Check valve

Abstract

A check valve which includes a body adapted at one end to receive a liquid source and at the other end to engage with a spray nozzle and having a bore therethrough, an internal annular recess within the body, the upstream end of which body provides a valve seat, a valve assembly located in the recess and having a valve member having a generally curved end directed towards the seat and bias means to normally hold the member against the seat until the pressure at the inlet reaches a predetermined minimum.

1 . A check valve in a spray nozzle assembly, comprising:
 a body having an upstream end for receiving a liquid source and a downstream end for engaging a spray nozzle with bore running through said body from said upstream end to said downstream end;   a first component adjacent said upstream end of said body;   a second component adjacent said downstream end of said body, said first component having a smaller diameter than a diameter of said second component;   a valve seat at a junction of said first component and said second component;   a valve assembly located substantially in said second component and having a valve member with a curved end directed towards said valve seat; and,   biasing means for holding said valve member against said valve seat until pressure at an inlet of said valve member attains a predetermined minimum pressure.   
   
   
       2 . The check valve in a spray nozzle assembly according to  claim 1 , wherein said curved end of said valve member is substantially hemispherical in shape. 
   
   
       3 . The check valve in a spray nozzle assembly according to  claim 1 , wherein said curved end of said valve member is substantially conical in shape. 
   
   
       4 . The check valve in a spray nozzle assembly according to  claim 1 , wherein said curved end of said valve member is made of a sacrificial material and forms a valve seal with said valve seat when said valve assembly is in a closed position. 
   
   
       5 . The check valve in a spray nozzle assembly according to  claim 4 , wherein said valve seat is shaped as a truncated cone. 
   
   
       6 . The check valve in a spray nozzle assembly according to  claim 1 , wherein said valve includes guide means for locating said valve member axially within the bore for permitting liquid to flow around said valve member when said valve assembly is in an open position. 
   
   
       7 . The check valve in a spray nozzle assembly according to  claim 6 , wherein said guide means is positioned upstream of, and adjacent to, the curved end of said valve member. 
   
   
       8 . The check valve in a spray nozzle assembly according to  claim 7 , wherein said guide means includes a plurality of arm members extending between an axial component of said guide means to about a surface of said first component, so that fluid flow over said guide means is minimally obstructed. 
   
   
       9 . The check valve in a spray nozzle assembly according to  claim 1 , wherein said biasing means is a spring. 
   
   
       10 . The check valve in a spray nozzle assembly according to  claim 9 , wherein said curved end of said valve member forms a valve seal with said valve seat when said valve assembly is in a closed position, said valve seal being connectable to said spring via a screw. 
   
   
       11 . The check valve in a spray nozzle assembly according to  claim 1  further comprising releasable retaining means for retaining said valve assembly within said body for providing a unitary check valve. 
   
   
       12 . The check valve in a spray nozzle assembly according to  claim 11 , wherein said releasable retaining means is a perforated sleeve passing over said biasing means and retaining said biasing means in a compression state when not released. 
   
   
       13 . The check valve in a spray nozzle assembly according to  claim 11 , wherein said releasable retaining means is bayonet fittings. 
   
   
       14 . The check valve in a spray nozzle assembly according to  claim 13 , wherein said biasing means is a spring cage and said bayonet fittings comprise lugs on said spring cage for engaging with bayonet slots in an interior of said body, said bayonet slots having sloping, or ramping, side walls. 
   
   
       15 . The check valve in a spray nozzle assembly according to  claim 1 , wherein fluid flows through said check valve in a substantially axial direction to the spray nozzle. 
   
   
       16 . The check valve in a spray nozzle assembly according to  claim 1 , further comprising at least one air passage passing through said body for entraining air into a fluid flow at said downstream end of said body when fluid is flowing through said body. 
   
   
       17 . The check valve in a spray nozzle assembly according to  claim 1 , wherein said valve seat is a removable, replaceable wear device having a push-fit construction. 
   
   
       18 . The check valve in a spray nozzle assembly according to  claim 1 , wherein said valve seat is used with a coaxial O-ring.