Valve

Abstract

A valve (19.1) is described, comprising: a flow path connecting a housing inlet (42) and an outlet (44); a valve seat (48) positioned in the flow path; a closure member (50) displaceable between a closed position and an open position; and a throttling element (52) displaceable with the closure member. The throttling element includes an incremental cross-sectional area forward portion (70), a frustoconical rear portion (72), and an intermediate portion (74) sufficiently long such that the intermediate portion enters a guide portion (49) of the flow path prior to contact of the seal (56) with the valve seat. The throttling element is configured to gradually reduce the effective cross-sectional area of the flow path when the closure member is displaced from its open position toward its closed position.

Description

Technical Field

[0001] The present invention relates to a valve and to a method of operating a valve. More particularly, it relates to a valve and to a pressure exchange chamber ("PEC") pumping system using the valve. It also relates to a PEC pumping system kit and a valve closing unit. Background Art

[0002] Sometimes, when a valve is used to regulate the flow of a medium, particularly where a fluid flowing at high speed needs to be stopped quickly, the valve may be subject to considerable shock loads when it is closed. In some cases, these shock loads may be so severe that they may damage the integrity of the system of which the valve forms a part.

[0003] One application where this may occur is in a PEC pumping system. A PEC pumping system typically includes one or more pipes, each pipe having a medium or pumping fluid valve device at one end and a drive fluid valve device at the other end. The combination of each pipe and its associated valve constitutes a PEC.

[0004] Operating a PEC involves rapidly changing the pressure inside the PEC, which means that conventional devices for preventing shock loads (also known as water hammer), such as gas dampers, cannot be used.

[0005] Shock loads may occur in a PEC, for example, when the medium outlet valve and the actuating fluid inlet valve are closed once the medium has been discharged from the PEC and before the medium inlet valve and the actuating fluid outlet valve are opened to fill the PEC. Due to the high flow rate of the actuating fluid, the closing of the actuating fluid inlet valve (which stops the fluid flow) may result in a considerable hydraulic shock or pressure shock wave with potentially destructive consequences.

[0006] There are many other applications where valves are used to stop fluids flowing at high speeds where this problem could potentially arise.

[0007] It is an object of embodiments of the present invention to provide an apparatus which may at least ameliorate this problem or provide a useful alternative. Summary of the invention

[0008] This summary is provided to introduce some concepts that are further described below in the Detailed Description.This Summary is not intended to identify essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0009] In this application, ordinal numbers (first, second, third, etc.) are arbitrarily assigned herein and are used to distinguish between parts and do not indicate a particular order, sequence, or importance. Where possible, features described as options with respect to one aspect are intended to be applicable as options to all other aspects.

[0010] According to a first aspect of the present invention, a valve is provided, comprising: a housing; an inlet leading into the housing; an outlet, the outlet leading out of the housing at a position spaced apart from the inlet; a flow path, the flow path connecting the inlet and the outlet in a flow-connected manner; a valve seat, the valve seat being positioned in the flow path and comprising a frustoconical portion, the frustoconical portion having a wide end and a narrow end spaced apart longitudinally; a guide portion, the guide portion extending coaxially therewith away from the narrow end of the frustoconical portion; a closure member, the closure member being displaceable between a closed position inhibiting a medium from flowing through the flow path and an open position allowing the medium to flow through the flow path; and a throttling element, the throttling element being displaceable together with the closure member The throttling element is displaced from the front portion and is inserted into the guide portion when the closure member is displaced toward its closed position, the throttling element comprising (i) a front portion, the cross-sectional area of ​​which increases away from the front end of the throttling element for at least a portion of the length of the throttling element, (ii) a frustoconical rear portion complementary to the valve seat, and (iii) an intermediate portion, the intermediate portion extending between the front portion and the rear portion and being long enough so that the intermediate portion enters the guide portion of the flow path before the seal contacts the valve seat, thereby adjusting the effective cross-sectional area of ​​the flow path when the closure member is displaced from its open position toward its closed position, and reducing impact loads by gradually reducing the cross-sectional area of ​​the flow path.

[0011] The valve closure member optionally comprises an elastomeric seal having a frustoconical sealing surface which sealingly abuts against the valve seat in the closed position.

[0012] The guide portion may define a circular cross-section, an elliptical cross-section, a polygonal cross-section or any other convenient shape.

[0013] The valve may comprise an actuated valve and may comprise an actuator for displacing the closure member between its open and closed positions.

[0014] The valve seat may be annular and disposed about the flow path such that the flow path extends through (or through) therein.

[0015] The valve seat may include a surface of a housing that may be hardened (eg, by coating or infiltration with a hard material), or an insert.

[0016] The throttling element preferably extends through the valve seat and into a portion of the flow path adjacent thereto, thereby gradually reducing the area between the side of the flow path and the throttling element and effectively reducing the cross-sectional area of ​​the flow path.

[0017] The seal may be fixed to the throttling element and displaceable with the throttling element, the seal being positioned adjacent to and radially projecting beyond the rear portion of the throttling element such that a sealing surface of the seal contacts the valve seat before the rear portion of the throttling element. The seal may include an elastomeric material.

[0018] The dimensions of the closure member may be selected to achieve a desired throttling curve. In one embodiment, the diameter of the intermediate portion of the closure member is between 0.5 and 1 mm smaller than the diameter of the guiding portion of the flow path.

[0019] The guide portion may have a circular cylindrical shape. Alternatively, the guide portion may have a different shape.

[0020] According to a second aspect of the invention, there is provided a PEC pumping system comprising: at least one PEC having a medium valve arrangement at one end thereof and a drive fluid valve arrangement at an opposite end thereof, at least one of the valve arrangements comprising at least one valve of the above-mentioned type.

[0021] In a preferred embodiment, at least the actuating fluid inlet valve of the actuating fluid valve means is a valve of the above-mentioned type. Optionally, the actuating fluid outlet valve of the actuating fluid valve means is a valve of the above-mentioned type.

[0022] The PEC pumping system may include a plurality of PECs arranged in parallel, and a supply device including a supply pump having a suction side and a discharge side connected in flow communication with a medium inlet valve.

[0023] Components of the PEC pumping system can be shipped disassembled or in knock-down kits for assembly on site.

[0024] Therefore, according to a third aspect of the present invention, there is provided a PEC pumping system kit comprising the parts of the second aspect.

[0025] According to a fourth aspect of the present invention, there is provided a method for reducing impact loads in a flow path of a medium in a pressurized pumping system, the method comprising: (i) reducing the effective cross-sectional area of ​​the flow path to throttle the flow of the medium; (ii) substantially closing the flow path after reducing its effective cross-sectional area; and (iii) elastically sealing the flow path only after substantially closing the flow path.

[0026] The method may be implemented using a formed valve body and housing.

[0027] The step of reducing the effective cross-sectional area of ​​the flow path to throttle the medium flow can be achieved by inserting a front portion of a throttling element into a portion of the flow path. The throttling element can have a front end, a rear end, and the front portion extends from the front end toward the rear end and has an increased cross-sectional area for at least a portion of the length of the throttling element.

[0028] The step of substantially closing the flow path after reducing the effective cross-sectional area of ​​the flow path may be achieved by inserting an intermediate portion of the throttling element into the lower portion of the flow path, wherein the intermediate portion is only slightly smaller than the diameter of the lower portion of the flow path.

[0029] The middle portion may extend between the front portion and the rear portion.

[0030] The step of resiliently sealing the flow path only after substantially closing the flow path may be achieved using an elastomeric seal mounted over a frustoconical rear portion complementary to the valve seat and protruding laterally beyond the frustoconical rear portion. The lateral protrusion may comprise a radial protrusion.

[0031] Due to this aspect, the throttling function is separated from the sealing function and precedes the sealing function.

[0032] According to a fifth aspect of the present invention, there is provided a valve closing unit for use with a valve of the above-mentioned type, the valve having a hollow shell defining a first opening, a second opening spaced apart from the first opening, a flow path connecting the first opening and the second opening in a flow-connected manner, and a valve seat arranged in the flow path, the closing unit comprising a closing member and a throttling element, the closing member being configured to be sealingly seated against the valve seat, the throttling element having a front end and a rear end, the lateral cross-sectional area of ​​the front end of the throttling element being smaller than the lateral cross-sectional area of ​​the rear end, the throttling element being displaceable together with the closing member so that when the closing member is displaced toward its closed position, the throttling element extends through the valve seat and into a portion of the flow path adjacent thereto, thereby gradually reducing the area between the side of the flow path and the throttling element, and effectively gradually reducing the cross-sectional area of ​​the flow path.

[0033] According to a sixth aspect of the present invention, a valve is provided, comprising: a housing; an inlet leading into the housing; an outlet, the outlet leading out of the housing at a position spaced apart from the inlet; a flow path, the flow path connecting the inlet and the outlet in a flow-connected manner and comprising a frustoconical portion, the frustoconical portion having a wide end and a narrow end spaced apart longitudinally and a circular cylindrical portion, the circular cylindrical portion extending coaxially therewith away from the narrow end of the frustoconical portion; a valve seat, the valve seat being positioned in the flow path and comprising a frustoconical portion; a closing member, the closing member being displaceable between a closed position and an open position, in the closed position the closing member being seated against the valve seat to inhibit a medium from flowing through the flow path, and in the open position the closing member allowing a medium to flow through the flow path, the closing member comprising an elastomeric seal having a frustoconical sealing surface, the frustoconical sealing surface sealingly abutting against the valve seat in the closed position; and a throttling element, the throttling element having a front The throttling element has a front end and a rear end, the transverse cross-sectional area of ​​the front end of the throttling element is smaller than the transverse cross-sectional area of ​​the rear end, the throttling element can be displaced together with the closure member and is inserted into the circular cylindrical portion when the closure member is displaced toward its closed position, the throttling element comprising (i) a front portion, the cross-sectional area of ​​the front portion increases away from the front end for at least a portion of the length of the throttling element, (ii) a rear portion, the rear portion is truncated conical in shape and complementary to the valve seat, and (iii) a middle portion, the middle portion extending between the front portion and the rear portion and is circular cylindrical in shape, wherein the length of the middle portion of the throttling element is long enough so that the middle portion enters the circular cylindrical portion of the flow path before the seal contacts the surface of the valve seat; thereby adjusting the effective cross-sectional area of ​​the flow path when the closure member is displaced from its open position toward its closed position, and reducing the impact load by gradually reducing the area between the side of the flow path and the throttling element and effectively reducing the cross-sectional area of ​​the flow path. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] These and other aspects of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

[0035] Figure 1 A schematic diagram of a PEC pumping system according to an embodiment of the present invention is shown;

[0036] Figure 2 A sectional view of a portion of a valve according to another embodiment of the present invention is shown, wherein the valve is formed Figure 1 Part of the PEC pumping system;

[0037] Figures 3 to 7 Shows Figure 2 The valve of FIG. 1 is a cross-sectional view of the valve, and the closure member of the valve is shown in sequence from the drawing Figure 2 The partially opened position shown in the drawings Figure 7 displacement of its closed position as shown in ;

[0038] Figure 8 Shows Figure 2 a three-dimensional view of a portion of a closure member of a valve;

[0039] Fig. 9 Shows Figure 8 a side view of a portion of a closure member shown in; and

[0040] Fig.10 Shown on an enlarged scale Figure 2 part of the valve. DETAILED DESCRIPTION

[0041] In the attached figure Figure 1 1 , reference numeral 10 generally refers to a portion of a PEC pumping system according to an embodiment of the present invention.

[0042] The PEC pumping system 10 comprises three (PECs) 11.1, 11.2, 11.3, each PEC being defined by a fluid container which in this embodiment comprises a length of tubing 12, 14, 16, to one end of which a medium or pumping fluid valve device 18, 20, 22 is connected, respectively, and to the opposite end of which a drive fluid valve device 19, 21, 23 is connected, respectively. In this embodiment, the tubing 12, 14, 16 extends longitudinally, but other configurations are possible.

[0043] Each medium valve device 18, 20, 22 comprises a medium inlet valve 18.1, 20.1, 22.1, through which the medium to be pumped can be allowed to enter the associated pipeline 12, 14, 16, and a medium outlet valve 18.2, 20.2, 22.2, through which the pumped medium can be discharged from the pipeline 12, 14, 16 along the discharge pipeline (or standpipe) 24. Similarly, according to an embodiment of the present invention, each driving fluid valve device 19, 21, 23 comprises an inlet valve 19.1, 21.1, 23.1, through which the high-pressure driving fluid can be allowed to enter the associated pipeline, and an outlet valve 19.2, 21.2, 23.2, through which the driving fluid can be discharged from the associated pipeline.

[0044] The PEC pumping system 10 also includes a supply device, a portion of which is generally indicated by reference numeral 26, which is configured to supply the medium to be pumped to the medium inlet valves 18.1, 20.1, 22.1. The supply device 26 includes a supply or delivery pump (not shown) having a suction side and a discharge side. The supply pump is typically a centrifugal pump. The supply device 26 also includes a pipeline 32 connected to a source of the medium, and three supply lines 35, 36, 37, each of which has an upstream end and a downstream end connected to the pipeline 32. The downstream ends of the supply lines 35, 36, 37 are connected to the medium inlet valves 18.1, 20.1, 22.1, respectively. In use, the medium to be pumped is delivered through the pipeline 32 and the supply lines 35, 36, 37 to the medium inlet valves 18.1, 20.1, 22.1.

[0045] In use, with the medium inlet valve 18.1, 20.1, 22.1 open and the corresponding drive fluid outlet valve 19.2, 21.2, 23.2 open, the medium enters the associated pipeline 12, 14, 16 and causes the drive fluid to be removed from the pipeline through the associated drive fluid outlet valve 19.2, 21.2, 23.2. When the desired amount of medium has entered the pipeline, the medium inlet valve and the drive fluid outlet valve are closed. The medium outlet valve 18.2, 20.2, 22.2 and the drive fluid inlet valve 19.1, 21.1, 23.1 are opened so that the high pressure drive fluid enters the pipeline and causes the medium to be removed from the pipeline through the medium outlet valve 18.2, 20.2, 22.2 and enter the discharge pipeline 24.

[0046] Once the medium has been discharged from the pipeline, the associated medium outlet valve and actuating fluid inlet valve are closed and the medium inlet valve and actuating fluid outlet valve are opened again in the manner described above to fill the pipeline with medium.

[0047] In order to allow more or less continuous pumping, the operation of the valves of the different PECs 11.1, 11.2, 11.3 is staggered so that filling the PECs 11.1, 11.2, 11.3 with medium and draining the medium takes place in a more or less continuous manner.

[0048] Each of the actuating fluid inlet valves 19.1, 21.1, 23.1 is substantially identical. For the sake of brevity of description, only the actuating fluid inlet valve 19.1 is described in detail below. In one embodiment of the present invention, the actuating fluid outlet valves 19.2, 21.2, 23.2 have a similar configuration to the actuating fluid inlet valves 19.1, 21.1, 23.1, and therefore the following description of valve 19.1 also applies to valves 19.2, 21.2, 23.2.

[0049] Now refer to the accompanying drawings Figures 2 to 10, the valve 19.1 includes a housing, a portion of which is shown in the drawings and generally indicated by reference numeral 40. An inlet 42 leads into the housing 40, an outlet 44 leads out of the housing 40 at a position spaced apart from the inlet, and a flow path (a major portion of which is generally indicated by dashed arrow 46) extends through the housing 40 and connects the inlet 42 and the outlet 44 in a flow communication manner, as described in more detail below. Arrow 46 shows flow in one direction; in other embodiments, flow can be in a direction opposite to the direction shown by arrow 46.

[0050] The valve 19.1 further comprises a valve seat, generally indicated by reference numeral 48, positioned between the inlet 42 and the outlet 44, and a closure member, generally indicated by reference numeral 50, which can be in a closed position (Fig. Figure 7 46, and an open position in which the inlet 42 and the outlet 44 are connected in a flow communication manner to allow the medium to flow through the flow path 46. In one embodiment of the present invention, the valve seat 48 can be formed by a hardened surface in the housing 40. In another embodiment shown in the drawings, the valve seat 48 is formed by an insert 51, which helps replace the worn valve seat 48.

[0051] The valve 19.1 also comprises a throttling device, generally indicated by reference numeral 52, which, as described in more detail below, is configured to reduce the effective cross-sectional area of ​​the flow path 46 when the closure member 50 is displaced from its open position towards its closed position. When the closure member 50 is closed, another flow path in the other valve has been opened, so that the flow rate of the medium through the valve 19.1 is reduced without generating any (or any significant) water hammer effect.

[0052] The housing insert 51 defines two portions of the flow path 46. The first portion is defined by the annular valve seat 48, which is frustoconical in shape (extending from a narrow end 48.1 to a wide end 48.2, at Figure 2 and the second portion of the flow path 46 defined by the housing insert 51 is a guide portion 49 which in this embodiment is a round cylindrical shape and has the same diameter as the narrow end 48.1 of the valve seat 48 and extends away from the narrow end. In this embodiment, the guide portion 49 is located at the lower portion of the flow path 46.

[0053] The closure member 50 comprises an annular seal 56 having a frustoconical sealing surface 58 of complementary shape to the surface of the valve seat 48. In this embodiment, the annular seal 56 comprises an elastomeric material.

[0054] The throttle device 52 includes a throttle element, which is generally indicated by reference numeral 60. The seal 56 is sandwiched between the throttle element 60 and the annular retaining member 62. An axially extending stud bolt 64 extends through the retaining member 62 and the throttle element 60, and a nut (or other fixing element) is mounted on the end portion of the stud bolt 64 to push the throttle element 60 and the retaining member 62 toward each other and thereby fix the seal 56 in place. The throttle element 60, the seal 56 and the retaining member 62 together form a valve closing unit generally indicated by reference numeral 65.

[0055] The stud bolt 64 is typically connected to an actuator, such as a hydraulically actuated piston and cylinder arrangement (not shown), whereby the valve closure unit 65 can be displaced between an open position in which the seal 56 is away from the valve seat 48 and a closed position in which the sealing surface 58 abuts the valve seat 48.

[0056] In this embodiment, the closure member 50 and the throttle element 60 comprise two parts of an integral component, but in other embodiments separate components coupled to each other may be provided.

[0057] The throttle element 60 has a front end 66 and a rear end 68 .

[0058] The throttle element 60 includes a front portion 70 (at Figure 8 and 9 ), for part of the length of the throttling element 60, the diameter of the front portion, and therefore the cross-sectional area, increases away from the front end 66. In addition, the throttling element 60 includes a rear portion 72 of frustoconical shape, and the diameter of the rear portion decreases away from the rear end 68 of the throttling element 60. The throttling element 60 includes an intermediate portion 74, which in this embodiment is of circular cylindrical shape (in other embodiments, it can have a different shape) and extends between the front portion 70 and the rear portion 72. The rear portion 72 is complementary in shape to the valve seat 48. In particular, the angle of the rear portion 72 is selected to ensure that there is a large contact area with the seat 48 when the valve closing unit 65 is in the closed position (at least before any wear of the rear portion 72 or the seat 48).

[0059] In use, when the closure member 50 is in its open or partially open position ( Figure 21 ), the throttling element 60 leaves the valve seat 48, allowing a more or less unrestricted flow through the flow path 46 between the inlet 42 and the outlet 44. However, when the closure member 50 is displaced towards its closed position, the front part 70 of the throttling element 60 enters the guide part 49 of the flow path 46, effectively reducing the cross-sectional area of ​​the flow path 46 and restricting the flow of the medium through the flow path 46. When the closure member 50 advances towards its closed position, the throttling element 60 is further inserted and further enters the guide part 49, and due to the increased diameter of the front part 70 of the throttling element 60, the annular space between the throttling element 60 and the guide part 49 is gradually reduced, thereby reducing the effective cross-sectional area of ​​the flow path 46, and thus gradually reducing the flow rate of the medium through the valve 19.1. Therefore, the throttling element 60 and the guide part 49 together form a throttling device 52.

[0060] As shown in the attached figure Fig.10 As can be best seen in FIG. 1 , the seal 56 projects radially beyond the frustoconical surface of the rear portion 72 of the throttling element 60 so that the sealing surface 58 contacts the surface of the valve seat 48 before the throttling element 60 when the closure member 50 approaches its closed position. Fig.10 The extent to which the seal protrudes beyond the frustoconical surface of the throttling element, indicated by the letter G in FIG. 4 , is limited to approximately 1-4 mm in order to reduce the risk of extrusion of the seal 56 between the opposing surfaces of the throttling element 60 and the valve seat 48 .

[0061] The diameter of the circular cylindrical middle portion 74 of the throttling element 60 is only slightly smaller, for example about 0.5-1 mm smaller, than the diameter of the circular cylindrical portion 49 of the flow path, so that maximum throttling occurs when the middle portion 74 enters the circular cylindrical portion 49 of the flow path.

[0062] The rate at which the medium flow rate is reduced can also be controlled by adjusting the speed at which the closure member is displaced toward its closed position and / or by changing the shape of the throttling element 60 .

[0063] The specific dimensions of the valve will be selected to obtain the desired performance characteristics. Thus, as an example, in the embodiment shown, the guide portion 49 has a diameter E of 74 mm. The front end 66 of the front portion 70 has a diameter A of 70 mm. The diameter B of the middle portion is typically between 0.5 and 1 mm smaller than E, i.e., 73-73.5 mm. The front portion 70 has a length C of 40 mm. The middle portion has a length D of 10 mm. Naturally, the dimensions of the valve may vary depending on the intended application.

[0064] By gradually reducing the cross-sectional area of ​​the flow path 46 before the closure member 50 reaches its closed position, the risk of hydraulic shock in high flow rate applications is prevented.

[0065] By including a circular cylindrical portion 74 that is only slightly narrower than the guide portion 49 and extends axially, there is a defined length where the cross-sectional area is constant. This ensures that when the valve 19.1 is closed there is a constant minimum cross-sectional area just prior to closing and sealing.

[0066] Although the valve described is a driving fluid inlet valve, it will be appreciated that the valve may be used for any other application, such as being used as a driving fluid outlet valve. In addition, in other applications, the direction in which the medium flows through the valve may be in the opposite direction, in which case the inlet and outlet will be reversed.

[0067] In other embodiments, the guide portion 49 may have a shape different from that described above. In other embodiments, the housing insert 51 may be an integral part of the housing 40 and contained within the housing, rather than a separate part.

[0068] It should be understood that the PEC pumping system may be first constructed according to embodiments of the present invention. The components of the PEC pumping system may be shipped in disassembled or kit form for assembly on site.

[0069] Alternatively, existing PEC pumping systems may be modified by replacing one or more valves with valves according to embodiments of the present invention.

[0070] Reference numerals list

[0071] Pressure Exchange Chamber (PEC) Pumping System 10

[0072] PEC 11.1, 11.2, 11.3

[0073] Pipeline 12, 14, 16

[0074] Medium valve devices 18, 20, 22

[0075] Medium inlet valve 18.1, 20.1, 22.1

[0076] Medium outlet valve 18.2, 20.2, 22.2

[0077] Driving fluid valve devices 19, 21, 23

[0078] Driving fluid inlet valve 19.1, 21.1, 23.1

[0079] Drive fluid outlet valve 19.2, 21.2, 23.2

[0080] Discharge pipe 24

[0081] Supply device 26

[0082] Pipeline 32

[0083] Supply lines 35, 36, 37

[0084] Housing 40

[0085] Entrance 42

[0086] Exit 44

[0087] Flow path 46

[0088] Valve seat 48

[0089] Seat narrow end 48.1

[0090] Guide (circular cylindrical) portion 49

[0091] Closing member 50

[0092] Housing insert 51

[0093] Throttling device 52

[0094] Seal 56

[0095] Sealing surface 58

[0096] Throttle element 60

[0097] Holding member 62

[0098] Stud bolt 64

[0099] Valve closing unit 65

[0100] Front end 66

[0101] Backend 68

[0102] Front section 70

[0103] Rear section 72

[0104] Middle section 74

[0105] AThe diameter of the front end 66

[0106] B Diameter of the middle portion 74

[0107] C The length of the front part 70

[0108] D The length of the middle portion 74

[0109] E The diameter of the guide portion 49

[0110] G seal protrusion

Claims

1. A valve, comprising: case; an inlet leading into the housing; an outlet leading from the housing at a location spaced apart from the inlet; a flow path connecting the inlet and the outlet in flow communication; a valve seat positioned in the flow path and comprising a frustoconical portion having a wide end and a longitudinally spaced narrow end; a guide portion extending coaxially therewith away from a narrow end of the frustoconical portion; a closure member displaceable between a closed position inhibiting the flow of a medium through the flow path and an open position allowing the flow of a medium through the flow path; as well as a throttle element which is displaceable together with the closure member and which is inserted into the guide portion when the closure member is displaced towards its closed position, the throttle element comprising (i) a front portion, the cross-sectional area of ​​which increases away from the front end of the throttle element for at least a portion of the length of the throttle element, (ii) a frustoconical rear portion complementary to the valve seat, and (iii) an intermediate portion extending between the front portion and the rear portion and being long enough so that the intermediate portion enters the guide portion of the flow path before the seal contacts the valve seat, Thereby, the effective cross-sectional area of ​​the flow path is adjusted when the closure member is displaced from its open position toward its closed position, and the impact load is reduced by gradually reducing the cross-sectional area of ​​the flow path.

2. A valve according to claim 1, wherein the closure member includes an elastomeric seal having a frustoconical sealing surface, which sealingly abuts against the valve seat in the closed position, and the seal is positioned adjacent to the rear portion of the throttling element and protrudes radially beyond the rear portion of the throttling element so that the surface of the seal contacts the valve seat before the rear portion of the throttling element.

3. A valve according to any one of claims 1 or 2, wherein the guide portion defines a circular cross-section.

4. The valve according to any one of claims 1 to 3, wherein the diameter of the intermediate portion of the closure member is between 0.5 and 1 mm smaller than the diameter of the guide portion of the flow path.

5. A pressure exchange chamber pumping system, comprising: At least one pressure exchange chamber having a medium valve arrangement at one end thereof and a drive fluid valve arrangement at the opposite end thereof, at least one of said valve arrangements comprising at least one valve according to any one of claims 1 to 4.

6. The pressure exchange chamber pumping system according to claim 5, wherein at least the actuating fluid inlet valve of the actuating fluid valve device is a valve according to any one of claims 1 to 4.

7. The pressure exchange chamber pumping system according to claim 5 or 6, comprising a plurality of pressure exchange chambers arranged in parallel.

8. A method of reducing shock loads in a flow path of a medium in a pressurized pumping system, the method comprising: (i) reducing the effective cross-sectional area of ​​the flow path to throttle the medium flow; (ii) substantially closing the flow path after reducing the effective cross-sectional area of ​​the flow path; (iii) elastically sealing the flow path only after substantially closing the flow path.

9. The method according to claim 8, wherein the step of reducing the effective cross-sectional area of ​​the flow path to throttle the flow of the medium is achieved by inserting a front portion of a throttling element into a portion of the flow path.

10. The method of claim 9, wherein the step of substantially closing the flow path after reducing the effective cross-sectional area of ​​the flow path is accomplished by inserting an intermediate portion of the throttling element into a lower portion of the flow path, wherein the intermediate portion is only slightly smaller than a diameter of the lower portion of the flow path.

11. A method according to any one of claims 8 to 10, wherein the step of elastically sealing the flow path only after substantially closing the flow path is achieved using an elastomeric seal mounted over a frustoconical rear portion complementary to the valve seat and projecting radially therefrom.

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