Patent Description:
Seals are used in a wide variety of applications including, for example, liquid pumps, mixers, agitators, and the like to provide fluid tight seals. Such seals are used to seal between rotating shafts and a housing in, for example, the chemical, pharmaceutical, gas and oil, power generation, mining and minerals, food and beverage, pulp and paper processing, wastewater and water management, and refrigeration industries. An example seal is an end face seal. End face seals include a seal interface that is lubricated by the fluid to be sealed or a separate barrier fluid introduced into the seal. When a seal interface is lubricated by the fluid to be sealed (e.g., process fluid), the fluid to be sealed may be driven into the seal interface via a hydrostatic effect and/or a hydrodynamic effect. The hydrodynamic effect promotes introducing process fluid into a seal interface with forces that are produced when a rotating portion of a seal interface is rotating, whereas the hydrostatic effect promotes introducing process fluid into a seal interface with just the forces resulting from a pressure differential across the seal interface.

<CIT> describes a mechanical seal assembly having a deep groove pattern formed in the face of the rotating seal ring. The groove pattern has two sets of angled grooves, which are angled in opposite rotational directions to provide pumping of barrier gas into the grooves.

<CIT> describes a sliding element for seals in order to reduce the friction coefficient on the sliding face during rotational motion. The sliding element comprises a first dam section, which is configured in an annular form on the sliding face. The element further has dimple sections which have a narrow groove that points towards the sealed fluid. These dimple sections are arranged in an annular array. There is then another dimple section which has a narrow groove point in an opposite direction compared with the first dimple sections, which is also arranged in an annular array.

<CIT> describes a dynamic sealing assembly where a liquid film is present between the sealing faces. The sealing face of one of a pair of parts has extremely shallow grooves and then deep fluid-introduction grooves for introducing a higher-pressure fluid are provided on the upstream side of the extremely shallow grooves.

<CIT> describes a negative pressure mechanism that generates negative pressure by relative rotational sliding of a stationary-side seal ring and a rotating-side seal ring, which contains a fluid between the sealing faces to reduce friction. In some embodiments, the negative pressure generation mechanism includes a dimple formed in the seal face.

<CIT> describes a hydrodynamic sealing assembly. The face of the face seal provides a sealing zone for maintaining a lubricant layer of about <NUM> micrometers between the face seal and the sleeve. A face of the seal contains annular and radial oil passages which distributes oil to the surface of the seal face.

<CIT> describes a rotary mechanical seal, which reduces distortions in the sealing washer caused by thermal expansion of the washer or by a change in pressure profile across the sealing face of the washer. This is achieved by providing shallow spiral grooves formed in one of the opposing faces of the seal, which are directed to produce a pressure across the face.

The present disclosure relates generally to rotary mechanical seals for fluid, and more particularly, devices, systems, and methods for reducing friction between seal faces forming a seal interface.

According to one embodiment, the a hydrostatic seal assembly is disclosed. The seal assembly includes: a first ring having a first side bounded by a first edge and a second edge; and second ring having a second side facing the first side. In this embodiment, a circumferential channel extends along the first side between, and spaced from, the first edge and the second edge, a plurality of sub-channels extend from the circumferential channel along the first side of the first ring and the circumferential channel and the plurality of sub-channels are configured to take up less than ten percent of a surface area of the first side, and the first ring and the second ring form a seal between the first side and the second side.

In the seal assembly of any prior embodiment, the plurality of sub-channels include a plurality of first sub-channels extending from the circumferential channel to the first edge along the first side of the first ring.

In the seal assembly of any prior embodiment, the circumferential channel and the plurality of first sub-channels promote introducing fluid between the first side of the first ring and the second side of the second ring causing hydrostatic lift between the first side of the first ring and the second side of the second ring.

In the seal assembly of any prior embodiment, wherein the plurality of sub-channels include a plurality of second sub-channels extending along the first side from the circumferential channel toward the second edge.

In the seal assembly of any prior embodiment, the plurality of sub-channels extending from the circumferential channel are located on the first side of the first ring such that first sub-channels of the plurality of first sub-channels and second sub-channels of the plurality of second sub-channels extend from the circumferential channel in an alternating order along a length of the circumferential channel.

In the seal assembly of any prior embodiment, a second sub-channel of the plurality of second sub-channels extends from the circumferential channel to a terminal end spaced from the second edge.

In the seal assembly of any prior embodiment, a ratio of a circumferential distance between each first sub-channel of the plurality of first sub-channels to a radial span of each first sub-channel is about <NUM>.

In the seal assembly of any prior embodiment, the first edge of the first ring is configured to be on a pressurized side of the seal.

In the seal assembly of any prior embodiment, the seal is configured to provide a seal against pressures on the pressurized side of the seal within a range of about <NUM> bar (<NUM> psi) to about <NUM> bar (<NUM> psi).

In the seal assembly of any prior embodiment, a ratio of a circumferential distance between each sub-channel of the plurality of sub-channels to a radial span of each sub-channel is about <NUM>.

In the seal assembly of any prior embodiment, the circumferential channel is co-axial with one or both of the first edge and the second edge.

In the seal assembly of any prior embodiment, the first side of the first ring has a width extending from the first edge to the second edge and the circumferential channel is spaced from the first edge by a distance of one-third of the width of the first side of the first ring.

In the seal assembly of any prior embodiment, the circumferential channel a depth of about <NUM> (<NUM> inches).

In the seal assembly of any prior embodiment, the circumferential channel has a width between about <NUM> (<NUM> inches) and <NUM> (<NUM> inches).

In the seal assembly of any prior embodiment, one or both of the first side of the first ring and the second side of the second ring are formed from one or more materials selected from a group consisting of carbon, silicon carbide, and tungsten carbide.

In the seal assembly of any prior embodiment, the circumferential channel includes a first circumferential channel portion and a second circumferential channel portion fluidly separated from the first circumferential channel portion.

Also disclosed is a liquid seal system configured to provide a seal between a housing defining a bore with pressurized fluid therein and a rotatable shaft extending through the bore. The seal system includes: a first annular ring having a first seal face; and a second annular ring having a second seal face facing the first seal face. An annular channel extends along the first seal face and a plurality of radial channels extend from the annular channel along the first seal face. The plurality of radial channels being fluidly connected via the annular channel. The first seal face and the second seal face interact via fluid received in the annular channel to form a hydrostatic seal.

In the seal system of any prior embodiment, a first set of the plurality of radial channels extend from the annular channel to a first edge of the first seal face.

In the seal system of any prior embodiment, a second set of the plurality of radial channels extend from the annular channel to a terminal end spaced from a second edge of the first seal face.

In the seal system of any prior embodiment, the first edge of the first seal face is an inner edge of the first annular ring and the second edge of the first seal face is an outer edge of the first annular ring.

In the seal system of any prior embodiment, the first edge of the first seal face is an outer edge of the first annular ring and the second edge of the first seal face is an inner edge of the first annular ring.

In the seal system of any prior embodiment, the first edge of the first seal face is on a higher pressure side of the hydrostatic seal than the second edge of the first seal face.

In the seal system of any prior embodiment, each radial channel of the first set of the plurality of radial channels extends a radial channel distance from the annular channel and each radial channel of the second set of the plurality of radial channels extends the radial channel distance from the annular channel.

In the seal system of any prior embodiment, the first annular ring is formed from a plurality of components.

In the seal system of any prior embodiment, the first seal face and the second seal face are formed from silicon carbide.

In the seal system of any prior embodiment, the annular channel and the plurality of radial channels promote introducing fluid between the first seal face and the second seal face to cause hydrostatic lift between the first seal face and the second seal face.

In the seal system of any prior embodiment, the annular channel and the plurality of radial channels form a continuous passageway for pressurized fluid from within the bore of the housing.

It shall be understood that any prior disclosed seal assembly can be included in a seal system.

Also disclosed is a method of forming an annular ring for a hydrostatic sealing assembly. The method includes: forming a circumferential channel in a surface of an annular ring; and forming a plurality of first radial channels in the surface of the annular ring, the plurality of first radial channels extending from the circumferential channel to a first edge of the surface. The circumferential channel fluidly connects the plurality of first radial channels in the surface of the annular ring and the circumferential channel and the plurality of first radial channels are configured to take up less than ten percent of a surface area of the surface of the annular ring.

In the method of any prior embodiment, the method can further include forming a plurality of second radial channels in the surface of the annular ring, the plurality of second radial channels extending from the circumferential channel toward a second edge of the surface. The circumferential channel can fluidly connect the plurality of first radial channels in the surface of the annular ring and the plurality of second radial channels in the surface of the annular ring.

In the method of any prior embodiment, the formed circumferential channel, the plurality of first radial channels, and the plurality of second radial channels take up less than five percent of a surface area of the surface of the annular ring.

In the method of any prior embodiment, the formed circumferential channel, the plurality of first radial channels, and the plurality of second radial channels are formed via laser engraving.

In the method of any prior embodiment, the circumferential channel and the plurality of first radial channels have a depth of about <NUM> (<NUM> inches).

In the method of any prior embodiment, the circumferential channel and the plurality of first radial channels have a width within a range of about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches).

The preceding summary is provided to facilitate an understanding of some of the innovative features unique to the present disclosure and is not intended to be a full description. A full appreciation of the disclosure can be gained by taking the entire specification, claims, drawings, and abstract as a whole.

The disclosure may be more completely understood in consideration of the following description of various illustrative embodiments in connection with the accompanying drawings, in which:.

It should be understood, however, that the intention is not to limit aspects of the disclosure to the particular illustrative embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

The term "diameter", as used in this specification and the appended claims, is generally employed in its sense as being a line passing from side to side of an object unless the content clearly dictates otherwise. In some cases, the diameter of an object may pass through a center of the object and/or may be a longest line passing from side to side of the object.

As used in this specification and the appended claims, and although the term "and/or" is sometimes expressly recited herein, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

Additionally, when particular features, structures, and/or characteristics are described in connection with one embodiment, it should be understood that such features, structures, and/or characteristics may also be used in connection with other embodiments whether or not explicitly described unless clearly stated to the contrary.

Mechanical seals may take on a variety of configurations. In pumps, mixers, agitators, and/or other systems utilizing a rotating shaft or portion, rotary mechanical end face seals may be utilized to facilitate a fluid tight seal between a housing and a rotating shaft. Such end face seals may include an axially-stationary annular ring (e.g., a mating ring) associated with the housing or the rotating shaft and an axially-adjustable annular ring (e.g., a primary ring) associated with the other of the housing or the rotating shaft. The axially-stationary ring and the axially-adjustable ring may include seal faces in a relatively rotating sealing relation to one another along a seal interface.

<FIG> depicts an illustrative seal arrangement in a seal assembly <NUM> (e.g., a rotary end face seal assembly) with process pressure or high pressure at an outer edge of the seal faces and ambient or low pressure (e.g., lower pressure than the process pressure or high pressure) at the inner edge of the seal faces. It is contemplated, however, that the processor pressure or high pressure may be at an inner edge of the seal faces and ambient or low pressure may be at an outer edge of the seal faces. The seal arrangement depicted in <FIG> may be configured to seal fluid, such as a liquid and/or a gas. Although the seal assembly <NUM> and configurations discussed herein may be primarily discussed with respect to sealing a process fluid that is a liquid (e.g., such that the seal assembly <NUM> is a liquid seal assembly or system), it is contemplated the seal assembly <NUM> and configurations may be utilized to seal a process fluid that is a gas (e.g., such that the seal assembly <NUM> is a gas seal assembly or system).

The seal assembly <NUM> depicted in <FIG> may seal fluid within a chamber <NUM> defined by a housing <NUM> and an attached gland plate <NUM>. A shaft <NUM> may extend through the housing <NUM>. In some cases, the shaft <NUM> may be configured to rotate relative to the housing <NUM> and a seal may be provided to inhibit or mitigate leakage of fluid from the chamber where the shaft <NUM> and the housing <NUM> meet.

The seal assembly <NUM> may include, among other components, a seal ring configuration including a primary ring <NUM> (e.g., a first ring or first annular ring) and a mating ring <NUM> (e.g., a second ring or second annular ring). As depicted in <FIG>, the mating ring <NUM> may be configured to rotate with the shaft <NUM> and the primary ring <NUM> may be axially adjustable and rotationally fixed relative to the mating ring <NUM>. The mating ring <NUM> and the primary ring <NUM>, however, may be configured in different relative configurations including, but not limited to, the primary ring <NUM> rotating with the shaft <NUM> and the mating ring <NUM> remaining rotationally fixed relative to the primary ring <NUM>.

As depicted in <FIG>, the mating ring <NUM> may be rotationally fixed relative to a sleeve <NUM> by one or more pins <NUM>. The sleeve <NUM> may be mounted on the shaft <NUM> and may rotate with the shaft <NUM> causing the mating ring <NUM> to also rotate with the shaft <NUM>. An o-ring <NUM> may seal the mating ring <NUM> to the sleeve <NUM> to prevent leakage of a process fluid through the mating ring <NUM>-sleeve <NUM> connection. The mating ring <NUM> may include a mating ring seal face <NUM> (e.g., an annular seal face or seal face taking on one or more other suitable configurations) defined by a first edge or outer edge and a second edge or inner edge. Further, mating ring <NUM> may be configured from a single component or two or more separable components connectable to form an annular ring.

The primary ring <NUM> may be retained within a gland adaptor assembly <NUM>, as depicted in <FIG>. The primary ring <NUM> may include a primary ring seal face <NUM> (e.g., an annular seal face or seal face taking on one or more other suitable configurations) defined by a first edge or an outer edge and a second edge or an inner edge. The primary ring seal face <NUM> may be configured to interact with the mating ring seal face <NUM> to form a seal interface <NUM> of the seal assembly <NUM>. Further, the primary ring <NUM> may be configured from a single component or two or more separable components connectable to form an annular ring.

The primary ring <NUM> may be axially biased by a biasing mechanism <NUM> (e.g., a spring or other suitable biasing mechanism). The biasing mechanism <NUM> may bias the primary ring <NUM> toward the mating ring <NUM>, urging the primary ring seal face <NUM> into face-to-face sealing relation with the mating ring seal face to form the seal interface <NUM>. In some cases, a disk <NUM> may be situated axially between the biasing mechanism <NUM> and the primary ring <NUM>.

The seal assembly <NUM>, the housing <NUM>, and the gland plate <NUM>, and/or other suitable components may define a pressure zone P<NUM> (e.g., a pressure zone or process zone) in the chamber <NUM> upstream of the seal interface <NUM>. A low pressure zone P<NUM> may exist downstream of the seal interface <NUM>. The sealing configuration depicted in <FIG> may be referred to as an outside diameter (O. ) pressurized seal assembly <NUM>, where the pressurized process fluid is adjacent an outer diameter of the seal interface <NUM>.

The seal interface <NUM> along the primary ring seal face <NUM> and the mating ring seal face <NUM> may inhibit process fluid from escaping the high pressure zone P<NUM> to the low pressure zone P<NUM>. Because, in the configuration depicted in <FIG>, the mating ring seal face <NUM> is wider in a radial direction than the primary ring seal face <NUM>, the seal interface <NUM> may be coextensive with the radial extent of the primary ring seal face <NUM>. In alternative configurations, the seal interface <NUM> may be defined by the mating ring seal face <NUM> operating against a primary ring seal face <NUM> of greater radial width than a radial width of the mating ring seal face <NUM>.

In some cases, the seal interface may be lubricated via fluid (e.g., a process fluid of liquid and/or gas) under pressure within the housing, where the fluid is introduced to the seal interface via a hydrodynamic effect and/or a hydrostatic effect. To facilitate introducing process fluid to a seal interface with a hydrodynamic effect, one or more seal faces of the seal interface may include surface texturing that promotes introduction of process fluid into the seal interface while a rotating portion of the seal interface is rotating. Such surface texturing may include applying hydro-pad relieved areas or depressions on one or both of the seal faces forming the seal interface. One example of seal faces including hydro-pad relieved areas or depressions is disclosed in <CIT>, which is hereby incorporated by references in its entirety for all purposes. Another example of seal faces including hydro-pad relieved areas or depressions is disclosed in <CIT> and published as <CIT>, which is hereby incorporated by references in its entirety for all purposes.

Other surface texturing techniques to promote lubrication between seal faces include micro-dimple surface texturing. Typical micro-dimples had a diameter of about <NUM> (<NUM> inches) and a dimple depth of about <NUM> (<NUM> inches), which results in a dimple size to depth ratio on the order of about twenty (<NUM>). In some cases, a dimple area density on a seal face of a seal assembly of about twenty percent has been utilized.

Although the hydrodynamic effect and known surface texturing may be relied upon to lubricate the seal interface of a seal assembly during rotation of a rotating portion of the seal, it has been found that better lubrication may be desirable at static pressure conditions and upon startup of the rotating portion of the seal assembly (e.g., a portion configured to rotate with a rotating shaft of a pump) to minimize or mitigate seal face damage. Ensuring adequate lubrication upon startup of rotation of a rotating portion of a seal may be of particular concern where process fluid is kept under high pressures and/or where process fluid has a particular chemical make-up as hard materials that can withstand high pressures without deformation and/or that resist chemical corrosion may be utilized for the seal faces forming the seal interface.

Example materials utilized for the seal faces forming the seal interface include, but are not limited to, carbon (C), silicon carbide (SiC), tungsten carbide (WC), and the like. Hard materials utilized for the seal faces forming the seal interface may include SiC, WC, and the like.

Running hard material against hard material at a seal interface may cause wear and tear on the seal faces and limit a life of a seal assembly. Although the seal assembly may be configured such that one of the seal faces formed from the hard material may include a matte finish and the other seal face may have a plain polish finish to facilitate introducing process fluid into a seal interface due to hydrostatic effects, such a matte finish may decrease some hydrodynamic load support capability of the plain polish finish due to a larger gap between the matte finish face and the plain polish finish face Additionally, although hydro-pad face patterning or texturing may be utilized to assist in promoting the introduction of process fluid into the seal interface during rotation of the seal assembly, the applicant has appreciated that such a configuration may increase leakage without adequately encouraging lubrication at the seal interface in static pressure situations (e.g., upon startup, etc.). It has been found, however, that applying channels (e.g., micro-channel surface texturing patterns), as discussed herein, to one or both of the seal faces forming the seal interface may increase process fluid penetration into the seal interface, particularly at pump start up and/or static pressurized conditions, to separate the seal faces with lower leakage relative to leakage expected when utilizing hydro-pad patterning.

<FIG> depict configurations of the primary ring seal face <NUM> configured to promote the introduction of process fluid between the primary ring seal face <NUM> and the mating ring seal face <NUM>. Although the seal face configurations depicted in <FIG> are discussed herein with respect to the primary ring <NUM>, such configurations may be utilized additionally or alternatively on the mating ring seal face <NUM>.

<FIG> and <FIG> depict plan views of the primary ring <NUM> showing the primary ring seal face <NUM> defined by a first edge <NUM> (e.g., a radially outer edge or periphery) and a second edge <NUM> (e.g., a radially inner edge or periphery) of the primary ring <NUM>. Although the first edge <NUM> is depicted and described herein as the outer edge and the second edge <NUM> is depicted and described herein as the inner edge, it is contemplated that the first edge <NUM> may be an inner edge and the second edge <NUM> may be an outer edge. The primary ring seal face <NUM> defines one or more channels that are configured to promote introducing process fluid between seal faces of a seal interface via a hydrostatic effect.

In the configuration depicted in <FIG>, the first edge <NUM> may be configured to be exposed to the process fluid and associated pressures. The seal face configurations discussed herein may be configured to be utilized in seal assemblies <NUM> that are used to maintain a fluid under pressure. For example, the seal face configuration may be configured to facilitate lubrication within a seal interface when the fluid under pressure is held within a range from about <NUM> bar (<NUM> pounds per square inch (psi)) or less to about <NUM> bar (<NUM> psi or more), or other suitable range. In one example, the seal face configuration may be configured to facilitate lubrication within a seal interface when the fluid under pressure is held within a range from about <NUM> bar (<NUM> psi) to about <NUM> bar (<NUM> psi).

The channels depicted in the primary ring seal face <NUM> of <FIG> may include one or more circumferential channels <NUM> (e.g., when there are two or more circumferential channels <NUM>, the circumferential channels <NUM> may be co-axial and/or take on one or more other suitable configurations) and a plurality of sub-channels <NUM> (e.g., radial channels or other channels radially extending from the circumferential channel <NUM>). In some cases, the plurality of sub-channels <NUM> may extend from the circumferential channel <NUM> such that the circumferential channel <NUM> and at least some of the plurality of sub-channels <NUM> may be fluidly connected and/or may form a continuous passageway. Such a configuration of channels may facilitate directing fluid into the seal interface of the seal assembly <NUM>, distributing the fluid along the circumference of the seal interface, and increase a fluid opening force between the seal faces (e.g., the primary ring seal face <NUM> and the mating ring seal face <NUM>) to reduce mechanical loads on the seal faces and improve seal performance.

The channels (e.g., the circumferential channel <NUM> and the sub-channels <NUM>) are configured to take up a desired percentage of a surface area of the primary ring seal face <NUM> such that a leakage of process fluid may be mitigated. The channels are configured to take up less than ten (<NUM>) percent. For example, the channels may be configured to take up less than about five (<NUM>) percent, and/or other suitable amount of a surface area of the primary ring seal face <NUM>. In one example, the channels may be configured to take up about three (<NUM>) percent of a surface area of the primary ring seal face <NUM>.

The circumferential channel <NUM> may have an annular configuration (e.g., an annular channel having a single, continuous circumferential channel segment or portion forming a ring on or in the primary ring seal face, as depicted in <FIG>) or the circumferential channel <NUM> may be formed from a plurality of circumferential channel segments or portions spaced from one another (e.g., as depicted in <FIG>). When the circumferential channel <NUM> is formed from a plurality of circumferential channel segments or portions, the circumferential channel <NUM> may include two (<NUM>) circumferential channel segments (e.g., circumferential channel segments or portions 40a, 40b depicted in <FIG>), three (<NUM>) circumferential channel segments or portions, four (<NUM>) circumferential channel segments or portions, or other suitable number of circumferential channel segments or portions. In some cases, each of the plurality of circumferential channel segments or portions may be located a same distance from a central axis of the primary ring <NUM>.

The circumferential channel <NUM> may take on a suitable configuration for distributing fluid along the primary ring seal face <NUM>. Example configurations may include, but are not limited to a circular configuration, an oval configuration, a star configuration, and/or other suitable configurations, as desired. In one example, the circumferential channel <NUM> may be generally circular and may be co-axial with one or both of the first edge <NUM> and the second edge <NUM> of the primary ring <NUM>.

The circumferential channel <NUM> may be positioned at any location between the first edge <NUM> and the second edge <NUM> of the primary ring. In some cases, the circumferential channel <NUM> may be spaced from the first edge <NUM> and the second edge <NUM>. For example, the primary ring seal face <NUM> may have seal face width S between the first edge <NUM> and the second edge <NUM>, and the circumferential channel <NUM> (e.g., a center of the circumferential channel <NUM>) may be located within a range of one-fourth to one-half of a distance of the seal face width S, or other suitable range, from the first edge <NUM> or otherwise an edge configured to be adjacent process fluid. In one example, the circumferential channel <NUM> may be located at one-third of a distance of the seal face width S from the first edge <NUM>, as depicted in <FIG> and <FIG>.

The plurality of sub-channels <NUM> may include a plurality of first sub-channels 42a and a plurality of second sub-channels 42b. Alternatively, the plurality of sub-channels <NUM> may consist solely of a plurality of first sub-channels 42a.

The plurality of first sub-channels 42a may extend from the circumferential channel <NUM> to the first edge <NUM> defining the primary ring seal face <NUM>. Such a configuration may facilitate promoting process fluid into the seal interface <NUM> as the plurality of first sub-channels in communication with the circumferential channel provide an avenue for pressurized process fluid to enter seal interface <NUM>, circulate around the seal interface <NUM> via the circumferential channel <NUM> and hydrostatic effect, and cause hydrostatic lift between the primary ring seal face <NUM> and the mating ring seal face <NUM> when in use in a manner similar to the configuration depicted in <FIG>. Such a configuration may form a hydrostatic seal between the primary ring seal face <NUM> and the mating ring seal face <NUM> at hydrostatic conditions, where a hydrostatic seal is known as a non-contacting mechanical seal that separates two different pressure zones used to establish a balanced pressure zone between two adjacent seal faces.

The plurality of second sub-channels 42b may extend from the circumferential channel <NUM> toward the second edge <NUM> defining the primary ring seal face <NUM>. Such a configuration may facilitate process fluid promoting hydrostatic lift between the primary ring seal face <NUM> and the mating ring seal face <NUM> by providing an avenue for the process fluid to penetrate deeper into the seal interface <NUM> than a location of the circumferential channel <NUM>. In some cases, one or more of the plurality of second sub-channels 42b may have a terminal end <NUM> prior to reaching the second edge <NUM> such that process fluid may be used to lubricate the seal interface <NUM> while mitigating leakage of process fluid through the seal interface <NUM>.

The plurality of second sub-channels 42b may extend a distance from the circumferential channel <NUM> toward the second edge <NUM>. The distance each of the second sub-channels 42b extend may be similar or the same for all of the second sub-channels 42b or one or more of the second sub-channels 42b may extend a distance from the circumferential channel <NUM> toward the second edge <NUM> that is different than a distance at least one other of the second sub-channels 42b may extend. In some cases, the second sub-channels 42b may extend a distance within a range of one-fourth to one-half of a distance of the seal face width S or other suitable range. In one example, one or more of the plurality of second sub-channels 42b may extend a distance of one-third of a distance of the seal face width S, as depicted in <FIG> and <FIG>.

When both are included in the configuration of the primary ring seal face <NUM>, the plurality of first sub-channels 42a and the plurality of second sub-channels 42b may be configured in a suitable manner with respect to one another. For example, the first sub-channels 42a of the plurality of the first sub-channels 42a may extend from the circumferential channel <NUM> at a same location as one of the plurality of second sub-channels 42b, the first sub-channels 42a of the plurality of the first sub-channels <NUM> and the second sub-channels 42b may extend from the circumferential channel <NUM> in an alternating or staggered order along a length of the circumferential channel <NUM> (e.g., as depicted in <FIG> and <FIG>), and/or the plurality of first sub-channels 42a may be configured on the primary ring seal face <NUM> in one or more other suitable manners with respect to how the plurality of second sub-channels 42b are configured on the primary ring seal face <NUM>.

The sub-channels <NUM> may be spaced a suitable distance from each other along the circumferential channel <NUM>. In some cases, the sub-channels <NUM> may be spaced a consistent distance from one another along the length of the circumferential channel, but this is not required. In one example, an angular separation between a same type of sub-channels <NUM> (e.g., between two first sub-channels 42a or between two second sub-channels 42b) may be within a range from about ten (<NUM>) degrees to about thirty (<NUM>) degrees or other suitable range. Alternatively or in addition, a distance between sub-channels <NUM> may be based on a ratio of a circumferential distance CD between the same type of sub-channels <NUM> to a radial span RS of a sub-channel <NUM> (e.g., a distance from a center of the circumferential channel <NUM> to a terminal end of the first sub-channel 42a or the second sub-channel 42b). The ratio of a circumferential distance CD between the same type of sub-channels <NUM> to a radial span RS of a sub-channel <NUM> may be within a range from about four (<NUM>) to about twenty (<NUM>) or other suitable range. In one example, the sub-channels <NUM> of a same type of sub-channel may be spaced along a length of the circumferential channel <NUM> such that the ratio of circumferential distance CD between the same type of sub-channels <NUM> to a radial span RS of the same type of sub-channel <NUM> may be about or may be eight (<NUM>) or less to facilitate promoting hydrostatic lift at the seal interface <NUM> while mitigating leakage of process fluid through the seal interface <NUM>. Alternatively or in addition, when the first sub-channels 42a and the second sub-channels 42b are consistently or equally staggered along the length of the circumferential channel <NUM>, a ratio of the circumferential distance between any two adjacent sub-channels <NUM> to a radial span of a sub-channel may be or may be about four (<NUM>) to facilitate promoting hydrostatic lift at the seal interface <NUM> while mitigating leakage of process fluid through the seal interface <NUM>. Other ratio values may be utilized, as desired, to determine a number of sub-channels to utilize and/or a spacing between adjacent sub-channels <NUM>.

<FIG> is a magnification of a portion of the illustrative primary ring <NUM> in <FIG> that is within circle-<NUM>. As can be seen in <FIG>, the first sub-channels 42a have a width W<NUM>, the second sub-channels 42b have a width W<NUM>, and the circumferential channel <NUM> has a width W<NUM>. In some cases, the widths W<NUM>, W<NUM>, W<NUM> may be the same, however, it is contemplated that one or more channels may have a width that may be different than a width of at least one other channel. In some cases, the widths W<NUM>, W<NUM>, W<NUM> may be configured to facilitate a flow of process fluid through the channels. The widths W<NUM>, W<NUM>, W<NUM> may be within a suitable rage of widths, such as within a range extending from about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches) or other suitable range. In one example, the widths W<NUM>, W<NUM>, W<NUM> may be about <NUM> (<NUM> inches).

<FIG> depict cross-sections of the primary ring <NUM> taken along lines <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>, respectively, of <FIG>. In the cross-section of <FIG>, the circumferential channel <NUM> is depicted in the primary ring seal face <NUM> as having a depth D<NUM>. In the cross-section of <FIG>, the first sub-channel 42a is depicted as extending from the circumferential channel <NUM> to the first edge <NUM> of the primary ring <NUM>, where the first sub-channel 42a is depicted in the primary ring seal face <NUM> as having a depth D<NUM>. In the cross-section of <FIG>, the second sub-channel 42b is depicted as extending from the circumferential channel <NUM> to its terminal end <NUM>, where the second sub-channel 42b is depicted in the primary ring seal face <NUM> as having a depth D<NUM>.

The depths D<NUM>, D<NUM>, D<NUM> of the channels may be equal to one another or, alternatively, one or more of the depths D<NUM>, D<NUM>, D<NUM> may be different from another one of the depths D<NUM>, D<NUM>, D<NUM>. In some cases, the depths D<NUM>, D<NUM>, D<NUM> may be configured to facilitate hydrostatic lift at the seal interface <NUM> by promoting the introduction of process fluid into the channels (e.g., the circumferential channel <NUM> and/or the sub-channels <NUM>). Illustratively, the depths may be within a range of <NUM> (<NUM> inches) and <NUM> (<NUM> inches) or other suitable range. In one example, the depths D<NUM>, D<NUM>, D<NUM> may be equal to about <NUM> (<NUM> inches), which is an order of magnitude deeper than depths of about <NUM> (<NUM> inches) used for dimple surface texturing. Channels of such depth may facilitate serving as a reservoir for fluid (e.g., in the event of a loss of pressurized fluid) and/or for collecting wear debris from the seal faces (e.g., the primary ring seal face <NUM> and/or the mating ring seal face <NUM>), if there is any, which may facilitate prolonging a life of the seal assembly <NUM>.

The above described channels of the primary ring <NUM> may be formed in the primary ring <NUM> (or the mating ring <NUM>) in a suitable manner capable of forming channels in hard materials (e.g., silicon carbide, tungsten carbide, etc.). In some cases, a laser (e.g., via laser engraving or ablating and/or other laser engraving or ablating techniques) or other suitable machining application may be utilized to form the circumferential channel <NUM> and/or the sub-channels <NUM> (e.g., the first sub-channels 42a and/or the second sub-channels 42b) in a surface of the primary ring seal face <NUM> of the primary ring <NUM> and/or a surface of the seal face <NUM> of the mating ring <NUM>, such that the formed circumferential channel <NUM> and the formed sub-channels <NUM> are fluidly connected (e.g., in some cases, the fluidly connected formed circumferential channel <NUM> and formed sub-channels <NUM> may form a continuous passageway to facilitate pressurized process fluid traveling around the seal interface <NUM>). A laser or other suitable machining application may be particularly configured to form the channels to the depths and widths described herein that promote introducing pressurized process fluid into the seal interface <NUM> while mitigating leakage of the process fluid all of the way through the seal interface <NUM>.

As discussed above, channels of seal faces in the seal assembly <NUM> may be configured in a variety of manners to facilitate improved lift (e.g., hydrostatic lift) between seal faces of a seal interface and reduce wear and tear on the seal faces. Below is an example non-limiting seal configuration of a seal face incorporating the above-discussed illustrative concepts.

In an example, a four (<NUM>) inch outer diameter seal assembly with a seventy (<NUM>) percent balance ratio and utilizing SiC as the material for the primary ring seal face and the mating ring seal face may include a circumferential channel and a plurality of sub-channels on the primary ring seal face. The circumferential channel and the sub-channels had a depth of about <NUM> (<NUM> inches) and a width of about <NUM> (<NUM> inches). The circumferential channel may be annular and located about one-third a width of the primary ring seal face from an outer diameter of the primary ring seal face, first sub-channels of the plurality of sub-channels may extend from the circumferential channel to the outer diameter circumference of the seal face, and second sub-channels of the plurality of sub-channels may extend from the circumferential channel toward an inner diameter circumference of the seal face about one-third the width of the primary ring seal face. The first sub-channels and the second sub-channels may be staggered equal distances away from one another. The sub-channels of a same type of sub-channel may be spaced along a length of the circumferential channel such that the ratio of circumferential distance between the same type of sub-channels to a radial span of the same type of sub-channel is about eight (<NUM>). Such a configured seal face assembly was tested for <NUM> hours in a pump holding water at <NUM> (<NUM> degrees Fahrenheit), the water having a maximum fluid pressure of <NUM> bar (<NUM> psi), and the pump having a shaft rotation of <NUM> rotations per minute. Post-test examination of the seal assembly revealed little wear, while leakage remained low (i.e., a leakage rate of <NUM>-<NUM> grams/hour) and/or within tolerances.

Claim 1:
A hydrostatic seal assembly (<NUM>) for sealing a liquid comprising:
a first ring (<NUM>) having a first side (<NUM>) bounded by a first edge (<NUM>) and a second edge (<NUM>); and
a second ring (<NUM>) having a second side (<NUM>) facing the first side;
wherein a circumferential channel (<NUM>) extends along the first side (<NUM>) between, and spaced from, the first edge (<NUM>) and the second edge (<NUM>);
wherein a plurality of sub-channels (<NUM>) extend from the circumferential channel (<NUM>) along the first side (<NUM>) of the first ring (<NUM>);
wherein the first ring (<NUM>) and the second ring (<NUM>) form a hydrostatic seal between the first side (<NUM>) and the second side (<NUM>),
characterized in that the circumferential channel (<NUM>) and the plurality of sub-channels (<NUM>) are configured to take up less than ten percent of a surface area of the first side (<NUM>).