Abstract:
A backflow preventer for water distribution installations includes a body having an inlet conduit arranged along an inlet axis, an outlet conduit arranged along an outlet axis, and a discharge conduit arranged along a discharge axis of the body. The backflow preventer is provided with check valves that prevent a backflow of fluid from the outlet to the inlet in the event of low pressure upstream of the backflow preventer and/or high pressure downstream of the backflow preventer. The backflow preventer further includes a discharge valve arranged along the discharge axis of the body of the backflow preventer for discharging fluid in the low and/or high pressure conditions. A discharge pipe is connected to the discharge valve to discharge the fluid outside the backflow preventer along an end discharging axis of the fluid outside the backflow preventer. Coupling elements are provided to adapt the backflow preventer to various applications for varying the angular position of the discharge pipe with respect to the body of the backflow preventer.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The object of the present invention is a backflow preventer for water distribution installations, intended to perform a water protection function. 
       State of the Art 
       [0002]    The backflow preventer is substantially a safety device that prevents the backflow of contaminated and/or polluted waters into the mains water network of the public water supply. 
         [0003]    The backflow preventer is installed between the mains water network and the user network and if there is a drop in pressure in the mains water network with respect to the user network the backflow preventer prevents the backflow of water from the user network to the mains water network. 
         [0004]    The drop in pressure in the distribution network can occur following a break in the pipe of the public water supply or following significant withdrawals by other user networks. 
         [0005]    The flow reversal condition can also occur not because of a drop in pressure in the mains water network but because of an increase in pressure in the user network that is for example due to the entry of water pumped from a well. 
         [0006]    The backflow preventer is usually a valve unit that comprises a check valve upstream, a check valve downstream, and a discharge valve in an intermediate reduced pressure area that opens when reversed flow conditions occur, enabling the discharge of the water contained in the intermediate area to the outside through a discharge pipe. 
         [0007]    There are very many applicational fields for the backflow preventer in view of the fundamental protective action that it performs. The backflow preventer can be used in heating plants, industrial plants, agricultural plants, hospital plants, irrigation plants and others. 
         [0008]    In view of the large variety of applications, the manufacturer of these plumbing devices has to provide a large number of backflow preventer models to adapt to the various geometries that are due to the positioning of the connections on which the backflow preventer is connected in the various applications. 
         [0009]    Providing different models of backflow preventer leads to problems for the manufacturer at the manufacturing, at the storage and at the transporting stage and also leads to problems for the retailers and fitters who have to manage these various models of backflow preventer. 
       Object of the Invention 
       [0010]    The object of the present invention is to propose a backflow preventer for water distribution installations that enables the aforesaid problems to be solved. 
       Short Description of the Invention 
       [0011]    This object is obtained by a backflow preventer for water distribution installations according to claim  1 . 
     
    
     
       SHORT DESCRIPTION OF THE DRAWINGS 
         [0012]    In order to understand better the invention, a description is set out below of an exemplifying non limiting embodiment thereof, illustrated in the annexed drawings in which: 
           [0013]      FIG. 1  is a perspective view of a backflow preventer for water distribution installations according to the invention; 
           [0014]      FIG. 2  is a side view of the backflow preventer of  FIG. 1 ; 
           [0015]      FIG. 3  is an axial section view of the backflow preventer of  FIG. 1 ; 
           [0016]      FIGS. 4,5  are respectively a perspective view and an axial section view of a component of the backflow preventer of  FIG. 1 ; 
           [0017]      FIGS. 6,7  are respectively a perspective view and a perspective view in a partial section of another component of the backflow preventer of  FIG. 1  in an operating configuration; 
           [0018]      FIGS. 8,9,10  show the operation of the backflow preventer of  FIG. 1  in the axial section view of  FIG. 3 ; 
           [0019]      FIGS. 11,12,13  show respectively in a perspective view, in an elevation view, and in a section view according to line  13 - 13  of  FIG. 12  the component of  FIGS. 6,7  in another operating configuration; 
           [0020]      FIG. 14  shows in a perspective view the backflow preventer of  FIG. 1  with the component of  FIGS. 6,7  in the operating configuration of  FIGS. 11,12,13 ; 
           [0021]      FIG. 15  shows in a perspective view the backflow preventer of  FIG. 1  in a further operating configuration. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    The illustrated backflow preventer, indicated generally with  10 , comprises a valve body  11  in which conduits are obtained and in which valve components are received. 
         [0023]    With reference to  FIG. 3 , in the valve body  11  there are obtained an inlet conduit upstream, indicated with  12 , and an outlet conduit downstream, indicated with  13 , both arranged along the same horizontal axis A. In the body  11  there are further obtained an intermediate conduit, indicated with  14 , communicating directly with the inlet conduit  12  and arranged along an axis B that is oblique to the axis A, and another intermediate conduit, indicated with  15 , that brings the intermediate conduit  14  into contact with the outlet conduit  13  and is arranged along an axis C that is perpendicular to the axis A and oblique to the axis B. 
         [0024]    The backflow preventer  10  has at the inlet conduit  12  a connection  16  for a water network and at the outlet conduit  13  a connection  17  for a user network. 
         [0025]    At the inlet conduit  12 , at the intermediate conduit  15 , and at the outlet conduit  13  three respective connections  18 , 19 , 20  are provided that are closed by respective caps  21 , 22 , 23 , to connect pressure gauges when it is necessary to conduct measurements of pressure inside the backflow preventer  10 . 
         [0026]    Inside the intermediate conduit  14 , which has a larger diameter than the other conduits, a cylindrical valve cartridge  24  is received, illustrated individually in  FIGS. 4, 5 , which includes a check valve  25  and a diaphragm discharge valve  26  that are both arranged along the axis B. 
         [0027]    With reference to  FIGS. 3,4,5 , the valve cartridge  24  comprises a cage  27  inside which the valves  25  and  26  are arranged. The cage  27  is fixed inside the conduit  14  by means of a threaded bush  28  that is screwed in an open threaded part  29  of the body  11  of the backflow preventer  10  at the conduit  14 ; the bush  28  locks the cage  27  against an annular seat  30  inside the body  11  of the backflow preventer  10 . 
         [0028]    The diaphragm discharge valve  26  has a hollow shutter cylinder  31  that is slidable on a piston  32  that is fixed at one end to the cage  27  of the cartridge  24  by a nut  33 . One end of the shutter cylinder  31  interacts with an annular seat  34  of the cage  27  to open or close a passage to the inside of the bush  28  according to the position of the shutter cylinder  31 . To the opposite end of the shutter cylinder  31  an annular diaphragm  35  is fixed by means of a ring  36  and a ring nut  37  between which the inner edge of the diaphragm  35  is interposed: the ring  36  is screwed onto the end of the shutter cylinder  31  and the ring nut  37  is screwed onto the ring  36 . The outer edge of the diaphragm  35  is locked between the cage  27  and the annular seat  30  of the body  11  of the backflow preventer  10 . On an annular seat  38  of the shutter cylinder  31  a coil spring  39  acts in the opening direction that reacts on the annular seat  34  of the cage  27 . 
         [0029]    The check valve  25  has a shutter  40  that is movable inside the shutter cylinder  31  and interacts with an annular edge  41  of the ring nut  37  for opening or closing the passage through the ring nut  37 . The shutter  40  is at side openings  42  of the shutter cylinder  31 . On an annular seat  43  of the shutter  40  a coil spring  44  acts in the closing direction that reacts on an annular seat  45  of the shutter cylinder  31 . 
         [0030]    With reference to  FIGS. 3,6,7 , to the bush  28  a discharge pipe  46  is fixed that is formed by a joint portion  47  and an outlet portion  48 , which are both cylindrical. The joint portion  47  is directed along the axis B and is fixed on the bush  28  via a snap coupling  49  that retains the portion  47  in the bush  28 , permitting rotation thereof with respect to the bush around the axis B. The joint portion  47  further has an outlet connection mouth  50 , which is tilted with respect to the axis B Likewise, the outlet portion  48  has an inlet connection mouth  51 , which is tilted with respect to the axis thereof, indicated with D. The two mouths  50  and  51  are connected via a snap coupling  52  that retains the end portion  48  on the joint portion  47  anyway permitting rotation with respect to the portion  47  around a common axis indicated with E. Both the mouths  50  and  51  have the same tilt with respect to the axes B and D of the respective portions  47  and  48 , and this tilt has a value of ¾ of a right angle. The outlet portion  48  has a shaped conveying part  53 , side safety discharge windows  54 , and a funnel end part  55 . 
         [0031]    In the outlet conduit  13  another check valve is located that is indicated generically with  56 . The valve  56  provides a cage body  57  in which a shutter  58  is movable that interacts with a seat  59  of the body  57  to open or close the passage along the conduit  13 . On the shutter  58  a spring  60  acts in a closing direction that reacts on an annular inner seat  61  of the body  57 . 
         [0032]    With reference to  FIGS. 8,9,10  the operation of the backflow preventer  10  is as follows. 
         [0033]    In this example it is supposed that the backflow preventer  10  is connected, in a water distribution installation, between a public mains water connection via the connection  16  and a private user network via the connection  17 . 
         [0034]    The conduit  12  defines an inlet area, the intermediate conduits  14 , 15  define an intermediate reduced pressure area, and the conduit  13  defines an outlet area. 
         [0035]    In a correct flow condition, illustrated in  FIG. 8 , the check valves  26  and  56  are open and thus the shutters  40  and  58  are open to contrast the action of the respective springs  44  and  60 . The water flows in the backflow preventer  10  from the water network to the user network via the conduit  12 , the ring nut  37 , the windows  42 , the conduit  14 , the conduit  15  and the conduit  13 , as indicated by the arrows. The pressure in the intermediate area is less than the inlet pressure by the effect of the load loss caused by the check valve  25 . In this situation the pressure acting upstream on the diaphragm  35  and on the shutter cylinder  31  is greater than the force exerted by the spring  39  on the shutter cylinder  31  and thus the discharge valve  26  remains shut. 
         [0036]    If the flow is stopped, the check valves  26  and  56  and thus the shutters  40  and  58  close by the action of the springs  44  and  60 . The pressure in the intermediate area is still less than the inlet pressure and the discharge valve  26  remains shut. 
         [0037]    With reference to  FIGS. 9,10 , in a flow condition, if the pressure in the inlet area decreases both the check valves  26  and  56  close. The discharge valve  26  opens at the moment in which the upstream pressure on the diaphragm  35  and on the shutter cylinder  31  is lower than the force exerted on the shutter cylinder by the spring  39 . At this point the shutter cylinder  31  lifts up by the action of the spring  39  to let the water contained in the intermediate area flowing to the discharge pipe  46 , where it flows through the portions  47  and  48  and then exits the pipe as indicated by the arrows. 
         [0038]    If the pressure in the outlet area rises above the value of the pressure in the inlet area, the check valve  56  closes, thus not permitting the backflow to the water network of the water already sent to the user network. If the check valve  56  had a seal defect and the water leaked into the intermediate area the check valve  25  would prevent any backflow of water to the water network. A pressure increase in the intermediate area would then cause the discharge valve  26  to open, as seen above. 
         [0039]    The backflow preventer  10  thus performs the protective function mentioned in the introduction. 
         [0040]    The particular coupling seen between the portion  47  and the portion  48  of the discharge pipe  46  enables the geometry of the discharge pipe to be varied. In fact, the rotation on tilted faces of the portion  48  with respect to the portion  47  around the axis E enables the axis D of the portion  48  to be rotated with respect to the axis B of the portion  47  and the angular position of the portion  48  to be thus varied with respect to the portion  47 . In particular, by rotating the portion  48  with respect to the portion  47  by 180° from the position illustrated in  FIGS. 1,2,6,7,8,9,10  an alignment position is reached of the axis D with respect to the axis B in which the discharge pipe  46  is no longer angled but rectilinear, as illustrated in  FIGS. 11-14 ; in this operating configuration the inlet/outlet axis of the disconnector  10  is tilted with respect to the horizontal lying of  FIG. 1 . 
         [0041]    In  FIG. 15  there is another operating configuration of the backflow preventer  10  that is obtained by rotating by 180° the portion  47  with respect to the bush  28 , starting from the angled position of the discharge pipe  46  of  FIG. 1 ; in this case the discharge pipe  46  is angled in an opposite direction to what is illustrated in  FIG. 1  and the inlet/outlet axis is vertical. 
         [0042]    The backflow preventer  10  can thus be adapted to the various geometries required due to the positioning of the connections to which the backflow preventer connects in the various applications. Having to use various backflow preventer models is thus avoided, the variable geometry backflow preventer  10  being sufficient. 
         [0043]    The cartridge  24  that incorporates the check valve  25  and the discharge valve  26  is very advantageous because it incorporates the two functions of retaining and discharging in a single component. Further, the coaxial arrangement of the check valve  25  and of the discharge valve  26  makes the cartridge  24  very compact. Replacing the cartridge  24  is very simple, inasmuch as it is sufficient to unscrew the bush  28 , remove the cartridge to be replaced, insert the new cartridge and retighten the bush  28 . This replacement is made possible by the use of a diaphragm discharge valve, namely the valve  26 , and permits simple maintenance of the backflow preventer  10 , leaving the body  11  installed in the water distribution installation. 
         [0044]    The connections  18 , 19 , 20 , once the respective caps  21 , 22 , 23  have been removed, enable pressure gauges to be inserted, as said above, to check correct operation of the various areas of the backflow preventer  10 . 
         [0045]    It is clear that variations on and/or additions to what has been disclosed and illustrated can be foreseen. 
         [0046]    In general, it is possible to provide any coupling between the valve body and the discharge pipe to vary the angle between the discharge direction in the valve body, in the embodiment seen above along the axis B, and the discharge direction of the discharge pipe, in the example along the axis D. For example, the discharge pipe can be rectilinear and have a spherical sealing coupling with the valve body. 
         [0047]    Variants in the configuration of all the components and conduits obtained in the body can be provided, which are disclosed and illustrated in the embodiment.