Flow control system and method for controlling the flow of liquid

Flow control systems and methods for controlling the flow of liquid into and out of a tubular member comprising a perforated portion that is configured to distribute a flow of liquid having a predefined fixed liquid pressure through the perforated portion to pressurize an intestine that is suspended on the tubular member is disclosed. The flow control system comprises a flow regulating valve having a slidably arranged valve structure arranged in a pressurized liquid filled water chamber and an elastic water-side diaphragm arranged in the water chamber and connected to the valve structure such that the water-side diaphragm allows the valve structure to be moved in a first direction along the longitudinal axis of the valve structure to increase the volume in the water chamber and be moved in the opposite direction to decrease the volume in the water chamber.

FIELD OF INVENTION

The present disclosure relates to systems and methods for controlling the flow of liquid in order to maintain a constant pressure in a tubular member having a perforated portion that is configured to distribute a flow of liquid through the perforated portion and hereby pressurize an intestine suspended on the tubular member.

BACKGROUND

To determine the quality and to cut the carcass into valuable parts of meat, the examination and processing devices are controlled relative to the location of anatomical parts of the carcass. Intestines from the animals are processed in a similar way, and e.g. natural casings are of major interest.

Processing of intestines from the animals involves several steps including cleaning the intestines, scraping of the inner wall of the intestines to remove the mucous layer and scraping of the outer part of the intestines. An additional step of measurement is carried out in order to pack the intestines according to their size and quality. In the step of measurement, the diameter of each intestine is detected so that the diameter can be used to classify the intestine and to cut the intestine into pieces based on the diameter along the length of the intestine.

The detection of the diameter is carried out by inflating the intestine with water or air in order to measure its diameter. In practice, the intestine is suspended on a tubular member having a perforated portion that is configured to distribute a flow of liquid through the perforated portion and hereby pressurize the intestine suspended on the tubular member.

Since the diameter of an intestine varies along its length, it is important to be able to perform a fast regulation of the flow of the fluid (typically water or air) used to inflate the intestine. When the diameter of an intestine increases, the fluid flows into the tubular member in order to inflate the intestine. When the diameter of an intestine decreases, however, there is a flow of fluid from the intestine via the tubular member out through an outlet port. This flow regulation must be done in a fast and reliable manner.

CN 209489408 U discloses a method and an apparatus for automatic detection of the diameter or leaks in an intestine. The apparatus comprises an electromagnetic flow control valve connected to a tube on which the intestine is suspended. A water tank is arranged between the flow control valve and the tube. The flow control valve is connected to a pressure sensor arranged to detect the water pressure. This solution is, however, not capable of allowing for draining excess water through the valve.

BRIEF DESCRIPTION

It is an object of the present invention to provide a method to carry out a sufficiently fast flow regulation in a fast and reliable manner.

It is also an object of the present invention to provide a system for controlling the flow of liquid in a reliable and sufficiently fast manner.

It is an object to have a valve that can be controlled such that the flow can be regulated such that the pressure is kept constant.

In an embodiment, a method for controlling the flow of liquid into a tubular member and from the tubular member, wherein the tubular member comprises a perforated portion that is configured to distribute a flow of liquid having a predefined fixed liquid pressure through the perforated portion and hereby pressurize an intestine that is suspended on the tubular member, wherein the method comprises the step of controlling the flow of liquid such that the pressure of liquid in the tubular member is maintained within a predefined pressure range. The method comprises the step of applying a flow regulating valve comprising:a water inlet port for letting liquid into the flow regulating valve;a water outlet port for draining liquid from the flow regulating valve;a flow port being in fluid communication with the tubular member;a flow regulating member being in fluid communication with the flow port, wherein the flow regulating member is configured and arranged to be positioned in:a) a first configuration, in which liquid from the water inlet port can flow into the flow regulating valve, wherein no liquid can be drained through the water outlet port;b) a second configuration, in which liquid from the flow regulating valve can be drained through the water outlet port, wherein no liquid from the water inlet port can flow into the flow regulating valve;a force generating device connected to the flow regulating member in such a manner that the motion of the force generating device causes motion of the flow regulating member anda force countering device connected to the flow regulating member in such a manner that the motion of the force countering device causes motion of the flow regulating member,
wherein the method comprises the step of applying a predefined force (Fair) towards the force generating device using a force generating unit.

Hereby, it is possible to provide a method to carry out a sufficiently fast flow regulation in a fast and reliable manner.

In an embodiment, the liquid is a water containing liquid. In an embodiment, the liquid is water.

Generally, the force generating unit is controllable. Hereby, it is possible to set and change the force applied to the flow regulating member.

In an embodiment, the force generating unit comprises a spring.

In an embodiment, the force generating unit is a spring.

In an embodiment, the force generating unit comprises a magnetic actuator.

In an embodiment, the force generating unit is a magnetic actuator.

In an embodiment, the force generating unit comprises a pneumatic actuator.

In an embodiment, the force generating unit is a pneumatic actuator.

In an embodiment, the force generating unit comprises a hydraulic actuator.

In an embodiment, the force generating unit is a hydraulic actuator.

In an embodiment, the method comprises the step of using a flow regulating valve that comprises:a slidably arranged valve structure arranged in a pressurized liquid filled water chamber;an elastic water-side diaphragm arranged in the water chamber and connected to the valve structure such that the water-side diaphragm allows the valve structure to:a) be moved in a first direction along the longitudinal axis of the valve structure and hereby increase the volume in the water chamber andb) be moved in the opposite direction along the longitudinal axis of the valve structure and hereby decrease the volume in the water chamber,
wherein the method comprises the step of providing a force towards the slidably arranged valve structure using a force generating unit arranged and configured to provide a predefined force to move the slidably arranged valve structure in a predefined direction.

By controlling the flow of liquid such that the pressure of liquid in the tubular member is maintained within a predefined pressure range, it is possible to measure the diameter of an intestine by inflating the intestine with the liquid (e.g. water).

In an embodiment, the method comprises the step of using the force generating unit to provide a force towards the slidably arranged valve structure using a force generating unit arranged and configured to provide a predefined force to move the slidably arranged valve structure in a predefined direction.

In an embodiment, the predefined direction corresponds to the opposite direction.

The tubular member may comprise a rod-shaped portion. In an embodiment, the distal portion of the tubular member tapers.

In an embodiment, the perforated portion is formed as a plurality of holes (through bores) in the radial surface of the tubular member.

In an embodiment, the perforated portion is formed as one or more slots provided in the radial surface of the tubular member.

In an embodiment, at least a portion of the tubular member is formed as a pipe.

In an embodiment, the method comprises the step of applying a flow regulating valve comprising a slidably arranged valve structure arranged in a pressurized liquid filled water chamber.

The valve structure may comprise a hollow central portion and a number of holes provided along the radial surface of the valve structure.

In an embodiment, the valve structure comprises a hollow cylindrical portion provided with a number of holes along its radial surface. Hereby, the valve structure can establish fluid communication between the tubular member via the hollow portion and an inlet or an outlet through the hole(s).

The elastic water-side diaphragm may be formed of any suitable material such as an elastomer. The water-side diaphragm is arranged in the water chamber and connected to the valve structure such that the water-side diaphragm moves the valve structure when a force is applied to the water-side diaphragm.

The water-side diaphragm is arranged and configured to allow the valve structure to be moved in a first direction along the longitudinal axis of the valve structure and hereby increase the volume in the water chamber. When the pressure inside the intestine increases because the diameter of the intestine decreases, the water pressure inside the flow regulating valve will increase accordingly since the flow regulating valve is in fluid communication with the tubular member and thus the water inside the intestine. The increased pressure will cause the valve structure to move and hereby establish fluid communication between the valve structure and an outlet port of the flow regulating valve in order to drain excess liquid from the intestine.

In an embodiment, the first direction is a direction in which the distal portion of the valve structure is moved towards the central portion of the flow regulating valve.

The water-side diaphragm is arranged and configured to allow the valve structure to be moved in the opposite direction along the longitudinal axis of the valve structure and hereby decrease the volume in the water chamber. When the pressure inside the intestine decreases because the diameter of the intestine increases, the water pressure inside the flow regulating valve will decrease accordingly due to the fluid communication between the flow regulating valve and the tubular member and thus the water inside the intestine. The decreased pressure will cause the valve structure to move and hereby establish fluid communication between the valve structure and an inlet port of the flow regulating valve in order to receive liquid delivered from a liquid supply (e.g. a water inlet pipe or a reservoir).

The step of providing a force towards the valve structure can be accomplished by using various types of force generating units arranged and configured to provide a predefined force to move the slidably arranged valve structure in a predefined direction.

In an embodiment, the force generating unit comprises a spring arranged and configured to press against the water-side diaphragm.

In an embodiment, the force generating unit comprises an electrical actuator arranged and configured to press against the water-side diaphragm.

In an embodiment, the predefined fixed liquid pressure is in the range 5-100 mbar.

In an embodiment, the predefined fixed liquid pressure is in the range 10-80 mbar.

In an embodiment, the predefined fixed liquid pressure is in the range 15-60 mbar.

In an embodiment, the predefined fixed liquid pressure is in the range 20-40 mbar.

In an embodiment, the predefined fixed liquid pressure is in the range 25-35 mbar.

In an embodiment, the predefined fixed liquid pressure is 30 mbar.

It may be an advantage that the force generating unit is integrated in the flow regulating valve. Hereby, a more compact solution can be provided.

In an embodiment, the force generating unit comprises an air-side diaphragm, wherein the flow regulating valve comprises an air or gas containing pressure chamber which is separated from a remaining portion of the valve via the air-side diaphragm. Hereby, it is possible to provide an air space that is compressible and thus capable of providing a force that can be transferred to and thus applied towards the slidably arranged valve structure. Moreover, it is possible to control the pressure inside the air or gas containing pressure chamber.

In an embodiment, the liquid containing water chamber is separated from a remaining portion of the valve via the water-side diaphragm, wherein the slider is slidably arranged in an inner space of the valve, wherein the air-side diaphragm and water-side diaphragm are arranged and configured in such a manner that air or gas in the pressure chamber provides a pressure that forces the air-side diaphragm to press against the slider, wherein a liquid (e.g. water) in the water chamber provides a pressure that forces the water-side diaphragm to press against the slider in the opposite direction than the air-side diaphragm. Hereby, it is possible to provide a simple and reliable and very fast flow regulation.

It may be an advantage that an intermediate chamber is provided between the water-side diaphragm and the air-side diaphragm.

In an embodiment, a method comprises the step of maintaining a pressure corresponding to the ambient pressure in the intermediate chamber. Hereby, it is not required to compensate for fluctuation in the ambient pressure when controlling the pressure inside the pressure chamber.

A flow control system according to an embodiment is a flow control system for controlling the flow of liquid into a tubular member and from the tubular member, wherein the tubular member comprises a perforated portion that is configured to distribute a flow of liquid having a predefined fixed liquid pressure through the perforated portion and hereby pressurize an intestine that is suspended on the tubular member,

wherein the flow control system comprises a flow regulating valve comprising:

a water inlet port for letting liquid into the flow regulating valve;a water outlet port for draining liquid from the flow regulating valve;a flow port being in fluid communication with the tubular member;a flow regulating member being in fluid communication with the flow port, wherein the flow regulating member is configured and arranged to be positioned in:a) a first configuration, in which liquid from the water inlet port can flow into the flow regulating valve, wherein no liquid can be drained through the water outlet port;b) a second configuration, in which liquid from the flow regulating valve can be drained through the water outlet port, wherein no liquid from the water inlet port can flow into the flow regulating valve;a force generating device connected to the flow regulating member such that the motion of the force generating device causes motion of the flow regulating member anda force countering device connected to the flow regulating member such that the motion of the force countering device causes motion of the flow regulating member;a force generating unit configured to provide a predefined force towards the force generating device.

In an embodiment, the flow regulating valve is a ball valve.

In an embodiment, the flow regulating valve is a needle valve.

In an embodiment, the flow regulating valve is a rotary valve (e.g. a butterfly valve).

In an embodiment, the flow regulating valve is a gate valve.

In an embodiment, a pressure regulating valve is used to control the flow regulating valve in a manner in which liquid from a liquid supply is allowed to enter the tubular member via the flow regulating valve if the pressure in the tubular member is too low (below PW1) and allow liquid to pass from the tubular member via the water outlet port to a drain if the pressure in the tubular member is too high (above PW2).

The functions of allowing a flow of liquid into and out from the tubular member, respectively, can take place in one or two different valves.

In an embodiment, the flow regulating valve comprises:a slidably arranged valve structure arranged in a pressurized liquid filled water chamber;an elastic water-side diaphragm arranged in the water chamber and connected to the valve structure such that the water-side diaphragm allows the valve structure to:a) be moved in a first direction along the longitudinal axis of the valve structure and hereby increase the volume in the water chamber andb) be moved in the opposite direction along the longitudinal axis of the valve structure and hereby decrease the volume in the water chamber,
wherein the flow control system comprises a force generating unit arranged and configured to provide a predefined force to move the slidably arranged valve structure in a predefined direction, wherein the force generating unit is configured to control the flow of liquid such that the pressure of liquid in the tubular member is maintained within a predefined pressure range.

Hereby, it is possible to provide a system for controlling the flow of liquid in a reliable and sufficiently fast manner.

In an embodiment, the force generating unit is integrated in the flow regulating valve. By integrating the force generating unit, a more compact system can be provided. Moreover, regulation of the flow can be accomplished in an easy and fast manner.

It may be advantageous that the force generating unit comprises an air-side diaphragm and that the flow regulating valve comprises an air or gas containing pressure chamber that is separated from a remaining portion of the valve via the air-side diaphragm. Hereby, the flow can be regulated using a pneumatic regulator that can provide the desired pilot pressure. Moreover, the pilot pressure can be changed in a fast and easy manner.

In an embodiment, the flow control system comprises:an air or gas containing pressure chamber which is separated from a remaining portion of the valve via an air-side diaphragm;a liquid containing water chamber that is separated from a remaining portion of the valve via a water-side diaphragm;a slider slidably arranged in an inner space of the valve,
wherein the air-side diaphragm and water-side diaphragm are arranged and configured in such a manner that air or gas in the pressure chamber provides a pressure that forces the air-side diaphragm to press against the slider, wherein a liquid (e.g. water) in the water chamber provides a pressure that forces the water-side diaphragm to press against the slider in the opposite direction than the air-side diaphragm.

In an embodiment, the liquid containing water chamber is separated from a remaining portion of the valve via the water-side diaphragm, wherein the slider is slidably arranged in an inner space of the valve, wherein the air-side diaphragm and water-side diaphragm are arranged and configured in such a manner that air or gas in the pressure chamber provides a pressure that forces the air-side diaphragm to press against the slider, wherein a liquid in the water chamber provides a pressure that forces the water-side diaphragm to press against the slider in the opposite direction than the air-side diaphragm.

In an embodiment, the liquid in the water chamber is water.

It may be an advantage that an intermediate chamber is provided between the water-side diaphragm and the air-side diaphragm.

In an embodiment, the intermediate chamber is in fluid communication with the surroundings by one or more vents. Hereby, the pressure in the intermediate chamber corresponds to the ambient pressure. Accordingly, it is not required to compensate for fluctuation in the ambient pressure when controlling the pressure inside the pressure chamber.

In an embodiment, the slidably arranged valve structure is a hollow rod member.

In an embodiment, the valve structure comprises a hollow central portion and a number of holes provided along the radial surface of the valve structure.

In an embodiment, the valve structure comprises a hollow cylindrical portion provided with a number of holes along its radial surface.

In an embodiment, the ratio between the product of the pressure and the area of the air-side diaphragm and water-side diaphragm is in the range R:1, where R is between 20 and 50.

In an embodiment, the ratio between the product of the pressure and the area of the air-side diaphragm and water-side diaphragm is in the range R:1, where R is between 25 and 40.

In an embodiment, the ratio between the product of the pressure and the area of the air-side diaphragm and water-side diaphragm is in the range R:1, where R is between 30 and 35.

In an embodiment, the ratio between the product of the pressure and the area of the air-side diaphragm and water-side diaphragm is in the range R:1, where R is 33.

It may be an advantage that the flow control system comprises an air pressure control unit, wherein the pressure chamber comprises an air inlet port for allowing a flow of air between the pressure chamber and the air pressure control unit. Hereby, the air pressure control unit can be used to change the predefined fixed pressure in the liquid chamber.

DETAILED DESCRIPTION

Referring now in detail to the drawings for the purpose of illustrating embodiments of the present systems and methods, a flow control system2is illustrated inFIG.1.FIG.2illustrates a schematic view of the flow control system2shown inFIG.1in a configuration, in which an intestine8has been suspended on a tubular member10of the processing unit20that comprises the flow control system2.

FIG.1andFIG.2illustrate schematic views of a flow control system2, according to an embodiment, used to regulate the flow to a processing unit20configured to detect the diameter D of intestines8.

The processing unit20is configured to detect the diameter D of an intestine8while the intestine8is suspended on a tubular member10having a perforated portion that is configured to distribute a flow of liquid6through the perforated portion and hereby pressurize the intestine8. Accordingly, the detected diameter can be used to classify the intestine8and to cut the intestine8into pieces. The tubular member10may be formed as a metal pipe. The perforated portion may be established by providing a plurality of slots or holes in the metal pipe.

The tubular member10extends horizontally. The processing unit20comprises two drive rollers24. At least one of the drive rollers24comprises a circumferential track configured to engage with the tubular member10.

At least one of the drive rollers24is arranged and configured to move the intestine8with a non-zero velocity V along the longitudinal axis of the tubular member10. Accordingly, at least one of the drive rollers24is connected to a motor (not shown). Accordingly, the drive rollers24are capable of pulling the intestine8towards the righthand side of the drive rollers24and hereby move the intestine with the velocity V as indicated inFIG.2.

In an embodiment, the drive rollers24are shaped in the same way so that both drive rollers24comprise a circumferential track configured to engage with the tubular member10. In an embodiment, the drive rollers24are shaped in the same way so that both drive rollers24comprise a circumferential track configured to engage with the tubular member10.

The processing unit20comprises two clamping rollers26arranged to be brought into a clamping configuration, in which the intestine8is clamped by the clamping rollers26.

In the processing unit20illustrated inFIG.1andFIG.2, detection of the diameter D is carried out by inflating the intestine8with water or another liquid. An optical sensor30is arranged to detect the diameter D of the intestine8.

A valve4is connected to a first end of the tubular member10. The opposite end of the tubular member10tapers and is configured to receive an intestine8. The valve4comprises a flow port22that is connected to the tubular member10. The valve4comprises a water inlet port that is connected to an inlet pipe16. Likewise, the valve4comprises a water outlet port18that is connected to an outlet pipe18.

In an embodiment, the inlet pipe16is connected to a water supply. In an embodiment, the inlet pipe16is connected to a water reservoir (e.g. a water tank).

In an embodiment, the outlet pipe18is connected to a drain.

In an embodiment, the flow control system2comprises a suction unit that is connected to the outlet pipe18. Hereby, the excess liquid can be sucked out of the valve4in a very fast manner.

The valve4must be configured to perform a fast regulation of the flow of water used to inflate the intestine8. When the diameter D of the intestine8increases, water flows from the valve4into the tubular member10in order to inflate the intestine8. When the diameter D of the intestine8decreases, the liquid (e.g. water)6will flow from the intestine8via the tubular member10into the flow port22of the valve4.

The inlet pipe16may be connected to a storage tank. In principle it is possible to connect the outlet pipe18to a tank in order to reuse the water used for inflating the intestine8. Typically, however, the excess liquid from the intestine8will be drained away.

In an embodiment, the valve4comprises a pressure chamber that is pressured by air. In this embodiment, the valve4is configured to enable flow regulation on the basis of the pressure within the air pressure. Accordingly, the valve4is controlled by regulating the air pressure using an air pressure control unit72that is connected to the air inlet port32of the valve4. The valve4comprises a housing50comprising several housing components.

The processing unit20is designed for processing an intestine8having an open end. In an embodiment, the processing unit20comprises an electrically conducting tubular member10. The tubular member10has a perforated portion that is configured to distribute a flow of liquid (such as water) through the perforated portion. The tubular member10is arranged and configured to receive the open end of the intestine8and hereby allow the intestine8to be suspended on the tubular member10and hereby pressurize the intestine8with the liquid.

The processing unit20comprises two clamping rollers26arranged to be brought into a clamping configuration, in which the intestine8is clamped by the clamping rollers26.

The distal end of the tubular member10is arranged between the drive rollers24and the clamping rollers26. The processing unit20comprises a detection unit2. The detection unit2is arranged between the drive rollers24and the clamping rollers26.

Each of the clamping rollers26is partly covered by a screen36. The screen36may be made of a non-conducting material (e.g. a plastic material). The processing unit20comprises a detection unit configured to detect a leakage hole in an intestine8suspended on the tubular member when the intestine8is being moved with a non-zero velocity V along the longitudinal axis of the tubular member10. The detection unit comprises an electrically conducting and axially extending sleeve-shaped surrounding portion74,74′ that is configured to be brought into a configuration (as shown inFIG.2), in which the surrounding portion surrounds the circumference of the tubular member10.

The detection unit comprises an electric circuitry arranged and configured to measure an electric quantity such as the electric resistance or the electric current which is established between the surrounding portion and the tubular member10.

The lowermost drive roller24and the lowermost clamping roller26are slidably mounted on a slide rod17for allowing an easy adjustment of the horizontal position of the rollers24,26.

InFIG.2an intestine8is suspended on an intestine detector38according to an embodiment. The intestine detector38comprises a first end detector40and a second end detector40′ arranged a non-zero distance from the first end detector. The intestine detector38comprises an intermediate detector42arranged and distanced between each of the end detectors40,40′ in such a configuration that the intermediate detector42will be electrically connected to any intestine suspended on the end detectors40,40′ and extending between the first end detector40and the second end detector40′.

Each of the end detectors40,40′ are shaped to receive and maintain an intestine suspended on the end detector40,40′. The end detectors40,40′ have the same geometric form. The end detectors40,40′ comprise a hook-shaped portion. The intermediate detector, however, has a straight distal portion extending between the first end detector40and the second end detector40′.

The end detectors40,40′ extend through a mounting box that comprises electrical connection structures for connecting an electric circuitry configured to perform one of more electrical measurements using the detectors40,40′,42.

The intestine8is received by the tubular member10and is suspended thereon. Furthermore, the intestine8is pressurized and thus inflated by water from the tubular member10. The intestine8is clamped between the clamping rollers26in a first position of the intestine8and by the drive rollers24in another position of the intestine8.

FIG.3illustrates a cross-sectional view of a valve4of a flow control system according to an embodiment. The valve4comprises a housing60having a first housing component56and a second housing component58that are attached to each other by bolts. The first housing component56comprises an inner space. A slider40is slidably arranged in the inner space of the first housing component56. Accordingly, the slider can be moved along the longitudinal axis X of the valve4. The slider40has a cylindrical body portion64provided with a series of openings66provided along the circumference of a central part of the cylindrical body.

A water inlet port36and a water outlet port38are provided next to each other. The water inlet port36extends from an inlet valve opening46provided in the inner space to the outer periphery of the first housing component56. Likewise, the water outlet port38extends from an outlet valve opening48provided in the inner space to the outer periphery of the first housing component56. Accordingly, these ports36,38are configured to establish fluid communication between the inner space and external pipes connected to the inlet port36and a water outlet port38, respectively, when the slider40is arranged in a position in which water can flow between the inner space and the valve openings46,48, respectively.

A water chamber70is provided in extension of the proximal portion of the inner space. The water chamber70is in fluid communication with the inner space and thus the water inlet36, the water outlet38and the flow port22.

A pressure chamber44is provided in the second housing component58. An intermediate chamber68is provided between the pressure chamber44and the plate member50from which the rod member62protrudes. The intermediate chamber68is connected to the surroundings via vents42. Accordingly, the pressure in the intermediate chamber68corresponds to the ambient pressure. By increasing the pressure PCin the pressure chamber44it is possible to move the rod member62.

The valve4comprises an air-side diaphragm52that separates the central portions of the pressure chamber44and the intermediate chamber68. Accordingly, the pressure gradient between the pressure chamber44and the intermediate chamber68will determine the magnitude and direction of the force with which the air-side diaphragm52presses against the rod member62. Since the rod member62is part of the plate member50which is mechanically attached to the slider40, the force from the air-side diaphragm52towards the rod member62will move the slider40along the longitudinal axis X of the valve4. The water in the water chamber70presses towards the water-side diaphragm54and plate member50covered by it. Accordingly, the position and motion of the slider40along the longitudinal axis X of the valve4is influenced by the forces applied to the pressure chamber44.

The working principle of the valve4is based on the equivalence between the forces acting on the air-side diaphragm52and the water-side diaphragm54, respectively. In an embodiment, the ratio between the product of the pressure and area onto which the pressure acts is 1:33.

If the pressure in the water chamber70is too small, the slider44is pushed to the left. This will cause the opening of the inlet valve opening46by aligning the opening66with the valve opening46. Accordingly, water will flow into the valve4through the water inlet36.

When the pressure in the water chamber70rises, the force on the water-side diaphragm50increases until an equivalence between the forces acting on the air-side diaphragm52and the water-side diaphragm54, is established and the slider44moves to its central position as shown inFIG.2, thereby closing the inlet valve opening46.

The slider44is pushed to the right if the water pressure increases further. In this case, the slider44will be arranged in such a positioned that it causes an opening of the outlet valve opening48. Thus, excess water will flow out from the valve4via the water outlet38.

When the pressure in the water chamber70has been decreased to the equivalence level, the slider44is pushed back to the center position, in which the slider44closes the water inlet36and the water outlet38.

The valve4is designed to accommodate a high flow at low pressure. Accordingly, the water inlet36and the water outlet38must be relatively large in order to reduce the flow resistance.

LIST OF REFERENCE NUMERALS