KR20080051097A - System and valve arrangement for fast emergency shut-down of hydraulically actuated valves - Google Patents

Abstract

A system and a valve apparatus for fast emergency shutdown of hydraulically actuated valves are provided to reduce cost without an additional pipe by using both a supply pipe and a return pipe as return pipes during emergency operation. A hydraulic control system(1) includes a first path(3) between a first connecting port(4) and a control port(5), a second path(7) between a second connecting port(8) and a second control port(9), an emergency path(15) between an emergency inlet(16) and the first control port, and a return path(17,18,19). The return path forms a flow path between the second control port and the second connecting port. The hydraulic control system further includes a valve apparatus(11) and an emergency valve apparatus(20). The valve apparatus prevents a fluid flow from the first control port to the first connecting port unless a predetermined pressure condition exists in the second path. The emergency valve apparatus prevents a fluid flow in the return path unless a predetermined pressure condition exists in the emergency path. The return path forms an additional flow path to connect the second control port and the first connecting port.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a system and a valve device for rapidly shutting off an emergency valve of a hydraulically actuated valve,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control system for use in connection with, for example, a hydraulic drive apparatus such as an actuator or a hydraulically operated valve. The present invention also relates to hydraulic systems, valves, and valve actuation methods.

The control system forms a first passageway between the first connection port and the first control port and a second passageway between the second connection port and the second control port. Whereby the fluid may be guided in either direction of passage, that is, under pressure, in a direction from the fluid source toward the hydraulic drive device, and also in a direction opposite to the other passage, i.e., from the hydraulic drive device toward the tank.

An emergency passage formed between the emergency inlet and the first control port can activate the hydraulic drive device at a different activation speed. Emergency passageways can provide a relatively large amount of fluid flow, for example, referred to hereinafter as an emergency fluid. For example, in the case of an emergency to guide the closing operation of the valve to block the chemical reaction or to prevent the flow of toxic or inert gas or liquid that is compressed and possibly dangerous and flammable, Lt; / RTI >

There is provided a return passage defining a flow path between the second control port and the second connection port for guiding fluid flow from the hydraulic drive to the tank during emergency operation, A valve device is used. If a constant pressure condition is not present in the second connection port or the second passage, the valve device is used to prevent fluid flow from the first control port to the first connection port. This prevents the emergency fluid from flowing out through the first connection port during emergency operation.

If the constant pressure condition does not exist in the emergency inlet or emergency passage, the emergency valve device is adapted to prevent fluid flow in the return passage. This flows through one of the control valves and prevents the fluid intended to act on the hydraulic drive device from returning to the tank without performing the intended operation.

The hydraulic control system is usually used in connection with a valve that controls gas or liquid. In this combination, the hydraulic drive apparatus is constituted by an actuator that actuates the valve and moves the valve member between the open and closed positions. As an example, a marine tank is sometimes managed based on a single actuated or dual actuated balanced actuator that actuates a valve shaft, which rotates the valve member or blade to control the fluid flow path.

However, sometimes a very fast reacting shut-off is required. As an example, for safety reasons, this rapid shutdown may be required to block the gas pipeline very quickly upon leakage. For emergency shutdown (hereinafter referred to as ESD), a separate hydraulic pipe carrying an emergency fluid is typically provided to move the valve to a closed position of the valve at a relatively high speed. To make it faster, the emergency fluid is usually provided at high pressure and high flow rates. The relatively slow valve control during normal ESD is switched off and the hydraulic fluid supplied to the hydraulic drive during ESD is delivered to the tank through an additional pipeline or pipeline used to return the control fluid during normal operation, Again. For economical reasons, in order to optimize space consumption, or to avoid oscillation, the dimensions of the return pipeline for normal operation are typically adapted to slow operation, and thus the return pipeline is undesirably large pressure It can cause a drop. A large pressure drop causes a slow closing of the valve during emergency operation, thereby impairing safety. Another problem is that the pressure drop in the return pipeline increases the pressure between the second connection port and the second control port so that the valve device unintentionally moves from the first control port to the first connection port Enables fluid flow.

It is an object of one embodiment of the present invention to improve control of a hydraulic actuating device such as a valve. In a first aspect, the present invention provides a hydraulic control system, wherein the return conduit forms an additional flow path between the second control port and the first connection port.

For example, for valve closure, the first connection port may be connected to a pipeline that provides pressure fluid acting on the hydraulic drive device, and the second connection port may be connected to a pipeline that returns fluid to the tank. For example, during movement in the opposite direction for valve opening, these ports can be reversely connected, i. E. The second connection port is connected to the pressure fluid and the first connection port is connected to the tank.

A pipeline used to return the fluid during normal operation, when the pressure fluid is provided to the first control port, i.e., during the closing operation of the valve, due to the additional flow path; All of the pipelines used to provide can be used to return fluid to the tank. Thus, the problem of the above-described pressure drop by the use of pipelines of a dimension suitable for slow activation can be reduced or completely prevented. In operation, for example, in marine installations of ships, it is common to arrange the supply of pressure fluid and the tank for return fluid at a great distance from the hydraulic actuating device. Thus, a very long supply pipe and return pipe connects the control system to the source and the tank, and the control system is arranged immediately adjacent to the hydraulic actuating device. According to the invention, both the very long supply pipe and the return pipe can be used as a return pipe during emergency operation and a much quicker closing, and it is not necessary to install additional costly and space-consuming piping on the vessel, Can be achieved.

The control system is coupled to the monolith, which is provided with a channel as a channel that extends between the apertures forming the port on the outer surface. The channel can be molded or drilled into the hole between the ports. The ports may also be provided with internal threads, brazed flanges, O-rings, bolts or similar means for the assembly of the conduits and ports of the hydraulic actuators and for attachment of the storage tank of the peripheral conduit system and fluid to provide pressure fluid have.

As mentioned at the introduction, the valve arrangement is adapted to prevent flow on the basis of certain pressure preconditions in each of the second passage and the emergency passage. In particular, this prerequisite may relate to a marginal difference between the reference pressure and the pressure in each of the second or emergency passages. For valve devices, the reference pressure can follow the pressure in the first passageway, and for the emergency valve device, the reference pressure can follow the pressure in the return passageway.

In a corresponding manner, the valve arrangement can further prevent fluid flow from the second control port to the second connection port if a constant pressure condition is not present in the first passage. The precondition may also be when the limit difference between the pressure in the first passageway and the reference pressure is exceeded and the reference pressure can follow the pressure in the second passageway.

The valve device is located between the connection port and the control port. Generally, as long as the pressure difference at the valve is lower than the valve cracking pressure, the valve device can remain closed. At this pressure, the valve member is lifted from the seat of the valve member to open the passageway.

The valve arrangement may comprise a check valve of the kind including a normal check valve, for example a spool movable within the housing based on the pressure of one of the passages. The check valve is located in one of the first and second passages to allow flow in one direction in the passageway and to prevent flow in the opposite direction. The check valve may comprise a pilot operated check valve (hereinafter referred to as PCV) in which the pressure of one of the first and second passages lifts the valve member in the other passageway, And a double pilot operated check valve (hereinafter referred to as DPCV) in which the pressure of all of the second passages lifts the valve member in the other passages. Thus, the DPCV prevents fluid flow from the first control port to the first connection port if there is no presumption of constant pressure in the second passageway, and if there is no presumption of constant pressure in the first passageway, 2 < / RTI > control port to the second connection port. The valve arrangement prevents fluid flow in both the first and second passages when the pressure in the escape passage exceeds the pressure in the first and second passages.

The return passageway may include a first portion with a PCV having a valve member, which typically prevents fluid flow from the second control port to the first and second connection ports. The valve member can be lifted from the seat of the valve member by the pressure in the emergency passage. Thus, if a constant pressure condition is not present in the escape passage, for example, if the limit difference between the pressure in the escape passage and the reference pressure is not exceeded, fluid flow is prevented in the first and second passages, At least depending on the pressure of one of the first and second connection ports.

In the downstream of the PCV (as viewed in the direction of flow from the control port toward the connection port), the return passage may be divided into a first path connected to the second connection port and a second path connected to the first connection port.

In addition to the valve and emergency valve devices described above, the hydraulic control system may include a check valve in each of these flow paths to prevent the flow in this flow path from the connection port toward the second control port.

In a second aspect, the present invention provides a pressurized fluid source, a tank for collecting return fluid,

And a hydraulic actuating device used to perform an operation on the object based on the flow of the pressure fluid. The hydraulic actuating device may be an actuator acting on the valve, and may include a first port and a second port, the fluid being received in one of the control ports and returned from the other of the control ports.

The hydraulic system further includes a hydraulic control system of the kind described above with respect to the first aspect of the present invention.

The hydraulic system further comprises a conduit system for supplying the high pressure fluid and returning the fluid to the tank. The conduit system may include a first conduit connected to the first connection port, and a second conduit connected to the second connection port. In this system,

A first structure in which the first conduit connects the first connection port and the pressure fluid source, and a second conduit connects the second connection port and the tank, and

A first conduit connects the first connection port and the tank, and a second conduit is movable between a second structure connecting the second connection port and the pressure fluid source.

The hydraulic system further uses a third structure in which the first and second connection ports are connected to the tank.

Because the emergency situation requires an increase in fluid amount or fluid pressure, the hydraulic system further includes an emergency pressure fluid source that is separate from the pressure fluid source and is connected directly to the emergency inlet by an additional emergency conduit. To reduce the pressure drop in an emergency situation, the emergency conduit may be larger than the first and second conduits. The emergency conduit may have a cross-sectional area between 1.5 and 2.5 of the cross-sectional area of one of the first and second conduits. On the other hand, the first and second conduits have the same cross-sectional area.

The hydraulic actuating device and the hydraulic control system may be positioned immediately adjacent to each other, attached to each other, or formed as a single element. On the other hand, the source and the tank may be located remote from the hydraulic actuating device and the hydraulic control system, whereby the first and second conduits, and optionally the conduit, Can be maintained relatively long compared to the passage between the control systems. In this way, the additional path between the second control port and the first connection port enables the use of both very long first and second conduits returning the fluid to the tank during emergency operation, thereby providing a low flow Resistance is facilitated to enable faster emergency operation of the system.

In a third aspect, the present invention provides an actuator comprising an element movable between two end positions under the influence of fluid flow into and out of the first and second ports.

The actuator comprises a control system of the kind described above with respect to the first aspect of the invention in which each control port is connected to a respective one of the first and second ports.

The actuator is of a type having two chambers separated by a piston. When a fluid enters one of the ports, the fluid displaces the piston, which pushes fluid out of the second port. The actuator is of the type in which fluid flows through the device from one port to another.

In a fourth aspect, the present invention provides a valve comprising a valve member movable between two end positions of a valve passage to provide different flow resistance in the valve passage. The actuator described above Thus, a control system of the kind described above for the first aspect of the present invention is used to move the valve member between the end positions.

In particular, the valve can be a quarter turn valve, in which case the valve member rotates through 90 degrees and moves from one of the end positions to the other end position.

In a fifth aspect, the present invention provides a method for controlling a flow of a fluid, the method comprising: providing a valve that can be opened and closed based on a flow of fluid, a forward conduit providing a forward flow of fluid towards the valve under a normal phase of operation, And an emergency conduit that provides an escape flow of fluid towards the valve under abnormal operating conditions.

The method includes blocking the forward flow of the fluid in the abnormal state and providing an emergency reverse flow of the fluid away from the valve in the forward conduit and the return conduit. The advance conduit may connect a valve to a high pressure fluid supply, for example, a hydraulic pump that supplies hydraulic fluid, and the return conduit may connect a valve to a location for the treatment of hydraulic fluid, e.g., a tank that collects hydraulic fluid.

A normal operating condition is a condition requiring normal opening and closing characteristics of the valve, and an abnormal operating condition is a condition requiring a more rapid opening and closing of the valve.

The method may comprise implicit steps in terms of the systems described for the first, second, third and fourth aspects of the present invention. In particular, the method may include preventing reverse flow if there is no forward flow and preventing emergency reverse flow if no escape flow is present. In addition, the method can reverse both the forward conduit and the return conduit, wherein the forward conduit under normal operating conditions provides a reverse flow of fluid away from the valve and the return conduit under normal operating conditions is advanced Flow.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

Fig. 1 shows a hydraulic control system 1 used for controlling the hydraulic control apparatus 2. Fig. The hydraulic control system includes a first passage (3) between the first connection port (4) and the first control port (5). The first control port 5 is connected to the control port 6 of the hydraulic control device 2. The control system further includes a second passage (7) between the second connection port (8) and the second control port (9). The second control port 9 is connected to the second control port 10 of the hydraulic control device 2. [

A double pilot operated check valve (DPCV) 11 includes valve members 12, 13 in respective passages. Each valve member prevents fluid flow from the control ports 5, 9 to the connection ports 4, 8 in the closed state of the valve member. The valve member 12 acting on the first passage 3 can be lifted from the seat of the valve member by the pressure in the second passage 7 and the valve member 12 acting on the second passage 7 13) can be lifted from the seat of the valve member by the pressure in the first passage (3). This is accomplished by the control passage 14 between the two valve members. As such, the forward flow in the first passage 3 toward the hydraulic control device 2 opens the return flow in the second passage 7 from the hydraulic control device 2 toward the second connection port 8 . The DPCV can be a spool that slides in the housing, thereby opening and closing the passage described above. The sliding in the one direction is made by the pressure in the first passage (3), and the sliding in the other direction is made by the pressure in the second passage (7). Thus, the pressure difference between the passages 3, 7 opens one of the valve segments 12, 13.

In the steady state, the control device 26 is located as shown in Figure 2, and the two connection ports 4, 8 are connected to the tank. Therefore, the hydraulic control apparatus 2 is stopped. In normal operation of the hydraulic control apparatus 2, one of the two connection ports 4, 8 is connected to the pressure pipeline, and the other of the two connection ports is connected to the tank pipeline. This structure is achieved by pressing the switch button 32 (see FIG. 2 and the corresponding description).

In the emergency state, the hydraulic control device 2 can be provided with a hydraulic fluid through an emergency passage 15 extending between the emergency inlet 16 and the first control port 5. [ If the hydraulic control device 2 is a valve actuator, the first control port 5 may be a closed port that closes the valve when pressure is applied. In this case, the emergency passage 15 provides a fast shut-down of the passage (not shown) into which the valve is inserted. When the fluid is supplied to the hydraulic actuating device 2 by the emergency passage 15, the fluid may be returned from the hydraulic actuating device 2 through the return passages 17, 18 and 19. By the additional path 17 the return passages 17,18 and 19 connect the second control port 9 and the first connection port 4 and in the second pass 18 the return passageway 17 , 18 and 19 connect the second control port 9 and the second connection port 8 to each other. In the initial passage 19, the return passages 17, 18 and 19 extend from the second control port 9 in the direction toward the first and second connection ports 4 and 8 And a PCV 20 to prevent fluid flow through the return passages 17,18,

Each of the first and second passages 17,18 prevents backflow to the second control port 9 and thereby prevents backflow from one of the connection ports 4,8 to the other of the connection ports 4,8. And a check valve (21, 22) for preventing shorting of the hydraulic compression flow.

Over-pressure valve 23 is inserted to protect the control system from too large a pressure. Connector assembly 24 facilitates connection of peripheral equipment such as pressure or temperature transducers.

Figure 2 shows the hydraulic system 25. The hydraulic system 25 includes a hydraulic control system 1 of the kind shown in Fig. 1, a tank T, a pressure pump P, an emergency pressure pump eP, a control device 26, a first conduit 27 And a second conduit 28. The pump P forms a pressurized fluid supply source which acts on the pressure-actuated device 2 via the hydraulic control system 1. The tank T collects the fluid returning from the pressure-activated device 2 and supplies the fluid to the pump P or the emergency pump eP through the suction pipe 29. The first conduit 27 is connected to the first connection port 4 and the second conduit 28 is connected to the second connection port 8 and the emergency inlet 16 is connected via the emergency conduit 30 Is connected to an emergency pump (eP) which forms an emergency fluid supply. The first and second conduits 27 and 28 can be longer in the interior of the control system 1 than in the other passages between the control system 1 and the device 2. [

The system includes a control device 26 that can be switched between three different structures. 2, both conduits 27, 28 are connected to the tank T, so that both conduits form a return passage for the emergency fluid during the emergency operation of the system 1. As the first switch button 31 is depressed the system is switched to a second configuration in which the first conduit 27 is connected to the tank T and the second conduit 28 is connected to the pump P . The first conduit 27 is connected to the pump P and the second conduit 28 is connected to the tank T as the second switch button 32 is depressed. The dimensions of the emergency conduit 30 and the tank conduit 32 are such that the flow of each of the first and second conduits 27, 28 is twice as high.

The pressure in the jets 16 may advantageously direct both the first and second conduits 27, 28 to the tank automatically. To this end, the control device 26 can be positioned as shown in FIG. 2 by the pressure of the emergency inlet 16, the emergency conduit 30, or generally the emergency fluid, or an additional valve (not shown) Can be inserted. The additional valve may be moved by the pressure of the emergency fluid and the first and second conduits 27, 28 may be connected to the tank T based on this pressure.

Figure 3 shows the actuator 34 arranged to move the valve member 35 between the position at which the valve member 35 blocks the valve passage 36 and the position at which the valve passage 36 is opened. The actuator 34 can advantageously be controlled by using a hydraulic control system of the kind described above.

Figure 4 shows an alternative hydraulic control system. This system corresponds to inserting an additional PCV 37 in the second passageway 7 in the system shown in Fig. The additional PCV 37 is provided with a spring 38 that deflects the PCV 37 toward the normally open position. However, the pressure in the emergency passage 15 causes the PCV 37 to close and the emergency fluid returning to the return passages 18 and 19 to pass through the second passage 8 between the second connection port 8 and the DPCV 11 7). This pressure can be caused by the pressure drop in the second conduit 28 between the second connection port 8 and the tank T. [ This pressure causes an unintentional opening of the first passage 3 so that the emergency fluid can flow from the emergency pump eP to the tank 3 without performing the intended operation in the hydraulic control device 2, (T). The PCV 37 is controlled by the pressure in the emergency passage 15 via the control line 39.

1 is a schematic diagram of a control system according to the present invention.

2 is a schematic diagram of a hydraulic system including the hydraulic control system shown in FIG.

3 is a view showing a valve operated by an actuator and an actuator.

4 is a schematic diagram of an alternative embodiment of a hydraulic control system according to the present invention.

Description of the Related Art

1: Hydraulic control system 2: Hydraulic control system

3: first passage 4: first connection port

5: First control port 6: Control port

7: second passage 8: second connection port

9: second control port 10: second control port

11: DPCV 12, 13: Valve member

14: control passage 15: emergency passage

16: Emergency entrance 17, 18, 19: Return passage

20: PCV 21, 22: Check valve

23: overpressure valve 24: connector assembly

25: Hydraulic system 26: Control device

27: first conduit 28: second conduit

30: emergency conduit 34: actuator

35: valve member 37, 38, 39: valve device

P: Pressure pump eP: Emergency pressure pump

T: tank

Claims (26)

A first passage 3 between the first connection port 4 and the first control port 5, a second passage 7 between the second connection port 8 and the second control port 9, (17, 18) which forms a flow path (18) between the second control port (9) and the second connection port (8), an emergency passage (15) And the valve device 11 is connected to the first control port 5 from the first control port 5 when the constant pressure condition is not present in the second passage 7, And the emergency valve device 20 is adapted to prevent fluid flow in the return passages 17, 18 and 19 unless a constant pressure condition is present in the emergency passage 15 In the hydraulic control system (1) Characterized in that the return passages (17,18, 19) form an additional flow path (17) connecting the second control port (9) and the first connection port (4). The method according to claim 1, A constant pressure condition in the second passage (7) is a condition that exceeds a limit difference between the pressure in the second passage (7) and the reference pressure. 3. The method of claim 2, Wherein the reference pressure is in accordance with the pressure in the first passage (3). 4. The method according to any one of claims 1 to 3, A constant pressure condition in the emergency passage (15) is a condition exceeding a limit difference between the pressure in the emergency passage (15) and the reference pressure. 5. The method of claim 4, The reference pressure is in accordance with the pressure in the return passages (17, 18, 19). 6. The method according to any one of claims 1 to 5, The valve arrangement 11 includes a hydraulic control system 1 adapted to prevent fluid flow from the second control port 9 to the second connection port 8 unless a constant pressure condition is present in the first passage 3, . The method according to claim 6, A constant pressure condition in the first passage (3) is a condition that exceeds a limit difference between the pressure in the first passage (3) and the reference pressure. 8. The method of claim 7, Wherein the reference pressure is in accordance with the pressure in the second passage (7). 9. The method according to any one of claims 1 to 8, Wherein the fluid flow is prevented in the first and second passages (3, 7) if a constant pressure condition is not present in the escape passage (15). 10. The method of claim 9, A constant pressure condition in the emergency passage (15) is a condition exceeding a limit difference between the pressure in the emergency passage (15) and the reference pressure. 11. The method of claim 10, Wherein the reference pressure corresponds to at least the pressure of one of the first and second connection ports (4, 8). 12. The method according to any one of claims 1 to 11, Wherein the flow in the flow path (18) and the additional flow path (17) is prevented in the direction towards the second control port (9). 13. The method according to any one of claims 1 to 12, And a valve device (37, 38, 39) for preventing fluid flow in the second passage (7) if a constant pressure condition exists in the escape passage (15). 14. The method of claim 13, A constant pressure condition in the emergency passage (15) is a condition exceeding a limit difference between the pressure in the emergency passage (15) and the reference pressure. 15. The method of claim 14, And the reference pressure follows the pressure in the second passage port (7). Pressure fluid source P, A tank (T) for collecting the returning fluid, A hydraulic actuating device (2) for performing an operation on an object based on the flow of the pressure fluid, and A hydraulic control system (1) comprising: The hydraulic actuating device 2 includes a first port 6 and a second port 10 and the fluid is received in one of the ports 6 and 10 and the fluid is also supplied to the other of the ports 6, Is returned from one, The hydraulic control system 1 includes a first passage 3 between the first connection port 4 and the first control port 5 and a second passage 5 between the second connection port 8 and the second control port 9, An emergency passage 15 is provided between the emergency port 16 and the first control port 5 and a flow path 18 is provided between the second control port 9 and the second connection port 8. [ The valve device 11 and the emergency valve device 20 are arranged such that the valve device 11 is closed when the constant pressure condition is not present in the second passage 7, The emergency valve device 20 is adapted to prevent fluid flow from the first control port 5 to the first connection port 4 and the return passage 17, 19. The hydraulic system of claim 1, wherein the return passages (17, 18, 19) are configured to connect the second control port (9) and the first connection port (4) To form an additional flow path (17). 17. The method of claim 16, Further comprising a conduit system having a first conduit (27) and a second conduit (28) The hydraulic system includes: A first conduit 27 connects the first connection port 4 and the pressure fluid source P and a second conduit 28 connects the second connection port 8 and the tank T. [ , And A second conduit 28 connects the first connection port 4 and the tank T and a second conduit 28 connects the second connection port 8 and the pressure fluid source P, Hydraulic system that can move between. 18. The method according to claim 16 or 17, Wherein the hydraulic system uses a third structure in which both the first and second connection ports (4, 8) are connected to the tank (T). 19. The method according to any one of claims 16 to 18, Further comprising an emergency pressure fluid source (eP) separate from the pressure fluid source (P). 20. The method according to any one of claims 16 to 19, And an emergency conduit (30) connecting the pressure fluid source and the emergency inlet (16). 21. The method of claim 20, The emergency conduit (30) has a cross-sectional area between 1.5 and 2.5 of the cross-sectional area of one of the first and second connecting conduits (27, 28). 22. The method of claim 21, The first and second conduits (27, 28) have the same cross-sectional area. And a control system (1) movable between first and second end positions under the influence of fluid flow into and out of the first and second ports (6, 10), the control system A first passage 3 between the first connection port 4 and the first control port 5, a second passage 7 between the second connection port 8 and the second control port 9, (17, 18) which forms a flow path (18) between the second control port (9) and the second connection port (8), an emergency passage (15) And the valve device 11 is connected to the first control port 5 from the first control port 5 when the constant pressure condition is not present in the second passage 7, And the emergency valve device 20 is arranged to prevent fluid flow to the connection port 4 and to prevent the flow of the fluid into the return passages 17, 18, 19 if a certain pressure condition is not present in the emergency passage 15. [ Wherein the first port (6) is connected to a first control port (5) and the second port (10) is connected to a second control port (9) The passageway (17,18, 19) forms an additional flow path (17) connecting the second control port (9) and the first connection port (4). Includes a valve member (35) located in the flow passage (36) and movable between two end positions providing different flow resistance in the flow passage and movable by an actuator (2, 34) The actuator (2, 34) comprises a control system (1) which is movable between first and second end positions under the influence of fluid flow into and out of the first and second ports (6, 10) The control system 1 includes a first passage 3 between the first connection port 4 and the first control port 5 and a second passage 3 between the second connection port 8 and the second control port 9, A flow path 18 between the second control port 9 and the second connection port 8 is formed in the passage 7 between the emergency port 16 and the first control port 5, The valve device 11 and the emergency valve device 20 are arranged such that a constant pressure condition is applied to the second passage 11, The emergency valve device 20 is arranged to prevent the flow of the fluid from the first control port 5 to the first connection port 4 if the pressure in the emergency passage 15 does not exist in the emergency passage 15 The first port 6 is connected to the first control port 5 and the second port 10 is connected to the second control port 9 so as to prevent fluid flow in the return passage, Characterized in that the return passages (17,18, 19) form an additional flow path (17) connecting the second control port (9) and the first connection port (4) Control valve. 25. The method of claim 24, The valve member (35) moves between two end positions by a quarter turn of the valve member (35). A return conduit that provides a reverse flow of fluid away from the valve under normal operating conditions, and a return conduit that provides a reverse flow of fluid away from the valve under normal operating conditions, A method of operating a valve system including an emergency conduit providing an emergency flow of fluid towards a valve under an operating condition, The method Blocking the forward flow of the fluid in the abnormal state, and Providing an emergency reverse flow of fluid away from the valve in the forward conduit and the return conduit.

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