Fluid flow regulator

Abstract

The present disclosure relates to a fluid regulator 10 comprising a valve body (12) defining an inlet 14, an outlet 16, with an outlet chamber 18 between them, and a valve cavity. Regulator 26 and Aux

Description

FIELD The present disclosure relates to a fluid regulator. BACKGROUND Fluid regulators are typically used in pressurised systems requiring fluid pressure to be regulated before delivery to an intended location. In the oil and gas industry, for example, hydraulic regulators may be used in flowlines for transporting high-pressure fluids to subsea infrastructure. During normal operation, the fluid regulator may be pressurized and operate to ensure that an outlet pressure of the regulator does not exceed a certain pressure. However, when the regulator is initially connected to a flowline, the flowline may be empty or contain fluid at low pressure. Therefore, the flowline may need to be pressurised before normal operation of the fluid regulator commences. This process may cause undesirable fluid excitation to occur, adversely affecting the performance of the regulator. SUMMARY An aspect of the present disclosure relates to a fluid regulator comprising a valve body defining an inlet, an outlet, a valve cavity and an outlet chamber, the outlet chamber disposed between the valve cavity and the outlet. A regulator flow extends between the inlet and the outlet chamber, and an auxiliary flow path extends between the inlet and the outlet chamber. A valve assembly is mounted within the valve cavity. The valve assembly comprises a regulator valve member movable between an open position, allowing fluid flow through the regulator flow path, and a closed position, preventing fluid flow through the regulator flow path. The valve assembly comprises an auxiliary valve member movable between an open position, allowing fluid flow through the auxiliary flow path, and a closed position, preventing fluid flow through the auxiliary flow path. The fluid regulator comprises a biasing arrangement for biasing the regulator valve member and the auxiliary valve member towards the open position. The biasing arrangement is configured such that: (i) the auxiliary valve member moves to the closed position when the fluid pressure within the outlet chamber achieves an auxiliary set-point pressure, and (ii) the regulator valve member moves to the closed position when a fluid pressure within the outlet chamber achieves a regulator set-point pressure, the regulator set-point pressure being greater than the auxiliary set-point pressure. The fluid regulator may provide a pressure regulating function with two flow capacity ranges (also referred to as “Cv values”). In this regard, the valve assembly may be defined as a dual-flow valve assembly. The fluid regulator may provide for a wider turndown ratio compared to prior-art fluid regulator designs, with the present fluid regulator being able to effectively control pressure from a zero or negligible pressure to the regulator set-point pressure. Further, the positions of the regulator and auxiliary valve members are determined in accordance with a fluid pressure in a single outlet chamber, thus providing for a compact design. The fluid regulator may operate in different modes of operation depending on the fluid pressure within the outlet chamber. When there is no or negligible pressure within the outlet chamber of the fluid regulator, the fluid regulator may operate in a first mode of operation (also referred to as a “medium flow mode”) with both the regulator and auxiliary valve members in the open position. In this mode of operation, pressure within the outlet chamber is allowed to increase as quickly as possible with the regulator and auxiliary flow paths being open to their maximum potential cross-sectional area. The auxiliary flow path may comprise a first effective flow area greater than a second effective flow area of the regulator flow path. When the fluid pressure within the outlet chamber achieves the auxiliary set-point pressure, the fluid regulator may change to a second mode of operation (also referred to as a “low flow mode”), wherein the regulator valve member is in the open position and the auxiliary valve member is in the closed position. The second mode of operation may allow for “trimming” of fluid pressure after the initial pressurisation stage by directing fluid flow through the regulator flow path only. When the fluid pressure within the outlet chamber achieves the regulator set-point pressure, the fluid regulator may change to a third mode of operation (also referred to as a “no-flow mode”), wherein both the regulator and auxiliary valve members are in the closed position thereby isolating the outlet chamber from the inlet. As the fluid regulator transitions from the first mode of operation to the third mode of operation, the auxiliary and regulator valve members may sequentially close in accordance with the fluid pressure within the outlet chamber. In a fourth mode of operation (also referred to as a “pressure relief mode”), the fluid regulator may perform a pressure relief function, which is discussed in more detail below. The inlet may be connected to an inlet coupling (such as a threaded coupling) for connecting to an inlet flowline, e.g. an inlet pipe, inlet line, etc. The outlet may be connected to an outlet coupling (such as a threaded coupling) for connecting to an outlet flowline, an outlet pipe, outlet line, etc. The outlet chamber may be in pressure communication with the outlet flowline. The fluid regulator may comprise a sensor element configured to sense the fluid pressure within the outlet chamber. The sensor element may be configured to control a position of the regulator and auxiliary valve members in accordance with the fluid pressure within the outlet chamber. The sensor element may be slidably disposed within a sensor holder fixed within the valve body. The sensor element may comprise first and second ends. The first end of the sensor element may be disposed within the outlet chamber. The first end of the sensor element may comprise an enlarged sensing surface. The second end of the sensor element may be disposed proximate the biasing arrangement. The second end of the sensor element may be configured to engage a spring seat member of the biasing arrangement. The second end of the sensor element may comprise a curved surface for engaging the spring seat member. The valve assembly may comprise a regulator connector for engaging the regulator valve member in accordance with a position of the sensor element. The regulator connector may comprise a first end disposed proximate the sensor element and a second end disposed proximate the regulator valve member. The valve assembly may comprise an auxiliary connector for engaging the auxiliary valve member in accordance with the position of the sensor element. The auxiliary connector may comprise a first end disposed proximate the sensor element and a second end disposed proximate the auxiliary valve member. The regulator and auxiliary connectors may be independently linked to the regulator and auxiliary valve members respectively. The regulator connector may be slidably disposed within the auxiliary connector. The regulator connector and the auxiliary connector may be concentrically arranged. The regulator connector and the auxiliary connector may be telescopically arranged. The auxiliary connector may comprise a connector sleeve. The regulator connector may comprise a connector pin. The connector pin may be disposed within the connector sleeve. The regulator valve member may comprise any type of valve member, for example a globe valve, a needle valve, etc. The regulator valve member may comprise a ceramic material. The auxiliary valve member may comprise any type of valve member, for example comprising a cylindrical valve member. The regulator valve member may be slidably disposed within the auxiliary valve member. The regulator valve member and the auxiliary valve member may be concentrically arranged. The fluid regulator may comprise an auxiliary valve seat disposed within the valve body. The auxiliary valve seat may be configured to be engaged by the auxiliary valve member when the auxiliary valve member is in the closed position. The auxiliary valve member may define a valve pocket. The auxiliary valve member may define a regulator valve inlet port. The regulator valve inlet port may be in fluid communication with the inlet and the valve pocket. The regulator valve inlet port may define a part of the regulator flow path. The regulator valve member may be disposed within the valve pocket. The regulator valve member may be movably disposed within the valve pocket. The valve assembly may comprise a regulator valve seat. The regulator valve seat may be disposed within the valve pocket. The regulator valve seat may be fixed within the valve pocket. The regulator valve seat may be configured to be engaged by the regulator valve member when the regulator valve member is in the closed position. The fluid regulator may comprise a baffle arrangement. The baffle arrangement may be configured to restrain a flow of fluid entering the outlet chamber, for example to protect the sensor element from damage during initial pressurisation. The baffle arrangement may comprise a bore through which the regulator and auxiliary connectors extend. The biasing arrangement may comprise a load spring (for example a coil spring). The load spring may be configured to bias both the regulator valve member and the auxiliary valve member towards the open position. The biasing arrangement may be disposed on a first side of the valve body. The biasing arrangement may be disposed in a spring cavity. The spring cavity may be provided by a valve bonnet connected to the valve body. The valve bonnet may be connected to the first side of the valve body. The valve bonnet may comprise a body portion and a head portion movable relative to the body portion to modify a length of the load spring and a magnitude of the force applied to the sensor element by the biasing arrangement. The head portion may be manually movable relative to the body portion, or the fluid regulator may be equipped with an actuator for moving the head portion relative to the body portion. The biasing arrangement may be defined as a first biasing arrangement. The fluid regulator may comprise a second biasing arrangement disposed on an opposing second side of the valve body. The second biasing arrangement may be configured to bias the first and second valve members towards the closed position against the first biasing arrangement. The first biasing arrangement may provide a greater biasing force than the second biasing arrangement such that the regulator and auxiliary valve members are unable to move to the closed positon until the fluid pressure within the outlet chamber respectively achieves the regulator and auxiliary set-point pressures. The second biasing arrangement may comprise a first spring element configured to bias both the regulator and auxiliary valve members towards the closed position. The second biasing arrangement may comprise a second spring element configured to bias the regulator valve member towards the closed position. The first spring element may be disposed in a first spring chamber. The first spring chamber may be defined by the valve body and a valve cap connected to the second side of the valve body. The first spring chamber may be in pressure communication with the outlet. The second spring element may be disposed in a second spring chamber. The second spring chamber may be defined by the valve pocket of the auxiliary valve member and a spring seat element fixed within the valve pocket. The first spring element and the second spring element may be separated by the spring seat element. The second spring chamber may be in pressure communication with the inlet. The fluid regulator may comprise one or more sealing elements (such as O-rings) disposed at suitable locations to permit an operation of the fluid regulator in accordance with the above. During an initial operation of the fluid regulator, both the regulator and auxiliary valve members may be provided in the open position. The pressure within the outlet chamber may be minimal, resulting in the first biasing arrangement applying a force to the sensor element which in turn applies a force to the regulator and auxiliary connectors to hold the regulator and auxiliary valve members in the open position. Fluid may flow from the inlet through the regulator and auxiliary flow paths into the outlet chamber causing a build-up of pressure against the sensing surface of the sensor element, which may cause the sensor element to begin to move towards and against the bias of the biasing arrangement. Movement of the sensor element towards the biasing arrangement relieves the amount of force that the sensor element applies to the regulator and auxiliary connectors. As such, as the sensor element moves towards the biasing arrangement, the regulator connector, auxiliary connector, regulator valve member and auxiliary valve member also move towards the first biasing arrangement under the action of the second biasing arrangement and the fluid pressure within the first and second spring chambers. When the fluid pressure within the outlet chamber achieves the auxiliary set-point pressure, the fluid pressure acting on the sensing surface of the sensor element may be sufficient to overcome a biasing force of the first biasing arrangement to allow the auxiliary valve member to move to the closed position. At this point, fluid flow may be directed through the regulator flow path only. As the fluid pressure within the outlet chamber continues to increase, the sensor element may begin to move further towards and against the bias of the biasing arrangement. As the sensor element moves further towards the biasing arrangement, the regulator connector and regulator valve member may also move towards the biasing arrangement relative to the auxiliary valve member and the auxiliary connector under the action of the second spring element and the fluid pressure within the second spring chamber. Consequently, the regulator valve member gradually moves closer to the regulator valve seat restricting the amount of fluid flowing through the regulator flow path and regulating an outlet pressure. When the fluid pressure within the outlet chamber achieves the regulator set-point pressure, the fluid pressure acting on the sensing surface of the sensor element may be sufficient to overcome a second bias of the first biasing arrangement to allow the regulator valve member to move to the closed position, thereby isolating the outlet chamber from inlet pressure. As noted above, the fluid regulator may also be configured to provide a pressure relief function. The fluid regulator may comprise a relief flow path extending between the outlet chamber and a vent port formed in the valve body. The sensor element may comprise a vent seat (for example secured to the sensor element by a vent seat nut) configured to engage the regulator connector during normal operation of the fluid regulator and to move away and separate from the regulator connector when the fluid regulator is operating in a pressure relief mode. The sensor element may comprise a blind bore terminating in a radial bore. The blind and radial bores of the sensor element together with the vent port may define the relief flow path. When the fluid regulator is operating under normal conditions, the vent seat may be engaged by the regulator connector such that the relief flow path is closed. When the fluid regulator is operating in the pressure relief mode, the force applied to the sensing element by the biasing arrangement may be relived such that the fluid pressure within the outlet chamber acting on the sensing surface of the sensor element may cause the sensor element and the vent seat to move towards the first biasing arrangement and away from the regulator and auxiliary connectors, opening the relief flow path. The regulator and auxiliary connectors may comprise a movement limiter configured to limit movement of the regulator and auxiliary connectors towards the first biasing arrangement. For example, the regulator and auxiliary connectors may respectively comprise first and second shoulders to limit movement of the regulator and auxiliary connectors towards the first biasing arrangement. The first shoulder of the regulator connector may be configured to abut an internal surface of the auxiliary connector. The second shoulder of the auxiliary connector may be configured to abut a part of the valve body, or a component (such as the baffle arrangement) fixed relative to the valve body. As such, as the sensor element and vent seat move towards the valve bonnet, movement of the regulator and auxiliary connectors may be limited by the first and second shoulders such that the sensor element and vent seat can separate from the regulator connector allowing the relief flow path to be opened to the outlet chamber. To relive the force applied to the vent seat by the first biasing arrangement, a position of the head portion of the valve bonnet may be adjusted relative to the body portion to reduce a magnitude of the force applied by the biasing arrangement to the sensor element, thereby allowing the vent seat to move away and separate from the regulator connector. Alternatively, if the fluid pressure within the outlet chamber acting on the sensing surface of the sensor element for any reason exceeds a relief set point pressure, the sensor element and the vent seat may move towards the first biasing arrangement and away from the regulator and auxiliary connectors, opening the relief flow path. An aspect of the present disclosure relates to a fluid regulator, comprising: a valve body defining an inlet, an outlet and a valve cavity; a regulator flow path extending between the inlet and the outlet; an auxiliary flow path extending between the inlet and the outlet; a valve assembly mounted within the valve cavity, the valve assembly comprising: a regulator valve member movable between an open position, allowing fluid flow through the regulator flow path, and a closed position, preventing fluid flow through the regulator flow path, and an auxiliary valve member movable between an open position, allowing fluid flow through the auxiliary flow path, and a closed position, preventing fluid flow through the auxiliary flow path; and a biasing arrangement for biasing the regulator valve member and the auxiliary valve member towards the open position, wherein the biasing arrangement is configured such that: (i) the auxiliary valve member moves to the closed position when a pressure within the fluid regulator achieves an auxiliary set-point pressure, and (ii) the regulator valve member moves to the closed position when the pressure within the fluid regulator achieves a regulator set-point pressure, the regulator set-point pressure being greater than the auxiliary setpoint pressure. An aspect of the present disclosure relates to a method for regulating fluid pressure, the method comprising operating the fluid regulator described hereinabove. The method may comprise connecting the inlet of the fluid regulator to an inlet flowline. The method may comprise connecting the outlet of the fluid regulator to an outlet flowline. The method may comprise pressurising the inlet flowline and flowing fluid through the auxiliary and regulator flow paths to the outlet flowline. The method may comprise closing the auxiliary flow path and flowing fluid through the regulator flow path after the fluid pressure within the outlet chamber has achieved the auxiliary set-point pressure. The method may comprise regulating a pressure of the fluid flowing from the inlet flowline to the outlet flowline via the fluid regulator. The method may comprise closing the regulator flow path after the fluid pressure within the outlet chamber has achieved the regulator set-point pressure. It will be appreciated that features described in relation to one aspect may be equally combined with any other aspect described herein. BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic illustration of a fluid regulator operating in a first mode of operation; Figure 2 is an enlarged view of a valve assembly of the fluid regulator illustrated in Figure 1, wherein the fluid regulator is operating in a third mode of operation; Figure 3 is a detailed view of part of Figure 1 schematically illustrating a regulator flow path and an auxiliary flow path of the fluid regulator illustrated in Figure 1; Figure 4 is a schematic illustration of the fluid regulator of Figure 1 operating in a second mode of operation; and Figure 5 is a schematic illustration of the fluid regulator of Figure 1 operating in the third mode of operation. DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 provides a schematic illustration of a fluid regulator 10. The fluid regulator 10 may be used in multiple applications for various purposes. However, for the purposes of providing an exemplary application, the following description generally relates to the fluid regulator 10 being used in an operation associated with an oil and gas wellbore. Figure 1 provides a schematic illustration of a fluid regulator 10 operating in a first mode of operation. The fluid regulator 10 comprises a valve body 12 defining an inlet 14, an outlet 16, a valve cavity and an outlet chamber 18, the outlet chamber 18 disposed between the valve cavity and the outlet 16. As best illustrated in Figures 1 and 3, the fluid regulator 10 comprises a regulator flow path 26 extending between the inlet 14 and the outlet chamber 18 and an auxiliary flow path 28 extending between the inlet 14 and the outlet chamber 18. Figure 2 provides an enlarged view of a valve assembly 20 of the fluid regulator 10 of Figure 1. The valve assembly 20 is mounted within the valve cavity and comprises a regulator valve member 22, such as a globe valve, movable between an open position allowing fluid flow through the regulator flow path 26 and a closed position preventing fluid flow through the regulator flow path 26. The valve assembly 20 further comprises an auxiliary valve member 24, such as a cylindrical valve member, movable between an open position, allowing fluid flow through the auxiliary flow path 28, and a closed position, preventing fluid flow through the auxiliary flow path 28. The auxiliary valve member 24 defines an internal valve pocket in which the regulator valve member 24 is movably disposed between the open and closed positions. The auxiliary valve member 24 includes a regulator valve inlet port 29 in fluid communication with the inlet 14 and the valve pocket, the regulator valve inlet port 29 defining a part of the regulator flow path 26. A regulator valve seat 42 is fixed within the valve pocket and configured to be engaged by the regulator valve member 22 when the regulator valve member 22 is in the closed position. An auxiliary valve seat 44 is disposed within the valve cavity and secured relative to the valve body 12 with a seat retainer 43. The auxiliary valve seat 44 is configured to be engaged by the auxiliary valve member 24 when the auxiliary valve member 24 is in the closed position. A sealing element 45 is disposed between the auxiliary valve seat 44 and the valve body 12. The fluid regulator 10 comprises a biasing arrangement 30 configured to bias the regulator valve member 22 and the auxiliary valve member 24 towards the open position. The biasing arrangement 30 comprises a load spring 62, such as a coil spring, configured to bias both the regulator valve member 22 and the auxiliary valve member 24 towards the open position. The biasing arrangement 30 is disposed in a spring cavity provided by a valve bonnet 64 connected to a first side of the valve body 12. The valve bonnet 64 comprises a body portion 64a and a head portion 64b movable relative to the body portion 64a to modify a length of the spring cavity and a magnitude of the force applied by the biasing arrangement 30 to the sensor element 32. The head portion 64b may comprise a turning wheel to allow the head portion 64b to be rotated relative to the body portion 64a. Alternatively, an actuator may be provided to rotate the head portion 64b relative to the body portion 64a or to move the sensor element 32 relative to the body portion 64. The fluid regulator 10 comprises a sensor element 32 having a first end 32a disposed within the outlet chamber 18 and comprising an enlarged sensing surface 33 configured to sense the fluid pressure within the outlet chamber 18. The sensor element 32 is slidably disposed within a sensor holder 34 fixed within the valve body 12. The sensor element 32 is configured to control a position of the regulator and auxiliary valve members 22, 24 in accordance with the fluid pressure within the outlet chamber 18. A second end 32b of the sensor element 32 is disposed proximate the biasing arrangement 30 and comprises a curved surface for engaging a spring seat 36 of the biasing arrangement 30. The sensor element 32 comprises first and second sealing elements 21, 23. The valve assembly 20 comprises a regulator connector 38, in the form of a pin connector, for engaging the regulator valve member 22 in response to a force from the sensor element 32. The regulator connector 38 comprises a first end disposed proximate the sensor element 32 and a second end disposed proximate the regulator valve member 22. The sensor element 32 includes a vent seat 50 attached to the sensor element 32 by a vent seat nut 52. The vent seat 50 is configured to engage the regulator connector 38 during normal operation of the fluid regulator 10 and to separate from the regulator connector 38 when the fluid regulator 10 is operating in a pressure relief mode, which will be discussed below. A sealing element 51 is disposed between the vent seat 50 and the sensor element 32. Further, the valve assembly 20 comprises an auxiliary connector 40, in the form of a sleeve connector, for engaging the auxiliary valve member 24 in response to a force from the sensor element 32. The auxiliary connector 40 comprises a first end disposed proximate the sensor element 32 and a second end disposed proximate the auxiliary valve member 24. The regulator connector 42 is slidably disposed within the auxiliary connector 40. A second biasing arrangement 70 is disposed on an opposing second side of the valve body 12 and configured to bias the first and second valve members 22, 24 towards the closed position, against the first biasing arrangement 30. The first biasing arrangement 30 provides a greater biasing force than the second biasing arrangement 70 such that the regulator and auxiliary valve members 22, 24 are unable to move to the closed positon until the fluid pressure within the outlet chamber 18 respectively achieves an auxiliary set-point pressure and a greater regulator set-point pressure. The second biasing arrangement 70 comprises a first spring element 72 configured to bias both the regulator and auxiliary valve members 22, 24 towards the closed position and a second spring element 74 configured to bias the regulator valve member 22 towards the closed position. The first spring element 72 is disposed in a first spring chamber 76 defined by the valve body 12 and a valve cap 80 connected to the valve body 12 on the second side of the valve body 12. Sealing elements 47, 81 are provided to prevent fluid leakage from the regulator 10 via the valve cap 80. The second spring element 74 is disposed in a second spring chamber 78 defined by an internal surface of the auxiliary valve member 24, a spring element seat 82 fixed within the valve pocket of the auxiliary valve member 24 and the regulator valve member 22. The first spring chamber 76 is in pressure communication with the outlet 16 and the second spring chamber 78 is in pressure communication with the inlet 14. This arrangement means that the regulator valve member 22 is balanced in design, minimising the load on the regulator valve seat 42 and making the regulator valve member 22 easier to open, thus improving pressure control. A sealing element 83 is disposed between the spring element seat 82 and the auxiliary valve member 24. The fluid regulator 10 comprises a baffle arrangement 60 configured to restrain a flow of fluid entering the outlet chamber 18, for example to protect the sensor element 32 from damage during initial pressurisation. The baffle arrangement 60 comprises a bore through which the regulator and auxiliary connectors 38, 40 extend. The fluid regulator 10 may provide a pressure regulating function with two flow capacity ranges (also referred to as “Cv values”). In this regard, the valve assembly 20 may be defined as a dual-flow valve assembly. The fluid regulator 10 may be connected to an inlet flowline via a threaded connection at the inlet 14 and to an outlet flowline via a threaded connection at the outlet 16. The outlet chamber 18 may be in pressure communication with the outlet flowline. The fluid regulator 10 may operate in different modes of operation depending on the fluid pressure within the outlet chamber 18. When there is no or negligible pressure within the outlet chamber 18 of the fluid regulator 10, the fluid regulator 10 may operate in the first mode of operation (also referred to as a “medium flow mode”) illustrated in Figure 1, in which both the regulator and auxiliary valve members 22, 24 are in the open position. In this mode of operation, pressure within the outlet chamber 18 is allowed to increase as quickly as possible with the regulator and auxiliary flow paths 26, 28 being open to their maximum potential cross-sectional area. The auxiliary flow path 28 may be provided with a larger flow area than a flow area of the regulator flow path 26. During an initial operation of the fluid regulator 10, the pressure within the outlet chamber 18 may be minimal, resulting in the first biasing arrangement 30 applying a force to the sensor element 32 which in turn applies a force to the regulator and auxiliary connectors 38, 40 to hold the regulator and auxiliary valve members 22, 24 in the open position. Fluid may flow from the inlet 14 through the regulator and auxiliary flow paths 26, 28 into the outlet chamber 18 allowing rapid flow from the inlet 14 to the outlet 16 until the flow demand has been met. This process causes a build-up of pressure within the outlet chamber 18 that acts against the sensing surface 33 of the sensor element 32, causing the sensor element 32 to begin to move towards and against the bias of the biasing arrangement 30. Movement of the sensor element 32 towards the biasing arrangement 30 relieves the amount of force that the sensor element 32 applies to the regulator and auxiliary connectors 38, 40, which in turn moves towards the biasing arrangement 30. As the sensor element 32 moves towards the biasing arrangement 30, the regulator connector 38, auxiliary connector 40, regulator valve member 22 and auxiliary valve member 24 also move towards the first biasing arrangement 30 under the action of the second biasing arrangement 30 and the fluid pressure within the first and second spring chambers 76, 78. When the fluid pressure within the outlet chamber 18 achieves the auxiliary set-point pressure, the fluid pressure acting on the sensing surface 33 of the sensor element 32 may be sufficient to overcome a biasing force of the biasing arrangement 30 to allow the auxiliary valve member 24 to move to the closed position. At this point, the fluid regulator 10 changes to a second mode of operation (also referred to as a “low flow mode”) illustrated in Figure 4 in which the regulator valve member 22 is in the open position and the auxiliary valve member 24 is in the closed position, allowing for “trimming” of fluid pressure after the initial pressurisation has been completed via the regulator valve member. As the fluid pressure within the outlet chamber 18 continues to increase, the sensor element 32 may begin to move further towards and against the bias of the biasing arrangement 30. As the sensor element 32 moves further towards the biasing arrangement 30, the regulator connector 38 and regulator valve member 22 may also move towards the biasing arrangement 30 under the action of the second spring element 74 and the fluid pressure within the second spring chamber 78. Consequently, the regulator valve member 22 gradually moves closer to the regulator valve seat 42 thereby restricting the amount of fluid flowing through the regulator flow path 26 and regulating the outlet pressure. When the fluid pressure within the outlet chamber 18 achieves the regulator set-point pressure, the fluid pressure acting on the sensing surface 33 of the sensor element 32 may be sufficient to overcome a second bias of the biasing arrangement 30 to allow the regulator valve member 22 to move to the closed position. At this point, the fluid regulator 10 changes to a third mode of operation (also referred to as a “no-flow mode”) illustrated in Figure 5 in which both the regulator and auxiliary valve members 22, 24 are in the closed position, thereby isolating the outlet chamber 18 from inlet pressure. In the fourth mode of operation (also referred to as the “pressure relief mode”), the fluid regulator 10 performs a pressure relief function. The fluid regulator 10 comprises a relief flow path defined by blind and radial bores 56, 68 of the sensor element 30, a vent port 54 formed in the valve body 12 and a lateral bore (not shown) formed in the sensor holder 34. The regulator and auxiliary connectors 38, 40 respectively comprise first and second shoulders 46, 48 to limit movement of the regulator and auxiliary connectors 38, 40 towards the first biasing arrangement 30. The first shoulder 46 of the regulator connector 38 is configured to abut an internal surface of the auxiliary connector 40 and the second shoulder 48 of the auxiliary connector 40 is configured to abut the baffle arrangement 60 within the valve body 12. As such, as the sensor element 32 and vent seat 50 move towards the valve bonnet 64, movement of the regulator and auxiliary connectors 38, 40 is limited by the first and second shoulders 46, 48 such that the sensor element 32 and vent seat 50 can continue moving towards the biasing arrangement 30 and separate from the regulator connector 38, allowing the relief flow path to be opened to the outlet chamber 18. 5 To relive the force applied to the vent seat 50 by the sensor element 32, a position of the head portion 64b of the valve bonnet 64 may be adjusted relative to the body portion 64a to reduce a magnitude of the force applied by the biasing arrangement 30 to the sensor element 32, thereby allowing the vent seat 50 to move away and 10 separate from the regulator connector 38. Alternatively, if the fluid pressure within the outlet chamber 18 acting on the sensing surface 33 of the sensor element 32 for any reason exceeds a relief set point pressure, the sensor element 32 and the vent seat 50 may move towards the first biasing arrangement 30 and away from the regulator and auxiliary connectors 38, 40, opening the relief flow path.

Claims

1. A fluid regulator, comprising:a valve body defining an inlet, an outlet, a valve cavity and an outlet chamber, the outlet chamber disposed between the valve cavity and the outlet;a regulator flow path extending between the inlet and the outlet chamber;an auxiliary flow path extending between the inlet and the outlet chamber;a valve assembly mounted within the valve cavity, the valve assembly comprising:a regulator valve member movable between an open position, allowing fluid flow through the regulator flow path, and a closed position, preventing fluid flow through the regulator flow path, andan auxiliary valve member movable between an open position, allowing fluid flow through the auxiliary flow path, and a closed position, preventing fluid flow through the auxiliary flow path; anda biasing arrangement for biasing the regulator valve member and the auxiliary valve member towards the open position,wherein the biasing arrangement is configured such that: (i) the auxiliary valve member moves to the closed position when the fluid pressure within the outlet chamber achieves an auxiliary set-point pressure, and (ii) the regulator valve member moves to the closed position when the fluid pressure within the outlet chamber achieves a regulator set-point pressure, the regulator set-point pressure being greater than the auxiliary set-point pressure.

2. The fluid regulator of claim 1, wherein the regulator flow path comprises a first effective flow area and the auxiliary flow path comprises a second effective flow area greater than the first effective flow area.

3. The fluid regulator of claim 1 or 2, comprising a sensor element configured to sense the fluid pressure within the outlet chamber and control a position of the regulator and auxiliary valve members in accordance with the fluid pressure within the outlet chamber.

4. The fluid regulator of claim 3, wherein the sensor element is slidably disposed within a sensor holder fixed within the valve body.

5. The fluid regulator of claim 3 or 4, wherein the sensor element comprises a first end disposed within the outlet chamber and a second end disposed proximate the biasing arrangement.

6. The fluid regulator of any one of claims 3 to 5, wherein the valve assembly comprises a regulator connector for engaging the regulator valve member in accordance with a position of the sensor element, and an auxiliary connector for engaging the auxiliary valve member in accordance with the position of the sensor element.

7. The fluid regulator of claim 6, wherein the regulator connector and the auxiliary connector are concentrically arranged.

8. The fluid regulator of claim 6 or 7, wherein the auxiliary connector comprises a connector sleeve, and the regulator connector comprises a connector pin, the connector pin slidably disposed within the connector sleeve.

9. The fluid regulator of any preceding claim, wherein the auxiliary valve member defines a valve pocket, and the regulator valve member is disposed within the valve pocket.

10. The fluid regulator of claim 9, wherein a regulator valve seat is fixed within the valve pocket and configured to be engaged by the regulator valve member when the regulator valve member is in the closed position.

11. The fluid regulator of any preceding claim, wherein the auxiliary valve member comprises a cylindrical valve member.

12. The fluid regulator of any preceding claim, wherein the regulator valve member comprises a globe valve.

13. The fluid regulator of any preceding claim, wherein the biasing arrangement comprises a load spring configured to bias both the regulator valve member and the auxiliary valve member towards the open position.

14. The fluid regulator of any preceding claim, wherein the biasing arrangement is disposed in a spring cavity provided by a valve bonnet connected to the valve body.

15. The fluid regulator of claim 14, wherein the valve bonnet comprises a body portion and a head portion, the head portion movable relative to the body portion to modify a length of the spring cavity and a magnitude of the force applied by the biasing arrangement.

16. The fluid regulator of any preceding claim, wherein the biasing arrangement defines a first biasing arrangement disposed on a first side of the valve body, and the fluid regulator further comprises a second biasing arrangement disposed on an opposing second side of the valve body, the second biasing arrangement configured to bias the first and second valve members towards the closed position.

17. The fluid regulator of claim 16, wherein the second biasing arrangement comprises a first spring element configured to bias the regulator and auxiliary valve members towards the closed position, and a second spring element configured to bias the regulator valve member towards the closed position.

18. The fluid regulator of claim 17, wherein the first spring element is disposed in a first spring chamber, the first spring chamber in pressure communication with the outlet.

19. The fluid regulator of claim 17 or 18, wherein the second spring element is disposed in a second spring chamber, the second spring chamber in pressure communication with the inlet.

20. The fluid regulator of any preceding claim, comprising a baffle arrangement configured to restrain a flow of fluid entering the outlet chamber.

21. The fluid regulator of any preceding claim, wherein the fluid regulator is configurable to provide a pressure relief function allowing fluid from the outlet chamber to be vented from the fluid regulator.

22. The fluid regulator of claim 21, wherein the sensor element comprises a blind bore terminating in a radial bore, the blind and radial bores defining a relief flow path.

23. The fluid regulator of claim 21 or 22, when dependent on any one of claims 6 to 5 8, wherein the sensor element comprises a vent seat configured to engage theregulator connector during normal operation of the fluid regulator and to separate from the regulator connector when the fluid regulator is providing the pressure relief function.

24. The fluid regulator of claim 23, wherein the regulator and auxiliary connectors 10 comprise a movement limiter configured to limit movement of the regulator and auxiliary connectors towards the first biasing arrangement.

25. A method for regulating fluid pressure, comprising operating the fluid regulator of any preceding claim.

Images