WO2014028970A1

WO2014028970A1 - Liquid supply control system

Info

Publication number: WO2014028970A1
Application number: PCT/AU2013/000927
Authority: WO
Inventors: Philip George Doust
Original assignee: Philip George Doust
Priority date: 2012-08-22
Filing date: 2013-08-20
Publication date: 2014-02-27
Also published as: AU2013305477B2; AU2013203987A1; AU2013305477A1

Abstract

A water control supply system (10) has a first inlet (12), a second inlet (14), and an outlet (16). The first inlet (12) is connected to a mains supply while the second Inlet (14) is connected to a water tank via a pump. The system (10) also has a first hydraulic valve (18) and a second hydraulic valve (20). The first valve (18) is arranged to open and close a first fluid flow path (22) (depicted by dash line). The fluid flow path (22) is a flow path for mains water at the first inlet (12) to the outlet (16). The valve (20) is arranged to open and close a second flow path (24) (depicted by a dot line) from the second Inlet (14) to the outlet (16). The valve (20) also operates a bleed valve (74) that controls the operation of the valve (18). When the valve (20) opens it operate the bleed valve (74) to effectively close the valve (18).

Description

LIQUID SUPPLY CONTROL SYSTEM

Technical Field The present document discloses a liquid supply control system and in particular, although not exclusively, for controlling the supply of liquid such as water from at least two different supplies to a common outlet.

Background Art

It is becoming more common and economically viable to supplement mains water usage with water from alternate sources. The alternate sources may be for example water tanks that are fed by runoff from the roof of a building. Indeed in Australia some state governments have introduced legislation requiring new home builders to install rain water tanks to supply water for non-consumption use such as for toilets, laundries and reticulation.

When water is not available from the alternate supply for example due to it being empty or loss of power to an associated pump, it is necessary to provide water via the mains supply. Various controllers and valves are currently available that enable the supply of water to be automatically switched between an alternate supply such as a rain water tank and mains water.

A pump is normally used to pump the water from the alternate supply. Usually the pump provides the water at a different pressure to mains pressure. When water is being supplied from the alternate supply via the pump there is a possibility that the mains supply will leak into the outlet. Thus a mixture of mains water and water from the alternate supply are provided rather than water from the alternate supply only. Summary of the Disclosure

In one aspect there is disclosed a liquid supply control system comprising:

a first inlet, a second inlet, and an outlet;

a first hydraulic valve arranged to selectively open and close a first fluid path between the first inlet and the outlet;

a second hydraulic valve arranged to selectively open and close a second fluid path between the second inlet and the outlet; the first and second valves being arranged to cooperate with each other when the outlet is open so that when one of the valves is shut the other valve is open.

In one embodiment the first and second valves are arranged so that when the outlet is shut both of the first and second valves are shut.

In one embodiment the first and second valves are arranged so that when the outlet is shut the first and second valves are held shut by a common hydraulic pressure. In one embodiment the liquid supply control system comprises a fluid bleed path between the first and second valves enabling the first and second valves to be held shut by the common hydraulic pressure.

In one embodiment the liquid supply control system comprises a bleed valve arranged to open and close the fluid bleed path wherein the bleed valve is controlled by the second valve.

In one embodiment the second valve is operatively associated with the bleed valve to cause the bleed valve to close the fluid bleed path when the second valve is open, and to open the fluid bleed path when the second valve is shut.

In one embodiment each of the first and second valves comprises a movable diaphragm coupled with a corresponding pressure chamber and a valve seat, the valve seat providing communication between the corresponding inlet and the outlet, wherein the diaphragm is movable between a closed position in which the diaphragm bears on the seat and closes an associated fluid path between the corresponding inlet and outlet, and an open position where the diaphragm is lifted from the seat to open the associated flow path, the diaphragm having one or more orifices to enable fluid communication between the associated inlet and corresponding pressure chamber; and wherein the fluid bleed path extends between respective pressure chambers.

In one embodiment the liquid supply control system comprises a mechanical actuator coupled between the diaphragm on the second valve and the bleed valve. In one embodiment the first inlet is arranged to connect to a mains water supply.

In one embodiment the second inlet is arranged to connect to a pump configured to pump water from a water storage facility.

In one embodiment the liquid supply control system comprises a sensor within a pump arranged to provide a signal to facilitate turning ON of the pump when the outlet is open, power is available to the pump and the water storage facility has at least a minimum level of water.

In a second aspect there is disclosed a liquid supply control system comprising:

a first inlet, a second inlet, and an outlet;

a second hydraulic valve arranged to selectively open and close a second fluid path between the second inlet and the outlet; and,

a bleed valve arranged to open and close a fluid bleed path between the first and second valves wherein the bleed valve is controlled by the second valve.

In a third aspect there is disclosed a liquid supply control system comprising:

a first inlet, a second inlet, and an outlet;

a second hydraulic valve arranged to selectively open and close a second fluid path between the second inlet and the outlet; and

a fluid bleed path between the first and second valves,

wherein the second valve is operable to close the fluid bleed path when in an open state wherein liquid entering the first inlet hydraulically closed the first valve and the first fluid path.

In a fourth aspect there is disclosed a method of controlling a supply of a liquid from first and second separate sources of the liquid, the method comprising:

plumbing the first and second sources to a first and second valve respectively; providing a fluid flow path from each of the first and second valves to a common outlet;

operatively associating the first and second valves such that the second valve controls the first valve be held closed when liquid is supplied from the second source to the outlet and wherein the first valve automatically opens to supply liquid from the first source to the outlet when the outlet is open and no liquid is able to be supplied from the second source to the second valve. In one embodiment the second valve operates a bleed valve to selectively open and bleed path between the first valve and the outlet.

In one embodiment the second valve operates to: close the bleed path when the second valve is open; and, to open the bleed path when the second valve is closed.

Brief Description of the Drawings Notwithstanding any other forms of the liguid supply control system that may fall within the scope as set forth in the Summary, specific embodiments will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 is a schematic representation of a liquid supply control system in accordance with the present disclosure when in a no flow state;

Figure 2 is a schematic representation of the liquid supply control system shown in Figure 1 when in a tank supply state; Figure 3 is a schematic representation of the water supply control system depicted in Figure 1 but when in a mains supply state; and

Figure 4 is an enlarged view of a bleed valve incorporated in the water supply control system shown in Figures 1 - 3.

Detailed Description of the Preferred Embodiments

For ease of description herein after the system 10 and its operation will be described in an application where the liquid is water. However the system 10 is not limited to use with water and may be used to control the flow of the liquids such as beverages or liquid fuels.

Figure 1 illustrates an embodiment of a water supply control system 10 in an OFF state. In the OFF state no water is supplied by the system 10.

The water control supply system 10 comprises a first inlet 12, a second inlet 14, and an outlet 16. In this embodiment the first inlet 12 is arranged to be connected to a mains supply while the second inlet 14 is arranged to be connected to a water tank via a pump (not shown). The system 10 also comprises a first hydraulic valve 18 and a second hydraulic valve 20. The first valve 18 is arranged to open and close a first fluid flow path 22 (depicted by a line of full dots). The fluid flow path 22 is a flow path for mains water at the first inlet 12 to the outlet 16. The valve 20 is arranged to open and close a second flow path 24 (depicted by a line of open dots) from the second inlet 14 to the outlet 16.

The outlet 16 can be connected to one or more downstream devices that use or otherwise dispense water such as, but not limited to: a toilet cistern; valve controlled inlet of a washing machine; a valve of a garden reticulation system; an outdoor tap or any other valve (none of which are shown in the drawings). The outlet 16 is

considered to be "open" when such devices are in a state that consume or otherwise distribute water so as to cause a flow of water from the outlet 16, such as immediately after the flushing of a toilet or the turning ON of the outdoor tap. Conversely the outlet 16 is considered to be closed or shut when no such downstream device is operated to consume or otherwise distribute water.

As explained in greater detail below the valves 18 and 20 are arranged to cooperate with each other so that when the outlet 16 is open one of the valves 18, 20 is shut and the other valve 18, 20 is open. More particularly, in the event that water is available in the supply coupled to the inlet 14, and power is available to the pump providing water from the supply to the inlet 14, then the valve 20 will open and the valve 18 will close. This relative configuration of the valves 18 and 20 is shown in Figure 2 and will be termed as the "pump supply state". However, again with the outlet 16 open, if water is not available at the inlet 14, for example by reason of the pump not being energised or the level of water in the supply being below a predetermined level, then the valve 20 will close and the valve 18 will open so that water from the mains supply will flow from the inlet 12 to the outlet 16. This configuration is shown in Figure 3 and will be termed as the "mains supply state".

The system 10 comprises a body 26 which is configured to form the first and second inlets 12 and 14, and the outlet 16. In addition the body 26 houses and forms part of the first and second valves 18 and 20. To facilitate the construction of the system 10, the body 26 is made from a number of parts. In the present embodiment the body 26 comprises a first part 28 and a demountably attachable second part 30. The part 28 is formed with tubular portions 32, 34 and 36 which form the first inlet 12, second inlet 14, and outlet 16 respectively. Demountable screw fittings 33, 35 and 37 are screwed onto the portions 32, 34 and 36 respectively. These fittings are optional and act as adaptors to facilitate connection with other pipes and devices (now shown). First and second valve seats 38 and 40 are also formed in the first part 28 of a body 26. The seat 38 is formed as a flat annular surface at an end of a throat 42 formed internally of the first part 28. The throat 42 leads to a diagonal tube 44 that connects with tubular portion 36 and subsequently the outlet 16. By this arrangement when the valve 18 is open water from the inlet 12 can flow through tube 44 into the outlet 16.

First valve 18 comprises in conjunction with the seat 38, a resilient diaphragm 48 and a spring 50. The spring 50 is retained between a central plug 52 of the diaphragm 48 and recess 54 formed in the second part 30 of the body 26. The diaphragm 48 is configured so that when it abuts the seat 38, it extends beyond the outer radius of, and completely closes, the seat 38. The combination of the second part 30 and the diaphragm 48 form part of a pressure chamber 56 of the first valve 18. At least one orifice 58 is formed in the diaphragm 48 allowing fluid communication between the inlet 12 and the pressure chamber 56. Optional check valves 59 are shown in the inlet 12 to prevent a back flow of water into the mains supply.

As will be recognised by those skilled in the art, the valve 18 which comprises the seat 38, diaphragm 48, spring 50 and pressure chamber 56 is of the same basic

configuration as a common solenoid controlled diaphragm valve often used in domestic reticulation systems and household appliances such as washing machines.

Looking at the valve 18 in isolation, the general principle of operation is as follows. Assume as initial conditions that water at mains pressure is present at the inlet 12, the outlet 16 is closed and the pressure chamber 56 to be completely sealed (save for the orifice 58). The mains water will flow through the orifice 58 into the chamber 56. The spring 50 is arranged so that by itself it is not sufficiently strong to resist water pressure from the inlet 12 from lifting the diaphragm 48 from the seat 38 and thus opening the valve 18. However because water is bleeding into the chamber 56 via orifice 58 eventually the chamber 56 fills with water at the same pressure as that available at the inlet 12. So now the same water pressure is acting on opposite sides of the diaphragm. The force of the spring 50 added to the water pressure in chamber 56 now overcomes the inlet water pressure and closes the valve 18. With the diaphragm 48 seated on the seal 38, closing the valve 18 there will be a difference in the surface area on which the water pressure acts on opposite sides of the diaphragm 48.

Specifically, in the chamber 56, water pressure is able to act on the entire surface area of the diaphragm 48. But on the opposite side water pressure available at the inlet 12 is only able to act on the surface area of the diaphragm 48 which does not include the area encompassed by the seat 38. Accordingly the total force of the water pressure acting downwardly on the diaphragm 48 onto the seat 38 is greater than the force of the water pressure acting in an opposite direction. Thus, the water pressure at the inlet 12 in effect holds the valve 18 shut. That is, the valve 18 is held closed by the mains water pressure. The valve 18 will indeed remain closed even if the outlet 16 is opened unless the pressure in the chamber 56 is relieved. As explained below such pressure relief can be provided by action of the second valve 20 which operates a bleed valve 74.

The valve 20 is of similar construction and operation to the valve 18. In this regard the valve 20 comprises a diaphragm 60 formed with a central plug 61 , at least one orifice 62 and a pressure chamber 64. The pressure chamber 64 is formed between the first and second parts 28 and 30 of the body 26 encasing the diaphragm 60. The valve 20 also includes a spring 66 that is arranged to bias the diaphragm 60 onto its seat 40. The spring 66 is retained within a recess 63 formed in the second part 30 and by a spindle 67. An end of the spindle 67 distant the spring seats in the central plug 61.

The valve seat 40 is formed as an annular surface at an axial end of a throat 68 formed integrally with the body portion 28. The throat 68 leads to a diagonal tube 70 that connects with tubular portion 36 and thus the outlet 16. The second valve 20 is also utilised to operate a bleed valve 74 (also shown in enlarged view in Figure 4) which is used to control flow of water through a bleed path 76 (depicted by arrows A in Figure 4) formed between the chambers 56 and 64, and thus enable pressure relief in the chamber 56. With particular reference to Figure 4 the bleed valve 74 comprises a body 78 that is formed integrally with the second part 30 of the body 26. The body 78 is sealed at an upper end by a cap 80. The bleed path 76 comprises an internal bore 82 formed in the body 78 and a contiguous tube 84 that leads to a bleed hole 86 formed in a valve seat 88. The valve seat 88 is formed in a transverse wall 90 in the body 78. The bleed path 76 enables fluid communication between the chamber 56 and an internal chamber 92 of the bleed valve 74. The bleed path 76 further extends from the internal chamber 92 through openings 93 and 94 to the tubular portion 36 and subsequently the outlet 16. The opening 93 is formed in the wall 90 while the opening 94 is formed in a portion of the body part 28 which engages the body 78. The portion of the bleed path 76 constituted by the openings 93 and 94 is always in fluid communication with the chambers 64 and 92.

A valve needle 96 is slidably retained in the bleed valve 74. The valve needle 96 has transverse pin 97 extending on opposite sides of an upper portion 98. The upper portion 98 is slidably retained within a sleeve 100 that extends downwardly from an inside surface of the cap 80. An opposite end of the valve needle 96 is formed with a tapered point 102 that is configured to extend into the bleed hole 86. A transverse shoulder 104 is formed immediately above the tapered point 102 and is able to abut the valve seat 88 about the bleed hole 86. A spring 106 is retained on the valve needle 96 between the shoulder 104 and a slidable button 108. The bleed valve 74 is operated by a mechanical actuator 110 that is able to control movement and/or position of the valve needle 96 to selectively open or close the bleed path 76. The mechanical actuator 110 is operated by the pump valve 20 and in particular the position of the diaphragm 60. The mechanical actuator 1 10 comprises in combination: the spindle 67; and a lever arm 1 12. The lever arm 1 12 is formed with several bends and has a length 1 14 at one end that extends through a transverse hole 116 formed in the spindle 67. Diametrically opposed and inwardly projecting bumps 1 18 are formed in the hole 1 16 and act as cam surfaces for the length 1 14. The lever arm 112 is pivoted at an intermediate location 1 18 to a post 120 depending from an inside of the part 30 within the chamber 64. The lever 112 also extends through an opening 122 formed between the valve 20 and bleed valve 74. A length 124 of the arm 112 distant the length 1 14 is formed with a hole 126 through which the upper end 98 of the valve needle 96 extends. The hole 126 is dimensioned so that its inner circumferential wall does not contact or at least applies no sideways load to the valve needle 96 for the full range of motion of the arm 112.

When the valve 20 is in the closed position (such as when a pump supplying the inlet 14 is OFF) the diaphragm 60 abuts the seat 40, the mechanical actuator 1 10 and in particular arm 112 is arranged and positioned to apply an upward force on the pin 97 and lift the valve needle 96 from the seat 88 and open the bleed hole 86 and bleed path 76 (shown in Figures 1 and 3). In this event fluid pressure can be communicated from chamber 56 through bleed path 76 and opening 94 to the outlet 16. Therefore when the valve 20 is closed the pressure in chamber 56 can be relieved (assuming the outlet 16 is opened) and accordingly the valve 18 can and will open. Thus the mains supply at inlet 12 acts as a default supply whenever no water is available at the inlet 14 for example due to power failure to the pump or insufficient water level in a tank used to provide water to the inlet 14. When the valve 20 is open the diaphragm 60 is displaced from and raised above the seat 40. This causes an upward displacement of the spindle 67 and by virtue of the pivot connection of the lever arm 112 a

corresponding downward motion of the length 124 of the lever arm onto the button 108. This in turn via the spring 106 pushes the valve needle 96 onto the valve seat 88 so that the tapered point 102 now closes the bleed hole 86. The provision of the spring 106 allows for differential linear displacement between the spindle 67 and the valve needle 96. In particular, the diaphragm 60 ordinarily would lift a greater distance upward than the downward distance of the valve needle 96 required to fully seat onto the seat 88. The spring 106 enables the arm 112 to continue to pivot in a clockwise direction about the intermediate point 118 as the spindle 67 moves in the upward direction to accommodate for this differential linear motion.

When the bleed path 76 is closed by virtue of the above described action, it is no longer possible for the pressure within the chamber 56 to be relieved. Thus mains water pressure is acting on opposite sides of the diaphragm 48. However due to the action of the spring 50 the diaphragm 48 remains seated on the valve seat 38 thus the mains valve 18 is held shut. This will remain the case even if the outlet 16 is open. Indeed, in this event there is even greater sealing pressure on the valve 18 keeping it shut due to the relative low pressure beneath the central plug 52. As previously explained, in this circumstance the mains pressure acts on a greater surface area of the diaphragm 48 on an upper side of the diaphragm in comparison to the lower side. This adds further "closing force" to the valve 18. The operation of the system 10 will now be described.

In this description it is assumed that the inlet 12 is connected to a mains supply of water. The inlet 14 is connected via a pump to a water tank or other water reservoir or supply. The outlet 16 may be connected to a hose or any device that consumes water. For ease of description, we will assume that the outlet 16 is connected to a simple tap. The pump (not shown) connected with the inlet 14 is provided with non-return valves and pressure switches so that it will turn itself off if subjected to a prescribed back This is a standard feature of pumps of the type used in water supply

Assume that the outlet 16 is shut. As the outlet 16 is shut, the pump supplying water to the inlet 14 will not operate. This is due to the operation of the pump's pressure switch. However at all times water at mains pressure is available at the inlet 12. As the outlet 16 is shut the mains water cannot flow out of the outlet 16. In addition the pump coupled to the inlet 14 prevents mains water from the inlet 12 flowing to the supply coupled via the inlet 14. The mains water flows through the orifices 58 into the chamber 56. As the pump at inlet 14 is OFF the action of the spring 66 alone will force the diaphragm 60 onto the seat 40. Thus the lever arm 112 abuts the pin 97 and lifts the valve needle 96 off its seat to open the bleed path 76. Therefore water at mains pressure can also flow into chamber 64 via the orifices 58, the bleed path 76 and the opening 122. There will be a back flow of water from orifices 62 to, but not past, the pump connected to the inlet 14, as well as a flow of mains water form chamber 64 through opening 94 to the outlet 16. If desired, a check valve (not shown) may be installed in the inlet 14 to prevent this back flow from passing beyond the inlet 14. In this configuration it will be appreciated that mains water pressure is now acting on both diaphragms 48 and 60 and thus holding closed both of the valves 18 and 20 which will not allow backflow in either valve. This is depicted in Figure 1.

With reference to Figure 2, let us now assume that the outlet 16 is opened, power is available for the pump connected to the inlet 14, and the supply to which the pump is connected has a viable volume of water.

Opening of the outlet 16 causes an immediate pressure drop that automatically commences operation of the pump by action of its pressure switch. The pump will thus present water to the inlet 14 at the pump pressure. Simultaneously, the drop in pressure is communicated to the chamber 64 via the hole 94. At the instant of opening of the outlet 16 the bleed valve 74 is also open so that the drop in fluid pressure is also momentarily communicated to the chamber 56 via the bleed path 76. However as the pump is turned ON, water pressure is also virtually instantaneously available at the inlet 14 to act on the underside of diaphragm 60. Due to the release of pressure within the chamber 64, the pump pressure is able to overpower the spring 66 and lift the diaphragm 60 from the seat 40. Accordingly water provided by the pump flows through the flow path 24 to the outlet 16. As the diaphragm 60 lifts off the seat 40, the mechanical actuator 110 operates to pivot the lever arm 112 to push down on the button 108 and thus push and hold the valve needle 96 on its seat 78 and more over the tapered point 102 in the bleed hole 86. This closes the bleed valve 74. Due to the closing of the bleed valve 74 fluid pressure within the chamber 56 is unable to escape. As a consequence mains pressure which acts in the chamber 56 via the orifices 58 holds the valve 18 shut. Accordingly substantially no mains water flows into the outlet 16 while water is being supplied via the inlet 14. In a worst case scenario, there may be a momentary flow of water from the mains when the outlet 16 is open where the mains pressure may be sufficient to temporarily lift the diaphragm 48 from the seat 38 during the period while the bleed valve 74 is closing. However upon closure of the bleed valve 74 mains pressure communicated through the orifices 58 will very quickly close the valve 18.

Thus water is now being supplied to the outlet 16 via the inlet 14, while the inlet 12 is shut by the action of mains water pressure. This is the pump supply state of the system 10.

From this state, two scenarios are possible. The first scenario is that the outlet 16 is shut. The second scenario is that water from the tank supplying inlet 14 is exhausted, or power is lost to the pump.

In the event that the outlet 16 is shut, there will be a build-up in water pressure at the outlet 16 and subsequently in chamber 64. This will be detected by the pressure switch of the pump causing the pump to turn OFF. The turning OFF of the pump equalises the pressure at the inlet 14 thus allowing the spring 68 to assist the diaphragm 60 in a downward direction onto the seat 40. This in turn operates the mechanical actuator 110 to lift the valve needle 96 from it's seat 88 thus opening the bleed valve 74. The chambers 56 and 64 are now in fluid communication with each other via the bleed path 76. Thus now mains pressure is again communicated to chamber 64. This pressure in addition to the spring 66 forces the diaphragm 60 onto the seat 40 thus closing the valve 20. The system 10 is now reverted to the configuration shown in Figure 1.

The effect of the alternate scenario where either water in the tank is exhausted, or power to the pump is cut will now be described with reference to Figure 3.

It should also be remembered that at all times mains water pressure remains available at the inlet 12. With the outlet 16 open and the supply of water to the inlet 14 cut, there is an immediate reduction in pressure at the inlet 14. Also, as the outlet 16 remains open, water pressure from the chamber 64 is able to bleed via the hole 94 to the outlet 16. The spring 66 assisted by pressure biases the diaphragm 60 toward the seat 40. This in turn operates the mechanical actuator 110 to open the bleed valve 74.

Opening of the bleed valve 74 allows water pressure from the chamber 56 to bleed via the bleed path 76, chamber 64 and opening 94 resulting in a drop in water pressure in the chamber 56. The mains pressure acting at inlet 12 is now able to lift the diaphragm 48 from the seat 38 so that the mains water can now flow through path 22 to the outlet 16. Accordingly mains water now supplies the outlet 16.

By way of analogy the functionality and operation of the system 10 may be considered in terms of a regular solenoid operated reticulation valve as follows. The mains valve 18 may be considered to be analogous to the diaphragm valve part of a regular solenoid operated reticulation valve, while the combination of valve 20 and bleed valve 74 may be considered as analogous to solenoid part of the regular solenoid operated reticulation valve. In the instance of embodiments of the current system 10, the "solenoid part" analogue is now a fluid pressure activated valve (20 and 74) that controls the opening and closing of the mains valve 18. But when the fluid pressure activated valve (20 and 74) operates to close the mains valve 18 it also provides an alternate supply of water.

Now that an embodiment of the valve has been described it will apparent to those of ordinary skill in the art that numerous variations and modifications can be made without departing from the basic inventive concepts. For example the specific physical configuration and form of the hydraulic valves is not critical. Also one or more switches may be provided that are operated by the motion of the spindle 67. For example a switch can be provided which, when operated by the spindle, activates a display or other indicator to indicate that the pump is supplying liquid to the outlet. All such variations and modifications together with those that would be obvious to those of ordinary skill in the art are deemed to be within the scope of the present invention the nature of which is to be determined form the above description and the appended claims.

Claims

. A liquid supply control system comprising a first inlet, a second inlet, and an outlet;

a second hydraulic valve arranged to selectively open and close a second fluid path between the second inlet and the outlet;

the first and second valves arranged to cooperate with each other when the outlet is open so that when one of the valves is shut the other valve is open,

2. The liquid supply control system according to claim 1 wherein the first and second valves are arranged so that when the outlet is shut both of the first and second valves are biased to shut.

3. The liquid supply control system according to claim 2 wherein the first and second valves are arranged so that when the outlet is shut the first and second valves are held shut by a common hydraulic pressure. 4. The liquid supply control system according to claim 3 comprising a fluid bleed path between the first and second valves enabling the first and second valves to be held shut by the common hydraulic pressure.

5. The liquid supply control system according to any one of claims 1 - 3 comprising a fluid bleed path between the first and second valves.

6. The liquid supply control system according to claim 4 or 5 comprising a bleed valve arranged to open and dose the fluid bleed path wherein the bleed valve is controlled by the second valve.

7. The liquid supply control system according to claim 6 wherein the second valve is operativeiy associated with the bleed valve to cause the bleed valve to close the fluid bleed path when the second valve is open, and to open the fluid bleed path when the second valve is shut.

8. The liquid supply control system according to any one of claims 4 - 7 wherein each of the first and second valves comprises a movable diaphragm coupled with a corresponding pressure chamber and a valve seat, the valve seat providing communication between the corresponding inlet and the outlet, wherein the diaphragm is movable between a closed position in which the diaphragm bears on the seat and closes an associated fluid path between the corresponding inlet and outlet, and an open position where the diaphragm is lifted from the seat to open the associated flow path, the diaphragm having one or more orifices to enable fluid communication between the associated inlet and corresponding pressure chamber; and wherein the fluid bleed path extends between respective pressure chambers. 9, The liquid supply control system according to claim 8 when appended directly or indirectly onto claim 6 comprising a mechanical actuator coupled between the diaphragm on the second valve and the bleed valve.

10. A liquid supply control system comprising:

a first inlet, a second inlet, and an outlet;

1 1. The liquid supply control system according to claim 0 wherein the second valve is operatively associated with the bleed valve to cause the bleed valve to close the fluid bleed path when the second valve is open, and to open the fluid bleed path when the second valve is shut.

12. The liquid supply control system according to claim 10 or 11 wherein each of the first and second valves comprises a movable diaphragm coupled with a corresponding pressure chamber and a valve seat, the valve seat providing communication between the corresponding inlet and the outlet, wherein the diaphragm is movable between a closed position in which the diaphragm bears on the seat and closes an associated fluid path between the corresponding inlet and outlet, and an open position where the diaphragm is lifted from the seat to open the associated flow path, the diaphragm having one or more orifices to enable fluid communication between the associated inlet and corresponding pressure chamber; and wherein the fluid bleed path extends between respective pressure chambers.

3. A liquid supply control system comprising:

a first inlet, a second inlet, and an outlet;

a fluid bleed path between the first and second valves,

wherein the second valve is operable to close the fluid bleed path when the second valve is in an open state wherein liquid entering the first inlet hydraulically closes the first valve and the first fluid path.

14. The liquid supply control system according to any one of claims 1 - 13 wherein the first inlet is arranged to connect to a mains water supply.

15. The liquid supply control system according to any one of claims 1 - 14 wherein the second inlet is arranged to connect to a pump configured to pump water from a water storage facility. 16. The liquid supply control system according to claim 15 comprising a sensor arranged to provide a signal to facilitate turning ON of the pump when the outlet is open, power is available to the pump and the water storage facility has at least a minimum level of water. 17. The liquid supply control system according to any one of claims 1 - 16 comprising a second valve bleed path between the second valve and the outlet. 8. The liquid supply control system according to claim 17 wherein the second valve bleed path provides fluid communication between the first valve and the outlet when the fluid bleed path between the first and second valves is open.

19. A method of controlling a supply of a liquid from first and second separate sources of the liquid, the method comprising:

plumbing the first and second sources to a first and second valve respectively;

providing a fluid flow path from each of the first and second valves to a common outlet;

operatively associating the first and second valves such that the second valve controls the first valve be held closed when liquid is supplied from the second source to the outlet and wherein the first valve automatically opens to supply liquid from the first source to the outlet when the outlet is open and no liquid is able to be supplied from the second source to the second valve.

20. The method according to claim 19 wherein the second valve operates a bleed valve to selectively open and a bleed path between the first valve and the outlet.

21. The method according to claim 20 wherein the second valve operates to: close the bleed path when the second valve is open; and, to open the bleed path when the second valve is closed.