Abstract:
A backflow and back-siphonage preventer assembly, consisting of a ball valve and a double check valve backflow preventer with an atmospheric vent, provides isolation protection on high pressure plumbing supply lines, such as high pressure hose drops used for the washdown of equipment and facilities, e.g. in food processing plants. The backflow preventer includes a housing with an inlet, an outlet, and a drain outlet therebetween. A first valve is upstream of the drain outlet passage, and a second valve is downstream of the drain outlet, a sealing member moves between a first position in which the drain outlet passage is closed, and a second position in which the drain outlet passage is open. A reinforcing member operatively coupled to the sealing member permits operating pressures of greater than about 500 psi without blow-out of the sealing member.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/147,368, filed Aug. 5, 1999. 
    
    
     This invention relates to backflow and back-siphonage preventers, in particular for use on high pressure plumbing supply lines. 
     BACKGROUND OF THE INVENTION 
     High pressure hose drops, e.g. operating at pressures of up to 400 psi, are often used for the washdown of equipment and facilities, such as in food processing plants. It is recognized that it is desirable to protect a plumbing supply line providing water to hose drop stations against contamination by reverse flow through the hose (i.e. backflow and/or back-siphonage) of potentially contaminated water from the processing and rendering areas into the potable water supply. 
     SUMMARY OF THE INVENTION 
     According to the invention, a high pressure hose drop is equipped with a backflow and back-siphonage preventer assembly consisting of a ball valve and a double check valve backflow preventer with an atmospheric vent. The backflow and back-siphonage preventer assembly of the invention is particularly suited for isolation protection on high pressure plumbing supply lines, such as high pressure hose drops used for the washdown of equipment and facilities, e.g. in food processing plants. 
     According to one aspect of the invention, a backflow preventer includes a housing defining a fluid flow channel, an inlet at an upstream region of the housing in fluid communication with the fluid flow channel, an outlet at a downstream region of the housing in fluid communication with the fluid flow channel, and a drain outlet passage between the upstream region and the downstream region. A first valve is located upstream of the drain outlet passage for controlling fluid flow in the fluid flow channel, and a second valve is located downstream of the drain outlet passage for controlling fluid flow in the fluid flow channel. The backflow preventer includes a sealing member configured to move between a first position in which the drain outlet passage is closed to limit fluid communication between the drain outlet passage and the fluid flow channel, and a second position in which the drain outlet passage is open to permit fluid communication between the drain outlet passage and the fluid flow channel. A reinforcing member is operatively coupled to the sealing member to permits operating pressures of greater than about 500 psi without blow-out of the sealing member. 
     Embodiments of this aspect of the invention may include one or more of the following features. The sealing member is biased toward the first position in the absence of backflow in the fluid flow channel. The first valve includes a valve member. The valve member is moved out of engagement with the sealing member during normal flow. The valve member is biased toward a position in engagement with the sealing member by, for example, a spring. 
     In the illustrated embodiment, the valve member is biased toward a closed position against a seat. The reinforcing member is biased toward the first position. The sealing member provides the seat and a biasing force for biasing the reinforcing member toward the first position. 
     The reinforcing member is configured to move between a first position in which the drain outlet passage is closed to limit fluid communication between the drain outlet passage and the fluid flow channel, and a second position in which the drain outlet passage is open to permit fluid communication between the drain outlet passage and the fluid flow channel. The sealing member and the reinforcing member are coupled such that movement of the sealing member during backflow conditions allows the reinforcing member to move toward its second position. The reinforcing member is biased toward its second position by, for example, a spring. The reinforcing member is positioned between the sealing member and the outlet passage. 
     A ball valve and a strainer are located upstream of the first valve. 
     According to another aspect of the invention, a valve assembly includes a housing defining a fluid flow channel, an inlet at an upstream region of the housing in fluid communication with the fluid flow channel, an outlet at a downstream region of the housing in fluid communication with the fluid flow channel, and a drain outlet passage between the upstream region and the downstream region. A valve is located upstream of the drain outlet passage for controlling fluid flow in the fluid flow channel. The valve assembly includes a sealing member configured to move between a first position in which the drain outlet passage is closed to limit fluid communication between the drain outlet passage and the fluid flow channel, and a second position in which the drain outlet passage is open to permit fluid communication between the drain outlet passage and the fluid flow channel. A reinforcing member is operatively coupled to the sealing member to permit operating pressures of greater than about 500 psi without blow-out of the sealing member. 
     The backflow and back-siphonage preventer assembly of the invention advantageously provides protection against back-siphonage and back-pressure backflow to resist reverse flow of potentially contaminated water from the processing and rendering areas into the potable water supply. The backflow preventer safeguards the water supply, thus ensuring that the water is safe to drink and safe for use in processing meat within the facility. 
     The assembly is also advantageously designed for non-health hazard applications, and for use where continuous pressure conditions exist. For this purpose, the assembly advantageously incorporates a bronze ball valve shutoff on the inlet of the assembly and incorporates, on the outlet of the assembly, a dual check with atmospheric vent specifically designed to handle temperature and pressure conditions commonly found in the meat processing industry. 
     Other features and advantages will be apparent from the following description of a presently preferred embodiment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a somewhat diagrammatic perspective view of a high pressure hose drop backflow and back-siphonage preventer assembly of the invention mounted for use, e.g., for washdown of equipment and facilities; 
     FIG. 2 is a plan view of a high pressure hose drop backflow and back-siphonage preventer assembly of the invention; 
     FIG. 3 is a plan view, partially in section, of the high pressure hose drop backflow and back-siphonage preventer assembly of FIG. 2 shown in a rest or normal backflow prevention position; 
     FIG. 4 is a plan view, partially in section, of the high pressure hose drop backflow and back-siphonage preventer assembly of FIG. 2 shown in position for normal flow; and 
     FIG. 5 is a plan view, partially in section, of the high pressure hose drop backflow and back-siphonage preventer assembly of FIG. 2 shown in position for preventing backflow when the primary check valve has failed. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 and 2, a backflow and back-siphonage preventer assembly  10  of the invention is installed at a hose drop  12  of a high pressure plumbing supply line  14 . The backflow and back-siphonage preventer assembly  10  includes a ball valve  16  and a dual check backflow preventer  18 . The assembly  10  preferably features all bronze ball valve and backflow preventer body construction, with stainless steel internal parts and durable, tight seating check valve assemblies. 
     Referring also to FIG. 3, ball valve  16  has a body  20  defining an assembly inlet  17  which is connected, i.e. threaded, to plumbing supply line  14 . The backflow preventer  18  has a body  28  defining an assembly outlet  19  at which there is connected, i.e. threaded, a hose  22  (FIG. 1) terminating in a spray nozzle  23 . Body  28  also defines a vent outlet  24  at which there is connected, i.e. threaded, a drain line  26  (FIG.  1 ). Preferably, the assembly inlet  17  is a female national pipe thread inlet connection and the assembly outlet  19  is a male national pipe thread outlet connection, e.g. ¾ inch or 1 inch; and the vent or drain outlet  24  is a ½ inch threaded connection. 
     Body  28  includes three sections  28   a ,  28   b , and  28   c . Body section  28   a  is connected to ball valve  16  by a union nut  21   a , body sections  28   a  and  28   b  are threadedly connected at  23 , and body section  28   c  is connected to tail piece section  28   b  by a union nut  21   b . Located between ball valve  16  and body section  28   a  is a gasket seal  25   a  of suitable material, located between sections  28   a  and  28   b  is an o-ring seal  25   b , and located between sections  28   b  and  28   c  is a gasket seal  25   c  of suitable material. Body section  28   b  defines vent outlet  24 , and body section  28   c  defines assembly outlet  19 . Sections  28   a  and  28   b  are of bronze construction with a brass male tail piece section  28   c.    
     The ball valve  16  is a two piece construction with an ASTM B-584 bronze body  20 , an ASTM B-16 or B-124 ENP (electroless nickel plated) brass ball  30 , DURAFILL™ or UNISEAL™ reinforced/enhanced PTFE (poly tetra fluoro ethylene) seats  32 , Teflon® (PTFE) stem packing  34  (Teflon® is a registered trademark of E.I. DuPont de Nemours &amp; Company, Inc.), a blow-out proof stem  36 , and a low profile oval handle  38  for opening and closing ball valve  16 . 
     The dual check valve  18  with atmospheric vent  24  includes a primary check valve  40  utilizing a rubber disc  42  seating against a seat part  44  of a brass insert  45  to ensure tight sealing. Valve  18  also includes a secondary check valve  46  utilizing a Teflon® (PTFE) disc  48  engaging upon a diaphragm  50  to provide protection against backflow if primary valve  40  fails. Diaphragm  50  is relatively stiff, having a durometer of  40  (Shore D scale), and is supported by a Belleville spring disc  60  to resist blow-out of diaphragm  50  under relatively high working pressures, e.g. up to about 400 psi (27.5 bars). To safely allow for such working pressures, disc  60  reinforces diaphragm  50  such that blow-out of diaphragm  50  at pressures greater than about 500 psi, and preferably up to 600 psi, is prevented. 
     Disc  42  of primary valve  40  is mounted to a four-pronged guide  70  between a base  72  and a disc  74  of the guide. Fixed to guide  70 , and extending from guide base  72 , is a rod  76  having a flared end  78 . Slidably mounted to rod  76  between two washers  80   a ,  80   b  is a three-pronged guide  82 . Guides  70  and  82  are biased to the spaced position shown in FIG. 3 by spring  83 . Insert  45  defines a channel  84  for receiving an o-ring seal  86 . The outer diameter of insert  45  is less than the inner diameter of body section  28   b  such that a fluid passage  88  is defined therebetween. Disc  60  is pushed up against a lip  62  defined by insert  45  by diaphragm  50 . A light spring  90  biases disc  60  away from lip  62 . Diaphragm  50  seals against a seat  92  defined by insert  45 . Diaphragm  50  and disc  60  together act to control fluid communication between the main fluid path  94  through valve  18  and passage  88 . 
     Disc  48  of secondary valve  46  is mounted to a rod  96  having an enlarged end disc  98 . Rod  96  is free to slide along the axis, A, of valve  18  under pressure from forward or back flow acting upon discs  48  and  98 . Trapped between body sections  28   a  and  28   b  are an edge  100  of diaphragm  50 , and edge  102  of a spring support  104 , and a seal washer  106 . Support  104  defines through holes  108  for fluid flow. Positioned between support  104  and an enlarged end  110  of rod  96  is a spring  112  which biases disc  48  against diaphragm  50 . 
     An integral stainless steel strainer  54  upstream protects the primary and secondary check assemblies  40 ,  46  from fouling due to dirt and debris in water from the plumbing supply line. (Prior to installation, the pipe lines should be flushed to remove foreign material, and the strainer should be cleaned every six months, or otherwise as conditions require.) 
     The backflow and back-siphonage preventer assembly  10  of the invention is designed for use in non-health hazard continuous pressure applications, e.g., a Series 912 HP High Pressure Hose Drop Backflow Preventer, commercially available from Watts Regulator Company of North Andover, Mass., and embodying the invention, is rated at a maximum working pressure of 400 psi (27.5 bars) and a maximum temperature of 160° F. (71° C). The assembly should be installed at all hose drops to provide protection against back-pressure and back-siphonage backflow. It can be installed vertically for flow-down (as shown in FIG.  1 ), or it can be installed vertically, for flow-up, or installed horizontally. 
     Referring to FIG. 4, in a normal flow situation, indicated by arrow, F, with the ball valve  16  open, water flowing through strainer  54  displaces disc  48  of secondary check valve  46  from its sealing engagement with diaphragm  50 , against the bias from spring  83 , to permit flow through the secondary check valve  46  toward primary check valve  40 . The flowing water also displaces rubber disc  42  from sealing engagement upon seat  44 , against the bias from spring  112 , to permit flow through the primary check  40  toward the assembly outlet  19 , and then to hose  22  and spray nozzle  23 . Under normal flow conditions, the vent or drain outlet  24  is closed by pressure of diaphragm  50  against drain seat  90 . Disc  60  supports diaphragm  50  during normal flow to resist blow-out of diaphragm  50  under relatively high working pressures. 
     In normal backflow or back-siphonage conditions, with water flowing back toward the outlet  19  (arrow, B, of FIG. 3) from hose  22 , the rubber disc  42  is urged into sealing engagement upon seat  44 , as shown in FIG. 3, thereby to resist backflow of potentially contaminated water through the primary check valve  40  of the backflow preventer  18 , toward the plumbing supply line  14  (FIG.  1 ). 
     Referring to FIG. 5, in the event of fouling of the downstream (primary) check valve  40 , leakage past the primary check valve is vented to atmosphere by way of the vent or drain outlet  24 , thereby providing a visual indication of failure of the check assembly. In particular, pressure of water backflow (arrow, B) bears upon the secondary check valve  46 , urging the disc  48  into sealing engagement upon the diaphragm  50 , thus to resist backflow of potentially contaminated water through the secondary check valve  46  of the backflow preventer  18 , into the plumbing supply line  14 . At the same time, the backflow pressure acts to deflect the diaphragm  50  (in the direction of arrow, B), thereby moving diaphragm  50  out of engagement with seat  90 . The force of spring  88  acts to slide disc  60  out of engagement with lip  62 . The movement of diaphragm  50  and disc  60  opens a path for fluid communication to passage  88  and outlet  24  to allow the potentially contaminated water to exit from the backflow preventer  18  by way of the drain line  26  (FIG.  1 ). 
     Some discharge from the vent outlet  24  is also to be expected, especially during start-up, until all seating surfaces seal. However, continuous discharge is an indication that the check valve components may require cleaning or replacement. Quick closing valves, water hammer, and/or supply pressure fluctuations can also cause intermittent discharge. The installation of a water hammer arrestor (e.g. a Series 05 water hammer arrestor available from Watts Regulator Company) or a water pressure reducing valve (e.g. an N35B water pressure reducing valve, also available from Watts Regulator Company) may be installed to correct the problem. 
     Referring again to FIG. 1, the discharge or drain line  26  should be piped in accordance with local code requirements. It is important also that the backflow and back-siphonage preventer assembly  10  be installed where discharge from the vent outlet  24  will not cause damage. A physical air gap, G, should be maintained between the end of the discharge pipe  26  and the associated floor drain  64 , e g. by cutting the pipe on a 45° bevel, at a distance of 12 inches above the floor drain or through an air gap piped to a floor drain. 
     Other embodiments are within the scope of the following claims.