GB1574788A - Valves - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO VALVES (71) We, ASSOCIATED ELECTRIC- AL INDUSTRIES LIMITED, of 1 Stanhope Gate, London W1A 1EH, a Brit ish Company, do hereby declare the inven tion, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to a valve for preventing back-syphoning of a liquid and has an important application in shower units incorporating instantaneous water heaters.

According to the invention a valve for preventing back-syphonage of liquid comprises a tubular housing having inlet and outlet regions, a wall intermediate the inlet and outlet regions and apertured centrally for the passage of liquid from the inlet to the outlet region, a valve plate extending across the inlet region and spaced axially from said wall to form a chamber therebetween, which chamber communicates with the re mainder of the inlet region and with the outside of the housing through at least one off-centre passage in the valve plate and the wall respectively, and a blanking-off member located movably within the chamber and capable, in alternative positions, of blanking off the off-centre communication passage or passages of either the wall or the valve plate respectively, whilst leaving the centrally located aperture or apertures in the wall unobstructed.

Thugs the blanking-off member will, under normal flow conditions. blank off said off centre passages to the outside of the hous ing, and the liquid will flow freely through the inlet region of the valve. the passage or passages in the valve plate and thence, through the centrally located aperture or apertures in the said wall into the outlet region. If. however, the pressure in the liquid supply line falls to an extent such as to cause a reversal of the fluid flow, the blanking-off member will move towards the valve plate so as to close the passage. or passages therein, the member thus acting as a non-return valve, while at the same time admitting the medium surrounding the housing e.g. air, into the chamber through the passage or passages in said wal,, thereby to break the suction on the liquid in the outlet region of the valve beypnd.

Conveniently the inlet and outlet regions of the valve are provided by coaxial but axially displaced first and second tubes of larger and smaller dianieters respectively, which have their adjoining ends connected by an annular web which forms the said wall; the off-centre passage or passages of the wall which connect the chamber to the exterior of the valve housing can then extend through the web in a generally axial direction.

Whilst it will, in general, be convenient for the wall intermediate the inlet and outlet regions of the valve to have a single centrally located aperture for the passage of liquid, it may in some cases have a plurality of apertures formed in a central region of the wall.

Preferably, the housing is of circular cross-section through-out but at least some parts may be of a different cross-section, e.g. hexagonal or square.

The two outer ends of the housing may be provided with suitable connecting means.

Alternatively, these connecting means could be provided on extensions to the housing on the inlet and/or outlet side.

These connecting means may be in the form of threads, such as pipe threads.

Other forms of connections may be made by use of compression couplings, or permanently joining the housing the adjoining components.

Preferably, the valve plate and the said intermediate wall each incorporates more than one of said off-centre communication passages.

These communication passages may conveniently be of circular cross-section or in the form of arcuate slots, but they can alternatively be of triangular, square, or any other suitable shape.

The sealing face of the valve plate and/or the wall, that is to say the face which cooperates with the blanking-off means, may be formed with an annular or partannular groove with the communication passage or passages located in the base of the groove.

Alternatively if there is a suitable structural connection between the inlet and outlet regions other than the wall the communication passage in the wall may be in the form of a completely annular slot.

In a preferred form, the blanking-off means is a circular washer; it must, of course, have a diameter small enough to ensure that its edges are prevented from jamming between the side walls of the chamber. In addition where a communication passage is formed as an arcuate or annular slot or the sealing face of the valve plate and/or wall is formed with an annular or part annular groove, the diameter of the washer must, of course, be large enough to prevent jamming of the washer between the side wall of the chamber and a said slot or groove as the case may be. The central bore of the washer conveniently is of a diameter slightly less than that of a single central aperture of the intermediate wall or of the adjoining end of the outlet regions of the valve.

Conveniently, the sealing surfaces of the valve plate and the wall are, except for any grooves referred to above, flat and smooth so as to ensure proper sealing by the washer in the respective positions.

Preferably, all the parts of the valve are moulded from a synthetic material, e.g.

acetal copolymer.

Integral moulding of the housing, and possibly its extensions, may be the most suitable form of manufacture.

A valve for preventing back-syphonage in accordance with the invention may be part of a shower unit incorporating an instantaneous water heater.

The invention shall be explained further by way of example only and with reference to the accompanying drawings. of which: Figure 1 shows, in Figures la, 1b and 1c, a series of schematic diagrams of a valve in accordance with the present invention, and the operation thereof under different flow conditions: Figure 2 is a composite drawing of a valve in accordance with the invention, showing constructional details; and Figure 3 illustrates a shield as shown in the righthand half of Figure 2.

Using as an example a valve according to the invention as incorporated into a shower unit, and referring at first to Figures la, lb, ic, the valve comprises a tubular housing 1 incorporating an inlet region 4 of relatively larger diameter terminating in the outer rim of an annular wall 2, and an outlet region 3 of relatively small diameter projecting from the inner rim of the wall 2. A valve plate'8 extends across the bore of the inlet region 4 of the valve to form a chamber 7 between the plate and the wall 2. The valve plate 8 incorporates off-centre communication bores 5, leading into the chamber 7 from the main part of the inlet region 4 and the wall 2 is also provided with communication passages 6, either in the form of off-centre communication bores or in the form of an annular slot, leading from chamber 7 to the outside of the housing 1. A blanking-off member, in the form of a washer 9 having a central bore 10, is located within the chamber 7, the washer 9 being dimensioned such that jamming of the edges 11 and/or 12 on the side walls of the chamber 7 is prevented, even if the washer lies diagonally across the chamber and, if the communication passage is an annular slot, is dimensioned such as to prevent jamming of the rim of the washer between the sidewalls and the slot.

Under normal flow conditions as shown in Figure la, the water flow indicated by the twin-tailed arrows is from the inlet region 4 of the housing 1 through the bores 5 of thevalve plate 8 into the chamber 7, and thence through the central bore 10 of thewasher 9 into the outletregion 3. Gravity and, once the water enters chamber 7, the water pressure holds the washer 9 against the surface 15 of the wall 2, thereby blanking off the bores 6 in a water-tight manner.

If for some reason, e.g. a break in the water supply mains, the pressure of the water falls below the surrounding air pressure, the flow of water will be reversed, lifting the washer 9 from the surface 15 and moving it into contact with surface 16 of the valve plate 8, sealing the bores 5 and at the same time allowing air to enter chamber 7 through the bores 6 (as indicated by the broken arrows) to break the suction on the water in the outlet region 3 and onwards, and hence preventing back-syphonage of water from the outlet side of the valve into the supply mains.

Should, however, some foreign body 17, or scaling of the valve plate surface 8 and/or the washer 9, prevent the complete sealing of bores 5, then, as shown by the broken arrows in Figure ic, air admitted into the chamber 7 will be drawn into the supply mains rather than the possibly contaminated water beyond the outlet region 3.

Figure 2 shows, with parts similar to those of Figure 1 carrying the same number. the constructional details of a valve in accord ance with the present invention. In this example, the inside wall of the part of the housing 1 forming the inlet region 4 incorporates a shoulder 18, the part above the shoulder being provided with an internal pipe thread 19 into which is screwed an inlet pipe 20, which also serves to retain the valve plate 8 in position by compressing it between the face 26 of the inlet pipe and the shoulder 18. At the same time, the valve plate 8 is used as sealing washer for the pipe 20. This arrangement allows the washer 9 to be inserted, prior to attaching the valve plate 8, without it having to be bent or otherwise deformed, ensuring a consistent seal even under low pressures.

If the valve is used with an instantaneous water heater (not shown) connected directly to the cold mains supply, the pipe 20 may form part of the outlet coupling of the water heater.

Integrally moulded with the housing 1 is an extension 27 of the outlet region 3 of the valve housing 1, which extension carries a male thread 21 to which further pipes, or e.g. the shower head, may be fitted. Air reaches the bores 6 through a plurality of passages 24 leading radially inwards to the outside wall of the part of the housing forming the outlet region 3. A nut 25, forming an integral part of the housing, enables the valve to be held and, if necessary, rotated during installation. A recess 23 around the valve housing 1 serves to retain a shield 22 (for the sake of clarity only shown in the right hand half of Figure 2) which is a snap fit on the housing and prevents accidental blocking of the passages 24.

The shield is of frusto-conical shape and is further illustrated in Figure3.

Although the above example refers to the application of the valve to shower units, other uses such as in the water supply for washing machines or storage tanks are obviously included in the scope of the present invention.

Furthermore, by surrounding the housing with a suitable medium other than air, the valve can easily be adapted for use with liquids, for which contact with air is either undesirable or hazardous.

Also included in the scope of the invention are any modifications such as biassing the blank-off means towards the intermediate wall by means of springs.

WHAT WE CLAIM IS: 1. A valve for preventing backsyphonage of a liquid comprises a tubular housing having inlet and outlet regions, a wall intermediate the inlet and outlet regions and apertured centrally for the passage of liquid from the inlet to the outlet region, a valve plate extending across the inlet region and spaced axially from said wall to form a chamber there between, which chamber communicates with the remainder of the inlet region and with the outside of the housing through at least one off-centre passage in the valve plate and the wall respectively, and a blanking-off member located movably within the chamber and capable, in alternative positions, of blanking off the off-centre communication passage or passages of either the wall or the valve plate respectively, whilst leaving the centrally located aperture or apertures in the wall unobstructed.

2. A valve as claimed in claim 1, wherein the inlet and outlet regions of the valve are provided by coaxial but axially displaced first and second tubes of larger and smaller diameters respectively which have their adjoining ends connected by an annular web which forms the said wall, and wherein the off-centre passage or passages of the wall, which connect the chamber to the exterior of the valve housing, extend through the web in a generally axial direction.

3. A valve as claimed in any preceding claim wherein the wall intermediate the inlet and outlet regions of the valve has a single centrally located aperture for the passage of liquid.

4. A valve as claimed in any preceding claim having a housing of substantially circular cross-section throughout.

5. A valve as claimed in any preceding claim, wherein the blank-off means comprises a circular washer having a central bore.

6. A valve as claimed in any preceding claim, having a structural connection between the inlet and outlet regions other than said wall, wherein said off-centre communication passage through the wall is formed by an annular slot.

7. A valve as claimed in any preceding claim the parts of which are moulded from synthetic material.

8. A valve as claimed in claim 7 the parts of which are moulded from acetal copolymer.

9. A valve as claimed in claim 7 or 8 having the housing and any extensions thereto integrally moulded.

10. A valve as described with reference to, and shown in Figures 1 to 3 of the accompanying drawings.

11. A shower unit incorporating a valve as claimed in any preceding claim.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. ance with the present invention. In this example, the inside wall of the part of the housing 1 forming the inlet region 4 incorporates a shoulder 18, the part above the shoulder being provided with an internal pipe thread 19 into which is screwed an inlet pipe 20, which also serves to retain the valve plate 8 in position by compressing it between the face 26 of the inlet pipe and the shoulder 18. At the same time, the valve plate 8 is used as sealing washer for the pipe 20. This arrangement allows the washer 9 to be inserted, prior to attaching the valve plate 8, without it having to be bent or otherwise deformed, ensuring a consistent seal even under low pressures. If the valve is used with an instantaneous water heater (not shown) connected directly to the cold mains supply, the pipe 20 may form part of the outlet coupling of the water heater. Integrally moulded with the housing 1 is an extension 27 of the outlet region 3 of the valve housing 1, which extension carries a male thread 21 to which further pipes, or e.g. the shower head, may be fitted. Air reaches the bores 6 through a plurality of passages 24 leading radially inwards to the outside wall of the part of the housing forming the outlet region 3. A nut 25, forming an integral part of the housing, enables the valve to be held and, if necessary, rotated during installation. A recess 23 around the valve housing 1 serves to retain a shield 22 (for the sake of clarity only shown in the right hand half of Figure 2) which is a snap fit on the housing and prevents accidental blocking of the passages 24. The shield is of frusto-conical shape and is further illustrated in Figure3. Although the above example refers to the application of the valve to shower units, other uses such as in the water supply for washing machines or storage tanks are obviously included in the scope of the present invention. Furthermore, by surrounding the housing with a suitable medium other than air, the valve can easily be adapted for use with liquids, for which contact with air is either undesirable or hazardous. Also included in the scope of the invention are any modifications such as biassing the blank-off means towards the intermediate wall by means of springs. WHAT WE CLAIM IS:

1. A valve for preventing backsyphonage of a liquid comprises a tubular housing having inlet and outlet regions, a wall intermediate the inlet and outlet regions and apertured centrally for the passage of liquid from the inlet to the outlet region, a valve plate extending across the inlet region and spaced axially from said wall to form a chamber there between, which chamber communicates with the remainder of the inlet region and with the outside of the housing through at least one off-centre passage in the valve plate and the wall respectively, and a blanking-off member located movably within the chamber and capable, in alternative positions, of blanking off the off-centre communication passage or passages of either the wall or the valve plate respectively, whilst leaving the centrally located aperture or apertures in the wall unobstructed.

2. A valve as claimed in claim 1, wherein the inlet and outlet regions of the valve are provided by coaxial but axially displaced first and second tubes of larger and smaller diameters respectively which have their adjoining ends connected by an annular web which forms the said wall, and wherein the off-centre passage or passages of the wall, which connect the chamber to the exterior of the valve housing, extend through the web in a generally axial direction.

3. A valve as claimed in any preceding claim wherein the wall intermediate the inlet and outlet regions of the valve has a single centrally located aperture for the passage of liquid.

4. A valve as claimed in any preceding claim having a housing of substantially circular cross-section throughout.

5. A valve as claimed in any preceding claim, wherein the blank-off means comprises a circular washer having a central bore.

6. A valve as claimed in any preceding claim, having a structural connection between the inlet and outlet regions other than said wall, wherein said off-centre communication passage through the wall is formed by an annular slot.

7. A valve as claimed in any preceding claim the parts of which are moulded from synthetic material.

8. A valve as claimed in claim 7 the parts of which are moulded from acetal copolymer.

9. A valve as claimed in claim 7 or 8 having the housing and any extensions thereto integrally moulded.

10. A valve as described with reference to, and shown in Figures 1 to 3 of the accompanying drawings.

11. A shower unit incorporating a valve as claimed in any preceding claim.