WO2025133289A1

WO2025133289A1 - Water mains pressure reducing system and method for controlling pressure in water networks

Info

Publication number: WO2025133289A1
Application number: PCT/EP2024/088158
Authority: WO
Inventors: David Brian Taylor
Original assignee: Polymer Technologies Ltd
Current assignee: Polymer Technologies Ltd
Priority date: 2023-12-22
Filing date: 2024-12-20
Publication date: 2025-06-26
Anticipated expiration: 2026-06-22

Abstract

The invention defines a water mains pressure reducing system comprising: • a valve comprising a valve body having an interior comprising a fluid-flow chamber through which liquid can pass, an inlet to the chamber and an outlet from the chamber, a valve element, which is moveable between a closed position wherein the valve element prevents liquid from passing through the chamber and one or more open positions wherein liquid may flow from the inlet, through the chamber and out through the outlet and a substantially incompressible connector connected at a first end to the valve element and at a second end to a controllable motor drive. • a flow meter • a controller arranged to receive flow data from the flow meter and to control the motor drive for withdrawal or advancement of the valve element in accordance with the flow rate measured by the flow meter and the relationship between fluid flow and fluid pressure The invention also defines a method of controlling water pressure in a local network.

Description

WATER MAINS PRESSURE REDUCING SYSTEM AND METHOD FOR CONTROLLING PRESSURE IN WATER NETWORKS

The present invention relates to a Flow Controlled Pressure Reducing Valve System for use in a fluid pipe network and to an improved method of controlling dynamic pressure in distribution networks.

Background of the Invention

Many different fluids are transported in pipes and pipe networks and all these networks can be subjected to leakage. With many of these fluids, any leaks occurring result in priority actions to seal them as the fluid may be noxious, explosive, or very detrimental to the environment into which they are released. Some may be inflammable, such as oil or petrol, and others may be explosive, such as natural gas etc. In addition, some fluids may contaminate the surrounding environment, such as crude oil, acids etc. Draw-off or demand from such networks is usually within the control and discretion of the network controller. Leaks in such pipe networks always need to be repaired or sealed as soon as possible or the supply into the network is shut off whilst repairs are carried out.

Water supply has some unique problems because flow rates in water pipes generally vary as different users can demand or draw off water without reference to the controllers of the network. Generally, water supply networks have fixed or set inlet pressures because of reservoir elevation, fixed pump outlet pressure or installed PRVs supplying the network. Available pressures within the network are constantly changing in response to demand or flow friction losses resulting from the movement of water and pressure losses through leakage. When demand is low, friction losses reduce and therefore pressure rises within the network because the inlet pressure to the network is fixed due to the factors mentioned above. Leakage flow also leads to pressure losses arising from friction losses, but also loss in pressures arising from the difference between the pressure inside the pipes and the atmospheric pressure outside the pipes. It will be understood, therefore, that as pressure increases as demand falls, leakage consequently increases. It is also understood that some amount of leakage is always likely to be present in a water mains system.

Some of the other unique issues or problems that water supply pipe networks face are due to the condition of the pipes in water supply networks. This varies greatly due to at least the following reasons:

Many water pipe networks are old, many as old as 75 years and some over 100 years. Many water pipe networks comprise sections of pipe made from different materials e.g. cast iron, ductile iron, steel, lead, various plastics etc., having been laid over a long period of time.

• Because of the above, the actual condition of the inside and outside of the pipes also varies greatly due to factors such as corrosion, wear etc.

• Water pipes are almost exclusively laid underground and can be subject to damage from the ground they pass through. Ground movement can bring water pipes into contact with rocks, etc. leading to pressure points on the pipe, which in turn leads to mechanical failure from stress at the pressure point.

• Fatigue failure in the pipes, valves and other fittings resulting from constantly changing pressures within the network because of friction loss changes from constantly changing demand.

• Failures of pipe joints are a further source of water leakage. Such failures can result from poor weld quality in electrofusion joints, often exacerbated by freezing conditions, or by seal failure in or damage to mechanical pipe joints.

• The pressures in water supply networks fluctuate over a greater range of pressure changes because of the nature of uncontrolled demand and the statutory requirements for levels of pressure and flow requirements placed on water supply organisations.

Leakage in water networks is generally considered to be benign because water is not explosive, flammable, or noxious and so leakage may not be tackled with the same sense of urgency as other fluids unless damage is evidently being caused. Water has in the past been considered as an almost limitless and cheap resource but growth in populations and development has changed this perspective. Water is now generally recognised as a scarce resource and leakage must therefore be tackled with urgency. In addition, it is now known that chemicals in the water leaking into the environment damage local habitats affecting vegetation and wildlife.

A major water company in the UK has said that as much as 46% of leakage never appears at the surface. Indeed, one such leak of 3,000,000 litres per day was found in their area and they did not know how long this leak had been running. Leakage losses in the UK are estimated to be 3 billion litres or 3 million cubic metres per day and worldwide at 346 million cubic metres per day. Even the international investigations into leakage from water mains consider these figures to be gross under-estimations.

Other sources have estimated that as much as 76% of leakage never appears at the surface. The unseen leakage does however cause underground damage which in time can lead to collapse of ground, damage to roads and progressive deterioration of the pipe carrying the water.

The scale of the problem is growing all the time because of increasing growth in worldwide demand for water, and changing climate. Because of these unique factors affecting water supply, the use of the present invention will be addressed primarily to water supply networks but the benefits can also be applied to pipe networks carrying other fluids.

Water supply networks typically comprise outputs from storage facilities or pumping stations feeding a high-pressure Primary Feeder mains network connected to a plurality of Secondary Feeder mains which in turn supply a plurality of Distributor Mains supplying local area networks which may sometimes be called district metered areas (DMAs). Water pressures in the Primary, Secondary, or Distributor mains-are generally too high for consumers in the local networks and therefore pressure reducing valves (PRVs) are often positioned at the interface between the high-pressure mains and the local area network to reduce the pressures. By way of example, the water pressures in Distributor Mains may be of the order of 5 to 10 Bar whereas the pressures required within the local area network (e.g. DMA) may be of the order of 3 to 6 Bar or less.

Local area networks (or DMAs) may typically comprise approximately 800 - 1500 properties/users and therefore the PRV controls the flow of water to these properties/users.

A typical or conventional pressure reducing valve (PRV) comprises a chamber having an inlet connected to a high-pressure mains and an outlet connected to a local network (e.g. DMA). Typically, the valve has two chambers, a first (e.g. upper) and a second (e.g. lower) chamber separated by a diaphragm. Water passes through the PRV via the lower chamber. A reduced downstream pressure is achieved by allowing a hydraulic connection between the upstream pressure and the upper chamber of the PRV. In this hydraulic control system, the water from the upstream side passes through a much smaller pilot valve with a spring- loaded diaphragm arrangement to allow water to escape from the upper chamber if the pressure in the upper chamber exceeds a predetermined level and vice versa. More sophisticated conventional PRV’s incorporate further hydraulic circuits to give more accurate control of the downstream pressure using various arrangements of differential control valves (DCV).

A feature of many water supply networks is that conventional pressure reducing valves at the entrance to a local area network are set up to provide a substantially constant water pressure into the network. A problem with this is that, for much of the time, when demand is lower (e.g., at night), the local network will be over-pressurised. This will in turn exacerbate the problem of leakage.

Our earlier patent applications, WO 2021/089986 and WO 2022/233420, describe improved pressure reducing valves where the valve is biased to a closed position by a spring. The compression in the spring is adjusted by a controllable motor device which in turn adjusts the pressure of fluid exiting the valve. WO 03/057998 describes spring-biased secondary pilot valves for use in PRV’s controlling water pressures in local area networks (for example pilot control valves and differential control valves).

The Invention

Although the invention is suitable for use with many different fluids, it will be generally described, for ease of explanation, in relation to the most common use of managing the pressure in water mains and pipe networks.

Conventional PRVs include a low strength spring for biasing a valve element into a closed position in relation to a water inlet when there is insufficient hydraulic pressure in the upper chamber. Pressure in water mains fluctuates due to variations in demand and consumption can also lead to pressure fluctuations at the inlet to installed PRV’s.

The inventor of the present invention has found that at low flow rates, these pressure fluctuations can lead to uncontrolled opening and closing of the valve, sometimes called “hunting”. Due to the upstream pressure variations on the underside of the valve element or diaphragm, there may be insufficient pressure to open or keep open the valve due to the force of the spring acting on the topside of the diaphragm tending to close the valve. Therefore, when demand is low, for example, at night, and when the upstream pressure is also fluctuating, the water upstream pressure on the valve is not high enough to keep the spring suitably compressed and therefore the valve will tend to close until the upstream pressure builds up to become sufficient to open the valve from its closed position. It is also evident that the upstream pressure acts on the smaller area of the underside of the valve element when in the closed position rather than the much larger area of the diaphragm even if the valve is only just open. These phenomena can lead to hunting and may even mean that the valve will not open at all with a consequent loss of supply into the network.

An object of the present invention is to provide an improved flow-controlled pressure reducing valve which overcomes and alleviates the problems in known pressure reducing valves that have been described above.

According to one aspect of the invention, there is provided a pressure reducing valve (PRV) comprising:

• a valve body having an interior comprising a fluid-flow chamber through which fluid can pass,

• an inlet to the fluid-flow chamber and an outlet from the fluid-flow chamber,

• a valve element, which is moveable between a closed position, in which the valve element prevents fluid from passing through the chamber, and one or more open positions wherein fluid may flow from the inlet, through the chamber, and out through the outlet, and

• a substantially incompressible connector connected at a first end to the valve element and at a second end to a controllable motor drive for moving the valve element.

As described below, the pressure reducing valve (PRV) may form part of a flow-controlled pressure reducing valve system (FCPRVS), which, in addition to the PRV itself, may comprise one or more of the following components, as described in further detail below:

• a flow meter in line with the pressure reducing valve;

• one or more pressure sensors - upstream and downstream of the pressure reducing valve and in a critical location(s) in the network being supplied;

• a controller in communication with a flow meter, pressure sensors and a controllable motor drive; and/or modems or other means of communication between the components of the FCPRVS. The invention may therefore provide a Supervisory Control and Data Acquisition (SCADA) system that is a computer-based system that monitors and controls the PRVs described herein to provide real-time control of water main pressure reducing valves and systems.

DEFINITIONS

As noted above, the invention will be described using the fluid, water, as an example but it should be noted that the problem of dynamic pressure control is present in the transport of many fluids through pipe networks.

For the sake of clarity, the following definitions are intended when describing this invention:

Fluid: a liquid, gas or other material that continuously deforms under an applied external force.

Water mains:

• Primary Feeders are used to connect water treatment plants, reservoirs and Service Areas,

• Secondary feeders connect primary feeders to distributor mains,

• Distributor mains connect Secondary mains to local area networks,

• Local Area Networks connect users to distribution mains.

Networks: several pipes connected together and to the same main source.

Local area networks of pipes are sometimes called District Metered Areas (DMAs).

High Pressure Mains: a mains pipe immediately upstream of a PRV, which may supply fluid at a pressure of up to 10 bar or greater, for example 15 bar or greater or 20 bar or greater. The High Pressure Mains is typically a Distributor Mains but may, in some networks be a Secondary Feeder.

Upstream Pressure: the pressure measured immediately on the inlet side of a valve or other device. Here, the term immediately means at a point between the valve and the first branch point (i.e. additional inlet or outlet) or leak upstream of the valve.

Downstream Pressure: the pressure measured immediately on the outlet side of a valve or other device. Again, the term immediately means at a point between the valve and the first branch point or leak downstream of the valve. Control Valves: valves that control flow into a pipe or pipe network

Pressure Reducing Valves (PRVs): valves that reduce the upstream pressure to a desired lower downstream pressure as the fluid passes through the valve.

Flow Control Pressure Reducing Valve System (FCPRVS): a valve of this invention connected to a control system such that the downstream pressure can be controlled to increase (rise) or decrease (fall) in response to instructions received from an electronic controller of this invention irrespective of upstream pressure changes on a real time basis.

Controllable Motor Drives (e.g. servo drives): rotary or linear motors controlled by the controller of this invention whereby the position of a drive connector is changed. The term ‘linear motors’ also includes proportional solenoid actuators.

Leakage: uncontrolled and unwanted escape of fluid from a pipe or pipe connector through which it is transported.

Management by Exception in the context of this invention means a response to unexpected changes in the behaviour of the fluid passing through a pipe or pipe network beyond programmed parameters.

Real Time in the context of this invention means the time required to respond to the analysis of data collected and the issuing of instructions in response to this data as it relates to changes in fluid flow or pressure as it occurs.

Time period: the time set for the collection of consecutive sets of data relating to the flow or pressure of a fluid in a pipe or pipe network. This may be 1 second or greater, for example 10 seconds or greater, or 20 seconds or greater. In some instances, the time period may be 1 minute greater or 5 minutes or greater. It will be appreciated that the time period will depend on local conditions in the water network and/or the level of accuracy and analysis required.

Critical Location(s) in a network: the location(s) where the available pressure is, as a result of pressure losses arising from friction losses caused by the movement of fluid in the pipe network, at the lowest and/or where the elevation of the location above the inlet to the network causes the pressure available to be below a desired minimum. Excess pressure in a pipe network is the pressure above that which is required to maintain a desired pressure at a critical point(s) in the pipe network.

Flow Pressure Profile: the relationship between flow into a network and the downstream pressure required to maintain a desired pressure at a critical location.

Hunting: the uncontrolled rise and fall of pressure downstream (e.g. immediately downstream) of pressure control valve/pressure reducing valve.

Users: consumers, households or businesses that draw water from water mains for consumption or other process uses.

Demand: fluid drawn off by users.

Remote-control Facility may be referred to herein for convenience as a remote-control room, even though it may not be a room as such.

SCADA Supervisory Control and Data Acquisition

Particular Embodiments of the Invention

The connector/actuator is substantially incompressible and inextensible in at least an axial direction, that is, in a direction perpendicular to the orifice that the valve element closes. In the context of this application, the terms “connector” and “actuator” may be used interchangeably and have the same meaning.

The inlet and outlet of the chamber typically take the form of or comprise one or more orifices (the “inlet orifice(s)” and the “outlet orifice(s)”). Here, the term orifice refers to openings which are in fluid communication with the chamber and receive fluid from an upstream input source of the valve or direct fluid to the downstream water or fluid supply distribution network.

The valve element may be a covering element which covers the inlet orifice. Alternatively, the valve element may be a blocking element, which blocks the inlet orifice. In each case, the valve element restricts or prevents some or all fluid from entering the chamber at all by preventing fluid from passing through the inlet orifice. Alternatively, the valve element may restrict or prevent fluid from passing through the chamber by covering or blocking the outlet orifice. The valve element may take the form of a plate which covers or obscures the inlet or outlet of the chamber to prevent or restrict the flow of fluid through the chamber. Alternatively, the valve element may take the form of an obturator which is inserted into the inlet or outlet orifice to prevent or restrict fluid flow through the chamber.

The valve element is moveable between a closed position and one or more open positions. The one or more open positions typically restrict flow to a differing extent to thereby control the pressure of the water at the outlet of the pressure reducing valve. The one or more open positions may differ by the distance between the valve element and the orifice. One of the one or more open positions is a “fully” open position where flow of water through the orifice is not reduced (at least to any significant extent) by the presence of the valve element. The valve element may be moveable between an open position and a closed position in a number of discrete steps, or it may be capable of continuous movement between open and closed positions.

The valve element is connected to the controllable motor drive by a “substantially incompressible” connector/actuator. It will be appreciated that all materials may be compressible or extendible to some degree. The term “substantially incompressible” is not intended to exclude generally rigid connectors that do not compress to a significant extent, but nevertheless may be formed of materials which can be compressed (e.g., upon application of a very large force to cause a very small change in length). Instead, the term “substantially incompressible” is intended to exclude connectors that are compressible to a significant extent, such as springs. For example, the term “substantially incompressible” may mean that the connector is compressible by 5% or less, typically 2% or less, for example 1% or less or 0.5% or less of its length. In some instances, the extent of compression may be measured when a compressive force of 10kN or more (for example 30kN) is applied to the connector for a period of 2 minutes or shorter, for example 1 minute or shorter or 30 seconds or shorter.

In addition, to being substantially incompressible, the connector is also substantially inextensible (i.e. when in use in the pressure reducing valve of the invention). Again, the term “substantially inextensible” is intended to exclude connectors that may be extended to a significant extent, but nevertheless it is noted that all materials may be, to some extent, extendable (provided sufficient force is applied). The term “substantially inextensible” may mean that the connector is extendable by 5% or less, typically 2% or less, for example 1% or less or 0.5% or less of its length. In some instances, the extent of extension may be measured when an extensive force of 10kN or more (for example 30kN) is applied to the connector for a period of 2 minutes or shorter, for example 1 minute or shorter or 30 seconds or shorter.

The valve element may be connected directly to the end of the connector, such that there is a direct relationship between movement of the connector and movement of the valve element. In other words, the valve element may be directly coupled to the controllable motor drive via one or more incompressible and/or inextensible connector(s). Alternatively, the valve element may be connected indirectly to the end of the connector, via one or more incompressible and/or inextensible linkers, again such that there is a direct relationship between movement of the connector and movement of the valve element. When the connector is formed from multiple linked component parts, the term “connector” refers to the entire assembly such that a first end of the connector is connected to the controllable motor drive and the second end is connected to the valve element. In other words, the term “connector” refers to the entire assembly linking I in between the valve element and controllable motor drive.

The connector may be linear in shape, such that it has its first and second ends at opposing ends along the length of the connector.

The term “direct relationship” here typically means that there is a linear (e.g. a directly proportional) relationship between movement of the connector and movement of the valve element. For a linear relationship, movement of the valve element and movement of the connector can be described by the expression y = mx + c, wherein the distance moved by the valve element is y, the distance moved by the connector is x and m and c are constants.

Embodiments of the invention that employ a rod or shaft as the connector, give rise to a direct relationship between movement of the connector and movement of the valve element. Accordingly, the connector may be a rod or shaft which is at one end connected to the valve element and at the other end connected to the controllable motor drive to provide a direct relationship between movement of the controllable motor drive and the valve element.

In further embodiments of the invention the motor drive, connector and valve element may act linearly within the same plane such that the motor drive causes linear movement of the connector, which in turn effects linear motion of the valve element. Establishing a direct linear relationship between movement of the connector and movement of the valve element prevents undesirable lateral (i.e., side-to-side) movements of the valve element and connector, ensuring accurate control over the position and movement of the valve element. The connector may be formed from a metal material, preferably one such as stainless steel which is corrosion resistant, or from a suitably tough plastics material (for example engineering plastics such as polyamides, polyesters, and polyacetals, e.g., polyoxymethylene), or from a combination of metal and plastics materials.

It will be appreciated that when the connector comprises a spring, there is not a directly proportional relationship between movement of the connector and movement of the valve element as some of the force exerted onto the connector is used to compress or extend the spring, and thus not all force applied is used to move the valve element. This direct relationship between the connector and the valve element overcomes the problems discussed above with conventional valves at low demands, as it is no longer necessary for the inlet or upstream water pressure in the valve to displace the spring from the “valve- closed” position before water can flow through the valve. The valve element is therefore directly controlled by the controller irrespective of pressures on the diaphragm, piston or plunger, etc.

Movement of the connector by the controllable motor drive may directly control the distance between the valve element and the inlet. Alternatively, movement of the connector by the controllable motor drive may directly control the distance between the valve element and the outlet.

The connector may provide a force of 3kN or greater to move the valve element. For example the connector may provide a force of 5kN or greater, typically 10kN or greater or 15kN or greater, preferably 30kN or greater.The inlet typically takes the form of a fluid supply orifice into the flow chamber. The valve element may prevent fluid from passing through the fluid supply orifice by being inserted into the orifice or by covering the orifice. It will be appreciated that the valve element may be partially opened (i.e. , the orifice may be partially unblocked or partially uncovered) to allow fluid to pass through the orifice at a reduced pressure, compared to when the valve is fully open (i.e., the orifice is fully unblocked or uncovered).

In one embodiment, the valve element is connected to a diaphragm, either by being directly attached to the diaphragm or by being connected via a rod or other non-extendable/non- compressible linker. The diaphragm may partition the valve body interior to give the fluidflow chamber on the one side and a dry chamber on the other side. The controllable motor drive is typically provided in or above the dry chamber such that it does not come into contact with fluid in the flow chamber during use. In another embodiment, the valve element may attach (directly or via an incompressible linker) to a piston. The piston may be arranged for reciprocating movement in a cylinder formed or mounted within the body. The use of a piston arrangement limits the movement of the valve element to longitudinal movement (i.e., towards and away from the inlet orifice, perpendicular to the orifice). Undesirable lateral (i.e., side-to-side) movements are prevented by the piston cylinder. The cylinder may be a formation integrally formed with the body, or it may be formed separately and secured inside the body, for example by mechanical fastenings, interference fit, welding, adhesive, and combinations thereof. The cylinder may be formed from a metal material, preferably one such as stainless steel which is corrosion resistant, or from a suitably tough plastics material (for example engineering plastics such as polyamides, polyesters, and polyacetals, e.g., polyoxymethylene), or from a combination of metal and plastics materials.

The cylinder and piston may partition the valve body interior to give the fluid-flow chamber on one side and a dry chamber on the other side (in the same way as the diaphragm described above). Again, the controllable motor drive is typically provided in or above the dry chamber such that it does not come into contact with fluid in the flow chamber during use.

Longitudinal movement of the piston may be effected by a connector. The connector may be attached at one end to the top of the piston and the other to the controllable motor drive to give linear motion of the piston and consequently, the valve element.

The piston may likewise be formed from a metal material, preferably one such as stainless steel which is corrosion resistant, or from a suitably tough plastics material, or from a combination of metal and plastics materials.

In one embodiment, both the piston and the cylinder may be formed from a metal material selected from stainless steel and aluminium (or an alloy thereof). The piston and cylinder are typically of circular cross section.

A fluid-tight seal is provided between the piston and the cylinder. The seal is typically provided by means of a sealing ring extending around the piston. The sealing ring may be formed from a suitable elastomeric sealing material, for example a synthetic rubber material such as neoprene, nitrile rubber or butyl rubber and may take the form of one or more O- rings. The O-rings may have a conventional circular cross-section, or they may have a noncircular cross-section provide that the cross-section shape does not hinder movement of the piston. Alternatively, the sealing rings (e.g. O-rings) may be formed from a suitable metal material or from a combination of a metal material and an elastomeric sealing material, or from a combination of an elastomeric sealing material and a non-elastomeric polymeric material such as polytetrafluoroethylene (PTFE). Suitable materials for use in forming sealing rings are well known to the skilled person. The seals (e.g., O-rings) may be seated in a circumferential groove(s) in the piston.

The length of the cylinder is selected to ensure that a desired range of movement of the piston can be accommodated without the piston being expelled from the cylinder by unexpectedly high fluid pressures.

The side of the piston facing the fluid supply inlet orifice acts as a valve element and can be moved towards the orifice to restrict or prevent the flow of fluid into the fluid-flow chamber. The piston is advantageously mounted on a guide rod which is received in a guide channel in the orifice, thereby ensuring that the piston is correctly centred and moves along a reciprocating path.

Instead of the piston itself acting as the valve element, a separate valve element may be mounted on the piston, for example on a mounting rod or shaft extending axially from the piston.

In another embodiment, the connector may be attached to a linkage connecting a plunger on the one end and the controllable motor drive on the other. The plunger may be arranged for reciprocating movement in a cylinder formed or mounted within the body. The use of a plunger arrangement limits the movement of the valve element to longitudinal movement (i.e. towards and away from the outlet or inlet orifices and perpendicular to the orifice).

Undesirable lateral (i.e. side-to-side) movements are prevented by the plunger cylinder. The cylinder may be a formation integrally formed within the body, or it may be formed separately and secured inside the body, for example by mechanical fastenings, interference fit, welding, adhesive, and combinations thereof. The cylinder may be formed from a metal material, preferably one such as stainless steel which is corrosion resistant, or from a suitably tough plastics material (for example engineering plastics such as polyamides, polyesters, and polyacetals, e.g., polyoxymethylene), or from a combination of metal and plastics materials.

The cylinder and plunger may partition the valve body interior to give the fluid-flow chamber on the one side and a dry chamber on the other side (in the same way as the diaphragm described above). The plunger is typically placed inside the cylinder to separate the dry chamber from the flow chamber. The controllable motor drive is typically provided outside the valve body such that it does not come into contact with water in the flow chamber during use.

Longitudinal movement of the plunger may be effected by pivoting lever arms. The lever arms are mounted on a shaft or shafts passing through the body and cylinder and may be driven by the controllable motor drive. The lever arms convert rotational motion of the shaft into a linear motion of the plunger and consequently, the valve element. Suitable seals are mounted on the shafts to prevent the passage of water from the flow chamber.

The plunger may likewise be formed from metal material, preferably one such as stainless steel which is corrosion resistant, or from a suitably tough plastics material, or from a combination of metal and plastics materials.

A fluid-tight seal is provided between the plunger and the cylinder. The seal is typically provided by means of a sealing ring extending around the piston. The sealing ring may be formed from a suitable elastomeric sealing material, for example a synthetic rubber such as neoprene or butyl rubber and may take the form of one or more O-rings. Alternatively, the sealing rings (e.g. O-rings) may be formed from a suitable metal material or from a combination of a metal material and an elastomeric sealing material, or from a combination of an elastomeric sealing material and a non-elastomeric polymeric material such as PTFE. Suitable materials for use in forming sealing rings are well known to the skilled person. The seals (e.g., O-rings) may be seated in a circumferential groove(s) in the piston.

The length of the cylinder is selected to ensure that a desired range of movement of the plunger can be accommodated without the plunger being expelled from the cylinder.

The side of the plunger facing the fluid outlet orifice acts as a valve element and is biased towards the orifice to restrict or prevent the flow of fluid out of the fluid-flow chamber. The plunger is advantageously connected with an connector which is in turn connected to a lever arm ensuring that the plunger is correctly centred and moves along a reciprocating path.

As discussed above, the body may have an interior void partitioned by the diaphragm or cylinder into a fluid-flow chamber on one side of the diaphragm/cylinder and a dry chamber on the other side of the diaphragm/cylinder, wherein the fluid-flow chamber is provided with the fluid supply orifice into the chamber and a fluid outlet. By dry chamber, it is meant that the interior of the chamber does not come into contact with the fluid passing through the valve. This contrasts with the conventional hydraulically controlled pressure reducing valve (such as the valve disclosed in WO 03/057998) where both chambers on either side of the diaphragm in the PRV are “wet” chambers, i.e., are exposed to the fluid (in that case water) passing through the valve.

As discussed above, for the sake of brevity and clarity the PRVs of the invention are described for use when the fluid is water in a water mains network and for reducing the pressure of water from the mains to suitable pressures for downstream pipe networks. Accordingly, the pressure reducing valves are generally larger in capacity than other valves (that may be present in other water mains pressure reducing valves), such as pilot valves and differential control valves.

Accordingly, the inlet to the chamber may take the form of or comprise a fluid supply orifice. The fluid supply orifice may be circular in shape and may have a diameter of 20mm or greater, for example 20mm or greater, preferably 50mm or greater, such as 80mm or greater, 200mm or greater or 500mm or greater. By way of example, the fluid supply orifice may have a cross-sectional area of from about 300mm² to about 95000mm², more usually from about 1000mm² to about 50000mm², and more typically from about 2000mm² to about 32000mm². Similarly, the chamber may have a volume of 50cm³ or greater, for example 500cm³ or greater, preferably 1750cm³ or greater, such as 5000cm³ or greater.

As the pressure reducing valve is connectable to a source of mains water, the pressure reducing valve is typically able to withstand input water pressures of 10 bar or greater, for example 15 bar or greater or 20 bar or greater. The output pressure of the valve (i.e. the pressure of the water leaving the valve at its outlet) may be 15 bar or less, typically 10 bar or less, for example 6 bar or less, such as 3 bar or less or 1 bar or less.

In yet a further embodiment, the controllable motor drive may be coupled to the valve element through a rotational mechanism, whereby rotary motion is converted into linear motion via the connector. For example, the valve element may be connected to the controllable motor drive through a cam mechanism that translates rotary motion from the motor drive into linear motion of the valve element. It should be appreciated that the “cam mechanism” constitutes the “connector” in this embodiment as it refers to the entire assembly linking I in between the valve element and controllable motor drive.

The cam mechanism may comprise a cam in combination with a cam follower, wherein the cam is coupled to the controllable motor drive and the cam follower is coupled to the valve element. In other words, the cam and the cam follower form the connector. The cam may be designed with a specific contoured surface (profile) to impart a predetermined type of motion to a cam follower. Examples of cam profiles include eccentric, circular, or irregular profiles, each capable of generating distinct linear motion; for instance, an eccentric cam profile can produce sinusoidal linear motion.

In the cam mechanism, the cam follower may contact the cam surface and convert the rotary motion of the cam, driven by the controllable motor drive, into linear motion. As the cam rotates, the follower moves in a manner dictated by the cam's geometry and as the cam follower moves, the valve element opens or closes accordingly, regulating the flow of water. The cam may be coupled to the controllable motor drive via a camshaft, wherein the camshaft’s rotational speed determines the rotational speed of the cam. In the pressure reducing valve of the present invention, movement of the valve element which controls the flow of water from the high-pressure mains to the downstream/lower pressure distribution network is controlled directly by the controllable motor drive. The valves of the invention are therefore advantageous in that they are of a simpler construction and do not require the presence of pilot or other control valves with all the associated pipework, fixed orifices, filters, and isolating valves etc.

Thus, in a preferred embodiment, the pressure reducing valve (PRV) of the invention does not have a hydraulic control mechanism comprising a pilot valve, and in particular does not comprise a hydraulic control mechanism comprising a pilot valve and optionally a differential control valve (DCV) connected in a bypass pipe to the PRV. As discussed above, the pressure reducing valves of the invention may form part of a flow-controlled pressure reducing valve system (FCPRVS). The FCPRVS may include a pressure reducing valve (as described herein) and further comprises an electronic data store held within or being in communication with a controller. The data store contains data defining a relationship between fluid flow rate and output pressure into a downstream pipe network to maintain a desired pressure at a critical remote location to which the FCPRVS is connected.

Leaks within a water distribution network can be reduced by reducing the pressure of water being supplied to the network. It is preferable, however, that the water pressure at critical points is maintained by the FCPRVS at minimum predetermined levels. Therefore, the FCPRVS of the present invention can be controlled in response to the water pressure measured by a pressure sensors at one or more critical points remote from the FCPRVS to avoid unnecessary/undesired over-pressurisation of the network, which in turn reduces leakages in the network being supplied. It will also be appreciated that by reducing overpressurisation of the system, the overall water consumption by consumers can also be decreased. Although some uses of water (e.g. filling a kettle or a bath) will require the same volume of water regardless of the water pressure, other uses (such as washing hands or articles under a running tap) may consume less water when a lower water pressure is used, while still achieving the desired purpose. A high water pressure is generally not required for all domestic uses (including hand washing, cleaning teeth, rinsing vegetables, showering, etc...) and therefore using a lower water pressure may result in a reduction in water usage by users.

Thus, the controller may be arranged to receive flow data from the flow meter and to control the controllable motor drive for withdrawal or advancement of the valve element in accordance with the flow rate measured by the flow meter and the relationship between water flow and water pressure in the downstream pipe network. This varies the position of the valve element to give a calculated output pressure at the measured flow rate that is required to provide the desired pressure at the critical location(s) in the downstream network.

The present inventor has also noted a correlation between on the one hand the flow into the network and the pressure required downstream of an FCPRVS to maintain a desired pressure at a critical point of a local network. As will be appreciated, the FCPRVS is typically situated between a high-pressure mains supply and a local network. The required regulated output pressure and the flow on the downstream side of the FCPRVS are related.

In this application, references to a “critical” location(s) of a network refer to a location(s) in the network where the fluid pressure is at its lowest, for example because of pressure losses arising from friction losses as the demand for water plus flow arising because of usage and leakage moves through the network. It is noted that the increase of flow because of leakage also increases the friction losses because of this flow. Thus, it is desirable to keep leakage flow losses at a minimum to reduce pressure losses that need to be overcome as water flows through a network. The critical point may therefore be the most remote (furthest away) location in the network from the FCPRVS, where the fluid pressure is at its lowest.

Alternatively, it may be geographically closer to the FCPRVS but located at a point where there are other factors that cause a reduction in fluid pressure, for example a location at the end of an uphill length of the pipework in the network. In general, references to a critical point of a network include references to users at the critical point, for example users at the critical locations or users located at the top of a hill.

In a second aspect, the invention provides an actuation system suitable for use in a water mains pressure reducing valve, the actuation system comprising: • a substantially incompressible connector connected to a controllable motor drive, such that there is a direct relationship between movement of the connector and the controllable motor drive;

• a flow meter; and

• a controller and an electronic data store held within or being in communication with the controller, the data store containing data defining a relationship between fluid flow rate and fluid pressure in a downstream pipe network to which the water mains pressure reducing valve is connected; wherein the controller is arranged to receive flow data from the flow meter and to control the motor drive in accordance with the flow rate measured by the flow meter and the relationship between fluid flow and fluid pressure.

The substantially incompressible connector, controllable motor drive, flow meter, controller and electronic data store are all as defined earlier in the application. The actuation mechanism is configured such that it is connectable to a pressure-reducing valve as described herein. When employed in a pressure-reducing valve as described herein, the actuation system replaces the corresponding components in the pressure reducing valve (i.e. the connector, controllable motor drive, flow meter, controller and electronic data store).

When the actuation system is employed in a pressure-reducing valve as described herein, the actuation system withdraws or advances the valve element of the pressure-reducing valve to restrict or permit the flow of water. When used in a pressure-reducing valve, the actuation system is coupled to the valve element via the substantially incompressible connector.

In response to signals derived from flow and pressure data, the controller manipulates the controllable motor drive, causing the substantially incompressible connector to move. When employed in a pressure-reducing valve as described herein, the motor drive may therefore alter the position of the valve elements via movement of the connector as described earlier in the application.

As described earlier, the controller continuously adjusts the motor drive in response to flow data collected from a flow meter. This enables “real time” regulation of the motor drive according to the measured flow rate and the established relationship between fluid flow and pressure. Additionally, the actuation system may log flow data for performance monitoring, enabling ongoing analysis and comparisons to ensure optimal system operation and reliability. In a further aspect, the invention provides a flow-controlled pressure reducing valve system (FCPRVS) apparatus comprising: a pressure reducing valve, as described herein;

• a flow meter; and

• a controller and an electronic data store held within or being in communication with the controller, the data store containing data defining a relationship between fluid flow rate and fluid pressure in a downstream pipe network to which the pressure reducing valve is connected wherein the controller is arranged to receive flow data from the flow meter and to control the motor drive for withdrawal or advancement of the valve element in accordance with the flow rate measured by the flow meter and the relationship between fluid flow and output fluid pressure.

It will be appreciated that, typically, the data store contains data defining a relationship between fluid flow rate and fluid pressure in a downstream pipe network to which the pressure reducing valve is connected in order to maintain a pre-determined pressure at a critical point/location

Preferably, the controller is arranged to control the motor drive in real time for withdrawal or advancement of the valve element, with the term “real time” being as defined herein. In other words, the movement of the valve element takes place as soon as the controller is able to collect, process and respond to the analysis of data collected relating to changes in fluid flow or pressure as it occurs.

By varying the position of the valve element and thereby fluid flow through the chamber, a desired downstream fluid pressure (e.g. at a remote user) can be maintained.

Preferably the controllable motor drive is a servo motor drive. The controller can be adapted for calculation of the controllable motor drive action and thus the position of the valve element in accordance with a relationship between flow and pressure losses in a network downstream of an FCPRVS and therefore the required outlet pressure of the FCPRVS that is required to maintain a required pressure at a critical point in the network. The calculation can be based on the pressure to be achieved in terms of the controllable motor drive positioning of the valve element. Alternatively, it can be adapted for controllable motor drive action in accordance with a lookup table of downstream pressure and flow rate which can be stored in the controller. Again, the lookup table can include values of pressure to be achieved, but it preferably can also include valve element positions and/or required movements of the substantially incompressible connector in order to achieve a desired valve position. The lookup table provides the output pressure required to maintain the desired pressure at the critical point.

For example, when the fluid is water and the pressure reducing valve is installed in or connected to a local water network, the controller can be programmed, or instructed by a remote control centre, to vary the flow rate so as to ensure that the minimum water pressure provided to a remote user in the network (i.e. the user at which there is the greatest pressure drop) is within the range from 0.5 Bar to 3 Bar. More usually, the controller is programmed, or instructed by a remote control centre, to vary the flow rate so as to ensure that the minimum water pressure provided to a remote user in the network is within the range from 1 Bar to 2 Bar, typically 0.6 Bar to 1.5 Bar, more typically 0.7 Bar to 1.2 Bar. In one embodiment, the minimum water pressure provided to a remote user in the network is approximately 1 Bar.

The pressure reducing valve is preferably a valve for controlling the flow of water to a local area network or a district metered area (DMA). The pressure reducing valve may therefore be connected at its upstream end to a high-pressure mains (e.g. pressures of 6 bar or greater, for example, pressures of 10 bar or greater, 15 bar or greater or even 20 bar or greater) and at its downstream end to a network of distribution pipes forming a district metered area.

The FCPRVS apparatus of the invention may be connected to a remote-control facility. Any or all of the flow meter, pressure sensors and controller may be connected to the remotecontrol facility for example by wired or wireless communication. In one embodiment, only the controller is connected to the remote-control facility, although it will be appreciated that data from the flow meter and pressure sensors may be transmitted to the remote-control facility via the controller. In another, and preferred, embodiment, the controller is connected to the remote-control facility.

Whilst the FCPRVS is intended to function without the need for specific user input, by connecting the FCPRVS of the invention to a remote-control facility, it is possible for local control of the FCPRVS to be overridden remotely (e.g. manually), for various operational reasons, such as the detection of abnormally high or low flows of water in the network that are indicative of a major leak, for example a burst pipe or arising from maintenance work or changes made for network management purposes. The controller may be programmed to send alarm signals to the remote-control facility if water flows exceed or fall below a certain threshold level, which may be indicative of a major leak upstream or downstream of the FCPRVS or other unusual demand such as irrigation, fire attendance etc.

Accordingly, in a further embodiment, the invention provides a fluid pressure reducing valve apparatus comprising a pressure reducing valve (e.g. as described herein), a controllable motor drive, a flow meter and controller as defined herein, wherein the fluid pressure reducing valve apparatus is linked (e.g. wirelessly) to a remote control facility, from which remote control facility, the operation of the apparatus can be remotely controlled.

A local network will typically form part of a larger network in which a plurality of lower pressure local networks are each connected to a high pressure main by the FCPRVS’s of the invention.

The FCPRVS’s of the invention are typically installed into a water distribution network underground and so may need to be protected from damage from water in the ground surrounding elements/components of the FCPRVS.

Accordingly, the FCPRVS may comprise a casing which may enclose the controller, the modems (for transmission and receipt of data) and batteries. Alternatively, the controller, modems and/or batteries may be provided in a separate casing to the PRV, provided that the controller, modems and/or batteries are linked (wired or wirelessly) to the PRV.

The casing is typically waterproof to ensure that the components contained within are not affected or damaged by water.

Accordingly, in a further aspect of the invention there is provided a water distribution network control unit comprising: a) a pressure reducing valve, as described herein; b) an electronic controller in electronic communication with a transmitter and a receiver and the controllable motor drive of the pressure reducing valve; and c) a casing for housing at least part of the pressure reducing valve, the electronic controller, transmitter and receiver.

The electronic controller, transmitter and/or receiver are typically electrically powered. Thus, the control unit may also comprise a battery (e.g. a rechargeable battery) housed within the casing and/or a mini-water turbine electricity generator. The electronic controller is typically programmed with software to control the output pressure of the pressure reducing valve in real-time by advancement or withdrawal of the incompressible connector so that it can be increased or decreased according to a Flow/Pressure profile, which is calculated to ensure a minimum desired pressure at a critical location. The software may also be capable of raising alarms in the event of unexpected changes in flow rates and pressure levels, either upstream or downstream of the pressure reducing valve. For example, the controller may raise an alarm and allow pressure and flow rates to change in the event of an unusual or unexpected change in demand for water. Such an event may be a fire downstream of the PRV, where an increase amount of water is required.

The electronic controller is in electronic communication with a transmitter and a receiver to allow the pressure reducing valve to be fully controlled from a remote control facility and/or a mobile control device (such as a laptop, tablet or mobile telephone).

The electronic controller may contain a data store which maintains a lookup table or control formulae derived from the calculated Flow/Pressure relationship for real-time advancement/withdrawal of the incompressible connector. It may be possible for the controller to be reprogrammable (manually or automatically) in the event of changes to the downstream water network (e.g. the development of new housing estates or factories).

The casing is typically waterproof to ensure that the components of the water distribution network control unit contained within are not affected or damaged by underground water. The casing may be formed from a corrosion-resistant metal (such as stainless steel) or a suitable plastics material. Parts of the casing are typically provided with appropriate seals to form a waterproof encasing.

The term “waterproof” as used herein may refer to the ability to withstand the ingress of water when submerged in 50cm or more, for example 1 m or more or 2m or more of water for a period of 30 minutes or longer, for example 1 hour or longer or 2 hours or longer.

The pressure reducing valve and/or a casing within which the pressure-reducing valve is at least partially housed can be provided with one or more security devices for detecting and/or preventing unauthorised access to the valve and/or casing. The security devices can be, for example, selected from sensors, switches, electronic security tags and cameras. The security devices are preferably in communication with (e.g. by cabling or wirelessly), either directly or through the electronic controller, to a remote control facility so that unwanted interference can be notified to an operator of a water distribution network. In one embodiment, the security device(s) can take the form of one or more switches or security tags that are triggered by the opening or partial or complete removal of the casing. The triggering of the switch(es) by the opening/removal of the casing may initiate a warning to the remote control facility to indicate that the casing has been tampered with.

Communications signals sent between the electronic controller, a remote control facility and any security devices present are preferably encrypted to prevent hacking and control over the network being acquired by unauthorised parties.

As the control units are typically positioned in the ground at depths of approximately 0.5m to 2 m, the control unit typically comprises an antenna, which extends out of the casing. The antenna may comprise a cable or a wire of 1m or greater in length, for example 2m or greater, preferably 5m or greater in length. In order to increase the range of the transmitter and/or receiver, the antenna (or more specifically, the antenna cable/wire) may be connected or connectable to a metallic structure at or near ground level, such as a manhole or cover thereof, which itself can act as part of the antenna.

A water distribution network control unit, as defined herein, comprising an antenna linked to a metallic structure at or near ground level, such as a manhole or cover thereof, which itself can act as part of the antenna, represents a further embodiment of the invention.

To enable recharging of the battery in situ, there may also be provided a generator which can generate electricity as a result of the flow of fluid through the unit. The generator may be in line (or in series) with the FCPRVS, and the generator may be upstream or downstream of the valve, such that fluid passing through the valve can be used to generate electricity by the generator. Alternatively, the FCPRVS may be provided with a bypass conduit, in which the generator may be located. The bypass conduit may be connected and in fluid communication at its upstream end with the source of high-pressure water (i.e. , upstream of the valve element in the pressure reducing valve) and the other end in communication with the low-pressure side of the valve. Accordingly, a small proportion of high-pressure water may bypass the valve element via the bypass conduit to generate electricity to power the electronic components of the pressure reducing valve apparatus. A bypass control valve may be present in the bypass conduit to control the flow of water into the generator. The bypass control valve may be in electronic communication with and thereby controlled by the controller.

The FCPRVS also preferably comprises a flow meter in electronic communication with the electronic controller for measuring the flow of water. The flow meter is in-line with the pressure reducing valve. Accordingly, it may be upstream or downstream of the pressure reducing valve. The flow meter is typically located such that there is no take-off of water between the flow meter and the pressure reducing valve. Alternatively, the flow meter (e.g. an insertion meter) may be located within the chamber of the pressure reducing valve. In use, the receiver may receive a signal by wired or wireless communication from a remote transmitter. The signal may be indicative of the water pressure at a critical location in the local network with which the FCPRVS is associated or indicative of whether the valve should be opened or closed. By means of the electronic controller, in response to this signal, the controllable motor drive can be controlled to facilitate movement of the connector and therefore increase or decrease the position of the valve element and so affect the downstream pressure of the FCPRVS.

It is known and not surprising that Primary, Secondary and Distributor mains supplying a plurality of other networks follow similar patterns of pressure fluctuations as the networks they supply. This in turn exacerbates leakage in these mains in the same way as described above for some local area networks. It follows therefore that an FCPRVS such as described herein can be placed at the beginning or in intermediate places along the Primary, Secondary and Distributor mains and so help protect these mains from pressure fluctuations as described above and so reduce leakage in these mains. The critical location for such a system then becomes the local area network in the most critical part of the network supplied by the Primary, Secondary or Distributor mains.

Accordingly, in a still further embodiment, the invention provides a water supply system. The water supply system typically comprises a plurality of local networks, each of the local networks being provided with an FCPRVS of the invention as defined herein. The water supply system typically comprises a remote-control facility to which the controllers of each of the pressure reducing valve apparatuses of the local networks are linked. Additionally, or alternatively, the flow meters, pressure sensors and controllable motor drives of each of the FCPRV’s of the local networks may be connected to the remote-control facility.

In another embodiment, the invention provides a method of controlling the water pressure in a water supply network having an FCPRVS connecting the local water network to a high- pressure mains supply, the method comprising: a) providing a pressure reducing valve, as described herein (i.e. that comprises a controllable motor drive that can vary the water pressure into the network upon receipt of signals from a controller) with an associated electronic controller, b) providing the network with a flow meter and pressure sensors (e.g., immediately downstream and/or upstream) of the pressure reducing valve and a pressure sensor at a critical location, the flow meter and pressure sensors being in communication with the electronic controller, c) measuring flow rates and pressures to establish a relationship between flow rate and pressure of water flowing into the network, and storing this data and establishing the relationship in the controller and/or a remote-control facility, d) using the said relationship to establish a pressure reducing valve setting at a given time point based on a measured flow rate to maintain a desired minimum pressure at a defined critical location in the network; and e) monitoring changes in the flow rate in the network detected by the flow meter and actuating the controllable motor drive to change the pressure reducing valve setting in response to the changes in the flow rate to maintain the desired minimum pressure at the defined critical location in the network.

The pressure reducing system used in the above method is necessarily an FCPRVS in accordance with the invention as defined and described herein.

Following an initial calibration phase, the FCPRVS can be controlled to maintain a desired pressure at the defined critical location based solely on measurements taken by the flow meter at the FCPRVS which is the normal operating mode. Accordingly, in use, the FCPRVS does not rely on receiving signals relating to water pressure from the critical point. This is possible due to the relationship between the flow measured by the flow meter at the FCPRVS and the water pressure that needs to be provided by the FCPRVS to maintain a desired pressure at a downstream critical location. As a result, once the relationship between the flow and downstream pressure is known, it is possible to set the FCPRVS to the required pressure for all flow rates measured by the flow meter. The controller is programmed so that if necessary or desired the controller allows the remote pressure signal to override the downstream pressure determined by the flow and pressure relationship adjusting the downstream pressure until the remote pressure is brought within the range of pressures as set by the network management.

The relationship between flow and pressure within a network will vary depending on a number of variables, including the length/condition of the pipes in the network, the number/location of the users and the number/size of any leaks in the network. Therefore, step c) of the method involves establishing a relationship (referred to herein as a “Flow/Pressure Profile” relationship) to establish the pressure output of the PRV that is necessary to maintain a desired water pressure at a critical location. Accordingly, step c) may comprise measuring the flow rate at the PRV, the pressure at the PRV and the pressure at the critical location and then adjusting the pressure reducing valve to change the output flow rate and/or pressure of the PRV so that the desired pressure at the critical location is maintained (for example, when the measured pressure at the critical location is within a predetermined tolerance of the desired value).

This process is typically repeated at multiple time points (e.g. with different PRV output pressures) to establish the Flow Pressure Profile relationship. At each time point, the flow rate at the PRV and the corresponding output pressure of the PRV that gives the desired pressure at the critical location are recorded. At each time point, these values are recorded. The measured critical location pressure (“p^RN”) and the desired critical location pressure (“P^R”) are compared. If P^RN is higher than P^R, the controller may instruct the controllable motor drive to move the valve element and thereby change the flow of liquid through the valve by a small (but preset) amount and vice versa if P^RN is lower than P^R. In this way the downstream pressure P^N is adjusted to match the desired value. This is repeated and continues until the difference between P^RN and P^R is within the preset tolerance that has been determined by the management team. All measurements may be recorded together with a time and/or date stamp.

The relationship may be based on a linear or a polynomial model, as described in the examples below.

The relationship may include data points over the course of a single day to provide a general daily Flow Pressure relationship for the pipe network. Alternatively, it can be established for each day of the week separately (to capture differences in the relationship between e.g. weekdays and weekends). This allows the recognition of changes in the expected flow rate for a particular day at a particular time and if necessary, and consequently the raising of an alert. A significantly larger than expected flow rate may be an indication of a “catastrophic failure” within the network, for example a major leak.

Once the relationship has been established, the flow rate through the PRV required to maintain a desired pressure at a critical location may be determined by measuring the pressure at the PRV and comparing it with the required pressure at the PRV as calculated from the flow rate using the Flow Pressure relationship. Accordingly, the PRV can be adjusted to maintain a desired pressure at a critical location using flow rate and pressure measurements from the PRV only (i.e. without having to directly measure the pressure at the critical location).

As noted above, the method may comprise comparing the measured flow rate with the expected flow rate and raising an alert if there is a significant difference between the expected flow rate (for a given day and time) and the measured flow rate. This large discrepancy may be indicative of a major leak within the network.

Accordingly, the method may also comprise establishing an expected flow rate for a given date and/or time in step c) and an additional step (“step f)”) of comparing the expected flow rate with the measured flow rate and providing an indication/alert if the difference is greater than a predetermined value.

In a further embodiment, there is provided a method of controlling the water pressure in a water supply network having an FCPRVS connecting the local water network to a high- pressure mains supply, the method comprising: a) providing a pressure reducing valve, as described herein (i.e. that comprises a controllable motor drive that can vary the water pressure into the network upon receipt of signals from a controller) with an associated electronic controller, b) providing the network with a flow meter and pressure sensors (e.g., immediately downstream and/or upstream) of the pressure reducing valve and a pressure sensor at a critical location, the flow meter and pressure sensors being in communication with the electronic controller, c) measuring flow rates and pressures to establish a relationship between flow rate and pressure of water flowing into the network at given time points (e.g. at certain times of the day and optionally on certain days of the week), and storing this data and establishing the relationship in the controller and/or a remote-control facility, d) using the said relationship to establish a pressure reducing valve setting at a given time point based on a measured flow rate to maintain a desired minimum pressure at a defined critical location in the network; e) monitoring changes in the flow rate in the network detected by the flow meter and actuating the controllable motor drive to change the pressure reducing valve setting in response to the changes in the flow rate to maintain the desired minimum pressure at the defined critical location in the network; and f) comparing the measured flow rate (from step (e)) and the expected flow rate for a given day/time (from step (c)) and alerting a remote-control facility if the difference exceeds a predetermined value.

Brief Description of the Drawings

Figure 1 is a schematic diagram showing a pressure reducing valve apparatus according to a first embodiment of the invention.

Figure 2 is a schematic diagram showing a pressure reducing valve apparatus according to a second embodiment of the invention.

Figure 3 is a schematic diagram showing a pressure reducing valve apparatus according to a third embodiment of the invention.

Figure 3a is an enlarged view of part of the valve apparatus of Figure 3.

Figure 4 shows a flow-controlled pressure reducing valve system (FCPRVS) according to an embodiment of the invention.

Figure 5 shows the FCPRVS of Figure 4 from an alternative angle.

Figure 6 is a schematic view of a local water supply network showing a water main having an FCPRVS and a local network comprising a plurality of user connections and leaks downstream of the FCPRVS.

Figure 7 is a schematic view of a trunk main supplying an elevated pressure main which in turn supplies one or more local networks serving users.

Figure 8 shows the daily flow and pressure pattern for a typical local supply network with a static input pressure

Figure 9 shows the daily flow and pressure patterns in a local network for the same day of the week in consecutive weeks.

Figure 10 is a table of flow rates and pressures in a local supply network when it is supplied by either a conventional pressure reducing valve or a valve of this invention. The data was collected on two consecutive weekdays.

Figure 11 shows flow and pressure information for the network of Figure 8 when using either a conventional PRV or an FCPRVS of this invention. Figure 11A shows the inlet pressure of the network, Figure 11B shows the flow rates and Figure 11C shows the downstream pressures.

Figure 12 shows the relationship between the flow and output pressure of the data in Figure 8 described as either a linear relationship (12A) or a polynomial relationship (12B).

Figure 13 shows the algorithm used for the Initial Setup Mode.

Figure 14 shows the algorithm used in the Normal Run Mode.

Detailed Description of the Invention

The invention provides an improved pressure reducing valve (PRV), as well as a Flow Controlled Pressure Reducing Valve System (FCPRVS) to regulate the output pressure of a pressure reducing valve using software to provide real time automatic management of output pressure in accordance with a Flow/Pressure Profile established for a network and that also has the capability of management by exception for unusual or unexpected exceptions to the normal flow patterns that would be expected in a supply network. The FCPRVS is equipped for automatically changing the downstream pressure of a pressure reducing valve by way of a control valve (such as a diaphragm, piston, or plunger valve etc), a controller, algorithms, purpose developed, designed and written control software, a servo motor, flow meter, local and remote pressure sensors, electronic controllers and modems for wired and/or wireless transmission or receipt of data. The controller contains various electronic components including digital storage - preferably solid state, programmable central processing units (CPUs), facilities for receiving and transmitting data, storing and analysing data received via wired and/or wireless communications from the pressure sensors, meters, the servo motor and modems. The controller can store, analyse, calculate, send and receive data to and from the servo motor so that it can be moved to specified positions according to instructions generated in the CPU by the installed software. In this way, the downstream or output pressure of the FCPRVS is changed to suit prevailing flow conditions in a pipe network which consists of a plurality of interconnected pipes. In some cases, this downstream network of pipes may be defined as a District Metered Area (DMA) as used for water supplies. The controller of the FCPRVS can work in isolation or be in communication with a remote-control facility, which may include a remote field-control unit (such as a portable computer device, e.g. a tablet) for remote control. A plurality of the FCPRVS’s can be in communication with a control room. The controller also has the facilities for controlling the output of a locally installed electrical generator for charging batteries, if used for the servo motor and the associated ancillary equipment. The controller has the facility for changing the output pressure of the FCPRVS in response to signals from a remote place in the downstream network of pipes overriding and independent of Flow/Pressure Profile if certain conditions are met.

To help the understanding of the invention, specific embodiments thereof will now be described by way of example and with reference to the accompanying drawings Figures 1 to 14.

Figure 1 shows a flow-controlled pressure reducing valve system (FCPRVS) (100) according to a first embodiment of the invention, wherein the valve element (109) is connected to a diaphragm (110). Referring to Figure 1, a pressure reducing valve (101) has a body (102) comprising upper and lower parts which are secured together with a fluid-tight joint by mechanical fastenings such as bolts and nuts (122). Some or all the bolts may be replaced with suitable support rods (121) to support an upper plate (120) that supports the servo motor (126). A diaphragm (110) held between the parts encloses a hollow interior which is partitioned into a fluid-flow chamber (103) and a dry control chamber (103a) by the diaphragm (110). An inlet (104) opens into the water flow chamber (103) via an inlet orifice (105).

The inlet is connected to a high pressure water main (106). An outlet (107) from the water flow chamber is connected to a network of pipes (108) for local distribution of water to individual users (sometimes called a district metered area or DMA). The valve has a flow pressure regulation plate or valve element (109) arranged opposite the inlet orifice (105). The diaphragm (110) is secured between a pair of diaphragm plates (111,112) and extends radially outwardly to the body, forming a seal with the body (102). Thus, the water flow chamber (103) is sealed in the lower part of the body by the diaphragm (110). The dry control chamber (103a) above the diaphragm (110) is a dry chamber and water does not flow into this space.

The valve element (109) is arranged opposite the orifice (105). The valve element (109) may form part of the lower plate (112) or may be separately provided on guide rod (114) extending from the lower diaphragm plate (112). The guide rod (114) extends down from the valve element (109) into a guide (116) in the inlet orifice (105). The guide rod (114) extends through the valve element (109), the diaphragm (110) and the diaphragm plates (111,112). At its top end, inside the dry chamber, the guide rod (114) carries a nut (117) bearing on a washer (118) and the upper diaphragm plate (111). The guide rod (114) is formed to be a clamping facility to hold the upper and lower diaphragm plates (111 and 112) along with the valve element (109) fixed in relation to each other. The arrangement centres, clamps and seals the diaphragm in a fluid tight manner around the guide rod (114). The arrangement also keeps valve element (109) centred over the inlet orifice (105).

A solid, inextensible, and incompressible drive connector (119) is secured to and extends from the upper diaphragm plate (111) through the dry control chamber (103a) and is attached to the end of a drive tube (125) of a servo motor (126). The drive tube is housed in a fixed tube of the servo motor. A lead screw is journaled for axial alignment in the drive tube within the fixed tube. A motor and gearbox are arranged to drive the lead screw. A nut, preferably a recirculating ball nut, is fast with the remote end of the drive tube (125), with the latter keyed to the fixed tube against rotation. Thus, the drive connector (119) can be advanced or retracted to directly move the valve element (109) towards or away from the orifice (105), by rotation of the motor and lead screw.

A flow meter (132 or 132a) and pressure sensors (131, 133 and 135) along with a servo motor (126) are all in communication with the controller (134).

Figure 2 shows a Flow Controlled Pressure Reducing Valve System (FCPRVS) (200) according to a second embodiment of the invention, wherein the valve element (209) is connected to the end of a piston (210). Referring to Figure 2, a pressure reducing valve (201) has a body (202) comprising upper and lower parts which are secured together by mechanical fastenings such as bolts and nuts (222). Some or all the bolts may be replaced with suitable support rods (221) to support an upper plate (220) that supports the servo motor (226). The interior of the body (202) is partitioned into a water-flow chamber (203) and a dry control chamber (203a) by a piston (210) and cylinder (211) arrangement.

An inlet (204) opens into the water-flow chamber (203) via an inlet orifice (205). The inlet (204) is connected to a high pressure water main (106). An outlet (207) from the water-flow chamber is connected to a network of pipes (108) for local distribution of water to individual users. A valve element (209) is positioned opposite the inlet orifice (205). The valve element (209) may form part of the piston (210) or may be separate, as shown, and carried on a guide rod (214).

An O-ring (not shown) formed from a suitable elastomeric sealing material such as neoprene or a nitrile rubber is mounted in a circumferential groove around the piston element (210) and forms a seal with the cylinder (211) preventing the leakage of water between the fluidflow chamber (203) and dry control chamber (203a). Alternatively, one or more metal piston rings may be used instead of the elastomeric O-ring. The control chamber (203a) is a dry chamber, and the water does not flow into this space.

The cylinder (211) can be a boring in the body or an inserted sleeve of a metal such as stainless steel or a suitably tough plastics material (such as a polyacetal engineering polymer) and is secured to the inner wall of the lower body part by a suitable means such as mechanical fastenings (not shown), an interference fit, adhesive or by welding. The piston element (210) is arranged for reciprocating movement in the cylinder (211) and has a guide rod (214) extending downwardly from it into a guide (216) in the inlet orifice (205). The guide rod (214) extends through the valve element (209), the piston (210), inside the dry control chamber (203a), and its upper end carries a nut (117) bearing on a washer (218).

The piston (210) and the valve element (209) are secured to the guide rod (214) The arrangement centres and clamps the piston around the guide rod (214). The guide rod (214) also carries seals (not shown) between the guide rod (214) and the piston (210). This arrangement also keeps the valve element (209) centred over the inlet orifice (205).

A solid, inextensible, and incompressible drive connector (219) is secured to and extends from the piston (210) through the dry control chamber (203a) and is attached to the end of a drive tube (225) of a servo motor (226). The drive tube is housed in a fixed tube of the servo motor (226). A lead screw is journaled for axial alignment in the drive tube within the fixed tube. A motor and gearbox are arranged to drive the lead screw. A nut, preferably a recirculating ball nut, is fast with the remote end of the drive tube (225), with the latter keyed to be a fixed tube against rotation. Thus, the drive connector (219) can be advanced or retracted to directly move the valve element (209) towards or away from the orifice (205), by rotation of the motor and lead screw.

A flow meter (232 or 232a) and pressure sensors (231, 233 and 135) along with a servo motor (226) are all in communication with the controller (134).

Figure 3 shows an FCPRVS (300) according to a third embodiment of the invention, wherein the valve is based on a plunger valve, wherein a plunger element (311) is connected to a pivoting lever arm (318) via a drive connector (314).

Referring to Figure 3, a pressure reducing valve (301) has a body (302) of a generally tubular shape. Within the body (302), there is located a dry control chamber (303a) defined by a plunger (311) and a plunger cylinder (310). The plunger (311) is generally tubular in shape having one end open and the other end closed. The closed end in this embodiment is hemispherical in shape. The upstream end of the plunger cylinder (310) is closed and may have a hemispherical-shaped end, whereas the downstream end of the cylinder has slidably received therein the plunger (311). The hemispherical end (309) of the plunger (311) acts as a valve element for controlling the flow of water through the valve.

Appropriate seals may be provided in grooves formed in the outer surface of the piston to form a water-tight seal between the dry control chamber (303a) defined by the cylinder (310) and plunger (311).

The water flow chamber (303) surrounds the cylinder (310) and the plunger (311) inside the body (302). Thus, the water flow chamber (303) is sealed in the outer regions of the body (302). The dry control chamber (303a) formed within the cylinder (310) and the plunger (311) is a dry chamber, i.e., water does not flow into this space.

An inlet (304) opens into the water flow chamber (303). The inlet (304) is connected to a high pressure water main (106). An outlet (307) from the water flow chamber (303) is connected to a network of pipes (108). The valve element (309) is arranged opposite the outlet orifice (307).

In this embodiment, the plunger (311) is situated opposite the outlet orifice (307). However, it may instead be opposite the inlet (304). The plunger (311) is pivotably connected to one end of a drive connector (314) which in turn is pivotably connected to one end of a lever arm (318) within the dry control chamber (303a). The lever arm (318) is key mounted on a shaft (316) to give a “big end” (320) key mounted on the shaft (316) and a “small end” (319) which is rotationally connected to one end of the drive connector (314). The other end of the drive connector (314) is rotationally connected to the plunger (311). The shaft (316) extends through the side walls of the cylinder (310) and the body (302). The lever arm (327) is key mounted on the shaft (316) after it leaves the body (302). The lever arm (327) is key mounted on the shaft (316) at the “big end” (320) and the other “small end” (324) is rotationally connected to one end of the drive connector (315). The shaft (316) has seals (not shown) where it passes through the cylinder (310) and the body (302) to prevent fluid leaking into the dry control chamber (303a) or out of the body (302). A servo motor (326) is arranged to impart reciprocating movement to the drive connector (315). Pivoting of the lever arms (327 and 318) results in the drive connector (314) being advanced or retracted to move the valve element (309) towards or away from the outlet orifice (307). An advantage of the use of the lever arm arrangement is that the less force is required to be imparted by the servo motor (326) to move the valve element (309) and therefore less energy is used in the operation of the valve.

A flow meter (332 or 332a) and pressure sensors (331 , 333 and 135) along with a servo motor (326) are all in communication with the controller (134).

Each of the embodiments of the FCPRVS (100, 200, 300) shown in Figures 1 to 3 has a pressure reducing valve (101, 201, 301). Each FCPRVS has a controller in communication with a flow meter (132, 232, 332,) pressure sensors (131, 231 , 331 , 133, 233, 333, 135) and a servo motor (126, 226, 326). Downstream of the pressure reducing valve (101, 201, 301) is a downstream pressure sensor (133, 233, 333) which may be mounted as shown or alternatively mounted in a tapping in the downstream outlet (107, 207, 307) as it joins the downstream pipe network (108). A flow meter may be mounted downstream (132, 232, 332) or upstream (132a, 232a, 332a) of the pressure reducing valve (101,201,301). Upstream of the pressure reducing valve (101 , 201 , 301) is an upstream pressure sensor (131 , 231 , 331) which may be mounted as shown or alternatively mounted in a tapping in the upstream part of the body (102, 202, 302) in the high-pressure inlet (104, 204, 304). Downstream of the pressure reducing valve in the downstream pipe network (108) in a critical location (136) is a remote pressure sensor (135). There may be one or more critical locations according to the topography of the downstream pipe network (108) in which case the controller is programmed to prioritise as may be necessary. The controller (134) may also be connected to a remote-control facility (139). The remote-control facility typically controls a plurality of local distribution networks each equipped with its own FCPRVS. It is conceivable that as an alternative to each local distribution network having its own controller, all the controllers may be located at the remote-control facility. Operation of the FCPRVS can then also be controlled directly from there if necessary.

As shown in Figure 6, the downstream pipework (108) forms a local area network of pipes (e.g. a DMA). There are typically various leaks (137), various users (138) and critical locations (136). Remote pressure sensors (135) are located at the critical locations (136). The flow rate of water out of the leaks increases with increasing water pressure in the pipe network (108). Within the pipe network (108) there are also a number of users (138) and it is these which are the primary determinant of the flow through the FCPRVS (100, 200, 300). If the valve were of the type permanently set to a fixed predetermined downstream pressure for maintaining sufficient pressure at the critical locations (136), at the times of maximum flow in the network, pressure would rise and fall with changes in demand. Pressure losses due to friction rise and fall in line with increases or decreases in the flow rates in the pipework. It follows that if the output pressure of a conventional PRV is set and fixed to maintain a certain pressure at the outlet to the pipe network at maximum demand then pressure at the critical location (136) will also rise as flow in the network reduces. As flow in the network decreases, pressure in the network rises and leakage increases and vice versa.

Figure 8 represents a typical flow pattern in a network being supplied through a conventional or fixed output pressure reducing valve. It will be appreciated that this flow pattern is only representative and actual flow patterns may be different depending on the nature of water use downstream of the PRV. It can, however, be seen that maximum flow only occurs for short periods of time or portions of a daily cycle. The flow or demand is shown in a solid line and the corresponding pressure feeding the downstream network is shown in the broken line. It can be seen that, most of the time, the network is over pressurised (i.e. the pressure is much greater than the “legal” or “recommended/desired” minimum pressure required to be provided for all users). This over pressurisation increases the rate of flow from the leaks (137) regardless of the rate of water demand by the users (138).

In the present invention, the FCPRVS apparatus includes the pressure reducing valve, the flow meter, the pressure sensors, a servo motor and the controller for controlling the pressure reducing valve in accordance with flow measured by the flow meter.

Water mains networks are typically provided underground and therefore, in use, the FCPRVS apparatuses of the invention are also situated underground. The FCPRVS apparatus including the ancillary equipment valve (101, 201, 301), flow meter (132, 132a), pressure sensors (131,133), servo motor and controller (134) will also typically be underground. The controller, modems and servo motor can be housed within a casing (127). The casing (127) may be formed from a hollow cylinder of stainless steel having a top plate sealingly attachable to the cylinder. The casing may also contain a battery for powering the controller (134) and the servo device (126, 226, 326). The casing is water- and dust-resistant to an IP68 rating and can withstand the ingress of water and dust etc for a defined period of time, e.g. at least 2 hours upon total immersion in up to 2m depth.

Alternatively, the servo motor may be itself classified as IP68 and the controller, modems and battery may be mounted in suitable enclosures, classified as IP68, in the pit (e.g. manhole) in which the FCPRVS is installed.

Figures 4 and 5 show the FCPRVS including a casing in situ in a water mains pipeline from two different angles. In Figures 4 and 5, components of the FCPRVS are encased within a casing. Wiring is omitted from these figures for the sake of clarity. In the Figures, the casing is partially cut away to show the components inside the casing. For illustration purposes, the components in Figures 4 and 5 are described with reference to the PRV shown in Figure 1. However, it will be appreciated that the FCPRVS shown in Figures 4 and 5 could instead comprise a PRV as described in Figures 2 and 3.

Figures 4 and 5 show a pressure reducing valve (100) in series in pipework between a high pressure main (106) and a downstream pipe network (108). The flow meter (132) and pressure sensors (131, 133) are shown on the pipework upstream/downstream of the PRV (100). On top of the PRV is mounted a casing (400) which contains the servo motor (126), the controller (134), a battery (412) and a modem (414). The controller (134) is connected to the servo motor (126), battery (412), modem (414) and other electronic components of the system by electrical wires (not shown).

The casing (400) is formed from two circular end plates (401, 402) and a cylindrical side wall (404). Circular support plates (406, 410) are also provided, which are dimensioned to fit within the cylindrical wall (404). The support plates (406, 410) are held together and spaced apart by four vertical support rods (408). The ends of the support rods (408) are provided with threaded ends. Each end of the support rod (408) passes through a hole in each of the support plates (406, 410) and is secured to the support plates (406, 410) by means of nuts (409), which engage with the threaded ends of the support rods (408). The end plates (401 , 402) are provided with O-ring seals, which form an IP68 standard waterproof seal with the circular wall (404) to form a sealed unit which houses the components of the FCPRVS.

Lower support plate (410) and lower end plate (401) are each provided with a central hole through which the end of the drive tube (125) remote from the valve may pass in order to engage with and be driven by the servo motor (126).

The lower end plate (401) is secured to the top of the body of the PRV (100) by a series of nuts and bolts, with a seal placed between the end plate (401) and the PRV (100) to form a watertight seal between the casing (400) and the PRV (100).

The casing (400) is typically designed to IP68 specification to withstand being submerged at a depth of up to 2m and for two hours or more. The casing (400), more specifically the end plates (401, 402) and side wall (404), may be formed a metal suitably treated to be corrosion-resistant, stainless steel or a suitable plastics material. The casing (400) may be secured to the body of the PRV (100) by a bolt (430) or other similar means, where required with suitable O-rings and/or a non-setting material such as a mastic, silicone (e.g. silicone grease) or other paste. The casing is also provided with a tamper detector which is connected to the controller and can trigger an alarm in the event that the casing is opened by an unauthorised person.

A generator (420) may also be provided which can be in-line or in a bypass tube and driven by the flow of water preferably from the high-pressure mains water (106). The electrical outputs of the generator (420) are connected to the battery (412) through the controller (134) to enable charging of the battery. This enables the apparatus to be powered without the need for connection to an external power supply. The generator (420) for charging the battery (412) may be in a bypass (422) between the upstream pipework (106) and the downstream pipework (108). The generator may alternatively (or additionally) be connected in-line between tappings in the inlet (104,204,304) and the outlet (107,207, 307) sides of the body (102, 202, 302) of the pressure reducing valve (101,201 ,301).

An electronically controlled valve (424) is provided within the bypass line containing the generator (420) which is controlled by the controller (134) to turn on and off the supply of water to the generator (420). This can ensure that the battery (412) is not overcharged.

Electrical wires from the generator (420), electronically controlled valve (424) and other components of the FCPRV external of the casing (400) (e.g. the flow meter (132), pressure sensors (131, 133) and aerial) are fed into the casing (400) through an IP68 sealing plug (not shown) in the cylindrical side wall (404) of the casing (400).

As noted above, the pressure reducing valve apparatus of the invention may be in communication with a remote-control facility (139) to enable information regarding the performance of the FCPRVS (e.g., flow rates, water pressures, connector position and other management information) to be monitored remotely. Increasingly, mobile or wireless communication means are being used and, accordingly, mobile modems may be used. These enable information to be transmitted from the remote point and received wirelessly by the controller as well as providing communications with a remote-control facility (139)

When the casing (400) is made from a material that does not easily allow the passage of a wireless signal, for example stainless steel, a cable connects the modem inside the casing to a point outside the casing. This connecting point may be a bolt attached to the casing with a point of cable connection, e.g. threaded, provided both inside and outside the casing. A further cable connects the casing to, for example, a manhole cover or a suitable metallic structure, which can also act as an antenna for wireless connection to the control room and/or the remote pressure sensor. The antenna may be dipole, monopole or an array. Alternatively, the casing may have a direct wired cable connection to the remote control room.

An existing local area network fitted with a conventional PRV and then a flow controlled pressure reducing valve fitted with a flow meter was observed on consecutive weekdays at the same times and the flow and corresponding outlet pressure for both the conventional PRV and an FCPRVS of this invention was recorded. The FCPRVS downstream pressure was able to maintain a pressure of 1 bar at the critical location. Figure 10 is a table showing the records. Figure 11 is the graphical representation of this table. Due to leakage, there is never zero flow rate even if there is no demand from any users (138) in the downstream network (108). Flow and output pressure readings can be made during periods of higher and lower flows while adjusting the pressure reducing valve, so as to provide the predetermined pressure at the critical location. These readings can be used to determine what is called, in this invention, a Flow/Pressure Profile for the pipe network (108). This profile can be used to predict the output pressure of the FCPRVS (by reference to flow rate) and will also indicate an unexpected increase or decrease in flow rate into the network or DMA. This data is stored in the controller and can be used to determine the Pressure Flow Profile downstream of the FCPRVs or simply a lookup table for pressures required at particular flow rates in order to maintain a desired pressure at a critical point downstream of the FCPRVS. The controller can then control the servo motor (126, 226, 326) to adjust the position of drive connector (119, 219, 315) and thus the valve element (109, 209, 309) to give the desired output pressure of the FCPRVS.

The nature of water mains networks means that fluctuating pressures occur both upstream and downstream of a PRV installation. This phenomenon becomes of more critical relevance at low flows when PRV’s are only marginally open. The inventor of the present application observed that in prior art PRVs (such as those described in WO 2021/089986 and WO 2022/233420), as flow through the PRV was reduced, “hunting” occurred and the diaphragm fluttered causing instability in the downstream or output pressure of the PRV. The effect of this fluctuating pressure became more critical at low flows when the spring was constantly shortening and lengthening in response to the pressure changes acting on the underside of the diaphragm. When the flow rate was reduced to expected night-time flow rates and the upstream pressure reduced and then increased by small amounts to simulate changes in demand during night usage, hunting became more noticeable and further small changes even caused the valve to close. When small pressure changes were applied after the valve closed, the valve did not open again. When the valve was closed under these conditions, a larger than expected withdrawal of the drive connector was required before flow was re-established. As soon as the valve reopened, upstream pressure was immediately transferred to the diaphragm which caused the spring to reduce in length, the valve member to open further and, because of this, the downstream pressure to increase more than required. This then had to be corrected and the controller caused the drive connector to advance so that downstream pressure was reduced and returned to that which was required by the low flow rate necessary to maintain the remote pressure at the required level. The area of the valve member is much smaller than the area of the diaphragm and so the forces acting on the valve member were higher as, just prior to closing, the forces exerted on the diaphragm were transferred and were now acting on the smaller valve member area only. The force in the spring however was still that required to move the diaphragm and therefore the valve member to the closed position. Immediately the force exerted by the spring to overcome the force acting on the underside of the diaphragm, because of the upstream pressure, was now acting on the valve member which had a much smaller surface area than the diaphragm and therefore was higher than that required to close the valve. As a consequence of this, the drive connector had to be withdrawn more than would be necessary to cause the valve to close in order to allow the valve to open again.

Similarly, when the valve was operating at low flows and small changes were made to the upstream pressure, as may occur in live water mains, a similar phenomenon occurred. Steps had to be taken, as above, to normalise the downstream pressure to maintain the pressure at the critical location.

To overcome this limitation, in the present invention, the spring in the pressure reducing valves of the prior art has been removed and replaced with a fixed length drive connector (119). The fixed and substantially incompressible and inextensible drive connector does not respond to the fluctuating pressure in the same way as the spring. At all flow rates, the effect of the dynamic pressure changes which caused fluttering of the diaphragm were removed and fluctuating pressure were not simply passed to the downstream. The potential for sudden closing of the valve at very low flows such as at night was removed as the diaphragm was always held in a fixed position as determined by the Flow Pressure relationship for the network. As the drive connector does not increase or decrease in length with varying forces acting on it in the same way as the spring did a much more controllable direct positioning of the valve member is always achieved irrespective of fluctuating upstream and downstream pressures at the valve installation. This improvement can also be applied to other Pressure Reducing Valves (201 , 301), such as those shown in Figures 2 and 3.

In Figures 1 and 2, the drive connectors (119, 219) of the FCPRVS act against the force exerted by the diaphragm (110) or the piston (210), which is subject to the pressure in the inlet (104, 204) to be regulated. Movement of the drive connector (119, 219) moves the valve element (109, 209) by the same amount thus causing a change in the output pressure of the FCPRVS.

In Figure 3, the drive connector (315) of the pressure reducing valve acts against the force exerted on the valve element (309) of the plunger (311) which is subject to the pressure in the inlet (304). Movement of the drive connector (315) moves the piston (311) and valve element (309) causing a change in the output pressure of the FCPRVS.

The movement of drive connectors (119, 219, 315) is recorded by the controller and so this data can then be used to predict the resulting downstream pressure at different flow rates required to maintain the desired pressure at the critical location.

The controller can be provided with a memory adapted to record a map of pressure and flow as opposed to merely memorising the movement of the drive connector and use this as a look-up table for the pressure to which an FCPRVS should regulate the downstream pressure as a function of measured flow.

The way the apparatus of the invention is set up to automatically control water pressure in real time in a network will now be described in more detail with reference to Figures 13 and 14.

The Flow/Pressure Profile characteristics of different local area networks (108) or a DMA will vary according to several variables including such things as the length of pipework, type of pipe material, the condition of the pipes, the number of users, the number of leaks in the network and the location of the most remote user etc. Therefore, when setting up the apparatus of the invention, an initial step is to establish a Flow/Pressure Profile relationship for the network and, in particular, to establish the output pressure of the FCPRVS into the network that is necessary to maintain a desired water pressure at the critical location (136) at all times during any twenty four hour period. To do this the flow rates and water pressures are measured by the flow meter (132, 232, 332) and pressure sensors (133, 233, 333) and the water pressure at the critical location (136) is measured by the remote pressure sensor (135). The output pressure of the FCPRVS is adjusted as necessary using the positioning of the valve element (109, 209, 309) to change the output pressure of the FCPRVS as required so that a desired pressure at the critical location (136) is maintained. The pressure and flow data are communicated from the flow meter and pressure sensors to the controller and the software establishes the Flow/Pressure Profile relationship between the flow rate and the output pressure as described above. This relationship can be updated from time to time if desired because of any network changes that may occur.

Initial Setup of FCPRVS System

In this mode, the controlling factor in the algorithm shown in Figure 13 is the remote pressure P^R. P^R is the desired pressure at the critical location. P^D is the downstream pressure of the FCPRVS at the flow rate F^D to give P^R. F^N is an instantaneous flow rate. P^N is the downstream pressure at a flow rate F^N. P^RN is the remote pressure at the flow rate F^N. T^p is the time frequency for measuring F^N, P^N and P^RN. A predetermined allowable tolerance is set for the difference between P^RN and P^R. This tolerance can be a percentage difference of measured pressure or a fixed amount, for example 0.1 bar. This tolerance is entered into the software when the FCPRVS is being installed. The desired remote pressure P^R and the time period T^p for adjusting downstream pressure P^N are determined by the network management team. The software stores the flow rate F^D and the corresponding output pressure P^D that gives the desired remote pressure P^R. After the passage of each time period T^p, F^N, P^N and P^RN are recorded. P^R and P^RN are compared. If P^RN is higher than P^R, the controller instructs the servo motor to drive the valve element towards the inlet orifice by a small (but preset) amount and vice versa if P^RN is lower than P^R. In this way the downstream pressure P^N is changed. This is repeated and continues until the difference between P^RN and P^R is within the preset tolerance that has been determined by the management team. All measurements are recorded with a time stamp. The time stamp includes the day, date and actual time.

After the initial set up period, the software can be used to generate the Flow Pressure Profile using either a linear relationship or a polynomial relationship. The type of relationship to be used is determined by the network management team. The software can generate either relationship formula. This relationship can be set as a general daily Flow Pressure relationship for the pipe network (108) or it can be established for each day of the week.

This allows the system to recognise changes in the expected flow rate for a particular day at a particular time and if necessary, raise an alarm. The management team can set the percentage variation from the expected flow rate before an alarm is raised. It can be shown that weekdays follow a pattern which is often different to that seen on a Saturday or Sunday - see Figures 9A - 9J.

The Flow/Pressure Relationship to be used for the control of an FCPRVS can be:

1) Linear or polynomial

2) An average of that estimated for each day of the week (i.e. Monday, T uesday, etc... ) over a predetermined historical period of time

3) An average of weekdays (Monday to Friday) and weekends (Saturday and Sunday) over a predetermined historical period of time.

What is to be used will be dependent on the nature of the downstream network (i.e. residential, commercial or a combination of both, etc...)

In the table in Figure 10, the data collected is for same network of pipes connected to (i) a conventional PRV and (ii) to a flow controlled PRV fitted with a flow meter at the same time on consecutive weekdays. The network of pipes being monitored is an existing local area network for a defined local water supply area. The flow and corresponding pressure measurements are shown for both types of installations. It is noted that there are considerable savings 21.54% of the water supplied or 27.54% of the water consumed during this period when the FCPRVS was in operation. This saving will result because with the reduced pressure actual consumption will be reduced and very importantly as leakage is reduced because excess pressure has been removed from the downstream network.

Figure 11 is a graphical representation of data in the table in Figure 10.

The graphs in Figure 12 show the Flow Pressure Profile for this network. Figure 12a shows the relationship calculated as a Linear relationship and Figure 12b shows the relationship calculated as a Polynomial Relationship for the same data set. The equations shown on the graph are used by the software to calculate the output pressure of the pressure reducing valve that is required to maintain P^R at the flow rate measured by the flow meter. The software than instructs the servo motor to move to the appropriate position and so adjust the output pressure of the pressure regulation valve. The software can establish both types of relationship. The polynomial relationship is calculated to the 6^th order in the example which is considered by the inventor to be adequate for the purposes of the invention however this order can be changed if considered necessary. The type of relationship to be used will be determined by the network management team. The R² value for both equations is very similar indicating that both styles of relationship give a similar output pressure for the same flow rate. The R² value is an indication of how well the data fits the calculated relationship. The closer R² approaches 1 the better the fit between the data and the calculated relationship. As more data is gathered the fit of the calculated data will be improved and the R² value will move nearer 1. The R² value obtained with this data set is considered by the inventor to be adequate for the purposes for which the invention will be used.

Linear Relationship y = 0.6029% + 2.6782 with R² of 0.8187

Where “y” is the output pressure required at pressure reducing valve for the flow rate of “x” to maintain the desired pressure at the critical location.

Polynomial Relationship y = —1.288x6 + 10.386x5 - 31.669x4 + 45.284x3 - 30.16x2 + 8.1639x + 2.5345 with

R² of 0.8718

It can thus be seen that the difference of output pressure obtained by each of the equations for the same flow rate is only marginal. Theoretically the numerical constant in each relationship formula corresponds to the output pressure required to maintain the leakage flow in the event of a zero demand with the desired remote pressure still being met. The water mains network must always have a pressure sufficient to supply the leaks otherwise instead of water leaking from the pipes surrounding ground water could be drawn into the pipes and so contaminate the pipe network. It is understood that a state of zero demand never exists because of the different living patterns of users.

Normal Running Mode

In this mode, the flow rate F^N is the controlling factor in the algorithm shown in Figure 14. F^N is a flow rate. P^N is the downstream pressure from the FCPRVS at the flow rate F^N. P^RN is the remote pressure at the flow rate F^N. P^c is a calculated downstream pressure of the FCPRVS at F^N using the selected form of Flow Pressure Profile formula. A predetermined allowable tolerance is set for the difference between P^N and P^c and between P^RN and P^R. These tolerances can be a percentage difference of measured pressure or a fixed amount, for example 0.1 bar. These tolerances are entered into the software when the FCPRVS is being installed. The flow rate F^N and the corresponding downstream pressures P^N and P^RN are recorded. If P^N is higher than P^c the controller instructs the servo motor to drive the valve element towards the inlet orifice and vice versa if P^N is lower than P^c. In this way the downstream pressure of the FCPRVS is changed. P^N and P^c are compared again, and the procedure repeated until the difference between P^N and P^c is within the preset tolerance. P^RN can be checked and compared with P^R at regular intervals as determined by the network management team however, the software can be programmed to instruct the controller to make appropriate adjustments to the position of the valve element if P^RN falls outside a predetermined tolerance.

The software can also compare F^N with the data recorded at the same time on the same days previously recorded. An acceptable maximum percentage change for F^N is determined by the management team. If the percentage change is outside the range determined an alarm is raised at the control room so that the management team can take any actions that they feel may be appropriate.

If there are any changes that affect the expected daily flows into the network takes place in the network being supplied through the FCPRVS the control parameters can be changed accordingly and the Flow Pressure Profile recalculated, and automatic normal running can be resumed with the new profile. These flow changes may follow redesign of the network, developments in the network such as new housing or factories being built etc all of which may require recalculation of the Flow Pressure Profile.

Thus, as described above the FCPRVS (100,200, 300) will check in real time the expected downstream pressure against the calculated pressure in real time for the measured flow rates. The controller is programmed to respond and raise alarms, if necessary, should unexpected changes occur.

It should be noted that by removing excess pressure in a pipe network leakage is reduced at every point in time. In a water supply networks, it can be shown that this is a significant proportion of the water supplied is lost to leakage and even more importantly an even higher proportion of the water consumed is lost.

This fact is very important since global Non-Revenue Water or leakage has been conservatively estimated at 346 million cubic metres per day or 126 billion cubic metres per year. Conservatively valued at US$0.31 per cubic metre this amounts to US$ 39 billion per year. This value of US$39 billion does not take account of the huge environmental impact of leakage or the necessity to produce water by desalination, purification of sewage effluent, etc. at considerably increase cost of $1-1.50 per cubic meter.

As is now commonly understood water is becoming an increasingly scarce resource. This invention seeks to reduce this waste of water through leakage and so reduce the money spent to produce the water simply lost through leakage.

It is well understood that a leak free water distribution can never be achieved because of the nature of the development of the systems - many water mains are over 50 years old, a large proportion of these are over 100 years old and the ground conditions in which they are laid etc. In recent years where water mains have been replaced at the cost of many millions leakage has increased as pressure loss savings at the leakage points in the old mains are simply transferred to other parts of the system which therefore increase the leakage in the other parts of the network. This invention provides the optimum measures for reduction of leakage from mains as it manages leakage across the whole of a system being supplied through each supply point of entry.

In conventional local water supply networks, pressure reducing valves are typically set up so that the water pressure measured immediately downstream of the pressure reducing valve is the minimum water pressure required to give a predefined pressure at critical location (136), at maximum flow which only occurs for short periods of time. As a result, the network is over- pressured for much of the time with the result that, inter alia, water losses through leakage are greatly increased. This problem is avoided using the FCPRVS of the present invention. The advantages of the FCPRVS the present invention compared to conventional pressure reducing valves set up to provide a constant water pressure are illustrated by the graphs shown in Figure 11. The table in Figure 10 indicates savings of 21.54% of water supplied in the time period analysed, which corresponds to water saving as a percentage of the water used by a conventional PRV (e.g. (65100L - 51075L) / 65100L x 100). Alternatively, this figure may be expressed as a percentage based on the total water used by the PRV of the invention as 27.46% (i.e. (65100L - 51075L) / 51075L x 100) - this is the figure named “water consumed” in Figure 10.

It is also known that the constant increasing and decreasing pressures in pipes leads to fatigue failure of the pipes and any ancillary equipment connected to the pipes. This invention reduces the range of pressure fluctuations as pressure is controlled to the minimum level required to maintain the pressure required to maintain an adequate supply. In this way factors leading to fatigue failure are greatly reduced. These fatigue failures coupled with leaks resulting from the damage that occurs to buried pipes because of mechanical damage from rocks etc and ground movement lead to the enormous levels of leakage which estimated at 3 million cubic metres a day in the UK and 346 billion cubic metres per day globally. Fatigue failure can lead to the catastrophic bursts that occur in mains networks. Leakage from catastrophic failures are not generally included in the calculation of leakage levels.

Aims of this invention are to:

• Minimise the pressure fluctuations in pipe networks to reduce fatigue failure of pipes and fittings and ancillary equipment.

• Reduce the amount of leakage in a network of pipes by reducing the pressure feeding the leaks.

• Reduce user consumption by keeping the pressure in a supply system to the minimum required for operational purposes.

Provide a means for determining if changes in flow are to be expected or are indicative of possible problems or a result of legitimate changes by comparing the current flow with historical data. • The management team can then quickly ascertain if the change is a result of extra demand from for example changes in the network layout due to operational changes or a factory washout, a farm irrigation scheme starts up, demand from a fire department attending a fire etc or indicative of a pipe failure etc. In this way sudden bursts or increases in leakage are quickly identified and maintenance teams dispatched more quickly to carry out repairs.

• Reduce hunting in a network

• Facilitate the design or redesign of distribution networks so that they are better able to handle catastrophic or other extraordinary events. These might include the ability to remotely divert flow through a different part of the network allowing a damaged section to be isolated for repair or even raising the pressure, where possible, in primary, secondary or distributor mains fitted with FCPRVS to accommodate these sudden and unexpected events.

The data gathered can also be used to develop more accurately placed maintenance of networks and pipe replacements schedules.

In the network shown in Figure 6, the controller (134) is linked to a Main or Remote-Control Facility (139), from which the networks can be controlled remotely if desired.

The Remote-Control facility (139) can be linked to a plurality of local networks as shown in Figure 7 all being supplied by a high-pressure Primary or secondary main (140), each of the local networks being provided with a pressure reducing valve apparatus of the invention.

Alternatively, or additionally, the flow meters and pressure sensors in each local network can be linked to the Remote-Control Facility (139) and alarm signals generated in the Remote- Control Facility if abnormal flow rates (e.g., indicative of a mains failure or major leaks such as burst pipe) are detected. By linking the controllers (134, 234,334) to a remote-control facility (139), remote control of the downstream pressures for measured flow rates encountered can be achieved, and changes made where required for operational purposes.

Where there is more than one critical location in a network of pipes downstream of a FCPRV the software can be programmed to prioritise the response of the FCPRV and monitor the outcomes of the pressure changes that are made.

It is known and not unexpected that pressures in Primary and Secondary high-pressure mains also varies with demand. This is shown in Figure 11 A which shows that the input pressure to a local network varies in a similar way to that found within the local network. To reduce pressure variations in primary and secondary mains and therefore leakage and fatigue failures in these mains, FCPRVS installations can also be placed at strategic points in the trunk main (140), as shown for example in Figure 7.

Claims

1. A water mains pressure reducing system comprising: a) a water mains pressure reducing valve comprising:

• a valve body having an interior comprising a fluid-flow chamber through which fluid can pass;

• an inlet to the chamber and an outlet from the chamber;

• a valve element, which is moveable between a closed position wherein the valve element prevents fluid from passing through the chamber and one or more open positions wherein fluid may flow from the inlet, through the chamber and out through the outlet; and

• a substantially incompressible connector connected at a first end to the valve element and at a second end to a controllable motor drive such that there is a direct relationship between movement of the connector and movement of the valve element; b) a flow meter; and c) a controller and an electronic data store held within or being in communication with the controller, the data store containing data defining a relationship between fluid flow rate and fluid pressure in a downstream pipe network to which the water mains pressure reducing valve is connected; wherein the controller is arranged to receive flow data from the flow meter and to control the motor drive for withdrawal or advancement of the valve element in accordance with the flow rate measured by the flow meter and the relationship between fluid flow and fluid pressure.

2. A water mains pressure reducing valve according to claim 1 wherein the valve element is connected to a diaphragm, which partitions the valve body interior to give the fluid-flow chamber on the one side and a dry chamber on the other side.

3. A water mains pressure reducing valve according to claim 1 wherein the valve element is connected to the end of a piston or the end of a plunger.

4. A water mains pressure reducing valve according to any one of claims 1 to 3 wherein the inlet and outlet of the chamber take the form of or comprise one or more orifices and the valve element covers or blocks the inlet orifice.

5. A water mains pressure reducing valve according to any one of claims 1 to 4 wherein the valve element takes the form of a plate.

6. A water mains pressure reducing valve according to any one of claims 1 to 5 wherein the connector is substantially inextensible (as well as being substantially incompressible).

7. A water mains pressure reducing valve according to any one of claims 1 to 6 wherein the valve element is connected directly to the end of the connector.

8. A water mains pressure reducing valve according to any one of claims 1 to 7 wherein the inlet takes the form of a fluid supply orifice having a diameter of 20mm or greater

9. A water mains pressure reducing valve according to any one of claims 1 to 8 which is able to withstand input pressures of 25 bar or greater.

10. An actuation system suitable for use in a water mains pressure reducing valve, the actuation system comprising: i) a substantially incompressible connector connected to a controllable motor drive, such that there is a direct relationship between movement of the connector and the controllable motor drive; ii) a flow meter; and iii) a controller and an electronic data store held within or being in communication with the controller, the data store containing data defining a relationship between fluid flow rate and fluid pressure in a downstream pipe network to which the water mains pressure reducing valve is connected; wherein the controller is arranged to receive flow data from the flow meter and to control the motor drive in accordance with the flow rate measured by the flow meter and the relationship between fluid flow and fluid pressure.

11. A water distribution network control unit comprising: a) a water mains pressure reducing valve (for example, a water mains pressure reducing valve as defined in any one of claims 1 to 9); b) an electronic controller in electronic communication with a transmitter and a receiver and the controllable motor drive of the water mains pressure reducing valve; and c) a casing for housing the water mains pressure reducing valve, electronic controller, transmitter and receiver.

12. A water distribution network control unit according to claim 11 further comprising an antenna, which extends from the transmitter within the casing to outside of the casing.

13. A water distribution network control unit according to claim 11 and 12 further comprising a battery and a generator.

14. A water distribution network control unit according to claim 13 wherein the generator is powered by fluid passing through the pipework upstream or downstream of the water mains pressure reducing valve or a bypass conduit of the water mains pressure reducing valve.

15. A method of controlling the water pressure in a local water network having a pressure reducing valve (e.g. a water mains pressure reducing valve as defined in claims 1 to 9) connecting the local fluid network to a high pressure mains supply, the method comprising: a) providing a pressure reducing valve that comprises a controllable motor drive that can vary the fluid pressure into the network upon receipt of signals from a controller, b) providing a programmable electronic controller having a CPU, electronic storage and connections for communication facilities, c) providing the network with a flow meter and pressure sensors (e.g., immediately downstream and upstream) of the pressure reducing valve and in a critical location, the flow meter and sensors being in communication with the controller, d) measuring flow rates and pressures to establish a relationship between flow rate and pressure of fluid flowing into the network, and storing this data and establishing the relationship in the controller and/or a remote-control facility, e) using the said relationship to establish a pressure reducing valve setting at a given time point based on a measured flow rate to maintain a desired minimum pressure at a defined critical location in the network; and f) monitoring changes in the flow rate in the network detected by the flow meter and actuating the controllable motor drive to change the pressure reducing valve setting in response to the changes in the flow rate to maintain the desired minimum pressure at the defined critical location in the network.