Flowmeter and orifice plate carrier assembly therefor

A flowmeter includes an orifice plate assembly having a carrier that includes an aperture, an annular rim disposed about the aperture, and an annular ledge extending radially inward from the rim to the aperture. An orifice plate and annular seal are disposed within the annular rim. The plate engages the ledge and is retained on the carrier by a retaining ring and the energized annular seal. The seal is disposed in a seal gland formed between the orifice plate, the carrier, and the ring member, and sealingly engages at least one surface of each.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

Not applicable.

BACKGROUND

This disclosure relates generally to flowmeters for measuring fluid flow rates through pipes or other conduits. More particularly, it relates to a flowmeter known as an orifice fitting, a meter which employs an orifice plate to help determine fluid flow rates. Still more particularly, the disclosure relates to an orifice plate carrier for use in orifice fittings.

Fluid flow rate is the quantification of bulk fluid or gas movement, typically measured as volumetric and mass flow rates. The ability to measure reliably and accurately fluid flow rates serves an important function in a variety of processes and industries (e.g., chemical processing, oil and gas transport and production, etc.). An orifice fitting is one of many devices that may be used to measure volumetric or mass flow rate of fluids flowing through a pipe or conduit.

An orifice fitting typically employs an assembly that includes a thin plate having a central orifice that is smaller in diameter than the diameter of the conduit in which the plate is disposed. The orifice plate is retained in a plate carrier, which is, in turn, supported and aligned within the flow bore of the orifice fitting. The orifice fitting determines the mass fluid flow rate through the conduit via calculations that employ the pressure differential that is measured across the orifice plate, as well as other parameters.

When using an orifice fitting to measure fluid flow, many factors must be considered in order to obtain accurate flow values, including effective sealing, such that all the fluid flow passes through the central aperture of the orifice plate, accurate positioning of the orifice plate so it is concentric with respect to the through bore, and accurate positioning of the orifice plate face so it is held perpendicular to the direction of fluid flow.

An effective seal between the orifice plate and the orifice plate carrier is an important consideration as it directs flow through the orifice plate's central aperture. Leakage around the orifice plate's central aperture will result in inaccurate flow values determined by the orifice fitting as the magnitude of the pressure drop across the orifice plate is reduced.

Overall, due to the demanding requirements to achieve accurate flow values, particularly in severe conditions, conventional orifice plate assemblies are complicated, being both difficult to manufacture and demanding to assemble and to properly secure in the flowmeter body. Thus features for an orifice plate assembly that enhance ease of manufacturing, assembly and provide continually reliable positioning are desirable. At least some convention orifice plate carrier assemblies include an orifice plate carrier in which the orifice plate is secured with o-ring seals on each side of the plate. A number of snap rings or clips are used to secure the orifice plate within the carrier and to maintain the seals in proper sealing engagement with the orifice plate. Centering tabs or ears are frequently required to position and align the orifice plate properly within the carrier as described, for example, in U.S. Pat. No. 7,461,563.

BRIEF SUMMARY OF DISCLOSURE

Disclosed is a flowmeter and components configured to measure precisely various characteristics of a fluid flowing in a pipe, as well as a method of making such a meter and components. The meter may include a body having a through passage for conveying fluid, and an orifice plate assembly disposed within the through passage.

In some embodiments, the orifice plate assembly comprises an orifice plate carrier having an aperture, an annular rim disposed about the aperture, and an annular ledge extending radially inward from the annular rim to the aperture. The carrier may be made by investment casting for precision and ease. The orifice plate includes a first facing surface engaging the annular ledge of the carrier, a second facing surface facing away from the annular ledge, and an edge facing the annular rim. An annular seal, such as an o-ring, having a central opening is disposed within the annular rim and engages the second facing surface of the orifice plate and engages the annular rim of the carrier. A retaining ring member having an annular flange and an annular lip axially extending from the annular flange is positioned such that the annular lip extends within the central opening of the o-ring seal, wherein the o-ring seal is retained between the second facing surface of the orifice plate, the annular lip of the ring member, the annular flange of the ring member, and the annular rim of the carrier.

In some embodiments, the intersection of the annular lip of the ring member with the annular flange of the ring member forms an acute angle, and in some embodiments, the annular lip has a maximum outer diameter that is greater than the relaxed diameter of the central opening of the o-ring. The ring member may be coupled to the carrier by radial forces applied to the ring member by the o-ring when the o-ring is disposed between the annular lip of the ring member and the annular rim of the carrier. In some embodiments, the first facing surface of the orifice plate is held against the annular ledge by axial forces applied by the o-ring when the o-ring is disposed between the ring member and the second facing surface of the orifice plate.

In some embodiments, the edge of the orifice plate has an outer diameter that is greater than the diameter of the aperture of the carrier, and less than the diameter of the annular rim of the carrier.

In some embodiments the carrier includes a first side and a second side, wherein the annular ledge is formed on the first side, and wherein the second side of the carrier includes an annular groove configured to receive an annular seal for sealing the assembly on the downstream side of the meter body.

In some embodiments, the annular lip of the ring member includes an outer diameter, and wherein the o-ring seal is elastomeric with its central opening defining a relaxed diameter before the annular lip is disposed into the central opening, and wherein the outer diameter of the annular lip is greater than the relaxed diameter.

In some embodiments, the outer diameter of the orifice plate, as defined by the plate's edge, is greater than the diameter of the aperture of the carrier, and in some embodiments, the annular flange of the ring member extends beyond the annular rim of the carrier. The annular lip of the ring member may include an outer diameter that is less than the outer diameter of the orifice plate.

In some embodiments, the ring member includes a central aperture having a diameter that is substantially equal to the diameter of the aperture in the carrier. A second annular seal may be included in an annular seal groove that is formed on the downstream facing side of the carrier, the side that is opposite the side having the annular ledge. The diameter of the groove securing the second annular seal may be equal to the diameter of the annular seal gland retaining the o-ring seal that is positioned on the opposite side of the carrier.

Also disclosed is an orifice plate carrier assembly comprising: a carrier body having an aperture, an annular shoulder disposed about the aperture, and an annular ledge extending radially outward from the aperture toward the shoulder. An orifice plate is disposed within the annular shoulder and includes a first facing surface engaging the annular ledge, a second facing surface facing away from the annular ledge, and an edge that faces the annular shoulder of the carrier. A ring member is coupled to the carrier wherein the orifice plate is retained between the carrier and the ring member. A first annular seal is disposed within an annular seal gland formed between the carrier and the ring member, the first annular seal having a central opening and having a first portion that engages the orifice plate, a second portion that engages the carrier, and a third portion that engages the ring member.

In some embodiments, the ring member comprises an annular flange and an annular lip extending from the annular flange, the ring member being positioned such that the annular lip is disposed within the central opening of the first annular seal; and wherein the first annular seal is retained within an annular seal gland defined by the second facing surface of the orifice plate, the annular lip of the ring member, the annular flange of the ring member, and the annular rim of the carrier.

In some embodiments, when viewed in cross section, the seal gland is formed to include at least one acute angle. In some embodiments, the annular lip of the ring member includes an outer diameter, and wherein the first annular seal is elastomeric with the central opening defining a relaxed diameter before the annular lip is disposed into the central opening, and wherein the outer diameter of the annular lip is greater than the relaxed diameter of the central opening of the first annular seal.

In some embodiments, the annular flange of the ring member extends beyond the annular shoulder of the carrier body, and in some embodiments, the annular lip of the ring member includes an outer diameter, and wherein the outer diameter of the ring member is less than the outer diameter of the orifice plate.

In some embodiments, the carrier body comprises a first side and a second side and the annular ledge is formed on the first side, wherein the carrier assembly also includes a second annular seal disposed in an annular seal groove that is formed on the second side of the carrier body. In some embodiments, the diameter of the annular seal groove is generally equal to the diameter of the annular seal gland, and in other embodiments, the diameter of the annular seal groove is less than the diameter of the annular seal gland.

In some embodiments, the orifice plate carrier assembly includes a ring member having an outer cylindrical surface, and wherein the seal member engages the outer cylindrical surface, and at least one annular surface of the ring member, and at least one annular surface of the carrier. In some embodiments, the seal gland includes surfaces that form at least one obtuse angle when viewed in cross section.

Also disclosed are methods of making an orifice plate carrier. One such method comprises: placing an orifice plate into engagement with an annular ledge in a carrier body, the carrier body having an aperture therethrough and having, on a first side, an annular rim and the annular ledge that extends radially inward from the annular rim, wherein the annular ledge and annular rim are disposed concentrically about the aperture. A first annular elastomeric seal is positioned about an annular lip of a ring member, and the annular lip of the ring member is positioned within the annular rim of the carrier body. The method further includes, using the first annular seal, sealing between the ring member and the carrier body and between the ring member and the orifice plate, and positioning a second annular elastomeric seal in an annular groove on a second side of the carrier body opposite the first side.

The foregoing has outlined rather broadly features of exemplary embodiments in order that the detailed description that follows may be better understood. Additional features will be described hereinafter that form the subject of certain of the claims.

DETAILED DESCRIPTION OF DISCLOSED EXEMPLARY EMBODIMENTS

The drawing figures are not necessarily to scale. Certain features of the disclosed embodiments may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown, all in the interest of clarity and conciseness.

In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” means either an indirect or direct connection. Thus, if a first component couples or is coupled to a second component, the connection between the components may be through a direct engagement of the two components, or through an indirect connection that is accomplished via other intermediate components, devices and/or connections. In addition, the terms “axial” and “axially” generally mean along or parallel to a given axis, while the terms “radial” and “radially” generally mean perpendicular to the axis. For instance, an axial distance refers to a distance measured along or parallel to a given axis, and a radial distance means a distance measured perpendicular to the axis.

FIG. 1illustrates a cross-sectional view of an orifice fitting10having an orifice plate assembly12in accordance with principles disclosed herein. As shown, orifice fitting10includes a lower portion16coupled to an upper portion18. Lower portion16includes a tubular body or conduit50. In the embodiment ofFIG. 1, the fitting10includes a flange14disposed at one or both ends and includes a central housing58there between. Flanges14are used to couple orifice fitting10between sections of a pipeline. Conduit50further includes a through passage or axial flow bore52therethrough, having a central axis55and upstream and downstream regions54and56, respectively. A fluid may flow through axial flow bore52from upstream region54to downstream region56generally in the direction indicated by arrow57. Housing58encloses a lower chamber20with a lower drive36, having a gear shaft and pinions, disposed therein. Upper portion18of orifice fitting10encloses an upper chamber22with an upper drive38, also having a gear shaft and pinions, disposed therein.

Orifice plate carrier60, described in more detail below, may be raised and lowered within orifice fitting10by operating lower drive36and upper drive38. InFIG. 1, orifice plate carrier60is shown in the measurement position, fully inserted into orifice fitting10. Lower portion16of fitting10further includes a plate carrier guide59which serves as a guide to assist in properly locating, aligning, and positioning orifice plate assembly12and orifice plate70within orifice fitting10. Specifically, carrier guide59is formed by a radial cut of axial flow bore52and includes an upstream sealing surface59aand a downstream sealing surface59b. In the measurement position, orifice plate assembly12rests perpendicular to the direction of fluid flow, indicated by arrow57, and in substantial concentric alignment with axial flow bore52between upstream sealing surface59aand downstream sealing surface59b.

Referring toFIG. 2, orifice plate assembly12includes a central axis15which is substantially aligned with flow bore axis55(FIG. 1) when orifice plate assembly12is disposed within the lower portion16of fitting10, as described above. Orifice plate assembly12includes a carrier60, orifice plate70, an upstream o-ring seal80a, a retaining ring90, and a downstream o-ring seal80b(FIG. 3). Each of the aforementioned components of orifice plate assembly12includes a through bore having a central axis aligned with central axis15: axis65for orifice plate carrier60, axis75for orifice plate70, axis85for upstream upstream o-ring seal80a, axis95for retaining ring90, and axis86for downstream o-ring seal80b.

Referring still toFIG. 2, carrier60has a generally rectangular body60athat includes an upstream facing surface67, a downstream facing surface69, and a central portion64that is coupled between a pair of elongate legs66. Each leg66includes a rack surface39on downstream surface69for engagement with lower and upper drives36,38(FIG. 1) when the orifice plate assembly12is moved in order to position it in, or to remove it from, its measurement position in axial flow bore52.

Carrier60further includes a central aperture62formed through the central portion64and aligned with axis65and having diameter D1Carrier60also includes annular rim61disposed about the central aperture62and having diameter D3, and an annular ledge63that extends radially inward from the annular rim61to central aperture62. Rim61is thus an annular step or shoulder that defines the outer terminus of the annular ledge63, and annular ledge63extends readily inwardly to define aperture62. Annular rim61and annular ledge63are coaxially aligned with axis65. In at least some embodiments, orifice plate carrier60is investment cast from materials such as aluminum, stainless steel, polymer, etc.

Orifice plate carrier60further comprises embedded markings or instructional text to assist the operator during installation of orifice plate carrier60into orifice fitting10and to prevent the operator from installing orifice plate carrier60in the wrong orientation, for example, upside down or with the upstream face of orifice plate carrier60facing downstream region56. In this exemplary embodiment, embedded markings or instructional texts41,42and43provide instructional guidance concerning information such as fluid flow direction, and installation orientation, respectively. The instructional text41,42and43may comprise words, letters, and/or symbols. For example, an arrow may be embedded to indicate the upper edge of orifice plate carrier60, as shown. As another example, the phrase, “This face toward inlet,” may be embedded to indicate the upstream face of orifice plate carrier60.

Referring still toFIG. 2, orifice plate70is an annular member (i.e. washer shaped) having central axis75, outer cylindrical edge71defining the plate's outer diameter D2, an upstream facing surface72, a downstream facing surface73, and a central aperture or orifice74extending between surfaces72,73and aligned with axis75. Orifice74is formed to have a smaller opening in the upstream facing surface72than in the downstream facing surface73, best shown inFIG. 4. In some embodiments, orifice plate70is made of stainless steel. Orifice plate70is disposed in carrier body60asuch that downstream facing surface73faces and engages ledge63of carrier60. Rim61is concentric to and faces cylindrical edge71of orifice plate70and is in very close proximity thereto, rim61essentially centering orifice plate70within carrier body60a. Central axis75is aligned with orifice plate assembly central axis15, such that upstream facing surface72and downstream facing surface73are substantially perpendicular to the fluid flow direction57(FIG. 1). As best shown inFIG. 1, orifice plate70is positioned within carrier60with upstream facing surface72positioned axially adjacent to upstream region54and with downstream facing surface73positioned axially adjacent to downstream region56.

Referring still toFIG. 2, upstream o-ring seal80aincludes a central opening82and is positioned such that its central axis85is aligned with orifice plate assembly central axis15. In this exemplary embodiment, upstream o-ring seal80ais circular in cross-section, but other embodiments may employ annular seals that have cross sections other than circular. In at least some embodiments, upstream o-ring seal80acomprises an elastomer, such as rubber, and provides sealing contact between orifice plate upstream surface72, rim61of carrier60, and ring90, as described in more detail below. Central opening82of seal80aincludes a relaxed diameter before the o-ring seal is stretched to engage the retaining ring90, as described below.

Referring now toFIGS. 2 and 4, retaining ring90includes a central aperture92, an annular flange96having a downstream facing surface94, and an annular, axially-extending lip97extending from flange96. Flange96and lip97are encircle aperture92and are concentric to one another to central axis95. Central aperture92is sized, in this example, to have substantially the same diameter as aperture62of carrier60. In some embodiments, retaining ring90is made of stainless steel. Retaining ring90is positioned in orifice plate assembly12such that axis95is aligned with orifice plate assembly central axis15and conduit central axis55, and such that annular lip97extends within the central opening82of upstream o-ring seal80a. The annular lip97is sized to have a maximum outer diameter that is greater than the relaxed diameter of central opening82of o-ring80.

As best shown in the cross-section view inFIG. 4, in this embodiment, the radially-outermost surface98of annular lip97is not cylindrical but is instead a tapered or beveled surface relative to axis95and to surface94of the flange96. In this way, retaining ring90includes an annular beveled notch93between lip97and flange96so as to better capture and retain o-ring seal80a. In this exemplary embodiment, the intersection of outermost surface98of lip97with downstream surface94of flange96forms an angle that is less than ninety degrees; however an angle of ninety degrees and angles greater than ninety degrees are anticipated in alternate embodiments. In at least some embodiments, retaining ring90comprises metal, such as stainless steel, to provide sufficient rigidity to support the sealing contact of upstream o-ring seal80aagainst orifice plate70and orifice plate carrier60.

Referring again toFIGS. 2 and 4, the components of orifice plate assembly12are stacked face-to-face while maintaining the coaxial alignment of the central aperture of each component along axes15,55. Specifically, orifice plate70is disposed within carrier60so that orifice plate edge71faces and is adjacent to carrier rim61, and so that downstream facing surface73of plate70abuts annular ledge63of the carrier60. The coaxial alignment of axes65,75and15is established via the close tolerances and resulting precise fit between edge71and rim61, while the perpendicular orientation of upstream facing surface72and downstream facing surface73, relative to flow direction57, is established via the engagement of the planar surfaces of the carrier's annular ledge63and the orifice plate's downstream facing surface73. Upstream o-ring seal80ais disposed within carrier60and abuts orifice plate70to establish circular contact along both rim61of carrier60and the upstream facing surface72of orifice plate70. Retaining ring90is likewise disposed with its central axis95in coaxial alignment with axes65,75,55, and15. The downstream facing surface94of flange96abuts against upstream o-ring seal80a, and beveled surface98of lip97engages the inside diameter of o-ring seal80a. O-ring seal80ais thus retained by an upstream seal gland81defined by the upstream facing surface72of the orifice plate, the annular rim61of the carrier60, the outer surface98of lip97, and the downstream facing surface94of retaining ring90.

Annular flange96of retaining ring90is sized, in certain embodiments, such that its overall outer diameter is greater than the diameter of the annular rim61of carrier body60a, so as to extend beyond the annular lip rim61when orifice plate assembly12is assembled, as best shown inFIG. 4. Retaining ring90squeezes the seal80aand thereby causes the orifice plate70to be pressed against the annular ledge63of carrier60, with upstream O-ring seal80abeing retained within angled notch93. That is, downstream facing surface73of orifice plate70is held against the carrier's annular ledge63by axial forces applied by o-ring80awhen o-ring80ais disposed between the retaining ring90and plate surface73. Similarly, retaining ring90is coupled to the carrier60by radial forces applied to retaining ring90by the energized o-ring80awhen the o-ring is disposed between the annular lip97of the retaining ring90and the annular rim61of the carrier body60a. Due to the close dimensional tolerances and resulting tight fit between the aforementioned components, the upstream o-ring seal80ais captured along four surfaces of seal gland81and establishes a seal between orifice plate carrier60, orifice plate70, and retaining ring90. When upstream o-ring80aand retaining ring90are coupled to carrier body60a, a gap89is present between the orifice plate's upstream facing surface72and the adjacent surface of annular lip97of retaining ring90.

FIG. 3depicts a view of the downstream face of orifice plate assembly12, which is on the side of orifice plate carrier60adjacent downstream region56when orifice plate carrier60is disposed within orifice fitting10. As shown, parallel racks39are adapted to interface with lower drive36and upper drive38to enable raising and lowering of orifice plate carrier60within plate carrier guide59(FIG. 1). The downstream facing surface69of plate carrier60further includes o-ring groove68coaxially aligned with central axis15. Carrier60is configured and is retained in fitting10such that its downstream facing surface69is perpendicular to axis15. In this exemplary embodiment, there are a plurality of embedded markings or instructional texts44,45on downstream facing surface69which may comprise words, letters and/or symbols and used, for example, to provide instructional guidance to users concerning fluid flow direction, installation orientation, branding, and orifice plate carrier60material.

Referring toFIGS. 3 and 4, downstream o-ring seal80bincludes central axis86which is aligned with orifice plate assembly central axis15and carrier axis65. Downstream o-ring seal80bis positioned within o-ring groove68that, in this embodiment, has a diameter substantially equal to the diameter of upstream seal gland81. As shown inFIG. 4, groove68, in cross section, includes a base surface46and a pair of sides47that may taper towards one another such that the groove68is narrower at the base46than at the groove opening. O-ring seal80bis captured by three contacting surfaces46and47therein forming a plurality of circular sealing surfaces with groove68. In this embodiment, seal80bis circular in cross-section, but other embodiments may employ annular seal members that are non-circular in cross section. In at least some embodiments, downstream o-ring seal80bcomprises an elastomer, such as rubber. and is substantially identical to upstream o-ring seal80aso that the seals80,80bare interchangeable. This uniformity eases assembly and reduces the number of parts that must be kept in inventory. When orifice plate assembly12is disposed within orifice fitting10in the measurement position as shown inFIGS. 3 and 4, downstream o-ring seal80babuts against conduit50along the portion that is axially adjacent to downstream region56so as to form a fluid seal therebetween.

The orifice plate carrier assembly12may be manufactured and assembled as follows. In some embodiments, an orifice plate70having central orifice74that is appropriately sized for the given application is placed into engagement with an annular ledge63in a carrier body60a, the carrier body60ahaving a central aperture62therethrough and having, on a first side, an annular rim61and the annular ledge63that extends radially inward from the annular rim61, wherein the annular ledge63and annular rim61are disposed concentrically about the aperture62. In some embodiments, the carrier body60ais made through an investment casting process. A first annular elastomeric seal, such as the upstream o-ring seal80a, is positioned about the annular lip97of the retaining ring90. The annular lip97of the retaining ring90is positioned within the annular rim61of the carrier body60a. The annular elastomer seal80amay alternatively first be placed within the annular rim61of the carrier with the annular lip97of the retaining ring90then being disposed within its central opening82. The first annular seal80aseals between the retaining ring90and the carrier body60aand between the retaining ring90and the orifice plate70. A second annular elastomeric seal, such as the downstream seal80b, is positioned in an annular groove68formed on the side of the carrier body60athat is opposite the first side. The orifice plate carrier assembly12may then be placed within a meter body for measuring fluid flow there through.

Unlike the orifice plate assembly12described above, conventional orifice plate assemblies are complicated and difficult both to manufacture and assemble properly. Conventionally, the orifice plate assembly comprises an orifice plate carrier, in which the orifice plate is secured, with o-ring seals positioned on each side of the orifice plate and centering tabs are needed to position the plate and seal assembly within the flowbore of the fitting. A number of snap rings or clips secure the orifice plate within the orifice plate carrier and maintain the seals in proper sealing engagement with the orifice plate. Retaining the plate and seals in proper position and in a sealing relationship is difficult to achieve with the convention centering tabs, clips, and snap rings.

The design for assembly12described above overcomes manufacturing and assembly challenges with a simplified configuration, whereby: (1) annular rim61of carrier60mates with cylindrical edge71of orifice plate70to precisely position plate70at the required concentric position relative to axial flowbore52; (2) orifice carrier assembly12need not employ centering tabs to properly position the orifice plate within the carrier, but relies entirely on the precision provided by the easier-to-manufacture circular ledge63and rim61of carrier60; (3) precise perpendicular orientation of orifice plate70relative to flow direction57is established by directly abutting downstream facing surface73of orifice plate70against planar annular ledge63of the carrier60; (4) sealing between orifice plate70and orifice plate carrier60is established using upstream o-ring seal80aand that is retained effectively, not by numerous clips and snap rings, but by a single component—a retaining ring90that can be precisely manufactured and easily placed during assembly to retain seal80ain sealing engagement; (5) only a single annular seal (upstream o-ring seal80a) engages the orifice plate70, the seal on the downstream side being accomplished using an annular seal80bthat sealing engages between the carrier60and an opposing surface on the orifice fitting10.

Referring now toFIG. 5, there is shown another orifice plate assembly112suitable for use in orifice fitting10in place of orifice plate assembly12previously described. Orifice plate assembly112includes a carrier60, orifice plate70, an upstream o-ring seal80a, a retaining ring190, and a downstream o-ring seal80b, each having a through bore with a central axis aligned with central axis15of assembly112and with axis55of fitting10once installed in the fitting. The components of orifice plate assembly112are stacked face-to-face while maintaining the coaxial alignment of the central aperture of each component along axis15. Orifice plate assembly112may be employed in any orifice fitting10, but has particular application in fittings in which the diameter of the flow bore52is ten inches or larger.

Referring still toFIG. 5, in this embodiment, carrier60has a generally rectangular body60bthat includes an upstream facing surface67, a downstream facing surface69, a central portion64that is coupled between a pair of elongate legs66, and a central aperture62. A seal groove68is formed in downstream facing surface69concentric with aperture62and retains downstream o-ring seal80b.

Upstream facing surface67of carrier body60bis formed to have a radially outer annular shoulder or rim161and a stair step profile167sized to receive orifice plate70, retaining ring190and upstream o-ring80aas described more fully below. Upstream facing surface67includes an annular ledge163asized to receive orifice plate70and that terminates in an annular step or shoulder164. Annular shoulder164is concentric to and faces edge71of orifice plate70. Shoulder164centers plate70and retains it within carrier body60bin the proper position. Upstream facing surface67further includes an annular ledge163band a seal engaging surface165extending between ledges163a,bfor sealing engagement with upstream o-ring seal80a. Seal engaging surface165includes a first annular portion165athat is generally perpendicular to carrier axis65, and a second annular portion165bthat is angled or beveled relative to surface165a. In this exemplary embodiment, the angle of intersection between surfaces165a,bis greater than ninety degrees and may be, for example an obtuse angle of 120 degrees or more.

Downstream facing surface94of retaining plate190includes an annular ledge195and a seal engaging surface196. Ledge195is sized to receive orifice plate70and terminates in an annular step or shoulder193. Step193cooperates with annular step164on carrier body60bto properly center and retain plate70within carrier body60b. Annular ledge195is generally perpendicular to ring axis95. Seal engaging surface196includes a first annular surface196athat is generally parallel to ledge195and a second annular portion196bthat is angled or beveled relative to surface196a. In this example, the angle of intersection between surfaces196a,bis greater than ninety degrees and may be, for example an obtuse angle of 120 degrees or more.

In this embodiment, upstream o-ring seal80ahas a larger diameter than o-ring seal80b, and o-ring80ais positioned so that its innermost surface is disposed about and engages the outer cylindrical edge surface71of orifice plate70. The relaxed, unstretched, inner diameter of upstream o-ring seal80ais smaller than the outer diameter of orifice plate70. Retaining ring190is sized to be retained within annular rim161of carrier body60b, rim161serving as an annular shoulder for retaining and centering retaining ring190within carrier body60b. With ring190positioned inside annular rim161, seal engaging surface196of ring190is positioned opposite seal engaging surface165of carrier body60b. Collectively, edge71of plate70and the opposing seal engaging surfaces165,196form a seal gland181for upstream o-ring seal80a. Carrier body60b, retaining ring190, o-ring80aand orifice plate70are sized so that, once carrier assembly112is assembled, carrier body60band retaining ring190apply an axially directed force to o-ring80aand ensure that o-ring80aseals against both seal engaging surfaces165,196. Due to the close dimensional tolerances and resulting tight fit between the aforementioned components, the upstream o-ring seal80ais captured within seal gland181and establishes a seal between orifice plate carrier body60b, orifice plate70, and retaining ring190. When upstream o-ring80aand retaining ring190are coupled to carrier body60b, a gap189is present between the orifice plate's upstream facing surface72and the adjacent surface194of retaining ring190.

Orifice plate carrier assembly112may be manufactured and assembled as follows. Orifice plate70having central orifice74that is appropriately sized for the given application is placed into engagement with ledge163awithin annular step164in carrier body60b. Upstream o-ring seal80ais positioned about edge71of orifice plate70and in engagement with seal engaging surface165of carrier body60b. Retaining ring190is positioned within annular rim161of carrier body60b, and is positioned such that: annular step193captures edge71of orifice plate70; annular ledge195faces upstream facing surface72of plate70; and such that seal engaging surface196is opposite surface165of carrier body60b. Further axial movement of ring190toward carrier body60bcauses surfaces165and196to come into sealing engagement with o-ring80a.

The design for assembly112described above overcomes manufacturing and assembly challenges over conventional assemblies with a simplified configuration, whereby: (1) annular step164of carrier body60band annular step193of retaining ring190precisely position plate70at the required concentric position relative to axial flowbore52; (2) orifice carrier assembly112need not employ centering tabs to properly position the orifice plate within the carrier, but relies entirely on the precision provided by the easier-to-manufacture circular structures described; (3) precise perpendicular orientation of orifice plate70relative to flow direction57is established by directly abutting orifice plate70against planar annular ledge163of carrier body60band annular ledge195of retaining ring190; (4) sealing between orifice plate70and orifice plate carrier60is established using upstream o-ring seal80aand that is retained effectively, not by numerous clips and snap rings, but by a single component—a retaining ring90that can be precisely manufactured and easily placed during assembly; (5) only a single annular seal (upstream o-ring seal80a) engages the orifice plate70, the seal on the downstream side being accomplished using an annular seal80bthat sealing engages between the carrier60and an opposing surface on the orifice fitting10.

While preferred embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teaching herein. The embodiments described herein are exemplary only and are not limiting. Many variations, combinations, and modifications of the systems, apparatuses, and processes described herein are possible and are within the scope of the disclosure. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. The inclusion of any particular method step or operation within the written description or a figure does not necessarily mean that the particular step or operation is necessary to the method. The steps or operations of a method listed in the specification or the claims may be performed in any feasible order, except for those particular steps or operations, if any, for which a sequence is expressly stated. In some implementations two or more of the method steps or operations may be performed in parallel, rather than serially.