AU3018699A - A valve with fluid shock absorbing properties - Google Patents

Description

WO 99/49252 PCT/AU99/00199 1 A VALVE WITH FLUID SHOCK ABSORBING PROPERTIES FIELD OF THE INVENTION This invention relates to an improved fluid shut off valve and particularly to a valve incorporating properties of fluid shock reduction in a 5 conduit such as a water pipe by combining physical design with material specification. The valve is particularly suitable for use in domestic water taps and industrial fluid circuits. The valves are used to regulate fluid flow through a particular conduit. For water supplies, valves are used to regulate the flow of water o10 through a water pipe. BACKGROUND ART One common use of valves is with screw down pattern taps and cocks which include a tap body having a fluid flow pathway extending therethrough, a valve seat located intermediate the fluid flow pathway, a tap 15 spindle which is moveable towards and away from the valve seat usually by rotation, with the tap spindle having a recess or bore located in the lower face, and a tap head which connects to the tap body and which houses the tap spindle. The tap head includes an opening in the top through which an upper portion of the tap spindle extends and about which a handle is fixed to 20 allow the tap spindle to be rotated in the tap head and towards and away from the valve seat. This type of tap is commonly used in domestic dwellings and industrial facilities as water outlet taps and also as the mains water isolation cock. Valves which are commonly used with this type of tap otherwise 25 known as a loose tap washer (more correctly as jumper valves) include a disc like a seal which overlies the valve seat and a stem which extends from the disc-like seal and locates within the tap spindle. In this manner, advancement of the tap spindle results in the seal being brought into the engagement with the valve seat thereby stopping fluid flow through the tap 30 body. One common problem existing with fluid supplies or more particularly with water supplies is the occurrence of water hammer resulting in WO 99/49252 PCT/AU99/00199 2 banging of the pipes. The water hammer is caused by a fluid shock which occurs when a valve is simply closed against an incompressible fluid, and the speed of closure is not necessarily a pre-condition for fluid shock to occur although rapid closure is usually associated with increased severity of fluid 5 shock. Many other conditions such as conduit geometry and conduit fastening methods affect the occurrence and severity of fluid shock. Solenoid valves usually found in machines such as dish washers or washing machines are examples of valves which shut off very quickly often resulting in a severe fluid shock extending through the water pipes causing water hammer o10 sufficient to cause damage to the conduit or the walls to which the conduit may be attached. The fluid shock is a high pressure and potentially damaging wave which requires only a very limited amount of an effective cushioning mechanism to absorb it. One prior method to control water hammer is to spring bias the 15 valve against the valve seat. When the valve is in the closed position, a shock load transmitted by the fluid against the valve will result in the valve moving against the bias of the spring to absorb the shock load. However, this type of movement in some designs can result in the tap adopting a partially open position which can result in an undesirable effect of periodic expulsion 20 from water from various taps in a domestic dwelling. The spring bias also prevents the free jumper valve from being affected by rapid turbulence induced oscillations which involve the valve being slammed against the valve seat with great force. This method of fluid shock prevention alone is often insufficient to control the shock reaction. 25 OBJECT OF THE INVENTION It is an object of the invention to provide a valve which may overcome the abovementioned disadvantages or provide the public with a useful or commercial choice. In one form, the invention resides in a valve for reducing fluid 30 shock in a conduit, the valve having a sealing face for sealing engagement with a valve seat which extends about a bore, and a fluid shock absorbing portion which, when the valve is in the closed position, overlies the bore.

WO 99/49252 PCT/AU99/00199 3 The valve is suitable for use in household taps and cocks or the mains isolating cock connecting the household to mains water supply although it should be appreciated that the valve is equally applicable in industrial situations, e.g. check valves (non-return) or commercial situations. 5 The sealing face is suitably formed on one front face of a sealing body. The sealing body may be substantially cylindrical in configuration to suit an annular valve seat. It should be appreciated that valve seats of different configurations (i.e. polygonal) will result in the sealing body adopting a similar configuration. 10 The face and preferably the sealing body is suitably formed from an elastomeric material and a suitable elastomeric material comprises rubber or a rubber blended with an elastomeric plastomer. A suitable rubber/plastomer blend is SANTOPRENE (registered trade mark of the Monsanto Corporation) 8000 Series butyl based rubber and EXCEED (trade 15 mark of the Exxon Corporation) metalocene polyolefine plastomer/elastomer. In one form, the EXCEED may be a polyethylene derived form which is currently used only as a packaging material and has not been used for engineering applications. The properties of EXCEED and other metalocene derived polyolefine plastomer/elastomers are beneficial for the purposes of 20 fluid seal construction described in the Elastomeric Seal Material Formulation below. The outer portion of the sealing face may be adjacent the peripheral edge of the sealing face. The outer portion may be profiled or otherwise configured to facilitate sealing engagement with the valve seat. 25 Suitably, the profile includes one or more ribs. Preferably, the profile comprises a pair of spaced ribs extending around the valve seat and for annular valve seats, these edges or ribs are suitably annular in configuration. The pair of spaced edges or ribs may define between them a recessed portion which suitably has a substantially inverted "V" configuration 30 to define inclined edges. Alternatively an inverted U-shaped configuration may be appropriate. The sealing face may also include a recess spaced inwardly WO 99/49252 PCT/AU99/00199 4 from the edges or ribs and suitably corresponding to the inner edge of the valve seat and adapted to extend across the inner edge. For annular valve seats, the inner recess is suitably annular in configuration. The recess may be substantially rectangular in cross-section. 5 The inner portion may extend substantially across the aperture defined as the valve seat. Suitably, the outer edge of the inner portion is defined by the annular recess described above. The sealing body is suitably provided with a configuration on a rear face thereof which can increase the strength of the body and also may 10 increase flexibility during deformation of the inner portion. The configuration is preferably dished shape. The configuration is preferably of a size corresponding at least to the size of the inner portion. The configuration suitably extends about 1/4through the sealing body. The inner portion has a projection extendable into the opening 15 defined by the valve seat. The projection may comprise a tapered hollow boss. The boss can also function as a self-aligning locating means to assist in locating the valve onto the valve seat. The tapered boss may include at lest one flute to assist in passing fluid along the boss. The flute(s) may be tapered to reduce the turbulence caused by the flow of fluid and induced 20 vibration of the sealing body upon insertion of the projection into the opening. The front face of the projection may be recessed to reduce moulding shrinkage and dimensional variation of the valve during moulding. The stem member suitably extends at right angles from a rear portion of the sealing body and is insertable into a tap spindle. Typically, the 25 stem member comprises a cylindrical rod. It is preferred that the stem member can exhibit limited pivotal motion relative to the sealing face. One manner of accomplishing this is to form the stem member and the sealing body monolithically from resilient material or to provide the stem member with a resilient base portion. 30 It is preferred that the valve sealing body and stem member are integrally formed from an elastomeric material and is suitably moulded by any convenient method, such as by injection moulding.

WO 99/49252 PCT/AU99/00199 5 The valve may include a biasing means to bias the sealing face into engagement with the valve seat. The biasing means may comprise a spring. The spring may be tapered and suitably includes a helical spring. One end of the biasing means may be accommodated by an 5 end member. The end member suitably includes an aperture to accommodate the stem member thereby allowing the end member to slide along the stem member. Suitably, the end member comprises a substantially flat body having a configuration similar to that of the sealing body. Thus, if the sealing 10 body is substantially cylindrical, the end member is preferably of a round disc-like configuration. The end member may include a lower recess to accommodate one end of the biasing means and together with the recess in the rear face of the sealing body form a flexing cavity enabling the centre portion of the 15 sealing body to move if impacted by a fluid shock wave. The lower recess suitably has a dished configuration. The lower recess together with the biasing means may assist in reducing fluid shock in the conduit upon operation of the valve by allowing the inner portion to deform at least partially into the lower recess. The lower face of the end member may be inclined 20 inwardly from a peripheral edge to the lower recess. The stem member may include a longitudinal recess or groove to allow the water to drain from or air to bleed from the recess in the tap spindle upon insertion in the stem member. Thereby facilitating the correct functioning of the biasing member. 25 BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described with reference to the following embodiments as illustrated in the accompanying drawings in which Figure 1 is an exploded view of a valve according to an embodiment of the invention. 30 Figure 2 is a section view of the valve of Figure 1 located between a tap spindle and a valve seat and in the open position. Figure 3 is a section view of the valve of Figure 2 in the closed WO 99/49252 PCT/AU99/00199 6 position. Figure 4 is a section view of the valve in Figure 3 absorbing a fluid shock. Figure 5 is a section view of an end member according to a 5 preferred embodiment of the invention. Figure 6 is a view of a valve stem and sealing body according to a further embodiment of the invention. Figure 7 is a view of the valve of Figure 6 in association with an end member and a spring and in the closed position. 10 Figure 8 is a view of the valve of Figure 7. Figure 9 is a composite view of a completed valve incorporating all of the abovementioned features. BEST MODE Referring to the drawings, Figure 1 discloses a valve for 15 reducing fluid shock in a conduit. The valve 10 comprises a stem member 11 and a sealing body 12 defining a sealing face 13. The valve further includes a biasing means 14 and an end member 15. Sealing body 12 and stem member 11 in the embodiment are integrally (monolithically) formed from an elastomeric material. It should be 20 appreciated however that the valve could also be formed from a two-part assembly. Sealing body 12 is cylindrical in configuration and includes an upper face 16 and a lower sealing face 13. Stem member 11 extends at right angles from face 16. 25 Lower sealing face 13 includes an outer portion 17 (which seals against the valve seat) and an inner portion 18 (which absorbs fluid shock). Outer portion 17 extends from an outer peripheral edge of sealing face 13, and to an inner edge which in use is adjacent the valve seat bore. Ribs 19, 20 are provided and define a recess 19A therebetween which has a 30 substantially inverted V-shaped configuration. Sealing face 13 further includes annular inner recess 22 which is positioned to extend about the inner edge 23 of valve seat 24 (see Figure WO 99/49252 PCT/AU99/00199 7 2). Ribs 19 and 20 function to facilitate sealing engagement of sealing face 13 with valve seat 24. The edges or ribs will provide a good line contact with valve seat 24 and any slight wear and tear can be 5 accommodated by the resilient nature of the edges or ribs. The ribs also provide a localised region of enhanced elasticity, by virtue of decreased cross-section, of sufficient magnitude to accommodate the pressures required to seal the fluid flow without exceeding the physical limits of the material. When the ribs are compressed and the conduit is sealed, the resistance 10 provided by the hardness of the mass of the disc portion of the sealing body rises rapidly to provide an end point to "feel" or feed back sensation to the operator that the valve has been shut off sufficiently and no further pressure is required. The ribs by their design provide additional mechanical advantage by "point loading" over a restricted zone and cross-sectional mass 15 buttressed by the relatively more massive cross-section of the sealing body disc of which they are a part. By these means effective function is achieved within the physical limits of the material and the design of the valve. In short, the elasticity and hardness of the material are able to be balanced by mechanical design and material properties not previously possible with 20 earlier designs and materials. As well, the recess 22 will be pressurised when in contact with water pressure which will assist in deforming ribs 19, 20 into tighter engagement with the valve seat in direct proportion to the pressure. This mechanism provides improved sealing and reduces the need to apply 25 unnecessarily, excess manual torque to the sealing mechanism. Annular recess 22 will also assist in reducing contact between sealing face 13 and the often sharp or roughened edge 23 of valve seat 24. Biasing means 14 in the embodiment comprises a tapered helical spring the upper end of which locates within end member 15 and 30 which by virtue of its dimensions is able to collapse into a space defined by its diameter and wire gauge thickness, thus requiring minimal space. End member 15 includes an aperture 27 to allow the member to WO 99/49252 PCT/AU99/00199 8 freely slide up and down stem member 11. Figure 2 shows how end member 15 abuts against the lower face of tap spindle or tap screw 28. In this fashion, the biasing member 14 causes sealing face 13 to be biased into engagement with valve seat 24. 5 Figure 3 shows the valve 10 in the closed position whereby fluid can no longer flow through the opening defined by valve seat 24. Figure 3 also shows how annular recess 22 prevents contact of sealing face 13 with the sharp or roughened edge 23 of the valve seat 24. Figure 4 shows how the valve assists in reducing fluid shock in 10 a conduit by coordinated mechanical movements and elastic deformation. Upon a shock wave S (indicated by the arrows in Figure 4) passing through valve seat 24, the inner portion 18 of sealing face 13 is resiliently deformed upwardly and results in absorption of the fluid shock. The shock absorbing mechanism takes the form of a fixed diaphragm formed 15 by the sealing body 12 being clamped to the valve seat 24 only over the valve seat surface, thus leaving the concave rear surface of the centre portion over the port opening defined by the valve seat 24 free to reciprocate against the biasing means 14 in response to fluid shock waves as they arise. To those skilled in the art, it is known that for practical 20 purposes, fluids such as water are incompressible and it serves no useful purpose to provide continuous solid back support over the whole of the rear of the sealing body 12. To provide such solid support across the rear surface of the sealing body, as is common practice in current tap washer/jumper valve designs, mitigates against the effective sealing by increasing the torque 25 requirement to seal the valve because pressure is distributed uniformly over the rear of the sealing body. This is unnecessary and increases the deformation of the seal body 12 beyond the elastomeric and physical limits of the sealing body material which is damaging to the sealing body and is unnecessary for sealing onto the seat. This leads to premature valve failure 30 by non-elastic deformation and leads to psychological conditioning effects upon the valve operator by which an expectation is created that such high torque is a requirement of closure and this leads to habitual and destructive WO 99/49252 PCT/AU99/00199 9 over tightening of the valves. This mechanism is also enhanced by the composition of the sealing body elastomeric properties described in The Material Description below. Outer portion 17 is still in sealing engagement with valve seat 5 24 upon deflection of inner portion 18 thereby allowing the valve 10 to absorb fluid shock while preventing opening of the valve. This effect is enhanced when more than one such valve is incorporated in the same fluid circuit creating a coordinated system whereby the fluid shock load is distributed over multiple valves. 10 By having a concave lower surface 26 (see Figure 5) in end member 15, the biasing means 14 can move from its position shown in Figure 3 to its position shown in Figure 4 to permit the resilient deflection of inner portion 18. Tapered portion 30 also assists in the deflection by distributing some of the clamping force radially inwards thus reducing radial "creep" or 15 cold flow distortion of the sealing body by opposing the opposite forces generated by the clamping pressure, pressure waves and the normal reaction from the fluid in the conduit. After the fluid shock has been accommodated, inner portion 18 resumes its normal position shown in Figure 3 which may be facilitated by 20 biasing means 14. Biasing means 14 takes the form of a helical tapered spring which is so dimensioned as to be able to collapse within the depth of its own wire gauge, and in so doing, requires a minimum of space to accommodate it. Thus, it can be seen that the valve according to the embodiment 25 of the invention is effective in facilitating the reduction of fluid shock while still maintaining a steady fluid seal by having an inner deformable portion and an outer clamped portion which maintains its seal upon deformation of the inner portion. Biasing means 14 provides further advantages in the prevention 30 of violent oscillation between fully open and fully closed positions which commonly occurs in non-biased valves and which is a contributing factor to severe and damaging fluid shock, by making the valve a spring relief valve WO 99/49252 PCT/AU99/00199 10 facilitating controlled opening and closing of the valve. A further advantageous and preferred feature of the invention in an embodiment is to have stem member 11 resiliently formed relative to the sealing body to allow the stem member and body to hinge. This allows the 5 sealing face 13 to engage with valve seat 24 in a fully mating manner notwithstanding that many tap spindles 28 are poorly machined and extend at an angle relative to the valve seat 24. If stem member 11 was rigid in construction, and the tap spindle 28 was slightly angled or bent, this would result in sealing face 13 contacting valve seat 24 at an angle and rotating in a o10 planetary motion resulting in a poor seal and accelerated destructive wear and tear on the sealing body generally and on the sealing face 13 occurring. Biasing means 14 also functions to minimise or prevent reflux or back suction occurring in the tap. The phenomenon is relatively common and results in fluid being sucked back into the fluid circuit thereby providing a 15 potential source of contamination. If the tap outlet were fitted with a non spring biased valve and connected via a garden hose to a fertiliser dispenser or insecticide sprayer, the back suction may result in potentially poisonous material being drawn into the mains supply thereby endangering all users of outlets on the main. Biasing means 14 therefore adds a safety check valve 20 function to the valve, if there should be insufficient fluid pressure present then the valve will close automatically by the action of the spring even when the tap spindle is fully open. Stem member 11 may include a longitudinal groove or recess. The groove is desirable if the stem is a close tolerance fit in the spindle bore 25 28a to prevent hydraulic resistance to the reciprocating action of the stem within the bore, which would interfere with the free movement of the valve. The longitudinal groove provides an avenue of escape for the fluid which may otherwise become trapped behind the stem within the bore. It is desirable that the stem be a close tolerance fit within the bore to help limit variation in 30 the seating location of the valve which is a major factor in premature valve failure. Stem 11 acts in cooperation with the hollow conical boss centre WO 99/49252 PCT/AU99/00199 11 portion of the sealing body 18 to maintain consistent axial alignment of the sealing body 12 with the valve seat 24. In the embodiment, a locating device in the form of a frusto-conical boss 18 is provided to prevent excessive elastic lateral displacement of the sealing body 12 by turbulence caused by the fluid 5 flow under pressure. The conical boss of the sealing body centre is so designed that even when the valve is fully open the conical portion is never fully withdrawn from the fluid port defined by valve seat 24. By this means, the sealing body is always held in axial alignment with valve seat 24. In the embodiment, boss 18 of the sealing body 12 possesses at least two o10 longitudinal tapered flutes along the sides. The flutes impose a degree of laminar flow on the fluid which aids in reducing undue turbulence induced by high fluid pressures thereby assisting in the consistent good sealing of the sealing'body 12. A further benefit appears to derive from the tapered flutes in that particulate matter in the fluid stream is less likely to lodge between the 15 sealing surfaces and reduce sealing capacity by interfering with the sealing of the valve. Boss 18 also can provide a degree of variable control of the fluid flow as the valve is opened or closed. This provides a variable degree of water flow control not possible with a flat discoid form of seal. 20 Boss 18 is hollow and open ended and can provide additional buttressing of the seal body against very high pressures which are encountered in some fluid systems. The hollow centre of the boss helps to reduce the excessive shrinkage which occurs in thick section moulded parts during the cooling stages of moulding thereby assisting in the maintenance of 25 dimensional stability. The biasing means 14 is advantageously designed to be of sufficient strength to maintain sealing face 13 into sealing engagement with valve seat 24 against any reflux or back suction to prevent contamination of the fluid in the main supply conduit. 30 Referring to Figures 6 to 8 there is shown a valve according to the embodiments of the invention described. In this embodiment, valve 40 has a valve stem 41 and a sealing body 42, the stem and body being WO 99/49252 PCT/AU99/00199 12 monolithically and integrally formed. The front face 43 of sealing body 42 is provided with a sealing face as described with reference to Figures 1 to 4, and a concave rear recess 45 extending about the base of stem 41. Recess 45 is annular in configuration and has a diameter larger 5 than the diameter of resiliently deformable inner portion 46. Figure 7 shows an assembled valve assembly comprising the valve of Figure 6 with an end member 47. End member 47 is formed with an aperture to allow it to slide up and down stem 41. The front face 48 of end member 47 is provided with a concave lo recess 49. Recess 49 is substantially planar in configuration and extends about the aperture through which stem 41 passes. A helical conical spring 50 is positioned about stem 41 and is sandwiched between recess 49 and recess 45. Figure 8 shows how this valve arrangement absorbs fluid shock. As disclosed in Figure 8, upon a fluid shock wave arriving in opening 51 (in 15 the boss 18), inner portion 46 deforms inwardly in the process the rear face 44 of valve 40 deforms upwardly to compress spring 50 within its recess. It can be seen that this arrangement is analogous to the arrangement described in Figures 2 to 4 with the exception that the concave recess is present on both the valve 40 and the end member 47. 20 Figure 9 discloses the current composite modification and subject of the invention. The valve as described in Figure 9 comprises a stem 60, and a sealing body 61 having a rear face 62 and a front face 63. Front face 63 includes the improved sealing means as also described with reference to the previous figures. Front face 63 has an inner deformable 25 portion 64 which can flex inwardly with reference to the seal body, or outwardly with reference to the fluid conduit, due to the combined cavity formed by the dished recess 65 on the sealing body and the concave recess 25 on the underside of member 12 Figure 5. In this embodiment inner portion 64 includes a locating means in the form of a tapered hollow boss 66 which 30 extends from the inner portion 64 and is configured to pass into the opening defined by the valve seat. Tapered boss 66 is formed with two or three opposed equidistant flutes 67 (only one shown in Figure 9). Each of these WO 99/49252 PCT/AU99/00199 13 flutes is tapered in configuration and converges toward the inner portion 64. The flute dimensions may be varied in dimension from relatively shallow to deep and wide to alter the tapered boss 66 to a star shaped configuration for the purposes of reducing vibration from turbulence and valve positioning in 5 high pressure applications. The flutes assist with the uniform passage of fluid along the tapered boss 66 as the valve moves in and out of the fluid orifice described by valve seat 24 and assists in the prevention of particulate entrapment under the sealing face 63. The end face 68 of tapered boss 66 may include a recess or hollow. The recess or hollow functions to assist in 10 moulding the valve by controlling shrinkage during the cooling phase of injection moulding. The valve shown in Figure 9 also reduces fluid shock by inward deformation of inner portion 64. Elastomeric Seal Material Specification In an embodiment, the valve is formed from specified materials 15 which complement the ability of the valve to absorb water hammer. The physical demands placed upon a screw down pattern valve seal are severe; not only must the valve be able to cope with a wide range of physical misalignments which are very common in valve housings such as water cocks, it must also be able to tolerate the habitual over tightening which is 20 also commonly applied by operators as a consequence of experience with badly designed valves and taps and the high mechanical advantage provided by the tap screw thread. If the valve does not shut off because of an alignment fault or other tap fault the operator usually and inappropriately responds by over tightening the valve in an attempt to force the valve to 25 close. This results in damage to the seal because of a fault which produces conditions outside the valves operational capability. The valves must also be able to tolerate a wide range of operating pressures ranging from 20psi to well over 1000psi as is common in domestic and industrial water supplies. The elastomeric material described previously for the 30 composition of the sealing body provides satisfactory material properties which can overcome the above problems. Thermoplastic Elastomeric materials capable of being injection moulded and performing these functions WO 99/49252 PCT/AU99/00199 14 has in the past been limited by levels of water absorption which seriously alters the physical properties of the material thereby often leading to an unacceptable degree of unreliability. In a water valve this is a serious problem which various manufacturers have tried to solve by a large variety of 5 mechanical and material designs but with varying and limited degrees of success. The elastomeric materials described above are effective in providing the valve with its mechanical potential. Previously, the problem of water absorption and hardness could only be solved either by blending either a hydrophobic compound such as 1o polypropylene into the elastomer, or by choosing a highly water resistant polymer such as polypropylene polyethylene alone. A disadvantage is that these tough plastomers are far too hard and are not sufficiently elastomeric and therefore suffer from permanent plastic deformation, "cold flow" and a high permanent compression set under load. These materials perform 15 inadequately in service by becoming quickly deformed and brittle, and lacked the resilience of an elastomer which enabled the physical tolerances to be accommodated. The result of this is that the consumer became accustomed to over tightening valves simply to get them to shut off resulting in premature failure of the valve. 20 A weakness of elastomers used in known valves has been the problem that the degree of elasticity required to seal a valve is quite small and this needs to be matched with a sufficient degree of hardness such that the valve could resist the effects of over tightening. At the same time, the material is required to provide a degree of physical sensation to the operator 25 of a screw down pattern valve such that a suitable end point has been reached and that this must coincide with the actual fluid flow shut off. By this means the operator not only observes that the valve has shut off but also obtains the coincidental physical sensation of resistance to further tightening which a successful closure provides. The difficulty with most elastomers is 30 that at the shut off point they still retain a large degree of elasticity and low levels of hardness i.e. they can continue to deform substantially beyond the shut off point without providing much feed back sensation of resistance. In WO 99/49252 PCT/AU99/00199 15 this circumstance the operator feels that the valve has not been shut of sufficiently and proceeds unnecessarily to apply yet more torque which leads to sever damage and the premature failure of the valve. Meeting these requirements has been very difficult if injection 5 moulding was to be used as a manufacturing method. Injection moulding is the preferred method of manufacture because it is much more efficient in terms of labour, energy and wastage. Other methods of manufacture required material to calendered into a sheet of appropriate thickness from which the washers are stamped out. The materials available were usually not 10 thermoplastic but thermosetting therefore with high compression set and cold flow indices. When seals are punched out of the sheet as much as 50% of the material can be wasted (cannot be reused). Injection moulding materials (thermoplastic) on the other hand provide the capacity to deliver just the right quantity of material to a die with usually less than 25% loss in the sprues and 15 gates but that 25% is recoverable and can be returned to the moulding process resulting in considerable economy of energy, labour and material. Injection moulding also permits the formation of complex shapes which are required to bring together the physical properties of the material with functional properties of the over all valve design. 20 To date, there has not yet been developed or used an effective composition which can be used in the manufacture of valves, and especially valves which can absorb fluid shock. On the one hand, there is a great advantage in using polyolefins such as polypropylene and polyethylene as these are cheap, can 25 be injection moulded, are water resistant and have other advantageous characteristics. However, polyolefins do not have significant or useful elastic properties and therefore are quite unsuitable for valve seals, even though they have great chemical stability. After much research and experimentation, compounds have now been found which hitherto have not been used in the 30 manufacture of valve seals but which have suitable properties. These compositions are polyolefins which are given elastic properties by production of the polyolefins using a metalocene catalyst.

WO 99/49252 PCT/AU99/00199 16 The metalocene manufactured plastomers acquire quite remarkable degrees of elasticity while retaining much of their original hardness and plastomeric properties, as well as their high water and chemical resistance properties. These materials offer large cost savings in 5 manufacture which allow more complex designs to be considered which in the past could not be used for reasons of cost or because such properties were simply not available. These new polymers blur the classification and division between plastomers and elastomers allowing plastomeric and elastomeric properties to be mixed in ways not hitherto possible. Further modification of o10 the balance between hardness and elastomeric properties can be achieved by the blending of the new plastomeric/elastomeric material with water repellent elastomers such as butyl based rubbers while retaining the advantageous properties of hardness, cold flow and compression set characteristics. 15 These new developments have produced suitable material properties for the purposes of valve manufacture and the mix of properties achievable with them are now those which previously were extremely difficult or impossible to obtain with older materials. It is the metalocene polyolefine plastomer/elastomers which are now the materials of choice for these 20 purposes. Because of their unusual combination of plastomeric and elastomeric properties they are not yet being used as engineering polymers at this time but instead they are being used as packaging thin film materials because the high elasticity in thin film lends itself to packaging where the older forms were also used but suffered from tearing. The new forms do not 25 tear easily and are providing significant improvements in the packaging applications. These are also low cost materials to produce and therefore they have a much lower environmental impact in production and subsequent manufacture. These materials have not previously been used for the 30 manufacture of valves yet they possess very closely the ideal properties required for such applications. The difference in cost of raw materials between the previous materials and these new materials is a reduction of the WO 99/49252 PCT/AU99/00199 17 order of a factor of 10. This is a major economic and environmental advancement. It is claimed that this is a novel approach to the achievement of the design principle embodied in the integrated valve invention described and that the use of these materials alone or in a blend in cooperation with the 5 physical design features which give full expression to these properties. It is therefore claimed that the use of metalocene polyolefine plastomeric elastomers is a unique application in the manufacture of fluid control valves which enables the potential of the physical design performance previously not achievable, for which a patent application is claimed. 10 Various other changes and modifications may be made to the embodiment described without departing from the spirit and the scope of the invention.

Claims (17)

1. A valve for reducing fluid shock in a conduit, the valve having a sealing face for sealing engagement with a valve seat which extends about a bore, and a fluid shock absorbing portion which, when the valve is in the 5 closed position, overlies the bore.

2. The valve of claim 1, wherein the fluid shock absorbing portion is deformable.

3. The valve of claim 2, wherein the fluid shock absorbing portion is resilient. 10

4. The valve of claim 3, wherein the fluid shock-absorbing portion comprises a projection adapted to extend into the bore.

5. The valve of claim 4, wherein the projection is a boss which is configured to act as a flow reducing member.

6. The valve of claim 5, wherein the boss is configured to act as a 15 locating member for the sealing face on the valve seat.

7. The valve of claim 5 or claim 6, wherein the boss is frusto conical, hollow and has an open lower end.

8. The valve of claim 1, including a stem member insertable into a tap spindle, the stem member being hinged to the remainder of the valve to 20 accommodate misalignment between the tap spindle and the valve seat.

9. The valve of claim 1, wherein the sealing face remains sealingly engaged to the valve seat when the fluid shock absorbing portion absorbs a fluid shock thereby preventing fluid from leaking past the valve.

10. The valve of claim 1, wherein the sealing face has a profile to 25 improve the seal.

11. The valve of claim 10, wherein the profile comprises a pair of spaced apart annular ribs.

12. The valve of claim 1, including an annular recess in the valve and adjacent the sealing face, the function of the recess being to prevent the 30 valve from contacting the corner between the valve seat and the wall of the bore, the corner often being sharp or ragged which can damage the valve.

13. The valve of claim 1, which has a seal comprising a sealing WO 99/49252 PCT/AU99/00199 19 body the sealing body having a lower face comprising the sealing face, and an upper face, a stem member attached to a central portion of the upper face and insertable into a tap spindle, the region about the attachment area of the stem portion to the upper face being recessed to form a thinner portion to the 5 sealing body.

14. A valve assembly containing a valve as claimed in any one of the preceding claims, and an end member which has an opening through it, the valve having a valve stem which passes through the opening in the end member to attach the two together and which is insertable into a tap spindle, 10 the end member in use abutting against a lower end of the tap spindle.

15. The assembly of claim 14, wherein a biasing means is provided between the valve and the end member to bias the valve into engagement with the valve seat.

16. The valve of claim 1 formed from a metalocene catalysed 15 polymer.

17. The valve of claim 16, wherein the polymer is EXCEED (Trademark of Exxon Corporation).