A flap valve

Abstract: A flap valve comprising an annular frame (10) defining an opening (11) through which liquid may flow in one direction, a closure flap (14) for said opening connected to the frame (10) by a hinge member(15), and a valve seat (12) against which the closure flap (14) may close to prevent reverse flow of liquid through the opening. The frame (10) may be bolted (at 18) to a wall or pipe flange, with integral sealing ribs (24, 25) on the rear face of the frame avoiding the need for a separate gasket. The entire assembly comprising frame, closure flap, hinge, valve seat and sealing ribs, is integrally moulded from a plastics material and is reinforced where appropriate by embedded steel plates (19, 20 and 21).

Description: THIS INVENTION concerns flap valves of the kind which may be wall mounted or flange mounted at the end of an otherwise open-ended pipe or duct for discharging liquid into a water course beneath the valve whilst preventing reverse flow of water into the pipe or duct when the water level rises to the same level as the valve. Flap valves are usually circular and consist of an annular frame surrounding the pipe end, with a closure flap or door hingedly attached to the frame above the opening therein and adapted to rest upon an inclined valve seat which is axially aligned with the pipe or duct. Whilst, originally, such valves were made predominantly of cast iron or steel, more recently, they have incorporated non-metallic materials such as rigid plastics, and in some cases, flexible hinge strips have been used to attach the closure flap to the frame thus minimising the use of relatively moving parts. In such cases the flexible hinge strip has been bolted to the closure flap and to the frame, although in one example the hinge was integrally formed with the closure flap, the latter being sufficiently flexible to enable it to deform or curl about one or more horizontal axes, together with the hinge strip. A flap valve as described in specification DE-A-3720822 includes a frame having an opening therein and an integrally formed closure flap for the opening. In this case, the hinge is also integrally formed with the closure flap immediately over the opening, but the valve does not have an inclined valve seat as required for a valve of the kind with which the present invention is concerned. Another example of integrally moulded flap valves is described in specification GB-A-990176 and comprises an integrally formed valve body and closure flap where one edge region of the flap serves as a resilient hinge, but again this valve does not present an inclined seating face around the entire opening against which the closure flap is seated. In specification US-A-4039004 (preamble of claim 1) a conventional flap valve is described including an annular collar extending from a frame and defining an inclined seating face, and a mechanical hinge the pivot for which lies immediately above the top of the inclined seat. The collar, frame and closure flap are provided as separate parts and made of one or more rigid materials. An object of the present invention is to provide a flap valve generally of the kind described above but wherein the closure flap is rigid so as to prevent it from being deformed into the pipe end, and in which the need for bolting a hinge strip to the door is avoided thus simplifying the process of manufacture and avoiding any exposed metal parts. According to the present invention there is provided a flap valve comprising a frame defining an opening through which liquid may flow in one direction; a short axial collar surrounding said opening and having an inclined annular seating face; and a closure flap closable against said annular seating face to prevent the flow of liquid through the opening in an opposite direction, the closure flap being joined to the frame by a hinge member; characterised in that the hinge member includes a first part extending forwardly from the frame and a second part substantially normal with the first part and extending co-planar with the closure flap; in that the first part of the hinge member has a reinforcing plate embedded therewithin; in that further reinforcing plates are embedded in the closure flap and the frame to render said closure flap and frame substantially non-flexible; and in that the frame, closure flap and hinge parts are integrally formed and made of plastics material. An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:- Fig. 1 is a partly sectional side elevation of a flap valve made in accordance with the invention; and Fig. 2 is a front elevation thereof; Referring now to the drawings the flap valve essentially comprises an annular frame 10 defining a central opening 11 about which is a short axial collar 12 having an inclined annular seating face 13, and a circular closure flap 14 which closes against the seating face 13 and is connected to the frame 10 by a flexible hinge member generally indicated at 15. The frame 10, hinge member 15 and closure flap 14 are integrally moulded from a substantially rigid plastics material. The hinge member 15 comprises a generally horizontal top portion 16, extending forwardly from an upper part of the frame 10, and a generally upright portion 17 extending downwardly from the portion 16 to the top of the closure flap 14. An annular series of bolt holes 18 enable the flap valve to be bolted to a wall or pipe flange about the opening 11. During the moulding process steel reinforcing plates are integrally formed and embedded within the members of the flap valve. These consist of an annular plate 19 around the frame 10, a disc 20 within the closure flap 14 and a rectangular plate 21 in the top part 16 of the hinge 15. Reinforcing fillets 22 and 23 are provided to strengthen the assembly in the region of the hinge 15. Moulded annular ribs 24 and 25 on the rear face of frame 10 avoid the need for a separate sealing gasket behind the valve. It will be seen from Fig. 1 that the thickness of the front portion 17 of hinge 15 is reduced with respect to that of the closure flap 14 to afford additional flexibility in the front part of the hinge which undergoes maximum deformation upon movement of the closure flap from the seat 13. It will be appreciated that the moulded form of the flap valve ensures that no metal parts are exposed to be corrodible. The flap valve is light in weight when compared with equivalent valves containing greater quantities of metal, or made of cast iron, and there is less likelihood of failure of the hinge since it is integrally moulded with the frame and closure flap as opposed to being attached thereto by bolts or the like. The structural integrity of the frame 10 and closure flap 14 is ensured by the steel reinforcement embedded therein. It is envisaged that this form of construction may be adopted entirely satisfactorily for a range of sizes of flap valve of between 75 and 600mm diameter although there is no apparent reason why it should not apply equally to valves which are smaller or greater than this range. Whilst a circular valve has been described and illustrated, the construction may be applied to rectangular flap valves.

Claims: A flap valve comprising a frame (10) defining an opening (11) through which liquid may flow in one direction; a short axial collar (12) surrounding said opening (11) and having an inclined annular seating face (13); and a closure flap (14) closable against said annular seating face (13) to prevent the flow of liquid through the opening (11) in an opposite direction, the closure flap (14) being joined to the frame (10) by a hinge member (15); characterised in that the hinge member (15) includes a first part (16) extending forwardly from the frame (10) and a second part (17) substantially normal with the first part (16) and extending co-planar with the closure flap (14); in that the first part (16) of the hinge member (15) has a reinforcing plate (21) embedded therewithin; in that further reinforcing plates (20, 19) are embedded in the closure flap (14) and the frame (10) to render said closure flap and frame substantially non-flexible; and in that the frame (10), closure flap (14), and hinge parts (16, 17) are integrally formed and made of plastics material. A flap valve according to Claim 1, including integrally formed reinforcing fillets (22, 23) to strengthen the assembly in the region of the hinge member (15). A flap valve according to Claim 1 or Claim 2, including integrally formed ribs (24, 25) on a rear face of the frame (10) to effect a seal upon fixing the frame (10) to a wall or pipe flange. A flap valve according to any preceding claim, in which the said second part (17) of the hinge member (15) is of reduced thickness with respect to the closure flap (14).

Inventors: AUSTIN ERIC PAUL, GARDNER FREDERICK BASIL, AUSTIN, ERIC PAUL, GARDNER, FREDERICK BASIL
Applicants: HARTLEY SIMON LTD, SIMON-HARTLEY LIMITED
Application year: 1991
Main classification: F16K15
IPC codes: F16K15