GB2461463A

GB2461463A - Ballcock diaphragm valve

Info

Publication number: GB2461463A
Application number: GB0919183A
Authority: GB
Inventors: Timothy Jonathon Platt
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-10-30
Filing date: 2009-10-30
Publication date: 2010-01-06
Anticipated expiration: 2029-10-30
Also published as: GB2461463B; GB0919183D0

Abstract

A ballcock diaphragm has a central closure portion 50 with a spheroidal valve surface 44 which seats on a conical valve seat 46 of a fixed nozzle 48. The diaphragm may be moulded from an elastomer. The valve is quieter in operation and has a better sealing ability than the prior art in which the valve surface 44 is conical.

Description

DESCRIPTION

Field of the Invention

The invention relates to diaphragm valves and diaphragm assemblies for ballcock -valves that are manufactured to British Standard No. 1212 Part 2.

Background Art

Diaphragm balicock valves manufactured to the above British Standard are well-known, and utilise a resilient diaphragm which in use is deflected against the sealing rim of a valve member to interrupt the flow of water through the valve. The water supply is through a central passage through the valve seat, and directed towards the diaphragm. The raising of a float by the water level in a reservoir causes a push rod to deflect the diaphragm until it is seated against the seat to interrupt the flow.

Conventional diaphragm ballcock valve assemblies have utilised a rubber diaphragm with a central bearing pad for pressing against the valve seat to interrupt the flow of water. The bearing pad is provided with a planar face for contacting the valve seat, and when the valve is open or partially open the jet of water passing through the valve orifice is directed normally against the bearing pad of the diaphragm. GB 934603 discloses such a diaphragm. In use, the rubber diaphragm does perish in water, and this perishing is exacerbated by the very high local pressure of the valve seat on the diaphragm when the valve is closed.

In recent years, there has been a policy of increasing mains water pressures, leading to a greater frequency of pressure surges, particularly at non-peak usage times. The rubber materials that have been used in ballcock valves for very many years are now proving inadequate and the incidence of leaking valves has greatly increased. In addition the increased pressures worsen the corrosion of the rubber in known valves so that they need to be replaced more frequently. There therefore exists a demand for balicock valves made of wear-resistant materials and capable of withstanding high pressures so as to be essentially maintenance free. *..* * . .

GB-A-2175671 and GB-A-2250802 each discloses a diaphragm balicock valve in which the valve member and valve seat are both conical surfaces.

That shape of valve surface has the advantage that the bearing pressures between the valve member and the valve seat can be much less to achieve a * given degree of valve sealing in the closed condition, and both mating valve parts can be made from a relatively hard plastics material. The ballcock valve of GB-A-2175671 tended to be very noisy in use, with the conical valve ::::. member vibrating laterally to produce quite an unacceptable degree of noise during the early stages of valve opening or the last stages of valve closing. No such lateral vibration is experienced when the valve member is planar as in the prior art, and it was thought that the adoption of a conical shaped valve seat imparts radial forces on the valve member which, if positioned at the centre of the flexible diaphragm, is therefore free to undergo rapid and noisy vibratory movement.

The problem of noisy operation was addressed in GB-A-2250802 which greatly reduced the noise of operation by forming the diaphragm as a disc-shaped diaphragm with at least one axially centred corrugation. Other features contributing to quieter operation included making multiple corrugations of the diaphragm progressively thinner-walled and therefore more flexible towards the outer periphery of the diaphragm.

The diaphragm ballcock valves of GB-A-2250802 have been in commercial use for over 17 years, and during that time it was believed that no further improvement in the quietness of operation was attainable. The valves of GB-A-2250802 have not, however, been completely silent and it has always been desirable to achieve the long life and leak-free properties of the valves of GB-A-2250802 alongside a silence of operation comparable with that of GB 934603.

Summary of the Invention

The invention provides a ballcock diaphragm valve according to claim 1 herein. The valve is significantly quieter in operation than the valves of GB-A- 2250802, and surprisingly appears to have an improved sealing ability. The spheroidal valve surface of the central valve closure portion establishes only line contact with the conical valve seat, and this appears to provide a better seal than the face to face contact of cooperating conical surfaces. "Chatter" of the valve closure portion against the conical valve seat is almost non-existent during valve opening and closing, and this is thought to be due to the reduction of turbulence in the water flowing through the valve assembly during the final moments of valve closure and the initial moments of valve opening, as compared with the valve of GB-A-2250802.

The parts of the new valve construction may be made of the same hard, extremely wear-resistant plastics materials as those of GB-A-2250802, those preferred materials being polypropylene for the valve seat and HYTREL 4056 NAT (a trade mark of Du Pont) for the diaphragm member. Even more ":. preferred materials for the diaphragm valve and valve seat according to this invention are, however, a polypropylene material for the valve seat sold under the Trade Mark EVOPRENE SUPER G, and a thermoplastic injection-mouldable elastomeric or rubbery material for the diaphragm valve itself.

* The present invention is also very suited to utilization of the improvement in the mounting of the valve seat element as disclosed in GB-A-2250802.

According to that improvement, the valve seat element is preferably : *. formed with a tapered outer rim on which it seats on the metal of the ballcock **** * valve fitting.

*S.*S* * * Drawings Figure 1 is a side elevation of a diaphragm balicock valve manufactured to British Standard No. 1212 Part 2.

Figure 2 is an axial section through a valve chamber of the bailcock valve of Figure 1, showing a prior art diaphragm and valve seat member; Figure 3 is an axial section similar to that of Figure 2, but through a diaphragm and valve seat according to the invention, in its OPEN configuration; and Figure 4 is the same axial section as that of Figure 3 but with the valve in its CLOSED configuration.

Referring first to Figure 1, the diaphragm bailcock valve assembly comprises a valve chamber 10 for connection to a cold water supply through an externally screw-threaded inlet pipe 12. An exit port 14 leads from the valve chamber 10 to discharge the mains water into a reservoir or tank in which the ballcock valve assembly is fitted, the water level in the reservoir being controlled by a float 16 carried on a float lever 18 pivotally mounted to the outside of the valve chamber 10 by a pivot pin 20.

When the float lever 18 is raised, a heel portion 22 thereon bears against a plunger member 24 which actuates the diaphragm within the valve chamber to interrupt the water supply.

Figure 2 shows the arrangement of diaphragm and valve seat in a known diaphragm ballcock valve according to BS 1212 Part 2. A diaphragm 30 is entrapped between mating parts of the valve chamber 10, with an outer bead 32 of the diaphragm being received in an annular recess in one of those mating parts. The diaphragm 30 comprises a flexible wall formed with a single circular convolutional pleat 34 between the outer bead 32 and a central planar disc portion 36. That disc portion 36 receives the bias of the plunger member 24 to urge it to the right, to the position illustrated in Figure 2, into contact with a valve seat 38 when the float lever 18 is raised. In that condition the flow of water from the mains supply in the direction of the arrow A is interrupted. *..

The diaphragm 30 is of unitary construction, and made from moulded rubber.

Unfortunately the life span of rubber in an aqueous environment is relatively short, and such diaphragms have to be replaced periodically.

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* The life span of the diaphragm is further reduced by the fact that the zone of contact between the disc portion 36 of the diaphragm and the valve seat 38 is : relatively small, producing high pressure loadings. *..

Figure 3 illustrates how the balicock valve assembly of Figure 1 can be used with a diaphragm and valve seat according to this invention. The diaphragm valve member 40 comprises an outer bead 42 similar to the bead 32 of Figure 2, for a peripheral anchorage of the diaphragm in the valve chamber 10. The diaphragm valve member 40 further comprises a valve member portion 44 which is formed as a hemisphere having a diameter slightly less than that of a conical mouth 46 of a valve seat 48. The valve member portion 44 a central disc portion 50 of the diaphragm valve member 40.

Figure 3 shows the valve OPEN, and Figure 4 shows it CLOSED, with the hemispherical valve seat 44 seated on and forming line contact with the conical surface 46 of the valve seat member 48. Surprisingly, it has been found that with the same sealing pressure exerted by the plunger member 24, the sealing pressure can be increased from 28 bar in the valve assembly of GB-A-2250802 to between 70 and 80 bar, with no other modification. Coupled with that is a silence of operation previously believed to be unattainable even using the teaching of GB-A-2250802. Between the outer bead 42 and the central disc portion 50, the diaphragm valve member 40 is formed as a convoluted connecting diaphragm web which is formed as a single annular corrugation 52.

The valve seat 48 is preferably injection nioulded from a hard plastics material such as polypropylene. It has an outer seating flange 56 for locating the valve seat 48 on the brassware of the ballcock valve assembly. As illustrated in Figures 3 and 4, that flange 56 is shown square-shouldered, but equally it could be formed with an outer conical surface to ensure an accurate seating on the brassware of the ballcock valve assembly. The taper of the conical surface is such that the seating is assisted by the mains water pressure. * S *

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Claims

CLAIMS1. A ballcock diaphragm valve comprising a central valve closure portion which defines a spheroidal valve surface for cooperating with a conical valve seat of a fixed nozzle, the central valve closure portion being located centrally on a disc-shaped diaphragm which is formed with at least one axially centred corrugation.
2. A ballcock diaphragm valve according to claim 1, wherein the diaphragm is substantially thinner walled and therefore more flexible towards its outer periphery than at its central valve closure portion around the spheroidal valve surface.
3. A balicock diaphragm valve according to claim 1 or claim 2, wherein the spheroidal valve surface has a diameter less than the maximum diameter of the conical valve seat of the fixed nozzle.
4. A balicock diaphragm valve according to any preceding claim that has been injection moulded from an elastomeric material.
5. A ballcock diaphragm valve according to any preceding claim that has been injection moulded from a rubbery material.
6. A ballcock diaphragm valve substantially as described herein with reference to Figure 3 of the drawings.
7. A diaphragm valve assembly comprising a ballcock diaphragm valve according to any preceding claim, in association with a valve seat member which has a valve seating surface that is conical and which dimensioned to receive on its conical surface, on valve closure, the spheroidal surface of the ballcock diaphragm valve.
8. A diaphragm valve assembly according to claim 7, in which the valve seat member is formed with an outer conical surface to ensure an accurate and fluid-tight seating on the housing of the ballcock valve assembly.r.
9. A diaphragm valve assembly substantiaUy as described herein with reference to Figures 1, 3 and 4 of the drawings.*S.*** * * ****** * * * ** * * * ****** * *