valve

Abstract

A valve is described that includes a housing (20), a flow path connecting an inlet and an outlet in flow communication, a valve seat (28) positioned within the flow path, and a valve body displaceable between a closed position and an open position. The valve body includes a resiliently deformable elastomeric seal (38) having (i) a contact surface (74) complementary to and abutting the valve seat, and (ii) a protrusion (84) extending radially outward at an upper portion of the protrusion. The valve also has a retainer with an inwardly projecting lip defining a recess for receiving the protrusion therein to assist in lifting the elastomeric seal.

Description

[Technical Field]

[0001] The present invention relates to valves, and more particularly to valves and pumping systems employing the valves. [Background technology]

[0002] One type of valve includes an annular valve seat and a valve body displaceable between an open position, which allows the flow of a medium through the valve, and a closed position, which prevents the flow of a medium through the valve. The valve body includes a complementary shaped annular contact surface that abuts against the valve seat when the valve body is in its closed position. In certain applications, the complementary surfaces of the valve seat and valve body are formed of metal. In some applications, an elastomeric valve ring is mounted on the valve body and seals against the valve seat when the valve is in the closed position.

[0003] While this arrangement generally works well, problems can arise when the valve body must open under large pressure differentials, as can occur for actuated valves. When the pressure on the side of the valve body with the elastomeric annulus is significantly higher (e.g., 1 MPa (10 bar) or greater) than the pressure on the side of the valve body opposite the elastomeric annulus, as the valve body displaces away from its closed position toward its open position, the pressure differential across the elastomeric annulus tends to urge it toward the valve seat and deform (stretch or extrude) to remain in contact with the seat, giving the impression of being "sticky" to the seat. This extrusion can lead to damage to the elastomeric annulus or, in some cases, partial or complete detachment from the valve body. This can also adversely affect the operation of the valve and the lifespan of the elastomeric annulus. The magnitude of the pressure differential that causes problems can depend on the size of the elastomeric annulus and the pulling force applied to the actuated valve body to open the valve.

[0004] One application where this can potentially occur is in pressure exchange chamber ("PEC") pumping systems, where an actuated valve may have to open despite a large pressure differential across the valve (e.g., 1 MPa (10 bar) or more). A PEC pump system typically includes one or more pipes, each of which has a media or pumped fluid valve arrangement at one end and a drive fluid valve arrangement at the other end. The combination of each pipe and its associated valve defines a PEC.

[0005] There are numerous other applications where valves are used to regulate the flow of media in high pressure applications where this problem could potentially arise. For example, another application where this could occur is in hydraulically driven positive displacement pumps that use actuated valves. You may have applications where check valves are used.

[0006] It is an object of one embodiment of the present invention, among other things, to provide a means that may at least ameliorate this problem, or to provide a useful alternative. Summary of the Invention [Means for solving the problem]

[0007] This Summary is provided to introduce a selection of 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.

[0008] In this application, sequence numbers (first, second, third, etc.) are assigned arbitrarily herein and are used to distinguish components and do not indicate a particular order, sequence, or importance.

[0009] According to a first aspect of the present invention, there is provided a valve comprising: a housing; an inlet leading into the housing; an outlet leading from the housing at a location spaced from the inlet; a flow path connecting the inlet and the outlet in flow communication; a valve seat positioned within the flow path; and a valve body displaceable between a closed position that inhibits flow of a medium through the flow path and an open position that permits flow of a medium through the flow path, the valve body including an elastomeric seal having (i) a contact surface that is complementary to and abuts the valve seat when the valve body is in its closed position, and (ii) a protrusion extending radially outward at an upper portion of the protrusion; and a retainer having an inwardly projecting lip that defines a recess for receiving the protrusion to assist in lifting the elastomeric seal, thereby minimizing or preventing sticking or deformation thereof when the valve body is displaced away from its closed position toward its open position.

[0010] The valve may include an actuator by which the valve body is displaceable between its open and closed positions. Optionally, the actuator may be moved hydraulically, pneumatically, or electrically. One suitable example is a linear hydraulic actuator.

[0011] The valve seat may comprise an integral part of a support (such as a housing) or a removable part that can be replaced when worn.

[0012] The valve seat may be annular and may be disposed around the flow path, such that the flow path extends through the valve seat. When the valve body is in a closed position, the valve seat may have a higher pressure side and a lower pressure side, and the diameter of the valve seat may decrease from the higher pressure side to the lower pressure side for at least a portion of its length. In one embodiment, the valve seat is frusto-conical in shape and has a constant angle of taper from its higher pressure side to its lower pressure side. When the valve is open, both sides of the valve seat may have higher pressure at any given time.

[0013] The valve body may include an engagement portion having an annular sealing surface (optionally frusto-conical in shape) that is complementary to and configured to sealingly abut against the valve seat when the valve body is in its closed position.

[0014] An elastomeric seal may be mounted on the mating portion.

[0015] The valve body (eg, an elastomeric seal) may include a cap portion and a tapered portion extending from the cap portion to the contact surface.

[0016] The retainer may form part of a piston connected to the cap portion, and the piston may be connected to the cap portion at an end of the elastomeric seal opposite the annular sealing surface.

[0017] The piston may extend laterally beyond the annular sealing surface of the engagement portion.

[0018] The lip may include a radially inward protrusion extending toward the central bore at least 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 25% of the distance from the outer surface of the piston toward the center of the elastomeric seal (e.g., the centerline of the central bore). In some embodiments, the protrusion may extend between 5% and 30% of the distance from the outer surface of the piston to the central bore.

[0019] The engaging portion may define a seal support surface against which an inner contact surface of the elastomeric seal rests, and the seal support surface may have a frusto-conical shape that widens as it extends toward the annular seal (optionally, the inner contact surface of the elastomeric seal is frusto-conical and disposed opposite thereto).

[0020] The retainer recess, the engaging portion seal support surface, and the inner contact surface of the elastomeric seal may combine to resist deformation of the elastomeric seal as the valve body moves from the closed position to the open position.

[0021] The contact surface of the elastomeric seal optionally protrudes laterally beyond the annular sealing surface of the engagement portion. This arrangement allows the contact surface of the elastomeric seal to contact the valve seat before the valve body reaches its fully closed position, where the annular sealing surface contacts the valve seat. Further displacement of the valve body toward its fully closed position results in deformation of the elastomeric seal and in contact of the annular sealing surface with the valve seat. Thus, the provision of the elastomeric seal (protruding laterally beyond the annular sealing surface) will impede the flow of medium through the valve, even if solid particles become trapped between the annular sealing surface and the valve seat, thereby preventing the valve body from displacing to its fully closed position.

[0022] The end of the cap portion optionally projects beyond the contact surface of the elastomeric seal.

[0023] The retainer may have any other convenient shape or configuration, for example, it may comprise an elongated instrument threaded or otherwise secured within the elastomeric seal.

[0024] According to a second aspect of the present invention, there is provided a closure device for sealing against a valve seat, the closure device comprising: (i) an engagement portion defining: (a) a sealing surface configured to be complementary to and sealingly abut against the valve seat when the closure device is in a closed position; and (b) a seal support surface; (ii) an elastomeric seal having a contact surface mounted on the seal support surface and configured to sealingly abut against the valve seat adjacent the engagement portion sealing surface; and (iii) a piston coupled to the engagement portion and comprising a retainer, wherein the elastomeric seal is held by the engagement portion and the retainer to resist displacement of the elastomeric seal when the closure device is displaced away from its closed position toward its open position.

[0025] The piston may facilitate lateral displacement of the elastomeric seal as the closure device is displaced from its open position to its closed position.

[0026] The engagement portion and the elastomeric seal may comprise a valve body.

[0027] The elastomeric seal may define an annular contact surface.

[0028] The contact surface of the elastomeric seal optionally projects laterally beyond the sealing surface of the engagement portion so that the contact surface contacts the valve seat before the sealing surface when the valve body is displaced toward its closed position.

[0029] The sealing surface optionally comprises an annular sealing surface.

[0030] The annular sealing surface optionally comprises a frusto-conical shape complementary to the frusto-conical shape of the valve seat.

[0031] The piston may define a body portion and an exterior sidewall projecting beyond the body portion, and the retainer may extend laterally inward from the exterior sidewall toward the engagement portion and may define a recess between an interior surface of the retainer and the body portion.

[0032] The elastomeric seal may define an annular tongue (or protrusion) that extends laterally (or radially) beyond a side portion of the elastomeric seal, which may extend from below the annular protrusion to the contact surface.

[0033] According to a third aspect of the present invention, there is provided an elastomeric seal for use in a valve, the elastomeric seal including: an annular body having a seat end, an actuation end, and a centrally located bore extending through the body between the ends; an annular contact surface at the seat end configured to sealingly abut against the valve seat; and a retention formation defined at or toward the actuation end of the body for engaging a retainer.

[0034] The retention formation may comprise an annular protrusion (such as a tongue).

[0035] The elastomeric seal may be formed as an indegradable, single molding of elastomeric material such as polyurethane rubber. Depending on the liquid and temperature used, any other convenient elastomeric material may be used, such as styrene-butadiene rubber (SBR), polyurethane rubber (PUR), ethylene propylene diene monomer (EPDM) rubber, fluoroelastomer (FKM) rubber, nitrile butadiene rubber (NBR), or hydrogenated acrylonitrile butadiene rubber (HNBR).

[0036] The annular contact surface may be frusto-conical in shape, with the diameter of the contact surface increasing away from the seat edge.

[0037] According to a fourth aspect of the present invention, there is provided a PEC pumping system comprising at least one PEC; a media valve arrangement at one end of the PEC and a drive fluid valve arrangement at an end of the PEC opposite the media valve arrangement, at least one of the valve arrangements comprising at least one valve of the types described above.

[0038] According to a fifth aspect of the present invention, there is provided an elastomeric seal for use in a valve, the elastomeric seal including: an annular body having a seat end, an actuation end, and a centrally located bore extending through the body between the ends; an annular contact surface at the seat end configured to sealingly abut against the valve seat; and a retention formation defined at or toward the actuation end of the body for engaging a retainer.

[0039] Features of one of the above aspects may be combined with other aspects.

[0040] These and other aspects of the invention will now be described, by way of example, with reference to the accompanying schematic drawings. [Brief explanation of the drawings]

[0041] [Figure 1] FIG. 1 shows an axial cross-sectional view of a portion of a valve according to one embodiment of the present invention. [Figure 2]FIG. 2 shows a cross-sectional view of a portion (an elastomeric seal) of the valve of FIG. 1 according to another embodiment of the present invention. [Figure 3A] FIG. 3A shows an enlarged portion of the valve of FIG. [Figure 3B] FIG. 3B shows a more enlarged detail of FIG. 3A. [Figure 3C] FIG. 3C shows a detail of FIG. 3B, with a portion (the elastomer seal) removed for clarity. [Figure 4] 4 to 8 show cross-sectional views of the valve of FIG. 1, illustrating successive displacements of the valve body of the valve from the partially open position shown in FIG. 1 of the drawings to its closed position shown in FIG. 6 of the drawings. [Figure 5] 4 to 8 show cross-sectional views of the valve of FIG. 1, illustrating successive displacements of the valve body of the valve from the partially open position shown in FIG. 1 of the drawings to its closed position shown in FIG. 6 of the drawings. [Figure 6] 4 to 8 show cross-sectional views of the valve of FIG. 1, illustrating successive displacements of the valve body of the valve from the partially open position shown in FIG. 1 of the drawings to its closed position shown in FIG. 6 of the drawings. [Figure 7] 4 to 8 show cross-sectional views of the valve of FIG. 1, illustrating successive displacements of the valve body of the valve from the partially open position shown in FIG. 1 of the drawings to its closed position shown in FIG. 6 of the drawings. [Figure 8] 4 to 8 show cross-sectional views of the valve of FIG. 1, illustrating successive displacements of the valve body of the valve from the partially open position shown in FIG. 1 of the drawings to its closed position shown in FIG. 6 of the drawings. [Figure 9A] FIG. 9A shows an enlarged cross-sectional view of a portion of the valve body of the valve of FIGS. 1-8 with the elastomeric seal in place. [Figure 9B] FIG. 9B shows an enlarged cross-sectional view of a portion of the valve body of the valve of FIGS. 1-8 with the elastomeric seal removed. [Figure 10] FIG. 10 illustrates diagrammatically the pressure differential across the elastomeric seal when the valve body of the valve is in its closed position. DETAILED DESCRIPTION OF THE INVENTION

[0042] Reference is now made to the drawings, in which reference numeral 10 designates a valve according to one embodiment of the present invention. Valve 10 includes a housing, a portion of which is shown in the drawings and generally designated by reference numeral 20. A first fluid port 22 (in this embodiment, an inlet) and a second fluid port 24 (in this embodiment, an outlet) are each defined by housing 20, and a flow path, generally designated by reference numeral 26, extends through housing 20 and connects fluid ports 22, 24 in flow communication, as described in more detail below. However, in other embodiments, first fluid port 22 may be used as an outlet and second fluid port 24 may be used as an inlet.

[0043] The valve 10 further includes a valve seat, generally designated by the reference numeral 28, which is positioned between the two fluid ports 22, 24. In one embodiment, the valve seat 28 may be formed by a hardened surface within the housing. In another embodiment shown in the drawings, the valve seat 28 is formed by an insert mounted on the housing 20, which facilitates replacement of the valve seat 28 when worn.

[0044] A housing sleeve 29 is provided above the valve seat 28 and includes an opening that defines the first fluid port 22. The housing sleeve 29 maintains the valve seat 28 in place by biasing the valve seat 28 into the housing 20. The housing sleeve 29 is a wear part that is replaceable when worn by solid particles in the medium conveyed through the valve 10.

[0045] Valve seat 28 is an annular seat and defines a portion of flow path 26. Valve seat 28 is frusto-conical in shape and, as is typical for valve seats, has a narrow end 30 and a wider end 32. In other embodiments, valve seat 28 may have a non-traditional shape.

[0046] A closure device 34 is provided to open away from and close against the valve seat 28, thereby opening and closing the flow path 26. The closure device 34 includes an engagement portion 36, an elastomeric seal 38 mounted on the engagement portion 36, and a piston 40 coupled to both the engagement portion 36 and the elastomeric seal 38. The combination of the engagement portion 36 and the elastomeric seal 38 may be referred to as a valve body 42.

[0047] Engagement portion 36 defines a frustoconical annular seal (or sealing) surface 44 that is configured to complement and sealingly abut valve seat 28 when valve body 42 is in its closed position. Seal surface 44 may have any convenient shape, but is preferably complementary to the shape of valve seat 28. In this embodiment, seal surface 44 is frustoconical. Engagement portion 36 has a metal (or alloy) composition in this embodiment, but may have a different composition (including, for example, ceramic) in other embodiments.

[0048] The engagement portion 36 also defines a seal support surface 46 upon which the elastomeric seal 38 is seated (e.g., by adhesive or as an interference fit). The seal support surface 46 has a frusto-conical shape that widens as it extends toward the annular sealing surface 44 (opposite to the frusto-conical shape of the sealing surface 44). The narrow end of the seal support surface 46 merges with a circular flange 48 from which a cylindrical sleeve 50 extends axially. The engagement portion 36 also defines a central bore 52 extending axially therethrough and leading to an enlarged cavity 53 (also defined by the engagement portion 36) having an opening at the opposite end of the piston 40.

[0049] The piston 40 is generally cylindrical and defines a narrow central bore 54 (of the same or very similar diameter as the central bore 52 of the engagement portion) and a wider central bore 56 that accommodates the cylindrical sleeve 50 of the engagement portion 36.

[0050] 2, elastomeric seal 38 includes an annular body 60 having a generally planar piston end 62 for coupling to piston 40 and a valve seat end 64 for coupling to valve seat 28. Body 60 defines a contoured central opening 66 extending therethrough and defining (i) a cylindrical piston portion 68 sized to fit around cylindrical sleeve 50 and to provide a relatively small expansion gap 69 (best seen in FIG. 9A ) therebetween to permit deformation of elastomeric seal 38 into the expansion gap during operation, and (ii) a frustoconical seat portion 70 (beneath cylindrical piston portion 68) having an internal frustoconical contact surface 72 sized to fit around seal support surface 46 of engagement portion 36 and optionally secured thereto by an adhesive. The annular body 60 also includes an outer frustoconical contact surface 74 (which tapers in the opposite direction from the inner frustoconical contact surface 72) that is sized to sealingly abut against the valve seat 28 when the valve body 42 is in the closed position.

[0051] A generally planar annular flange engagement surface 76 extends between the cylindrical piston portion 68 and the frusto-conical valve seat portion 70. The flange engagement surface 76 rests on the circular flange 48 of the engagement portion 36.

[0052] The annular body 60 further includes a tapered sidewall 80 that extends from above the outer frustoconical contact surface 74 below the cap portion 82 at the piston end 62, such that the cap portion 82 forms a protrusion 84 that extends laterally beyond the tapered sidewall 80. In this embodiment, the cap portion 82 is generally disk-shaped.

[0053] The distance from the periphery of contoured central opening 66 to the outer edge of cap portion 82 is labeled Dc in Figures 2 and 9A. As best seen in Figures 3A-3C (which are enlarged views of a portion of Figure 1) and also in Figure 9B, piston 40 further includes body 90 having an outer surface 92 and a generally planar elastomeric engagement surface 94 on a lower portion of body 90 and extending substantially the entire diameter of body 90. The lower portion of outer surface 92 extends axially beyond engagement surface 94 to form collar 95, which then projects radially inward toward central bore 54 to form lip 96, which terminates in an annular portion 98.

[0054] A recess 99 is defined between the engagement surface 94 , the collar 95 and the inwardly projecting lip 96 .

[0055] In this embodiment, lip 96 extends approximately 10% of the radius of cylindrical body 90. In other embodiments, lip 96 may extend 5% to 30% of the distance from outer surface 92 to central bore 54. Lip 96 acts as a retainer to grip cap portion 82, thereby holding elastomeric seal 38 in place.

[0056] In this embodiment, the inwardly projecting lip 96 is generally parallel to the engagement surface 94 and transverse (and in some embodiments perpendicular) to the longitudinal axis 100 of the central bore 54 .

[0057] In this embodiment, recess 99 is generally C-shaped with an opening facing (ie, opening toward) longitudinal axis 100 , and collar 95 circumferentially surrounds cap portion projection 84 .

[0058] 9B (in which elastomeric seal 38 is not shown), circular flange 48 and lip annulus 98 are separated by a distance Dg that is less than distance Dc. The combination of circular flange 48 and lip 96 provides support to elastomeric seal 38 that prevents or reduces its extrusion during valve opening and thereby prevents (or at least significantly reduces) the likelihood of elastomeric seal 38 pulling away from lip 96 when the valve is opened.

[0059] In some embodiments, Dg is less than 90% of Dc, in other embodiments, Dg is less than 85% of Dc, and in other embodiments, Dg is less than 80% of Dc.

[0060] The radius of cap protrusion 84 and the height of cap portion 82 are selected to be slightly smaller than the length and height of recess 99 (best seen in FIG. 9A ), so that cap portion 82 preferably fits easily within recess 99 when positioned therein and defines a lip extension cavity 102 (best seen in FIG. 9A ) between cap portion 82 and collar 95. This allows for deformation of cap portion 82 into recess 99. Fluid communication channels (not shown) may be provided in piston 40 (e.g., as external grooves and as internal openings) to allow fluid to fill any space between cap portion 82 and recess 99 and to allow passage of fluid from lip extension cavity 102 or expansion spacing 69 to the external groove.

[0061] Closure device 34 is assembled as follows: cap portion 82 of elastomeric seal 38 is inserted into recess 99 of piston 40 until it is firmly gripped in place (this may involve temporary deformation of cap portion 82). Engagement portion 36 is then inserted into the elastomeric seal 38 and piston 40 combination. This brings seal support surface 46 into contact with internal frustoconical contact surface 72 and also brings planar elastomeric engagement surface 94 into full contact with the top surface of cap portion 82. Circular flange 48 is also typically brought into contact with flange engagement surface 76. A threaded rod (or stud bolt) 110 is placed through the aligned bores 52 of the engagement portion 36 and the aligned bores 54 of the piston 40 and is secured in place by one or more nuts (or other fastening elements) 112 mounted on the end portions of the threaded rod 110 within the enlarged cavity 53 to urge the engagement portion 36 and the combination of the elastomeric seal 38 and piston 40 toward each other, thereby sandwiching the elastomeric seal 38 between the engagement portion 36 and the piston 40.

[0062] The outer frustoconical contact surface 74 of the elastomeric seal 38 is sized to protrude beyond a line extrapolated from the sealing surface 44 (best seen in FIG. 9 ) so that when the valve body 42 is displaced toward its closed position, the outer frustoconical contact surface 74 contacts the surface of the valve seat 28 before the sealing surface 44 of the engagement portion 36 contacts the valve seat 28.

[0063] The closure device 32 is movable along a central bore axis 100 to move the valve body 42 between a fully open position (see FIG. 1) and a fully closed position (see FIG. 8), and is a precision fit with the low-friction housing sleeve 29. Movement of the closure device 32 is accomplished by linear displacement of a threaded rod 110 that is typically connected to a linear hydraulic actuator (not shown), although other displacement mechanisms are possible.

[0064] As can best be seen in Figure 10 of the drawings, when the valve body 42 is in its closed position, due to the pressure differential across the valve body 42, the closing force indicated by arrow 122, i.e., the pressure exerted by the medium (such as a slurry) on the valve body 42, is substantially higher than the pressure exerted on the other side (i.e., the opening force) exerted on the valve body 42 by the medium on the side of the valve body, indicated generally by reference numeral 124.

[0065] To displace the closure device 32 (and thus the valve body 42 of which it is a part) from its closed position to its open position, an opening load is applied by the actuator to the threaded rod 110 in the direction of arrow 126. However, due to the pressure differential across the valve body 42, the outer frustoconical contact surface 74 of the elastomeric seal 38 typically remains in contact with the valve seat 28, and the elastomeric seal annular body 60 extends as the valve body 42 moves toward the open position (upward in this embodiment). Thus, in effect, the elastomeric seal 38 "sticks" to the valve seat 28. In extreme cases, deformation of the elastomeric seal 38 can lead to its damage or partial or complete disengagement of the elastomeric seal from the engagement portion 36.

[0066] However, in this embodiment of the invention, piston 40 provides support to a portion of elastomeric seal 38 (cap portion protrusion 84) at the opposite end of elastomeric seal 38 from exterior frustoconical contact surface 74, preventing, or at least significantly reducing, sticking of exterior frustoconical contact surface 74 to valve seat 28. Additionally, circular flange 48 provides further support to another portion of elastomeric seal 38 (flange engagement surface 76), further reducing such sticking and the possibility of cap portion protrusion 84 "coming off" recess 99.

[0067] This elastomer support function is provided by a lip 96 that projects radially inward toward central bore 54. Lip 96 engages protrusion 84 of cap portion 82, such that an upward force (in this embodiment) in the direction of arrow 126 is applied to the underside of cap portion 82 (by virtue of piston 40 being raised) to help lift the entire annular body 60 of elastomeric seal 38, thereby minimizing or preventing sticking. This upward force on the underside of protrusion 84 resists deformation of elastomeric seal 38 in the opposite direction.

[0068] Additionally, the protrusion 84 is sandwiched between the elastomeric engagement surface 94 and the lip 96, which functions to hold the protrusion 84 in place and allow some radial outward deformation thereof until it reaches the outer radial edge of the recess 99 (or fills the lip extension cavity 102).

[0069] Additionally, the complementary frustoconical surface 72 on the elastomeric seal 38 and the complementary frustoconical surface 46 on the engagement portion 36 further function to resist displacement of the elastomeric seal 38 in a direction opposite to the direction of arrow 126. It will be appreciated that, by virtue of the complementary internal frustoconical contact surface 72 of the elastomeric seal 38 and the seal support surface 46 of the engagement portion 36, any displacement of the elastomeric seal 38 relative to the engagement portion 36 in a direction opposite to the direction of arrow 126 will tend to radially expand the elastomeric seal 38, which urges the lip 96 more firmly into the recess 99 to hold the elastomeric seal 38 in place.

[0070] As a result, in use, when the valve body 42 is initially displaced away from its closed position, due to the natural resiliency of the material of the elastomeric seal 38, the outer frustoconical contact surface 74 of the elastomeric seal 38 will initially remain in contact with the valve seat 28, even after the annular sealing surface 44 (of the engagement portion 36) is no longer in contact with the valve seat 28. However, further displacement of the valve body 42 away from its closed position will cause the elastomeric seal 38 to displace along with the remainder of the valve body 42 to its open position, with the lip 96 functioning to hold the elastomeric seal 38 in place and to resist deformation that could lead to damage to the elastomeric seal 38.

[0071] The valve 10 described above can be used in any convenient application, for example in a positive displacement pump. The valve 10 may be used as an inlet or outlet valve in any convenient orientation.

[0072] Of course, a PEC pumping system can be constructed with multiple valves 10. The components of the PEC pumping system can be delivered in prefabricated or kit form for on-site assembly. Alternatively, an existing PEC pumping system can be modified by replacing one or more of the valves with a valve 10 according to one embodiment of the present invention. [Explanation of symbols]

[0073] List of Reference Numbers Valve 10 Housing 20 First fluid port (inlet) 22 Second fluid port (outlet) 24 Channel 26 Valve seat 28 Housing sleeve 29 Narrow end of valve seat 30 Wider end of valve seat 32 Closure device 34 Engagement part 36 Elastomer Seal 38 Piston 40 Valve body 42 Annular seal (or sealing) surface (of the mating part) 44 Seal support surface (engagement portion) 46 Circular flange (engagement part) 48 Cylindrical sleeve (engagement part) 50 Central hole (engagement part) 52 Enlarged cavity (in the engagement part) 53 Narrow central bore (of the piston) 54 Wider central bore (of piston) 56 Annular body 60 Piston end 62 Valve seat end 64 Contoured central opening 66 Cylindrical piston section 68 Expansion interval 69 Conical valve seat 70 Internal truncated cone contact surface 72 External truncated cone contact surface 74 Flange engagement surface 76 Tapered sidewall 80 Cap part 82 Projection 84 Cylindrical body 90 outer surface 92 Elastomer engagement surface (of piston) 94 Color 95 Lip 96 Annular part 98 Recess 99 Central bore axis 100 Lip extension cavity 102 Threaded Rod 110 Fixing nut 112 Closing force 122 Opening force 124 Open load 126

Claims

1. A valve, Housing and an inlet leading into the housing; an outlet leading from the housing at a location spaced from the inlet; a flow path connecting the inlet and the outlet in flow communication; a valve seat positioned within the flow path; a valve body displaceable between a closed position that prevents flow of a medium through the flow passage and an open position that allows flow of a medium through the flow passage, the valve body including an elastomeric seal having (i) a contact surface that is complementary to and abuts against the valve seat when the valve body is in its closed position, and (ii) a protrusion extending radially outward at an upper portion of the protrusion; a retainer including an inwardly projecting lip defining a recess for receiving the protrusion therein to assist in lifting the elastomeric seal, thereby minimizing or preventing sticking or deformation of the valve body as it is displaced away from its closed position toward its open position.

2. 10. The valve of claim 1, wherein the valve body includes an engagement portion having an annular sealing surface complementary to and configured to sealingly abut against the valve seat when the valve body is in its closed position.

3. 2. The valve of claim 1, wherein the elastomeric seal includes a cap portion and a tapered sidewall extending from under the cap portion to the contact surface, the cap portion including the protrusion.

4. The valve of claim 3 further comprising a piston coupled to the valve body and defining the retainer.

5. The valve of claim 4 , wherein the piston is connected to the cap portion.

6. 6. A valve as claimed in claim 4 or claim 5, wherein the lip extends at least 5% of the distance from the outer surface of the piston towards its centre.

7. 3. The valve of claim 2, wherein the engagement portion defines a seal support surface against which an inner contact surface of the elastomeric seal rests.

8. 2. The valve of claim 1, wherein the contact surface of the elastomeric seal projects laterally beyond the annular sealing surface of the engagement portion.

9. 4. The valve of claim 3, wherein an end of the cap portion projects beyond the contact surface of the elastomeric seal.

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