Patent Description:
The present invention generally relates to devices for providing robust sealing between surfaces in a pressurized system, such as for example, a chromatography system. In particular, the devices relate to consumable parts that can be reused and/or reinstalled while still providing a pressure tight sealing surface.

Pressurized systems, such as chromatography systems, require the capability of controlling fluid flow and pressure there through. It is typical to see pressures greater than <NUM> psi (e.g., <NUM> psi (<NUM> Pa), <NUM> psi (<NUM> Pa), <NUM> psi (<NUM> Pa), etc.) To create adequate pressure sealing about moving parts, such as a needle in a back pressure regulator or injector to a column, consumable parts are used. To create the pressure seals, the consumables formed of compliant materials are secured in place using torque. While torque manipulates and secures the consumable into position to create a tight seal, torque can also have deleterious effects on the consumable. In particular, during installation of the consumable, the compliant consumable can be sheared causing scratches and impurities on the sealing surfaces. Depending on the degree of scratches and impurities, pressure control can be compromised to an unacceptable level. As a result, the number of installations and/or the amount of torque used is limited to ensure that the consumable can provide a pressure tight seal during use (e.g., <NUM> psi, <NUM> psi,. <CIT> discloses a flow control valve having a resilient valve seat.

Provided herein are devices and methods for providing a pressure tight seal between moving parts in a pressurized system. Embodiments of the present technology provide for multiple installations or positioning of sealing devices between the moving members without compromising pressure control performance.

Disclosed but not independently claimed as such, is a method of installing a seat between a first surface and a second surface in a pressurized system. The method includes: (a) press-fitting the seat into a housing connectable to the first surface; (b) sliding a threaded nut over the housing; (c) crimping an end of the nut to the housing to provide a rotatably decoupled connection between the housing and the nut that allows the nut to freely rotate about the seat; and (d) securing the nut to the second surface. Due to the rotatably decoupled connection between the housing (containing the press-fitted seat) and nut, securement of the nut creates a pressure tight seal between the first and second surfaces within the pressurized system through rotation of the nut without applying torque to the seat.

Embodiments of this disclosure of the present technology can include one or more of the following features. In certain embodiments, the first surface is an outlet of a back pressure regulator (BPR) and the second surface is a head of the BPR. The head includes a fluid inlet and a needle. In some embodiments, the seat has a body defining a fluid flow path extending substantially axially between an inlet exterior sealing surface and an outlet exterior sealing surface. The inlet exterior sealing surface is configured to have less elastic deformation under force (e.g., axial compression) generated by securement of the nut than the outlet exterior sealing surface. In embodiments of the method, at least a portion of the inlet exterior sealing surface of the seat is rounded.

The present invention provides a resilient seat for sealing surfaces in a pressurized system. The resilient seat includes a body defining a fluid flow path extending substantially axially between an inlet exterior sealing surface and an outlet exterior sealing surface. The body includes an outer wall surface positioned between the inlet exterior sealing surface and the outlet exterior sealing surface. The inlet exterior sealing surface includes a deformation member configured to deform outward from the inlet exterior sealing surface toward the outer wall surface and away from an interior of the fluid flow path when the resilient seat is axially compressed. The outlet exterior sealing surface includes a sealing member that is configured to deflect inward from the outlet exterior sealing surface toward the fluid flow path when the resilient seat is axially compressed. The sealing member comprises a chamfer extending from the body.

Embodiments of this disclosure of the present technology can include one or more of the following features. In some embodiments, the inlet exterior sealing surface is configured to have less elastic deformation when the resilient seat is axially compressed than the outlet exterior sealing surface. That is, the inlet exterior sealing surface can be made of a different material, contain a different shape or contour, and/or have a different thickness. In some embodiments, the deformation member on the inlet exterior sealing surface is a flange extending outward from the fluid flow path. The flange has a rounded exterior contour. In certain embodiments, the fluid flow path is sized and shaped to receive a needle for controlling pressure through the resilient seat. In additional embodiments, the interior walls defining the fluid flow path are configured to substantially match the profile of the needle. In some embodiments, the sealing member on the outlet exterior sealing surface is a face seal. In certain embodiments, the outlet exterior sealing surface is configured to have greater elastic deformation when the resilient seat is axially compressed than the inlet exterior sealing surface. Some embodiments feature one or more protrusions on side exterior surfaces of the body. The one or more protrusions are adapted to provide an interference fit with a housing. Certain embodiments include one or more visual indicators (e.g., notch, color stripe, etc.) to aid in the placement of the resilient seat in a housing. Some embodiments of the resilient seat are adapted for use in a back pressure regulator. That is, some embodiments of the resilient seat are secured within a back pressure regulator. In some embodiments, the material forming the resilient seat has a lower elastic modulus than a needle material (i.e., a material used to form the needle in the BPR). In certain embodiments, the material forming the resilient seat has a lower elastic modulus than a housing material. In some embodiments, the material forming the resilient seat has a lower elastic modulus than a head of the BPR.

The present technology has numerous advantages. For example, by eliminating the application of torque to the compliant seat during installation, the seat can be exposed to numerous installation and adjustment procedures. In addition, the seat of the present technology is less likely to be scratched or sheared, which results in better sealing and pressure control due to the lack of impurities and gaps. In general the seat and the methods of installation are more robust than conventional seats and methods. That is, the seat of the present technology is resilient. Further, some embodiments of the technology provide increased robustness and usability of the BPR as the components (e.g., seat) can be tailored to and installed using a method which decreases torque stress, shear and wear of the seat.

A further advantage of the present technology is found within the configuration of the compliant or resilient seat. In particular, embodiments of the seat of the present technology are configured to have a portion that makes a rigid face seal and a portion that intentionally deforms during installation. As a result, the seat of the present technology can provide better sealing and be used in extreme pressure environments (e.g., above <NUM> psi (<NUM> Pa), above <NUM> psi (<NUM> Pa), above <NUM> psi (<NUM> Pa), above <NUM> psi (<NUM> Pa), above <NUM> psi (<NUM> Pa), above <NUM> psi (<NUM> Pa) and greater). In addition, certain embodiments of the seat provide for a reduction of internal volume. That is, certain configurations or geometries of the seat of the present technology are tailored to the internal geometry of a portion of the pressurized systems (e.g., a portion within a back pressure regulator (BPR), or between two metallic surfaces in an injector). As a result, internal volume of systems can be minimized which typically improves performance due to a reduction of volume.

The invention may be more fully understood from the following detailed description taken in conjunction with the accompanying drawings.

Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention.

In general, aspects of the present technology are directed to improved sealing between two surfaces in a pressurized system (e.g., a system environment of over <NUM> psi). In some embodiments not claimed as such, improvements are achieved by the removal of or minimization of torque applied to a compliant member positioned at a sealing joint. In some embodiments, the compliant member is a seat within a back pressure regulator. In other embodiments not claimed as such, the compliant member is a sealing ring situated between two metal faces in an injector to a chromatography column.

Certain embodiments feature a resilient seat that is configured to provide a flat face seal on a lower pressure surface in the pressurized system and a displacement seal on a higher pressure surface in the pressurized system. The resilient seat is axially compressible such that a pressure-tight seal can be made between the faces or ends of the seat and the first and second surfaces of the pressurized system without using torque on the seat. In certain embodiments, the displacement seal end of the seat is formed of a material and/or has a shape/contour that provides less elastic deformation during installation than the face seal end of the seat.

Referring to <FIG>, non-claimed embodiments of the present technology are directed to methods of installing a seat between a first surface and a second surface in a pressurized system. Method <NUM> shown in <FIG> can be used to install a seat or other seal between two regions in a pressurized system, such as, for example, between high and low pressure regions in a back pressure regulator (BPR), or between two metal surfaces within a sample injector to a chromatography column. Because method <NUM> utilizes a compliant or press-fittable member that is decoupled from a housing as a sealing element, installation method <NUM> eliminates the use of torque on the compliant seal. That is, as the seat is decoupled from a securing structure (e.g., a nut or threaded grooves on the outside of the housing), the seat moves only in the axial direction when the nut is rotated and secured in position. As a result, at least a portion of method <NUM> can be repeated multiple times (e.g., step <NUM>). The seal can be uninstalled and reinstalled numerous times without shearing or damaging the seal.

Method <NUM> includes four steps to install a seat between a first surface and a second surface in a pressurized system. In step <NUM>, a seat or seal is press-fitted into a housing connectable to the first surface. Next in step <NUM>, a threaded nut is slid over the housing. An end of the threaded nut is crimped to the housing to provide a rotatably decoupled connection between the housing and the nut that allows the nut to freely rotate about the seat in step <NUM>. Finally, the threaded nut is secured to the second surface in step <NUM>. Due to the rotatably decoupled connection, securement of the threaded nut to the second surface creates a pressure tight seal between the first and second surfaces through rotation of the nut. That is, no (or minimal) torque is applied to the seat during the rotation of the nut, because of the decoupled connection. The seat does not experience shear, but only axial compression to create a high pressure seal.

<FIG> illustrate method <NUM> as applied to installing a resilient seat within a BPR. For context, <FIG> is provided as a reference of the components and regions of a BPR. It is noted that <FIG> illustrates embodiments of the present technology. That is, <FIG> illustrates a connection portion of a BPR <NUM> after the installation method <NUM> has been performed to create a pressure tight seal between first and second surfaces.

In particular, <FIG> illustrates an enlarged view of the connection between a head portion <NUM> (high pressure portion) and the outlet <NUM> (located in the low pressure portion). In general, the outlet <NUM> is located in a housing <NUM>. Fluid flow within BPR <NUM> enters through inlet port <NUM>, is controlled by movement of needle <NUM> positioned within seal <NUM> through seat <NUM> and passes out of the BPR through outlet <NUM>. To create a pressure tight seal within regulator <NUM> and for maintenance thereof, nut <NUM> is rotatably secured (i.e., torqued) to the head <NUM> (e.g., a second surface in the BPR) until the housing <NUM> contacts the second surface on the head <NUM>. In prior art devices and methods a seat between the high and low pressure portions is directly coupled to the nut or a threaded housing. When the outlet portion is secured into the head of a conventional device, the housing and seat rotate together generating high shear forces acting at the ends of seat. As a result, conventional seats degrade during installation.

The seat <NUM> shown in <FIG> however is not coupled to the nut <NUM>. That is, the seat <NUM> is rotatably decoupled from the nut <NUM> allowing for a more direct connection between the head <NUM> and the outlet <NUM> (e.g., minimizes internal volume) and prevents undesirable shearing of the seat during installation events. Compare <FIG>, which illustrates a conventional BPR <NUM> connection using a seat <NUM> directly connected to housing <NUM>, with <FIG>. In <FIG>, head <NUM> is secured directly to the threaded housing <NUM> to provide connection to the outlet <NUM> residing in the low pressure portion of the system. Fluid flows through BPR <NUM> through inlet <NUM>. The flow of the fluid is controlled by the axial movement of needle <NUM> residing in seal <NUM> with tip <NUM> positioned in seat <NUM>. Seat <NUM> resides within housing <NUM> that has a threaded exterior surface <NUM> that directly connects to head <NUM>. As housing <NUM> is torqued into head <NUM> to create a seal, ends <NUM> and <NUM> of seat <NUM> are sheared.

In particular, the components of BPR <NUM> can be configured and installed using the following techniques to minimize internal volume as well as reduce shearing forces on seat <NUM>, as compared to conventional seats installed in conventional BPR or other pressurized devices. A method of installation is shown in <FIG>, in which seat <NUM> is first press-fit into housing <NUM>. See seat <NUM> with press-fit connection to opening in housing <NUM>. That is, seat <NUM> has an interference fit with the opening in housing <NUM>. A threaded nut <NUM> is slid over the housing <NUM> as shown in <FIG>. To provide the rotatably decoupled connection between the housing and the nut, the nut is positioned over one or more exterior groves <NUM> in the housing <NUM> as shown in <FIG>, and the ends <NUM> of the nut <NUM> are crimped to the housing <NUM> as shown in <FIG>. This type of connection allows the nut <NUM> to freely rotate around the housing <NUM>. As a result, when housing <NUM> including outlet <NUM> is installed in head portion <NUM> (see <FIG>) it can be tightened/secured as needed through rotation without any shearing effects on seat <NUM>. That is, while nut <NUM> is rotated and tightened to create a pressure seal with the head <NUM>, seat <NUM> does not rotate, but rather moves axially toward needle <NUM>. This installation and seat design allows for a more robust connection as the seat <NUM> does not experience shear. As a result, the housing <NUM> can be removed and reinstalled multiple times without destroying the seat <NUM>. For example, minimal (if any) scratches and particulates are generated during installation as compared to seat <NUM> during installation. Both scratches and particulates can lead to degraded or poor sealing as gaps are created by the scratches (removed material) within the seat and by the particulates that pool and collect along sealing surfaces.

In general, the present technology is also directed to a resilient seat or seal that can provide improved pressure tight connection between two different pressure regions (e.g., high pressure portion and low pressure portion) within a system. Embodiments of the resilient seat or seal can be used together with the methods of the present technology. In addition, the resilient seat or seal can be used to improve sealing by tailoring the geometry, shape and/or materials of the seat/seal to address environmental demands. For example, as the seat/seal is typically located at an interface between high and lower pressure zones, each end of the seats and seals of the present technology are configured with its environmental placement in mind. That is, in an embodiment used in connection with a BPR, one end of the seat interacts with the tip of the needle <NUM> and is exposed to high pressures, whereas the opposing end of the seat interfaces with the outlet <NUM> and is on the low pressure side of the regulator. To address these demands and to eliminate excess fluid paths within the seat, the seat <NUM> has a tailored geometry shown in <FIG>. A first end <NUM> of the seat <NUM> located at an end that interfaces with the needle (high pressure side) is formed to have a compliant surface, that is angled and sized to allow the needle <NUM> to be positioned within a range of axial positions therein. In certain embodiments, this portion of the seat's internal geometry includes surfaces <NUM> that closely match the profile of the needle <NUM> to provide a tight connection and to allow the flow path F-F to be tailored for a range of needle displacement through this first portion of the seat. The first end <NUM> is compliant and can deform especially during installation to allow for proper positioning of the seat <NUM> with the head portion <NUM>. The internal geometry of the seat transitions at point <NUM> from a cone or angled volume to a more narrowly tailored straight cylinder to address the demands of the low pressure side. The opposing end <NUM> of the seat, which is the side of the seat that interfaces with the outlet <NUM> includes a small flange (e.g., a chamfer) <NUM> with a face seal. Using finite element analysis it was found that the small flange or chamfer <NUM> on end <NUM> assists in controlling deformation into the seat inner diameter during use. In this embodiment, the flange <NUM> has an angled (i.e., not rounded) contour and extends from the outlet exterior sealing surface <NUM>. In other embodiments, flange <NUM> can be rounded. As the seat <NUM> is axially compressed, the angled contours of flange <NUM> deflect inward from the outlet exterior sealing surface <NUM> toward the fluid flow path (F-F) extending between surfaces <NUM> and <NUM>.

Utilizing finite element analysis, stress conditions around the ends of the seat <NUM> were studied and localized stress conditions were found to be in acceptable levels. <FIG> illustrates the results of deformation on the seat as a result of installation. As can be seen in <FIG>, the outlet exterior sealing surface <NUM> which forms the top face seal experiences the most deformation. Without wishing to be bound by theory, it is believed that the shape or amount of material present on the outlet exterior surface <NUM> creates a rigid seal resulting in deformation that is coaxial to the load and does not deform into the fluid flow path of the seat. It was noted during FEA that varying the angle of the internal chamfer on this surface varied the degree of deformation into the flow path. The inlet exterior surface <NUM> shows a change of shape in response to the applied axial deformation. The outer black boundary <NUM> shows the undeformed condition, whereas the interior shaded portion illustrates the shape of the seat after application of the load. As can be seen in <FIG>, surface <NUM> deforms such that material spills outside of its initial boundary. Without wishing to be bound by theory, it is believed that surface <NUM> changes shape as it is more flexible than surface <NUM> in that it lacks material (e.g., see gaps <NUM>, creating rounded lip/flange <NUM>). Flange <NUM> deforms outward towards surface <NUM>. By varying the angle of the internal chamfer defining the opening to the fluid flow path, one can vary the degree of deformation outward. That is, in this embodiment, if the internal chamfer had a steep angle (e.g., vertical) there would be less deformation outward to edge <NUM> than a soft angle (e.g., more horizontal). <FIG> shows the results using FEA regarding sealing pressures. In particular, sealing pressures on the raised structure <NUM> on surface <NUM> and on the rounded lip <NUM> on surface <NUM> was studied. For the boundary conditions applied, the raised structure <NUM> and the lip <NUM> both were capable of sealing up to <NUM>,<NUM> psi (<NUM> Pa).

In general, outlet exterior sealing surface <NUM> are configured to have greater elastic deformation when the seat is axially compressed than the interior exterior sealing surfaces <NUM>. That is, the materials, shapes configuration, and/or thicknesses of features extending from outlet exterior sealing surface provide less resistance to deformation than on the inlet exterior sealing surface. For example, outlet exterior sealing surface <NUM> can include angled flange <NUM> that will deflect inward and will deform more than flange <NUM> extending from inlet exterior sealing surface <NUM>. Flange <NUM> extends outward from the fluid flow path (see angled edge of fluid flow path F-F near end <NUM> that extends outward toward side exterior surfaces <NUM>). In addition to the outward flare, flange <NUM> includes a rounded exterior contour <NUM>. The rounded exterior contour <NUM> is easily deformable and will deform outward from the inlet exterior sealing surface <NUM> toward the outer was surface <NUM> and away from an interior of the fluid flow path F-F when the seat <NUM> is axially compressed. While seat <NUM> shown in <FIG>, has a rounded contour flange extending from its inlet exterior surface to provide the seat with a deformation member, other structures or materials can be used in addition or in replacement of the rounded contour flange. For example, a different material could be used on a portion of surface <NUM> corresponding to the location of <NUM> that is more deformable than an interior portion of surface <NUM>, rather than include the rounded counter. Additionally or alternatively, a different sized rounded flange or protrusion extending from surface <NUM> can be used as the deformation member. In fact, any deformation member that is configured to deform outward toward outer or side exterior surface <NUM> and away from the interior fluid flow path F-F can be used.

In addition to deformation and sealing features, the seat <NUM> of the present technology can include other structures or features on exterior surfaces. For example, seat <NUM> in <FIG> includes protrusions <NUM> on its side exterior surfaces <NUM>. Protrusions <NUM> extend radially and improve the interference fit of seat <NUM> in holder <NUM>. In addition to protrusions, the side exterior surfaces can include visual aids to help with the placement of the seat within a holder. In <FIG>, seat <NUM> includes visual aids <NUM> (e.g., notches) that in this embodiment correspond to the location of the transition <NUM>. The visual aids <NUM> in <FIG> indicate end that is inserted into the housing (e.g., aid the user in proper placement of the seat <NUM>). While the embodiment shown in <FIG> uses notches or cut-out groves , other visual aids are possible. For example, a color change or a band or stripe of color could be used instead of the notches. In addition, other patterns besides notches could be used to visually mark a desired orientation or position of the seat.

Seat <NUM> can be made of a single material, a graded material, or multiple materials. That is seat <NUM> can be formed from a unitary piece (e.g., a single material, or a graded material) or it can be a two piece structure, where each piece is formed from a different material and is bonded together. In the embodiment shown in <FIG>, seat <NUM> is a unitary piece formed of a single compliant material, such as a polyimide-based plastic (e.g., Vespel). The differences in elastic deformation between the inlet and outlet exterior sealing surfaces are created by the structures and features on those surfaces. In other embodiments, the differences in elastic deformation (the inlet surface <NUM> has less elastic deformation than the outlet <NUM>) by grading the material. That is additives can be incorporated into the material forming the seat such that surface <NUM> has less elastic deformation property than surface <NUM>. In other embodiments, not shown, seat <NUM> could be made from two different materials bonded together (such as at location of transition <NUM>) to provide the difference in elastic deformation property between surfaces <NUM> and <NUM>. The material or materials forming seat <NUM> are typically compliant materials that are resilient under axial compression. The seat <NUM> when installed will be compressed between metallic or rigid surfaces defining high and low pressure regions. In addition, in embodiments within a BPR, the seat will be exposed to the needle <NUM> moving in, out, and along flow path F-F with its tip possibly hitting transition <NUM> to control the flow of fluid therethrough. To provide resilience under these operating conditions, the material forming the resilient seat will typically have a lower elastic modulus than a material forming the needle. In addition, to ensure resilience of the seat <NUM> during multiple installation events, the material used to form the seat will have a lower elastic modulus than a housing material as well as a lower elastic modulus than the material forming the head of a back pressure regulator.

In general, the seats/seals and methods of installation within a pressurized system described herein provide enhanced pressure sealing capabilities. As a result, the present technology can be used in high pressure systems (e.g., in connection with <NUM> psi or more) robustly. This advantage is particularly attractive for use within a BPR used to control pressure changes in a chromatography system. The seats of the present technology also increase or enhance performance of pressure control by helping to eliminating unswept volume through the reduction of internal volume. Unswept volumes are portions accessible to fluid flow, but not within the primary solvent flow path used in the chromatographic separation. Portions of the solvent flow may diffuse into and out of the unswept volume at an irregular rate, resulting in band-broadening. Band broadening reduces the quality of a separation and my result in broad and potentially overlapping chromatogram peaks. In the present technology, the seat within the BPR can be tailored to reduce internal volume within the BPR. For example, at least a portion the fluid flow path F-F extending through the seat can be closely tailored to the exterior shape of the needle within the BPR. Another portion of the fluid flow path F-F (the portion above transition <NUM>) is sized to provide a narrower restriction which can also reduce the length of the fluid path, thereby eliminating internal volume. Examples <NUM> and <NUM> below illustrate improved performance of a BPR utilizing a seat in accordance with the present technology.

<FIG> shows back pressure regulator <NUM> which has not been configured for reduced internal volume (i.e., standard commercial stock BPR). Back pressure regulator <NUM> includes an inlet <NUM>, seal <NUM>, needle <NUM>, seat <NUM>, and outlet <NUM>. Needle <NUM> and seat <NUM> define restriction <NUM> at which needle <NUM> would meet seat <NUM> at one extreme of the range of motion of needle <NUM>. Back pressure regulator <NUM> also includes internal volumes that may be occupied by the mobile phase flowstream when the back pressure regulator is in use in a chromatographic separation. Head volume <NUM> (<NUM>µL) includes the portions of the flowstream from the inlet up to seal <NUM>, along needle <NUM> and up to seat <NUM>. Seal volume <NUM> (<NUM>µL) is proximate seal <NUM>. Seat volume <NUM> (<NUM>µL) is within seat <NUM>. Outlet volume <NUM> (<NUM>. <NUM>µL) is downstream of seat <NUM> at outlet <NUM>. The total internal volume of these components is <NUM>µL (<NUM>µL excluding seal volume <NUM>.

<FIG> shows back pressure regulator <NUM>, which has been configured for reduced internal volume. Back pressure regulator <NUM> contains the same basic components: Back pressure regulator <NUM> includes an inlet <NUM>, seal <NUM>, needle <NUM>, seat <NUM>, and outlet <NUM>. Needle <NUM> and seat <NUM> define restriction <NUM> at which needle <NUM> would meet seat <NUM> at one extreme of the range of motion of needle <NUM>. Back pressure regulator <NUM> also includes internal volumes that may be occupied by the mobile phase flowstream when the back pressure regulator is in use in a chromatographic separation. Head volume <NUM> includes the portions of the flowstream from the inlet up to seal <NUM>, along needle <NUM> and up to seat <NUM>. Seal volume <NUM> is proximate seal <NUM>. Seat volume <NUM> is within seat <NUM>. Outlet volume <NUM> is downstream of seat <NUM> at outlet <NUM>.

Back pressure regulator <NUM> is configured for reduced internal volume. That is, the relationships and positioning of various BPR components have been tailored to reduce internal volume (e.g., to minimize unswept volume). It should be appreciated that while the BPR shown in <FIG> has been tailored in multiple ways, a BPR does not need to be tailored in every way shown in <FIG> to achieve at least some advantage over commercially available BPRs. Head volume <NUM> has been reduced to <NUM>µL (<NUM>% reduction) by locating inlet <NUM> proximate seat <NUM> and providing inlet <NUM> perpendicular to needle <NUM> reducing the length of the flowpath to needle <NUM>. Seal <NUM> is positioned closer to seat <NUM>. Seal volume <NUM> is not reduced in the back pressure regulator <NUM> as depicted. Seat volume <NUM> has been reduced to <NUM>µL (<NUM>% reduction) by reducing the length of seat <NUM>, and shaping seat <NUM> so that its interior volume more closely approximates the shape of needle <NUM>. Restriction <NUM> is configured to define a sharp point at the interface of conical and cylindrical portions of seat <NUM>. Outlet volume <NUM> has been reduced to <NUM>µL (<NUM>% reduction) by connecting outlet <NUM> directly to the flowpath from seat <NUM>. Comparison of <FIG> also provides an example of reducing volume by reducing cross-sectional area at interfaces between BPR components. Seat volume <NUM> and outlet volume <NUM> are each reduced by minimizing the cross-sectional area at the interface of outlet <NUM> and seat <NUM> is configured such that it is not larger than the size of the flowpath. The total internal volume of back pressure regulator <NUM> is <NUM>µL, a <NUM>% reduction as compared to back pressure regulator <NUM>, or, excluding seal volume, <NUM>µL (<NUM>% reduction). In general, interfaces between components in unmodified back pressure regulators may have a larger area than the flowpath within the components and reducing these areas may reduce the volume within the back pressure regulator.

<FIG> shows a significant reduction in band distortion effects achieved using BPR <NUM>. <FIG> provides chromatograms for three various BPR designs and illustrates the effects on peak broadening and tailing. Trace <NUM> is a peak measured from a sample that was not passed through a single flow path including both a back pressure regulator and a detector. That is, trace <NUM> is a peak measured from a sample measured in a system having a split-flow interface design, where a make-up solvent is provided to the BPR and the detector is split from the flow line extending directly from the column. Since a sample that is associated with a split-interface design is not affected by the amount of unswept volume in a BPR, the sample associated with trace <NUM> has not experienced any sample band spreading - see area <NUM>. Trace <NUM> is sharp and symmetrical having a half width of about <NUM>. Trace <NUM> is a peak measured following the same method, except that the sample was passed through a back pressure regulator without the present technology (i.e., using the system shown in <FIG>). That is, the back pressure regulator was standard commercial stock, that was not tailored to reduce internal volume and instead of a split-flow interface as was used for the sample provided in trace <NUM>, a BPR interface flow design where the BPR is positioned on the same flow path between the column and the detector. Trace <NUM> shows a peak that is significantly broadened as compared to trace <NUM> (compare half widths of <NUM> for trace <NUM> to a half width of <NUM> for <NUM>), and which exhibits considerable tailing and some shouldering in area <NUM>. Trace <NUM> is also a peak measured in a system using the BPR interface design but including, BPR <NUM> (<FIG>, and described in Example <NUM>) configured with reduced internal volume according to the present technology. Trace <NUM> is a sharp, symmetrical peak, more closely aligned to trace <NUM> (compare half widths of <NUM> for trace <NUM> to <NUM> for trace <NUM>) and with significantly less broadening and shouldering in area <NUM> than in trace <NUM>.

Example <NUM> demonstrates embodiments of the present technology significantly reduces or eliminates band-broadening contributed by a back pressure regulator, permitting a separation quality on par with a separation performed in a split interface design. Thus, a user may achieve the advantages associated with a back pressure regulator, such as good pressure control with reasonable cost, and robust and wear-resistant operation, without sacrificing separation quality by implementing the methods, devices, and seats of the present technology.

Claim 1:
A resilient seat for sealing surfaces in a pressurized system, the resilient seat comprising:
a body defining a fluid flow path extending substantially axially between an inlet exterior sealing surface (<NUM>) and an outlet exterior sealing surface (<NUM>), the body including an outer wall surface positioned between the inlet exterior sealing surface (<NUM>) and the outlet exterior sealing surface (<NUM>);
the inlet exterior sealing surface (<NUM>) comprising a deformation member configured to deform outward from the inlet exterior sealing surface (<NUM>) toward the outer wall surface and away from an interior of the fluid flow path when the resilient seat is axially compressed;
the outlet exterior sealing surface (<NUM>) comprising a sealing member (<NUM>) configured to deflect inward from the outlet exterior sealing surface (<NUM>) toward the fluid flow path when the resilient seat is axially compressed,
characterised in that the sealing member (<NUM>) comprises a chamfer extending from the body.