GB2071277A - Water pressure regulator - Google Patents

Abstract

A water pressure regulator suitable for controlling flow to an instantaneous water heater comprises a body 1 having an inlet 2, an outlet 3, and a balanced piston valve 9 for controlling flow to the outlet under the influence of a diaphragm 16 in a low pressure chamber 4. The piston 9 is sealed in a well 6 housing a return spring 8 and has a stem 11 projecting through a seating 12 having ports 13 leading to the chamber 4. A diaphragm pressure plate 15 engages the stem 11 and a pressure balancing hole 14 through the piston leads from the well 6 to the chamber 4. The diaphragm 16 is acted on by a coil spring 20 through an adjustable spindle 23, having a manually operable control knob 24. <IMAGE>

Description

SPECIFICATION Water pressure regulator This invention relates to a water pressure regulator. The regulator has particular application for governing the reduction of high water pressure to a low water pressure and to prevent undesirable fluctuations in the low pressure outflow.

The control of low pressure outflow in water appliances is of importance especially where an instantaneous water heater is in the low pressure flow path. As will be appreciated, with such heaters, a sudden fluctuation in water pressure can lead to rapid temperature changes of the water outflow. These changes must be minimised in some installations to ensure a substantially constant temperature for a given flow rate through the heater. For instance, where the installation comprises a shower or hand spray outlet, the risk of a sudden rise in temperature caused by a drop in water pressure must be avoided to prevent scalding or other damage.

Changes in water pressure are quite common in water mains supply where an appliance is plumbed direct to the mains. Additionally, although an appliance is pumbed to the mains supply other appliances, faucets or the like may divert or reduce pressure. The risk of such changes is high in domestic plumbing installations for a number of reasons that include those just mentioned.

It has been proposed previously to safeguard the user of instantaneous water heaters by providing special electrical cut-outs or thermal responsive devices. However these additional provisions can be avoided by the use of a pressure regulator.

According to this invention, we provide a water pressure regulator comprising a body with an inlet for high pressure and an outlet for low pressure, downstream of said inlet a valve located in the flow path intermediate the inlet and the outlet, a seating engageable by the valve to close the flow path and communicating with a low pressure chamber, spring means biassing the valve towards the closed position on the seating for the operative range of low pressures, the lower pressure chamber including a pressure responsive diaphragm arranged to apply a load to the valve in the opposed direction to said spring means, and valve actuating means for setting the valve position for a desired low pressure outflow through the outlet, the arrangement being such that once the valve is set by the actuating means, variations in pressure in the low pressure chamber cause the diaphragm to respond so that the valve moves to compensate for the variation by increasing or decreasing the flow path from the inlet through the seating.

By such an arrangement, the water pressure regulator can be employed to preset a desired low pressure outflow and the low pressure can be maintained substantially constant despite variations in the high pressure. This means that where such regulator is connected to the flow to an instantaneous water heater, the actual water temperature can be governed by the manual or other adjustment of the actuating means.

Furthermore, by such arrangement, it is also possible to ensure that a wide variation in pressure differentials are accommodated by suitable settings of the opposed forces acting on the valve.

Preferably, the valve comprises a piston which has areas acted on by high inlet pressure and the low outlet pressure to balance such pressure forces. For this purpose the piston may be hollow and seated in a well in the body for relative movement in a sealed manner. The piston may include at least one pilot bore opening to the low pressure chamber and communicating with the well. Thus, by suitable design of the piston surfaces, the high inlet pressure and the low outlei pressure act on the piston in opposed senses to balance the reaction of the piston to the inlet and outlet pressures.

Conveniently, the well may locate the piston for axial movement towards and away from the seating. The well may also house a spring urging the piston towards the seating.

Preferably, the seating is concentric with the piston and provides at least one part opening to the low pressure chamber. A series of relatively spaced apart ports may be provided. The piston seat engageable with the seating is of large diameter so that high flow rates can be achieved for a small amount of piston movement.

Conveniently, the piston includes a concentric stem projecting through the seating and this is engaged by a pressure plate forming part of an assembly including the pressure responsive diaphragm and defining one wall of the low pressure chamber.

The diaphragm assembly also includes a diaphragm plate located in a cover connected to the body, and the pressure responsive diaphragm is disposed between the diaphragm plate and the pressure plate with the marginal peripheral edge ot the disphragm being secured between the body and the cover.

By such an arrangement, the pressure responsive diaphragm can be formed of thin reinforced rubber or elastomeric sheet which is adequately supported by the diaphragm plate to withstand high water pressure. Additionally, the diaphragm can respond to pressure variations and move with low hysteresis.

Preferably, the diaphragm plate also serves to provide a thrust plate for co-action with the adjustable actuating means. The actuating means may comprise a spindle mounted for movement co-axially with the piston on the opposed side of the diaphragm assembly. The spindle may be moved by a control knob rotatably mounted relative to the cover. A thrust washer is located between the cover and the spindle. The spindle is arranged to act on a yoke engaging a co.l spring through which the spindle extends. The coil spring acts between the diaphragm plate and the yoke, and by changing the position of the spindle relative to the cover, the pressure applied to the diaphragm plate is varied.Thus, for a given setting of the control knob, if the regulator is required to compensate for a change in low pressure, the diaphragm will have responded to the pressure change through the change in the load applied to the diaphragm by the water in the low pressure chamber and the apposing selected force applied by the diaphragm spring. By the transmission of the response through the pressure plate acting on the piston stem, the piston moves to compensate by increasing or decreasing the flow through the seating ports.

Various features can be incorporated in the invented water pressure regulator, in particular the actuator can be arranged by using a multi-start thread to give a full range of adustment within a few turns of the control knob. Certain parts, such as the cover and knob can be made of plastics for economy of manufacture while the valve (or piston) and seating can be machined to close tolerances from metal components.

The valve is preferably arranged also to act as a stop valve that closes automatically in a fluid-tight manner to isolate the high pressure supply. This enables the low pressure side, including the diaphragm assembly, actuator and any downstream appliance to be services or removed without difficulty.

An exemplary embodiment of one form of water pressure regulator in accordance with this invention will now be described with reference to the accompanying drawing which is a sectional view showing the construction thereof with the flow direction being indicated by the arrows.

The regulator comprises a body 1 providing an inlet 2 and an outlet 3 with a low pressure chamber 4 intermediate the inlet and the outlet. In known manner both the inlet and the outlets are adapted to be fitted by suitable glands to pipes.

The body 1 provides a partition 5 separating the inlet and the outlet for respective high and low pressures. The body is formed with a well 6 with a central upstanding boss 7 which locates a return spring 8 that is received within a hollow valve 9.

The valve 9 is in the form of a piston of which the base carries a seal 10 that engages with the wall of the well 6. The head of the piston is conical and includes a concentric stem 11 protecting therefrom. The head of the piston is arranged to engage with a seating 12 that provides a communication through a series of ports 13 to the low pressure chamber 4. The head of the piston provides a substantial diameter seat for engagement with the seating 12 to close the communication between the high pressure and low pressure sides of the body.

The piston is balanced by the special design of the surface areas that are acted on by the respective high and low pressures and there is a pilot hole 14 extending through the head of the piston from the low pressure chamber 4 to the well and the inside of the piston.

The low pressure chamber 4 is defined by a diaphragm assembly which comprises a pressure plate 1 5 that engages the free end of the piston stem 11 and which provides an annular support for a flexible pressure responsive diaphragm 1 6.

The opposed face of the diaphragm 1 6 is supported by a plate 17 that is also annular and locates on a central boss of the pressure plate 1 5.

The peripheral marginal edge of the diaphragm is clamped between a flange coupling 1 8 of the body 1 and a seal ring 26 which is tightened onto the diaphragm through a cover 1 9 which is screwed onto the flange coupling 18.

The cover 19 is a hollow cylindrical member in which there is received a coil spring 20 of which one end acts on the diaphragm plate 1 7 and the other end is engaged by a yoke 21. An annular thrust washer 22 acts between a spindle 23 and the cover 19. The yoke 21 is acted on by the axially movable spindle 23 that extends through the centre of the coil spring and which is coaxial with the piston 9.

The spindle 23 is movable axially relative to the cover to vary the spring loading applied to the diaphragm assembly through the coil spring 20 by a knob 24. The knob 24 has an internal thread in engagement with a hub 25 that is keyed to the spindle so that on rotation of the knob 24 the spindle is moved axially.

In use of the regulator, the knob is adjusted so that the desired water pressure is obtained at the outlet. As the regulator is possibly connected to an instantaneous water heater, the desired setting can be achieved by the user of the appliance by sensing the temperature of the heated water from the heater or an appliance connected thereto, for instance, a shower head or spray. On such setting being completed, the piston will initially be stable balancing the pressures relative to the setting and pressure applied to the diaphragm assembly.

On any change arising in the low pressure chamber, the pressure responsive diaphragm will move, either moving the piston to a more open position on a drop in pressure, or permitting it to close on an increase in the pressure. Thus, the low outlet pressure setting is maintained by a quick response from the pressure responsive diaphragm and the response is accurate having regard to the large diameter and careful design of the pistdn and seating.

The precision of operation and response can be varied by selecting the size of the diaphragm and the respective spring rates of the main diaphragm spring and the return spring.

In an alternative embodiment, not illustrated, a different construction of seating can be provided so that there is only one large port opening into the low pressure chamber. The seat has a through bore aligned with the piston, and the seat is located in the body in a manner similar to that described previously. The seating provides an annular sealing face with which the piston engages, and the sealing face leads to a contiguous cylindrical portion of the bore of short axial length. The port opening to the low pressure chamber is formed by a right-frusto-conical portion of the seating diverging from the short cylindrical part of the bore. The stem of the piston protrudes through the bore of the seating, and as previously described is located in a recess in the pressure plate of the diaphragm assembly.

The design of the body and the cover can be modified, and alternative type of manual actuator can be provided.

The body can have the inlet and outlet in nonaligned positions, and is desired the body and/or the cover could be formed in more than one part.

Other modifications using the principle of the invention can be applied and envisaged by those skilled in this field depending on the actual application and installation required for the pressure regulator.

Claims (14)

1. A water pressure regulator comprising a body with an inlet for high pressure and an outlet for low pressure, downstream of said inlet a valve located in the flow path intermediate the inlet and the outlet, a seating engageable by the valve to close the flow path and communicating with a low pressure chamber, spring means biassing the valve towards the closed position on the seating for the operative range of low pressures, the low pressure chamber including a pressure responsive diaphragm arranged to apply a load to the valve in the opposed direction to said spring means, and valve actuating means for setting the valve position for a desired low pressure outflow through the outlet, the arrangement being such that once the valve is set by the actuating means, variations in pressure in the low pressure chamber cause the diaphragm to respond so that the valve moves to compensate for the variation by increasing or decreasing the flow path from the inlet through the seating.

2. A regulator according to claim 1 wherein said valve comprises a piston having areas acted on by the high inlet pressure and the low outlet pressure in opposed senses to balance the reaction of the piston to the inlet and outlet pressures.

3. A regulator according to claim 2 wherein the piston is hollow and seated in a well in the body for relative movement in a sealed manner, and the piston includes at least one pilot bore opening to the low pressure chamber and communicating with the well.

4. A regulator according to claim 3 wherein the well locates the piston for axial movement towards and away from the seating.

5. A regulator according to claim 3 or claim 4 wherein the well houses a spring urging the piston rowards the seating.

6. A regulator according to any one of claims 2 to 5 wherein the seating is concentric with the piston and provides at least one port opening to the low pressure chamber.

7. A regulator according to claim 6 wherein a series of relatively spaced apart ports are provided in the seating.

8. A regulator according to any one of claims 2 to 7 wherein the piston includes a concentric stem projecting through the seating with the stem being engaged by a pressure plate forming part of a diaphragm assembly.

9. A regulator according to claim 8 wherein the diaphragm assembly defines one wall of the low pressure chamber.

10. A regulator according to claim 9 wherein the diaphragm assembly includes a diaphragm plate located in a cover connected to the body, and the pressure responsive diaphragm is disposed between the diaphragm plate and the pressure plate with the marginal peripheral edge of the diaphragm being secured between the body and the cover.

11. A regulator according to claim 10 wherein the diaphragm is formed of thin reinforced rubber or elastomeric sheet.

12. A regulator according to claim 10 or claim 11 wherein the diaphragm plate is arranged to coact with the adjustable actuating means.

1 3. A regulator according to any one of claims 2 to 12 wherein the actuating means comprises a spindle mounted for movement co-axially with the piston and on the side of the diaphragm opposed to the piston.

14. A regulator according to claim 13 wherein the spindle is movable by a control knob mounted for rotation relative to a cover connected to the body.

1 5. A regulator according to claim 14 wherein a thrust washer is located between the cover and the spindle, and the spindle is arranged to act on a yoke engaging said spring means constituted by a coil spring through which the spindle extends.

1 6. A water pressure regulator substantially as hereinbefore described with reference to the accompanying drawing.