thereby compress the springs. As a result, spring assembly  34  adjusts the load on piston  42  to increase or decrease the pressure effect on the piston. To adjust the effect of the spring assembly, adjustment member  36 , which is threaded onto valve stem  18 , may be turned about stem  18  to vary the compression on spring assembly  34  and adjust the load on the piston. Hence, the spring assembly and the piston provide an automatic pressure reducing system. As noted above, to limit the potential for valve stem  18  to rotate, piston  42  is rotationally coupled to member  38  and, hence, to body  12 .  
         [0035]     To optionally decouple this automatic pressure reducing function of the piston and the spring assembly, valve stem  18  of the present invention may include two stem portions—an outer stem member  60  and an inner stem member  62 , which is guided by outer stem member  60  and sealed against the inner surface of member  60  by a seal  62   a.  Adjustment member  36 , as noted above, is threaded onto stem  18  but at outer stem member  60  so that outer stem member  60  is coupled to the automatic pressure reducing system of valve  10 .  
         [0036]     In contrast, inner stem member  62 , which is guided in outer stem member  60 , is decoupled from the spring assembly, the adjustment member, and also the piston but coupled at its distal end to valve member  20 . Inner stem member  62  is selectively coupled to handle  29  by handle stem  64 , which is in threaded engagement with upper portion  28   b  of housing  28 . Handle  29 , which preferably comprises a hand wheel, is mounted to handle stem  64  by a fastener  29   a,  which is threaded into top  28   d  of housing, so that when handle  29  is rotated, handle stem  64  is urged into or out of housing  28 . To limit the movement of handle stem  64  into housing, handle stem  64  includes a transverse pin  64   a,  which provides a stop. In addition, stem  64  may include a cup-shaped sleeve  64   b,  which also forms a stop to indicate when valve stem  64  is fully inserted into housing  28 . When stem  64  is extended into housing  28 , stem  64  contacts and urges inner valve stem portion  62  toward valve seat  22 . The lower end of inner valve stem portion  62  is coupled to valve member  20  so that when valve stem portion  62  is pushed downward, as viewed in  FIG. 4 , valve member  20  is urged toward valve seat  22 . In this manner, when handle  29  is rotated, inner stem member  62  can be manually urged downward (as viewed in  FIG. 3 ) to urge valve member  20  against seat  22  without having to overcome the compression forces of spring assembly  34  or the pressure on piston  42 .  
         [0037]     In addition, valve  10  may include a supervisory switch  80 , which includes a plunger or actuator  82  that contacts stem  64  of handle  29  to detect when the valve is open or closed. Stem  64  includes a cam surface, which compresses plunger  82  when stem  64  is in its retracted position, which indicates valve  10  is open. When handle  29  is rotated and stem  64  is extended into housing  28 , plunger  82  rides on the cam surface, which allows plunger  82  to extend, which indicates valve  10  is closed.  
         [0038]     Although described in reference to a pressure reducing valve that facilitates manual opening of the valve by decoupling the manual adjustment from the automatic pressure reducing system, the pressure reducing valve may have a conventional automatic pressure reducing system in which the valve stem is rigidly coupled to the handle and is acted upon by the spring assembly so that adjustment of the valve requires the user to manually compress or decompress the spring to vary the pressure at outlet  16 .  
         [0039]     Accordingly, the present invention provides a pressure reducing valve  10  that has a more compact arrangement, which saves costs and, further, provides for a valve that is easier to handle and has a greater range of application due to its more compact configuration.  
         [0040]     While several forms of the invention have been shown and described, other forms will now be apparent to those skilled in the art. Therefore, it will be understood that the embodiments shown in the drawings and described above are merely for illustrative purposes, and are not intended to limit the scope of the invention which is defined by the claims which follow as interpreted under the principles of patent law including the doctrine of equivalents.