Abstract:
A backflow valve which includes a closure gate pivotally mounted along a substantially vertical pivot axis to one of the opposed sides of the valve body. A closure gate engaging profile positioned in a bottom of the valve body locks the closure gate in the open position. The closure gate is biased into the closed position. The closure gate moves to the closed position upon floating free of the closure gate engaging profile.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a backflow valve and, in particular, a backflow valve with a side mounted closure gate.  
         BACKGROUND OF THE INVENTION  
         [0002]    A backflow valve, also known as a backwater valve, is used to prevent a reversal of flow in a flow line. An example of a backflow valve is disclosed in Canadian Patent 2,114,602 and corresponding U.S. Pat. No. 5,406,972 granted to Coscarella et al.  
           [0003]    The Coscarella et al reference discloses a backflow valve that has a pivoting closure gate with an open position to accommodate flow in a desired flow direction and a closed position to close off the flow line when there is a reversal of flow. The closure gate is hinged to the bottom of the valve housing. In the open position, flow passes over the closure gate with the closure gate serving as a spillway. Secured to the closure gate is a float. When the level of liquid rises, the float causes the closure gate to rise and the reversed direction of flow pushes the closure gate into the closed position.  
           [0004]    The disadvantage of the backflow valve disclosed in the Coscarella et al reference is that when in the open position the liquid flow is always passing over the closure gate. In some applications, it would be advantageous to have a side mounted closure gate with the closure gate positioned to one side of the flow stream in order to reduce the exposure of the closure gate to the liquid flow. The closure gate disclosed in Coscarella et al, however, would not operate if the valve body of Coscarella et al were positioned on its side.  
         SUMMARY OF THE INVENTION  
         [0005]    What is required is an alternative configuration of backflow valve in which there is a side mounted closure gate.  
           [0006]    According to the present invention there is provided a backflow valve which includes a valve body adapted for use in a substantially horizontal orientation. The valve body has a top, a bottom, and opposed sides. A flow passage extends through the valve body. The flow passage has a longitudinal axis. A closure gate is pivotally mounted along an offset substantially vertical pivot axis to one of the opposed sides of the valve body for movement between an open position in which the closure gate is positioned on a plane substantially parallel to the longitudinal axis of the flow passage and a closed position in which the closure gate is positioned transverse to the longitudinal axis. A closure gate engaging profile is positioned in the bottom of the valve body along the one of the opposed sides to which the closure gate is pivotally mounted. The closure gate is locked in the open position by the closure gate engaging profile. The closure gate is capable of limited axial movement along the vertical pivot axis. The closure gate has a float which causes the closure gate to float free of the closure gate engaging profile in the bottom of the valve body as water rises. Means are provided for biasing the closure gate into the closed position. The closure gate moves to the closed position upon floating free of the closure gate engaging profile in the bottom of the valve body.  
           [0007]    With the backflow valve, as described above, the closure gate is held in the open position to one side of the flow passage by the closure gate engaging profile. When liquid starts to rise, the closure gate moves to the closed position upon floating free of the closure gate engaging profile in the bottom of the valve body.  
           [0008]    Although beneficial results may be obtained through the use of the backflow valve, as described above, for improved performance it is preferred that the side closure gate be further removed from the liquid flow. Even more beneficial results may, therefore, be obtained when the valve body has a closure gate accommodating cavity in one of the opposed sides and the closure gate is positioned in the closure gate accommodating cavity when in the open position.  
           [0009]    Although beneficial results may be obtained through the use of the backflow valve, as described above, debris floating behind the closure gate could potentially adversely affect the opening and closing of the closure gate. Even more beneficial results may, therefore, be obtained when the valve body has a baffle which restricts flow behind the closure gate when the closure gate is locked in the open position. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings, wherein:  
         [0011]    [0011]FIG. 1 is a top plan view, in section, of a first embodiment of a backflow valve constructed in accordance with the teachings of the present invention, in an open position.  
         [0012]    [0012]FIG. 2 is a top plan view, in section, of the backflow valve illustrated in FIG. 1, in a closed position.  
         [0013]    [0013]FIG. 3 is a side elevation view, in section, of the backflow valve illustrated in FIG. 1, in an open position.  
         [0014]    [0014]FIG. 4 is a side elevation view, in section, of the backflow valve illustrated in FIG. 1, in a closed position.  
         [0015]    [0015]FIG. 5 is a detailed side elevation view of the closure gate engaging profile of the backflow valve illustrated in FIG. 3.  
         [0016]    [0016]FIG. 6 is a top plan view, in section, of a second embodiment of a backflow valve constructed in accordance with the teachings of the present invention, in an open position  
         [0017]    [0017]FIG. 7 is a top plan view, in section, of the backflow valve illustrated in FIG. 6, in a closed position  
         [0018]    [0018]FIG. 8 is a side elevation view, in section, of the backflow valve illustrated in FIG. 6, in an open position.  
         [0019]    [0019]FIG. 9 is a side elevation view, in section, of the backflow valve illustrated in FIG. 6, in a closed position.  
         [0020]    [0020]FIG. 10 is a detailed side elevation view of the locking member of the backflow valve as illustrated in FIG. 6. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    The preferred embodiment, a backflow valve generally identified by reference numeral  10 , will now be described with reference to FIGS. 1 through 5.  
         [0022]    Referring to FIG. 1, there is provided a backflow valve  10  comprised of a valve body  12  adapted for use in a substantially horizontal orientation. Referring to FIG. 3, valve body  12  has a top  14  and a bottom  16 . Referring to FIGS. 1 and 2, valve body  12  has opposed sides  18  Valve body  12  has a closure gate accommodating cavity  20  in the one of opposed sides  18  to which a closure gate  22  is pivotally mounted for movement between an open position as illustrated in FIG. 1 and a closed position as illustrated in FIG. 2. Referring to FIGS. 1 and 2, a flow passage  24  extends through valve body  12 , with flow passage  24  having a longitudinal axis, generally indicated by reference numeral  25 . Referring to FIGS. 3 and 4, closure gate  22  is pivotally mounted along an offset substantially vertical pivot axis defined by hinge  27 . Referring to FIG. 1, closure gate  22  is accommodated out of flow passage  24  in closure gate accommodating cavity  20  of one of opposed sides  18  of valve body  12 . This permits movement between an open position in which closure gate  22  is positioned in closure gate accommodating cavity  20  on a plane substantially parallel to the longitudinal axis  25  of flow passage  24  and out of the flow stream as shown in FIG. 1 and a closed position in which closure gate  22  is positioned transverse to longitudinal axis  25  of flow passage  24  as shown in FIG. 2. The offset of the vertical pivot axis represented by hinge  27  is sufficient to bias closure gate  22  into the closed position.  
         [0023]    Referring to FIG. 5, closure gate  22  has an underlying engagement profile which, in the illustrated embodiment, is a semi-circular projection  23 . A mating closure gate engaging profile which, in the illustrated embodiment, is in the form of a depression  30 , is provided in bottom  16  of valve body  12  along the one of opposed sides  18  to which closure gate  22  is pivotally mounted. Closure gate  22  is locked in the open position when projection  23  of closure gate  22  engages depression  30  in bottom  16  of valve body  12 . As indicated by arrows  29 , closure gate  22  is capable of limited axial movement along the vertical pivot axis provided by hinge  27 .  
         [0024]    Referring to FIG. 3, closure gate  22  has built into its structure two floats  26 . Floats  26  cause closure gate  22  to float as water rises. Closure gate  22  rises along hinge  27  until projection  23  is free of depression  30  in bottom  16  of valve body  12 . Hinge  27  is positioned at an angle so that closure gate  22  closes by force of gravity when projection  23  is free of depression  30 .  
         [0025]    Referring to FIGS. 1 and 3, valve body  12  has a baffle  28  which restricts flow behind closure gate  22  when closure gate  22  is locked in the open position.  
         [0026]    Once the teachings of the present invention are understood, the construction of the backflow valve can be modified in various ways. Referring to FIGS. 6 through 10 there is illustrated a second embodiment of a backflow valve generally referenced by numeral  100 .  
         [0027]    Referring to FIG. 6, there is provided a backflow valve  100  comprised of a valve body  120  adapted for use in a substantially horizontal orientation. Referring to FIG. 8, valve body  120  has a top  140  and a bottom  160 . Referring to FIGS. 6 and 7, valve body  120  has opposed sides  180 . Valve body  120  has a closure gate accommodating cavity  200  in the one of opposed sides  180  to which a closure gate  220  is pivotally mounted for movement between an open position as illustrated in FIG. 6 and a closed position as illustrated in FIG. 7. Referring to FIGS. 6 and 7, a flow passage  240  extends through valve body  120 , with flow passage  240  having a longitudinal axis, generally indicated by reference numeral  250 . Referring to FIGS. 8 and 9, closure gate  220  is pivotally mounted along an offset substantially vertical pivot axis defined by hinge  270 . Referring to FIG. 6, closure gate  220  is accommodated out of flow passage  240  in closure gate accommodating cavity  200  of one of opposed sides  180  of valve body  120 . This permits movement between an open position in which closure gate  220  is positioned in closure gate accommodating cavity  200  on a plane substantially parallel to the longitudinal axis  250  of flow passage  240  and out of the flow stream as shown in FIG. 6 and a closed position in which closure gate  220  is positioned transverse to longitudinal axis  250  of flow passage  240  as shown in FIG. 7. The offset of the vertical pivot axis represented by hinge  270  is sufficient to bias closure gate  220  to the closed position.  
         [0028]    Referring to FIGS. 6 and 8, valve body  120  has a baffle  280  which restricts flow behind closure gate  220  when closure gate  220  is locked in the open position. Referring to FIG. 7, baffle  280  has a first side  300  and a second side  310 . A locking member  320  is positioned along first side  300  of baffle  280 . Second side  310  of baffle  280  faces closure gate accommodating cavity  200 . Referring to FIG. 10, locking member  320  has a first end  340  and a second end  360 . First end  340  of locking member  320  engages closure gate  220  while second end  360  is pivotally mounted by a bolt  350  to baffle  280 . Locking member  320  has a float  260  attached to first end  340 .  
         [0029]    Referring to FIG. 8, closure gate  220  is locked in the open position when locking member  320  of baffle  280  engages closure gate  220 . Referring to FIG. 9, float  260  causes first end  340  of locking member  320  to rise upward as water rises. As first end  340  of locking member  320  rises, locking member  320  disengages from closure gate  220 . Hinge  270  is positioned at an angle so that closure gate  220  closes by force of gravity when closure gate  220  is no longer restrained by locking member  320 .  
         [0030]    It will be apparent to one skilled in the art that modifications may be made to the illustrated embodiment without departing from the spirit and scope of the invention as hereinafter defined in the claims.