Pressure relief valve with bi-directional seat

A pressure relief valve includes a valve body including a monitored pressure inlet leading to a monitored pressure region, a piston having a shear seal bore and a surface facing the monitored pressure region, a vent passage and a the shear seal assembly comprising a seal plate having a sealing surface thereon, and the shear seal assembly includes a sealing surface facing the seal plate and having a first annular area, and a first surface having an annular surface area at least twice as large as the first area of the sealing surface, the first surface facing away from the first area, and a biasing seal in contact with the first surface.

BACKGROUND

Pneumatically and hydraulically operated equipment and control devices often incorporate, and are commonly interconnected to one another using, valves. Among these valves are relief valves, wherein a monitored fluid line is connected to an inlet of the relief valve, and the relief valve selectively opens to allow pressure in the monitored fluid line to vent from the monitored fluid line therethrough, through a relief valve vent opening connecting the relief valve to a vent, such as the local ambient pressure or a vent line. As a result, an overpressure condition in the monitored fluid line can be relieved. In these relief valve constructs, the relief valve commonly is connected to a spring housing, which provides a desired closing force against the fluid at pressure in the monitored fluid line to maintain the relief valve in the closed position when normal operating pressure is present in the monitored fluid line and thus preventing fluid flow form the monitored fluid line to the vent, and which force is insufficient to maintain the relief valve in the closed position once an undesirably high pressure is reached in the monitored fluid line and thus the relief valve opens to allow fluid in the monitored fluid line to flow to the vent. One such relief valve includes a piston having a shear seal element therein, the face of which faces a seal plate having a sealing face and an opening therethrough in fluid communication with the vent and commonly centered with respect to the sealing face thereof. A compressible element is present between the shear seal element and a bore in the piston within which the shear seal element is received and maintained. The compressible element is present to maintain the surface of the sealing face of the shear seal element against the sealing surface of the seal plate, the two sealing elements together forming a seal when in contact with one another and biased together, with the face of the shear seal element surrounding the opening in the sealing surface of the shear seal element. When the pressure of the fluid at the valve inlet, which is received through the inlet from the monitored fluid line and which fluid is in contact with the piston, creates a force on the piston greater than the force of the main spring holding the piston in place, the piston moves linearly to linearly move the shear seal element, and thus the sealing face thereof, past the opening in the seal plate, thereby allowing fluid to flow from the monitored fluid line and therethrough to vent. Thus, the fluid and pressure in the monitored fluid line can be relieved to the vent, and when the desired pressure is re-achieved in the monitored fluid line, the pressure of the fluid from the monitored fluid line against the piston is insufficient to maintain the piston in the retracted, vent open position, and the piston moves to again position the shear seal element over the opening in the seal plate.

Relief valves are constructed with a uni-directional seat bias, because the inlet pressure to the valve is used to bias the annular sealing face of the shear seal element against the shear plate to assist in the sealing off of the inlet pressure from the vent pressure during periods when normal pressure is present in the monitored fluid line, i.e., to maintain the sealing face of the shear seal element against the sealing surface of the seal plate in facing, sealing, contact. One issue encountered in this relief valve construct is the undesirable lifting off of the shear seal element from the seal plate occurring when the piston is in the valve closed position, which occurs as a result of an overpressure condition in the vent line causing the shear seal element to retract inwardly of the shear seal element bore in the piston. When this occurs, the sealing integrity of the relief valve is lost, and in some cases, the shear seal element can become cocked in the bore in a retracted position from the seal plate, and the shear seal element becomes resultantly seized in the piston, resulting in failure of the relief valve. One cause of such an overpressure condition is the connection of multiple valve outlets to the vent line, such that the vent line pressure can exceed the inlet pressure at the inlet to a relief valve connected thereto.

One attempt to overcome this issue is embodied in U.S. Pat. No. 6,651,696, wherein the shear seal element includes a through passage therein and thus the pressure is equal on either side of the shear seal element, even when the vent pressure is abnormally high. This can prevent the shear seal element from lifting off (i.e., backing away from), the seal plate, but the force of the sealing face of the shear seal element bearing against the sealing surface of the seal plate is insufficient to provide a reliable seal at that interface and the fluid in the monitored fluid line can leak past the sealing face of the shear seal element and the facing sealing surface of the seal plate, and thus to the vent.

Additionally, relief valves are commonly tested after their manufacture or refurbishment, to determine the inlet pressure at which the vent line will be exposed to the inlet pressure through the valve for a given spring force setting, commonly known as when the valve or seal of the valve seat “cracks” open. This testing can be performed by connecting the valve inlet to a variable pressure fluid source, raising the pressure at the valve inlet over a predetermined time period, and determining the occurrence pressure at which the seal of the valve cracks open, by the occurrence of fluid flowing through the valve vent passage or a change in the smooth rise of pressure being increased in the valve inlet, i.e., the monitored fluid line inlet. However, once the valve is installed in a fluid circuit, it becomes difficult or impossible to monitor the opening pressure of the relief valve in situ.

SUMMARY

Provided herein are relief valves wherein an overpressure condition in the vent bore has limited to no impact on valve performance, wherein a bi-directional seal is engaged between the shear seal element and a portion of the shear seal element bore. The shear seal element is received in a cross bore in the seal piston, which piston is biased inwardly of the valve body by a user settable bias spring, and the shear seal element includes an annular seal face having a first annular area, and an annular pressure leveraging face having an area at least twice that of the first annular area. Additionally, a seal element is provided surrounding the body of the shear seal element, in one aspect, in contact with the annular pressure-leveraging face of the shear seal element. The sealing element extends between the body of the shear seal element and the inner circumferential surface of the cross bore, to seal the inlet side pressure of the relief valve from the vent side pressure thereof.

Additionally, a relief valve having a mechanism to enable checking of the valve opening pressure in-situ, under valve operating ambient conditions, is provided. Here, a check valve is provided between the valve inlet and the piston of the valve, and is set to close off the inlet when the pressure in the interior volume of the valve is greater than the inlet pressure. A pumping port is provided through the body of the valve and it extends from the exterior of the valve into the interior volume thereof, on the side of the check valve opposite that of the inlet. A plug is normally maintained in this pumping port. However, to check the opening pressure of the valve, the pumping port plug is removed, and a variable fluid source is attachable to the pumping port to elevate the pressure in the inner volume of the valve to a value exceeding that of the check valve closing pressure vis a vis the inlet pressure, and to continue to raise that pressure to a pressure sufficient to cause movement of the piston to “crack” open the seal of the valve. The pressure being supplied into the valve interior volume is monitored to determine the pressure at which the valve opens in situ, and may be used to adjust the spring force on the piston to change the opening or “cracking” pressure of the valve, after which the opening pressure may be again checked by pumping fluid inwardly through the pumping port, which can be repeated until a desired opening pressure is achieved and the relief valve is thus properly calibrated.

DETAILED DESCRIPTION

Referring toFIGS. 1 and 2, the exterior of a relief valve10is shown, wherein the relief valve10includes a body12, connected to which are a spring cap14received within, and connected to, a spring bore22(FIG. 2) of the body12, such as by being threaded thereinto, a vent connector16received and secured in, a vent connector recess24(FIG. 2) extending inwardly of the body12, an inlet connector18secured over the base26of the body12, and a pumping port plug20releasably secured in an auxiliary pumping port28(FIG. 2) extending through the valve body12from the inner volume30to the outer surface32thereof. A spring34is provided within a volume formed of the spring bore22and the generally hollow interior of the spring cap14, and a spring plate36is provided at the base of the spring bore22. Spring cap22generally includes a cover portion37generally formed as a generally circular disk from which extends an annular sleeve38terminating at a distal annular end wall40. The outer surface of the annular sleeve38includes a continuous thread or threads42running on the outer surface thereof in the direction from the distal annular end wall40and terminating before reaching the end of the spring cap22, and a plurality of vents44in the form of openings extending through the annular sleeve38are disposed adjacent to the cover portion36end of the spring cap14. The inner surface of the spring bore22is likewise threaded with inner threads46which mate with threads42on the outer circumferential surface of the annular sleeve38. The spring plate36at the base of the spring bore is biased in the direction of the base of the spring bore22by the spring34. The force of the spring34against the upper surface of the spring plate36is adjustable and is set by adjusting the compression of the spring34, which here is configured as a coil spring. This adjustment is made by rotating the spring cap14with respect to the body12of the valve10, such that the distance between the inner surface of the cover portion37and the base of the spring bore22is changed by threading the spring cap22inwardly or outwardly of the spring bore22. To readily achieve this movement, a contoured opening48extends through the cover portion36of the spring cap14, and here it is configured as the female side of a hex connection, wherein a hex wrench having six equal sides may be inserted thereinto and pushed or pulled to rotate the spring cap14with respect to the body12Additionally, a lock nut50, having a generally circular inner opening having threads which mate with the threads42on the outer surface of the spring cap14is provided over the annular sleeve and threaded thereto. Once the desired location of the spring cap14is achieved with respect to body12and the base of the spring bore22, i.e., the proper spring force or compression has been set, the nut50is rotated to bring it to bear against the upper circumferential surface52of the body, to lock the spring cap14location with respect to the body12. Additionally, a plurality of secondary vent holes54(two shown) extend through the wall of the spring cap22.

Vent connector16extends inwardly of vent connector recess24and is secured therein such as by a plurality of fasteners extending through the vent connector16and into corresponding threaded holes in the body12, by being threaded therein, or other mechanism. A seal plate opening56, into which a seal plate adaptor58is received, extends inwardly of the body from generally the center of the vent connector recess24and into the inner volume30of the body12. The inner volume30of the body12further includes a central bore region, including a first bore60having a first opening area, a second bore62having a second opening area, and a third bore64having a third opening area. In this aspect, a piston66, having a first portion68and a second portion70, reciprocally extends within the second and third bores64,66, such that the first portion68is located within, and is reciprocally movable within, a portion of the second bore62, and the second portion70extends within a portion of the second bore62and in the third bore64, and inwardly of the spring bore22at one end thereof. The first bore60opening area (i.e., cross sectional area) here is larger in cross section than the second bore62opening area, which in turn is larger in cross section than the third bore64opening area. Here, the bores62,62,64have a circular, within machining tolerance, circumference, wherein the diameter of the first bore60is greater than the diameter of the second bore62with is larger in diameter of the third bore64. Resultantly, a first annular ledge72is present and extends between the first bore60and the second bore62inwardly of the body12, and a second annular ledge74(FIG. 3) is present and extends between the second bore62and the third bore64inwardly of the body12and is located between the first annular ledge72and the spring bore22.

FIG. 3depicts the basic interactive structure of the piston66, seal plate adaptor58and a shear seal element76received within a shear seal element bore78in the piston66. Piston66, includes the first portion68from which second portion70extends, each of which has a circular, within machining tolerances, circumference or cross section, wherein the circumference of the first portion68is one to 3 thousandths of an inch less than that of the second bore62, and wherein the circumference of the second portion70is one to 3 thousandths of an inch less than that of the third bore64, allowing sliding motion of the first and second portions68,70of the piston66within the second and third bores62,64respectively. First sealing guide shims61a, bare received in an annular groove63extending around the second portion70, and help center the second portion70in the third bore, and a second sealing guide shim65is received in a groove69extending inwardly of the circumference of the first portion68of the piston66, and helps center the second portion68in the second bore62. Sealing shims61a, band65also seal the annular gap between the outer surfaces of the first and second portions68,70of the piston66and the inner walls of the second and third bores62,64, to seal off the open area (spring bore22) of the spring cap14, which is at the ambient pressure surrounding the relief valve10, from the central bore region of the body10, i.e., the volume of the second bore62in the region of the second bore62between the second guide shim65and the first annular ledge72and the volume of the first bore60. Additionally piston66includes a flatted portion82, extending across the outer circumference thereof from the end84of the piston66distal of the second portion70to a limit ledge86extending generally perpendicularly to flatted portion82. The distance between the closest location of the seal plate adaptor to the second annular ledge74, less the distance between the limit ledge86and an annular wall90at the change in piston66circumference between the first and second portions thereof, defines the maximum stroke distance of the piston66within the second and third bores62,64.

Shear seal element bore78of the piston66includes a major bore92opening at the flatted portion82, and a minor bore94extending along the centerline of the major bore further inwardly of the piston66therefrom, and connected by an annular bore ledge96. Shear seal element76includes a corresponding major portion100received within the major bore92, a minor portion102received within the minor bore94, and an annular shear seal element ledge104interconnecting the major and minor portions100,102. Shear seal element78further includes a minor side face106, a major side end108having an annular seal face110surrounding a recess112, and a central shear seal element bore114extending from recess112thorough the minor side face106.

Body12further includes the seal plate opening56, into which the seal plate adaptor58extends from the base of the vent connector recess24through the wall of the body12and to the second bore68. Seal plate opening56includes a major seal plate opening bore116and a minor seal plate opening bore118, and an annular seal plate adaptor bore ledge120interconnecting the inner circumferential surfaces of the major seal plate opening bore116and minor seal plate opening bore118. Seal plate adaptor58likewise includes a major seal plate adaptor portion122received in the major seal plate opening bore116, a minor seal plate adaptor portion124received in the minor seal plate opening bore118, and an annular seal plate adaptor ledge126connecting the surface of the major seal plate adaptor portion122to the surface of the minor seal plate adaptor portion124. Here, the major seal plate opening bore116and minor seal plate opening bore118are, within machining tolerances, circular in section, and the major seal plate adaptor portion122and the minor seal plate adaptor portion124are likewise here, within machining tolerances, circular in section, having a circumference 1 to 3 thousandths of an inch less than that of the major seal plate opening bore116and minor seal plate opening bore118to allow the minor seal plate adaptor portion124to be slid into the seal plate opening56until the annular seal plate adaptor ledge126abuts the annular seal plate adaptor bore ledge120, thus positioning the circular end face of the seal plate adaptor58forming the seal plate surface130thereof inwardly of the second bore, in a spaced facing relationship with the flatted portion86of the piston66, such that the limit ledge86of the piston overlies, and is limited in motion in the direction away from the spring bore22, by the portion of the minor seal adaptor portion124extending inwardly of the second bore68, and the annular seal face110of the shear seal element76faces and contacts the seal plate surface130. A seal groove136extends inwardly of the circumferential surface of the minor seal plate adaptor portion124, and a seal ring134, and backing rings132on opposed sides thereof, are received in the seal groove136to provide a seal across the small annular gap between the outer circumferential surface of the minor seal plate adaptor portion124and the inner circumferential surface of the minor seal plate opening bore118. Seal plate adaptor58further includes a rear wall138, facing away from seal plate surface130and on an opposed end surface of the seal plate adaptor58therefrom, and a through vent bore140extends through the seal plate adaptor58from and through rear wall138and to and through seal plate surface130. Vent connector16includes a vent opening142therein which fluidly communicates with the through bore140of the seal plate adaptor58which in turn, in the relief valve closed position shown inFIG. 3, communicates with the recess112and central shear seal element bore114to communicate ambient pressure around the valve body12, or a vent line pressure where a vent line (not shown) is connected to the vent opening142, to a volume between base wall158(FIG. 4) of the minor bore94of the shear seal element bore78and the minor portion102of the shear seal element76. The vent connector16contacting the rear wall138of the seal plate adaptor58prevents backing of the seal plate adaptor58from the seal plate opening56to maintain the proper position of the seal plate surface130within the second bore62of the valve body12.

Referring toFIG. 4, the relative sizes of the regions of the shear seal element bore78and the annular seal face110are shown and described. In this aspect of the relief valve10, the annular seal face110has a radial width144, defining a first seal face surface area. Annular bore ledge96has a bore ledge radial width146defining a bore ledge area, and annular shear seal element ledge104has a radial width148defining an annular shear seal element ledge area. The annular bore ledge96is separated from the annular shear seal element ledge104by a gap152, in which a circumferential biasing seal150, such as an O-ring, is disposed and contacts and biases apart the annular bore ledge96and the annular shear seal element ledge104across the gap152. When the pressure in the second bore62is greater than that in the vent bore140, the biasing seal150surrounds and sealingly contacts the outer surface of the minor portion102of the shear seal element76and can become spaced from, i.e., can be lifted off of, the surrounding surface of the major bore92in the gap152, and can lift off of the annular shear seal ledge104. The outer diameter of the annular seal face110is greater than the inner diameter of the vent bore140, ensuring that a portion of the annular seal face110can surround the opening of the vent bore140into the second bore62. To ensure sealing of the interface of the seal plate surface130and the annular seal face110, the radial width144the annular seal face is chosen such that the annular shear seal ledge area of the annular seal shear ledge104is greater than the resulting first seal face surface area of the annular seal face110, such that the second bore pressure62on the annular seal ledge104forms a pressing force to push annular seal face110toward the seal plate surface130greater than that tending to push the shear seal element76away from the seal plate surface130. Likewise, the radial width146of the annular bore ledge96is chosen such that the resulting second seal face surface area is greater than the surface area of the annular seal face110.

The minor side face106of the shear seal element76is an annular surface having a radial width156establishing a first vent pressure biasing area on the shear seal element. The presence of the biasing seal150maintains the vent pressure on the minor side face106while preventing the second bore62pressure from reaching the minor side face106. The base of the shear element bore78is an annular wall158having a radial width154greater than that minor side face establishing a second vent pressure biasing area. A small annular area of the annular seal face110directly adjacent to the recess112is, in the relief valve fully closed position ofFIGS. 1 to 4, likewise exposed to vent pressure and thus forms a third vent pressure biasing area. As the second and third vent pressure biasing areas are, in sum, greater than that of the first vent pressure biasing area on the minor side face106, vent pressure tends to push the shear seal element76away from the shear plate adaptor58, or in other words, tends to lift the seal surface110off of the seal plate surface130. In contrast, the monitored fluid line pressure present in the second bore62communicates through a first annular passage174between the major portion100of the shear seal element76and the major bore92to maintain monitored fluid line pressure on the annular shear seal element ledge104, to push the annular seal face110into engagement with the shear plate130surface. By ensuring the area of the annular shear seal element ledge104is at least twice that of the annular seal face110, a safety margin is built into the seal arrangement for the relief valve to maintain the shear seal element76against the seal plate adaptor58, even when the vent pressure rises to that of, or slightly more than, the pressure in second bore62which is a monitored or protected line pressure.

A seal gland176is formed in the gap152bounded by the annular bore ledge96, the annular shear seal element ledge104, and portions of the outer circumferential surface of the minor portion102of the shear seal element76and of the major bore92of the shear seal element bore78extending therebetween. The biasing seal150here is an O-ring circumscribing the shear seal element76within the seal gland176. In its non-compressed state, the biasing seal150has a nominally, within manufacturing tolerance, circular cross section, and the seal gland176has a generally rectangular cross section, having a width178which is less than the diameter of the biasing seal150in its free, unbiased state and a radial depth which is likewise less than the diameter of the biasing seal150in its free and unbiased state. For example, the width178of the seal gland176is approximately 95% the diameter of the biasing seal150in the free, unconstrained, state of the biasing seal150, and the depth180of the seal gland176is approximately 83% the diameter of the biasing seal150in the free, unconstrained, state of the biasing seal150. Thus, when the shear seal element76is assembled into the shear seal element bore78of the piston66, and the shear seal element78contacts the seal plate adaptor58, the biasing seal150is compressed into an ovoid shape as shown inFIGS. 2 to 6, such that the biasing seal150is compressed into four flatted regions at the contact therewith with each of the annular bore ledge96, the annular shear seal element ledge104, and portions of the outer circumferential surface of the minor portion102of the shear seal element76and of the major bore92of the shear seal element76, and curved outer portions between adjacent flatted areas thereof. As shown inFIG. 4, the biasing seal150separates a monitored fluid line pressure annular area182when the valve is assembled and not under pressure at the inlet or vent initially bounded by surfaces of the biasing seal150extending between annular bore ledge96and the annular wall of the major bore92, and a vent pressure annular area184initially bounded by surfaces of the biasing seal150extending between the major bore92and the annular shear seal element ledge104of the shear seal element76.

During use, the pressure in the monitored fluid line communicated to the second bore62through the first bore60and the inlet170in the inlet connector18may experience a pressure increase sufficient to cause the piston66to move in the direction of spring bore22, causing the annular seal face110to likewise move in the direction of spring bore22. The spring plate36includes a generally planar lower face162, having a central conical detent160extending thereinto. The second portion70of the piston66includes, at the terminal end thereof opposed to the first portion68of the piston66, a hemispherical end portion166sized to be received within and engage the internal surface of the conical detent160, which resultantly causes circumferential line contact between the hemispherical surface of the end portion166and the surface of the conical portion160. This allows the spring plate36and the lower face162thereof, if moved away from the base wall168of the spring bore22, to tilt or move into a non-parallel relationship with the base wall168which occurs because the spring may load only against a portion of the spring plate36. As this movement of the piston66continues, the maximum movement of the piston from the position thereof inFIGS. 1 to 4is shown inFIG. 5, whereby the annular wall90of the piston abuts against, and is limited from further movement in the direction away from first bore60by contact with, the second annular ledge74.

The position and biasing functionality of the circumferential biasing seal ofFIGS. 2 to 6during valve use and operation is shown inFIGS. 7 and 8. Here, inFIG. 7, the vent pressure is at a low ambient pressure, for example atmospheric air pressure where the vent is open to the earth's atmosphere, or the water pressure at the depth of the valve installation location, and the valve10bore area, including the first and second bores60,62, is charged with a monitored fluid line pressure greater than the pressure of the vent. In this condition, the pressure in second bore62communicates through a gap172between the shear seal element76and the seal plate surface130(FIG. 4), thence along or through the annular passage174between the major portion100of the shear seal element76and the major bore92and thence into the monitored fluid line annular pressure area182of the seal gland176. This high pressure compresses the biasing seal150radially inwardly such that the biasing seal150no longer contacts the major bore92. The monitored fluid line pressure is thus present between the biasing seal150and the major bore92of the shear seal element bore78. As the monitored fluid line pressure is originally present at monitored fluid line pressure annular area182(FIG. 4), it is believed that the increase in monitored fluid line pressure further compresses the biasing seal150into the shape of the seal gland174leaving an outer circumferential gap186between the surface of the biasing seal150facing away from the minor portion102of the shear seal element76and the inner surface of the major bore92. The pressure in this outer circumferential gap186compresses the biasing seal such that the force exerted by the biasing seal150against the annular bore ledge96and opposed annular shear seal element ledge104is increased to approximately the pressure value of the monitored fluid line pressure, such that the compressed biasing seal biases against an area at least twice the annular area of the annular seal face110at or nearly at the increased vent pressure to maintain the seal between seal face110and the seal plate surface130.

In contrast, as shown inFIG. 8, vent pressure is communicated through the seal element bore114, between the region between the base of the minor bare and the minor side face106of the shear seal element76, through a second annular passage190and thence to the vent pressure annular area184. When an overpressure condition occurs in the vent and this pressure sufficiently exceeds the pressure in the monitored fluid line, this higher pressure pushes the biasing seal outwardly and extends the vent pressure annular area184and is believed to flatten or compress the biasing seal150against the inner circumferential surface of the major bore92, and the vent pressure compressing the biasing seal causes the pressure or force applied by the biasing seal150against the annular shear seal element ledge104to be approximately that of the vent pressure, and the area of the annular shear seal element ledge104exposed to the vent pressure is greater than the area of the seal face110contacting the seal plate surface130. By sizing the annular shear seal element ledge104to have an area at least twice that of the annular seal face110, maintenance of a seal between seal face110and the seal plate surface130is maintained because the area of the annular shear seal element ledge104is at least twice as large as the area of the annular seal face110facing the seal plate surface130, and an exposed portion of the annular shear seal element ledge104is also exposed to the higher vent pressure as well as the increased force of the biasing seal150which is now at, or near, the increased vent pressure likewise pushing against the shear seal element ledge104in the direction of the seal plate surface130.

As the piston begins moving from the valve fully closed position ofFIG. 4toward the fully opened position ofFIG. 5, when the initial movement distance exceeds the radial width144of the annular seal face110, at the point in time the lowermost portion of the major portion100moves past the lowermost portion of the bore140of the seal plate adaptor58, also known as when the seal “cracks”, the second bore62will become exposed to the vent bore142through the bore140of the seal plate adaptor58, and fluid will be vented from the second bore and thus from a monitored fluid line fluidly connected to the valve through the inlet bore170in the inlet connector18to relieve the pressure in the monitored fluid line as shown by arrow F inFIG. 6.

FIG. 9is a partial sectional view of an additional relief valve construct, showing a bi-directional sealing element therein. Here, in contrast to the relief valve10ofFIGS. 1 to 6wherein the vent pressure is located at a single port of the valve, here vent pressure openings are located at opposed sides of the valve and aligned with one another over the width of the valve body. The structure of the valve and the components thereof having the bi-directional sealing element are structurally the same as those having the uni-directional sealing element, except as shown inFIG. 9.

Here, to form the bi-directional relief valve200, valve10ofFIGS. 1 to 6is modified such that two shear seal assemblies, here first and second shear seal assemblies202,204, and two, here first and second, seal plate adaptors206,208are used, and the piston hereof has generally the same construct as piston66, except here it is a dual flatted piston210which is modified to include opposed flatted portions82a, band limit ledges84a, b. First shear seal assembly202is configured substantially the same as shear seal assembly76of valve10, and includes the annular seal face110and annular shear seal element ledge104having the same relative dimensions as those in valve10, and the biasing seal150having the same relative dimensions to the annular seal face110and annular shear seal element ledge104as it does in relief valve10. In contrast to the relief valve10, bi-directional relief valve200includes a second shear assembly204having a second annular seal face110aand second annular shear seal element ledge104a, and a through bore212having an inner surface214having a circumference or diameter slightly greater than the outer circumference or diameter of the minor portion102of the first shear seal assembly202. Dual flatted piston210also includes, in contrast to piston66, a through shear seal bore220having an inner circumferential surface222having a diameter or circumference. The space between the annular shear seal element ledges104,104a, and the portions of the inner circumferential surface222of the shear seal bore220and of the minor portion102of the first shear seal assembly202extending between the annular shear seal element ledges104,104aforms a bi-directional seal gland218. Additionally, here biasing seal150is present in the bi-directional seal gland, and where the valve is not under pressure, i.e., not installed, the biasing seal150forms four flatted portions contact the four surfaces defining the bi-directional seal gland218, similarly to the biasing seal150inFIGS. 2 to 6.

The bi-directional seal of the valve200operates substantially the same way as that of valve10, except here two vent bores142a,142bare collinearly provided on opposed sides of the valve body, and when the valve200is in the fully closed position, vent bore142ais aligned with recess112within the circumference of annular seal face110, and vent bore142bis aligned with through bore212. In this condition, pressure in the monitored fluid line is present in the second bore62, and communicates in the small clearance between the inner circumferential surface222of the shear seal bore220of the dual flatted piston210and the facing outer circumferential surfaces of the major portion100of the first shear seal202assembly and the outer circumferential surface of the second shear seal assembly204, to load the biasing seal150as shown inFIG. 7when a high pressure is present in the monitored fluid line. When an overpressure condition is present in the vent bores142a, b, through the small clearance between the minor portion102of the first shear seal assembly202and the inner surface214of the second shear seal assembly, to load the biasing seal such that the biasing seal is spaced from the outer circumferential surface of the minor portion102of the first shear seal assembly202and further biased against as the inner circumferential surface222of the shear seal bore220, similarly to the pressure biased position of the biasing seal as shown inFIG. 8. Again the surface area of the annular surfaces of each of the annular shear seal element ledges104,104ais at least twice that of the annular surface area of each of the annular seal faces110,110a, and the loading effect resulting from the annular seal element ledge being at least twice as large in area as the annular seal face110of the aspect hereon shown and described with respect toFIGS. 2 to 8is also achieved here.

Referring again toFIGS. 1 and 2, relief valve10further includes the auxiliary pumping port28extending from, and fluidly connecting, the exterior of the relief valve body12to the second bore62within the relief valve body12, within which a removable pumping port plug20is locatable and is configured to seal off fluid flow through the auxiliary pumping port28, and a check valve assembly304received in first bore60and secured therein between first annular ledge72and the facing surface of the inlet connector18secured over the base26of the body12. First bore60and an inlet bore170extending through the inlet connector18are aligned for fluid communication therebetween. Inlet connector18is secured over the base26of the body by, for example threaded fasteners, a clamp, or other attachment mechanism. As will be described further herein, the cracking pressure of the valve, or the shear seal therein, may be tested using the auxiliary pumping port28to increase the pressure in the second bore62independently of the pressure in the vent opening142in the vent connector16and the pressure in the monitored fluid line fluidly communicated to the second bore62through the inlet bore170.

Referring toFIGS. 11 and 12, the check valve assembly304and auxiliary pumping port region of the valve are shown enlarged and in section. InFIG. 11the closure element308of the check valve assembly is in the closed position as also shown inFIG. 2, and inFIG. 10the closure element308of the check valve assembly304has been moved to a valve open condition in contrast to the check valve closed position ofFIGS. 2 and 11. Here, check valve assembly304is received within the first bore60of the valve body12, and held between the first annular ledge72at the interface of the first and second bores60,62, and the body facing surface of the inlet connector18extending across the circumference of the opening of the first bore60at base26of the body12. Check valve assembly304includes a first body312in the form of a cup, a second body314having a male threaded portion316extending inwardly of the cup shaped recess of the first body314, a check valve spring318, the closure element308, a backing ring320and a conformable seal ring322having an inwardly facing frustoconical sealing surface. First body portion312here includes a base portion324having a central through opening326therethrough, the upper portion of which is configured as a seat356, an annular wall334extending therefrom further inwardly of the first bore60, and together with the base portion324creating a cup shaped recess having an inner circumferential wall330having threads, mating with those on male threaded portion316of the second body314. The cup shaped recess includes, at the base thereof, an annular backing ring ledge335surrounding a first opening area, and a conformable ring ledge336surrounding a second opening area having a smaller opening area than the first opening area. The second body314includes a first annular portion338from which the male threaded portion316in the form of an annular wall extends to end at an annular bias wall340. Closure element308includes a spring recess342formed of an annular closure element wall344and an annular closure element spring ledge346, and a cage348extending therefrom and including a plurality of flow openings350extending through a side wall thereof and terminating in a conical portion352having a frustoconical sealing or seating surface354thereon, which follows a different conical contour than that of the conical portion352and which seats against the frustoconical seat356and in so doing compresses the corner of a conformable seal ring to seal the second bore62from the first bore60.

To form or assemble the check valve assembly304, conformable seal ring322is located against conformable ring ledge336, and backing ring320is placed thereover to rest on backing ring ledge334. Closure element308is located in the cup shaped recess of the first body312such that conical portion faces the annular openings of the backing ring320and conformable seal ring322. The spring318is then placed in the cup shaped recess of the first body312of the closure element308, and the male threaded portion316of the second body314is threaded into the threads on the first body, thereby biasing the inner surface of the first annular portion338against the spring318and press the backing ring against the backing ring ledge334to secure the conformable seal ring322between the backing ring320and the conformable ring ledge336. The thus prepared check valve assembly is inserted into the first bore60such that the conical portion352faces away from the second bore62. The inlet connector18is then secured over the base26of the valve body12to secure the check valve assembly304in the first bore60.

InFIG. 10, the check valve assembly304is shown in the closure element308open position, which occurs when the force created by the inlet pressure from the monitored fluid line on the portion of the conical sealing surface354exposed within the inner circumference of the conformable seal ring322exceeds force of the spring318biasing the conical sealing face against the inner circumferential surface of the conformable sealing ring354, such as when an overpressure condition is present in the monitored fluid line. Note, that where the closing pressure of the closure element308against surfaces of the conformable seal ring354during normal operating conditions is less than that pressure required for the relief valve10to operate to relieve an overpressure condition in the monitored fluid line to the vent, the closure element308will commonly be seated against the seat356as shown inFIG. 11unless an overpressure condition is present in the monitored fluid line connected to the inlet170of the relief valve10.

Removable sealing plug20is received within the auxiliary pumping port28, and here is configured as a two-piece element, including a seal pin360having a conical head portion362and a shaft portion364extending from the conical head portion362with a retainer ledge366formed therebetween, and a threaded insert368having an outer threaded wall370and a central through bore372within which shaft portion364is received. Auxiliary pumping port includes a threaded first pumping port bore374extending inwardly of the outer surface of the valve body12and a smaller second pumping bore376leading therefrom and into the second bore62of the valve body12. The threaded insert368having the shaft portion364of the seal pin360therein, is threaded into the first pumping bore374to secure the conical head portion362of the shaft portion360in sealing engagement with a surface of the auxiliary pumping port. Here, a frustoconical annular ledge378extends between the first and second pumping bores374,376, and the conical head portion362engages, and seals, against the frustoconical annular ledge378.

To determine the opening pressure of the valve, or the pressure at which the valve seal “cracks”, the pumping port plug20is removed by unthreading it from the auxiliary pumping port28, and a threaded fitting380on the end of a tubing382extending from a fluid pump384is threaded. The pump384, here shown schematically as a manual pump but may also be a non-manual pump, is used to pump fluid directly into the second bore62by pumping the fluid through the auxiliary pumping port28, to increase the pressure thereof, whereby the check valve closure element308if not already seated on the seat356, becomes seated thereon, and fluid is pumped into the sealed volume of the second bore62until the piston66begins moving against the bias of the spring34to move the annular seal face110to the position thereof shown inFIG. 6, at which the pressurized fluid begins to vent from the second bore62into the vent, which pressure is the cracking or opening set pressure of the relief valve10. Thus, the opening pressure of the valve can be determined which the valve10is connected to other fluid components in a fluid circuit, such as a fluid control circuit, without adversely affecting the other components in the fluid circuit Additionally, this procedure can be repeated for different compression or spring force settings of the spring34. As the force of the spring34against the upper surface of the spring plate is adjustable and is set by adjusting the compression of the spring34by rotating the spring cap14with respect to the body12of the valve10, the procedure of determining the cracking pressure of the shear seal can be repeated for different rotation positions of the spring cap14with respect to the body12, and thereby the calibration of the rotatable setting of the spring cap14to the cracking pressure of the relief valve10(or200), or of the shear seal therein, can be reestablished while the relief valve is interconnected to a fluid circuit, such as between a monitored fluid line and a vent. Because the check valve assembly304isolates the inlet170, and thus the monitored fluid line attached thereto, from the second bore62, the pressurizing of the second bore to determine the opening or cracking pressure of the shear seal or valve can be performed without effecting the components connected to the monitored fluid line.