阅读说明：本技术 用于高压密封的方法和装置 (Method and device for high-pressure sealing ) 是由 E·J·伯格 J·A·什雷夫 于 2020-05-13 设计创作，主要内容包括：本技术整体涉及用于在加压系统诸如色谱系统中的表面之间提供稳固密封的设备、系统和方法。具体地讲,该设备、系统和方法涉及顺应性部件和弹性部件,该顺应性部件和弹性部件即使在高压环境(例如,1000psi或更大)内也可重复使用和/或重新安装,同时提供耐压密封表面。(The present technology relates generally to devices, systems, and methods for providing a robust seal between surfaces in a pressurized system, such as a chromatography system. In particular, the apparatus, systems, and methods relate to compliant and resilient components that can be reused and/or reinstalled even in high pressure environments (e.g., 1000psi or greater) while providing a pressure resistant sealing surface.)

1. A method of installing a mount between a first surface and a second surface in a pressurized system, the method comprising:

press-fitting the mount into a housing connectable to the first surface;

sliding a threaded nut on the housing;

crimping an end of the nut to the housing to provide a rotatably disengaged connection between the housing and the nut that allows the nut to freely rotate about the mount; and

securing the nut to the second surface, wherein the securing of the nut forms a pressure-tight seal between the first surface and the second surface via rotation of the nut without applying torque to the standoff due to the rotatably disengaged connection.

2. The method of claim 1, wherein the first surface is an outlet of a back pressure regulator and the second surface is a head of the back pressure regulator, the head comprising a fluid inlet and a needle.

3. The method of claim 1, wherein the seat includes a body defining a fluid flow path extending substantially axially between an inlet outer sealing surface and an outlet outer sealing surface, the inlet outer sealing surface being configured to have less elastic deformation than the outlet outer sealing surface under a force resulting from the securement of the nut.

4. The method of claim 3, wherein at least a portion of the inlet outer sealing surface is deformed outwardly away from the fluid flow path.

5. The method of claim 3, wherein at least a portion of the inlet outer sealing surface is rounded.

6. An elastomeric mount for sealing a surface in a pressurized system, the elastomeric mount comprising:

a body defining a fluid flow path extending substantially axially between an inlet outer sealing surface and an outlet outer sealing surface, the body including an outer wall surface positioned between the inlet outer sealing surface and the outlet outer sealing surface;

the inlet outer sealing surface comprises a deforming member configured to deform outwardly from the inlet outer sealing surface toward the outer wall surface and away from an interior of the fluid flow path when the elastomeric mount is axially compressed;

the outlet outer sealing surface includes a sealing member configured to deflect inwardly from the outlet outer sealing surface toward the fluid flow path when the elastomeric mount is axially compressed.

7. The elastomeric mount of claim 6, wherein the inlet outer sealing surface is configured to have less elastic deformation than the outlet outer sealing surface when the elastomeric mount is axially compressed.

8. The elastomeric mount of claim 6, wherein the deformation member on the inlet outer seal surface comprises a flange extending outwardly from the fluid flow path, the flange having a rounded outer profile.

9. The elastomeric mount of claim 6, wherein the fluid flow path is sized and shaped to receive a needle for controlling pressure through the elastomeric mount.

10. The elastomeric mount of claim 9, wherein an inner wall defining the fluid flow path is configured to substantially match a profile of the needle.

11. The elastomeric mount of claim 6, wherein the sealing member on the outlet outer sealing surface comprises a face seal.

12. The elastomeric mount in accordance with claim 6, wherein said outlet external sealing surface is configured to have a greater elastic deformation than said inlet external sealing surface when said elastomeric mount is axially compressed.

13. The elastomeric mount of claim 12, wherein a flange of material surrounds an outlet of the fluid flow path, the flange having an angled profile.

14. The elastomeric mount of claim 12, wherein the outlet outer sealing surface comprises a flange extending from the body.

15. The elastomeric mount of claim 6, wherein the lateral outer surface of the body comprises one or more protrusions adapted to provide an interference fit with the housing.

16. The elastomeric mount of claim 6, wherein the lateral outer surface of the body comprises one or more visual indicators adapted to aid in placement of the elastomeric mount in a housing.

17. The elastomeric mount of claim 6, wherein the elastomeric mount is secured within a back pressure regulator.

18. The elastomeric mount of claim 9, wherein a material forming the elastomeric mount has a lower modulus of elasticity than a needle material.

19. The elastomeric mount in accordance with claim 15, wherein a material forming said elastomeric mount has a lower modulus of elasticity than a housing material.

20. The elastomeric mount of claim 17, wherein a material forming the elastomeric mount has a lower modulus of elasticity than a head of the back pressure regulator.

Technical Field

The present invention generally relates to devices, systems, and methods for providing a robust seal between surfaces in a pressurized system, such as, for example, a chromatography system. In particular, the apparatus, systems, and methods relate to consumable components that can be reused and/or reinstalled while still providing a pressure resistant sealing surface.

Background

Pressurized systems, such as chromatography systems, require the ability to control the flow and pressure of fluids therethrough. Pressures greater than 500psi (e.g., 1000psi, 2000psi, 5000psi, etc.) are common. In order to form an adequate pressure seal around moving parts, such as the needle or post injector in a back pressure regulator, consumable parts are used. To form a pressure seal, a consumable formed of a compliant material is secured in place using torque. While torque manipulates the consumable and holds it in place to form a tight seal, torque can also have a detrimental effect on the consumable. In particular, during installation of the consumable, the compliant consumable may be sheared, thereby creating scratches and impurities on the sealing surface. Depending on the degree of scratching and impurities, the pressure control may be reduced to an unacceptable level. Thus, the number of devices and/or the amount of torque used is limited to ensure that the consumable can provide a pressure-tight seal (e.g., 1000psi, 2000psi, etc.) during use.

Disclosure of Invention

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

One aspect of the present technology relates to a method of installing a mount between a first surface and a second surface in a pressurized system. The method comprises the following steps: (a) press-fitting a holder into a housing connectable to a first surface; (b) sliding a threaded nut on the housing; (c) crimping an end of the nut to the housing to provide a rotatably disengaged connection between the housing and the nut that allows the nut to rotate freely about the abutment; and (d) securing the nut to the second surface. Due to the rotatably disengageable connection between the housing (containing the press-fit seat) and the nut, the securement of the nut forms a pressure-tight seal between the first and second surfaces within the pressurized system via rotation of the nut without applying torque to the seat.

Implementations of this aspect of the technology may 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 contains a fluid inlet and a needle. In some embodiments, the seat has a body defining a fluid flow path extending substantially axially between the inlet and outlet outer sealing surfaces. The inlet outer sealing surface is configured to have less elastic deformation than the outlet outer sealing surface under a force (e.g., axial compression) resulting from the securement of the nut. In an embodiment of the method, at least a portion of the inlet external sealing surface of the seat is rounded.

Another aspect of the present technology relates to an elastomeric mount for sealing a surface in a pressurized system. The elastomeric mount includes a body defining a fluid flow path extending substantially axially between an inlet outer sealing surface and an outlet outer sealing surface. The body includes an outer wall surface positioned between the inlet outer sealing surface and the outlet outer sealing surface. The inlet outer sealing surface includes a deforming member configured to deform outwardly from the inlet outer sealing surface toward the outer wall surface and away from an interior of the fluid flow path when the elastomeric mount is axially compressed. The outlet outer sealing surface includes a sealing member configured to deflect inwardly from the outlet outer sealing surface toward the fluid flow path when the elastomeric mount is axially compressed.

Implementations of this aspect of the technology may include one or more of the following features. In some embodiments, the inlet outer sealing surface is configured to have less elastic deformation than the outlet outer sealing surface when the elastomeric mount is axially compressed. That is, the inlet outer sealing surface may be made of different materials, contain different shapes or contours, and/or have different thicknesses. In some embodiments, the deformation member on the inlet outer sealing surface is a flange extending outwardly from the fluid flow path. The flange has a rounded outer profile. In certain embodiments, the fluid flow path is sized and shaped to receive a needle for controlling pressure through the elastomeric mount. In further embodiments, the inner wall defining the fluid flow path is configured to substantially match the profile of the needle. In some embodiments, the sealing member on the outlet external sealing surface is a face seal. In certain embodiments, the outlet external sealing surface is configured to have a greater elastic deformation than the inlet external sealing surface when the elastomeric mount is axially compressed. In further embodiments, the flange of material surrounds the outlet of the fluid flow path. The flange has an angled profile. In certain embodiments, the outlet outer sealing surface comprises a flange extending from the body. Some embodiments feature one or more protrusions on the lateral exterior surface of the body. The one or more protrusions are adapted to provide an interference fit with the housing. Certain embodiments include one or more visual indicators (e.g., notches, color bars, etc.) to aid in the placement of the elastomeric mount in the housing. Some embodiments of the elastomeric mount are suitable for use in a back pressure regulator. That is, some embodiments of the elastomeric mount are fixed within the back pressure regulator. In some embodiments, the material forming the elastomeric mount has a lower modulus of elasticity than the needle material (i.e., the material used to form the needle in the BPR). In certain embodiments, the material forming the elastomeric mount has a lower modulus of elasticity than the material of the housing. In some embodiments, the material forming the elastomeric mount has a lower modulus of elasticity than the head of the BPR.

The present technique has a number of advantages. For example, the mount may be subjected to a number of mounting and adjustment processes by eliminating the torque applied to the compliant mount during mounting. Furthermore, the standoffs of the present technology are less likely to be scratched or sheared, which results in better sealing and pressure control due to the absence of impurities and gaps. Generally, the mount and mounting method are more robust than conventional mounts and methods. That is, the mount of the present technology is resilient. Furthermore, some embodiments of the technology provide enhanced robustness and usability of BPR, as components (e.g., mounts) may be customized and installed using methods that reduce torque stress, shear, and wear of the mount.

Another advantage of the present technique resides in the construction of the compliant or resilient support. In particular, embodiments of the mount of the present technology are configured to have a portion that forms a rigid face seal and a portion that intentionally deforms during installation. Accordingly, the carrier of the present technology may provide better sealing and may be used in extreme pressure environments (e.g., above 1000psi, above 2000psi, above 3000psi, above 4000psi, above 5000psi, above 6000psi, and greater). Further, certain embodiments of the stand-off provide a reduction in internal volume. That is, certain configurations or geometries of the seat of the present technology are customized according to the internal geometry of a portion of the pressurization system (e.g., a portion within a Back Pressure Regulator (BPR), or a portion between two metal surfaces in an injector). Thus, the internal volume of the system may be minimized, which generally improves performance due to the reduced volume.

Drawings

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

Fig. 1 illustrates an embodiment of a method of installing a mount between two surfaces in a pressurized system, in accordance with embodiments of the present technique.

Figure 2 schematically illustrates a needle-holder type back pressure regulator in accordance with embodiments of the present technique.

Fig. 3A-3C schematically illustrate a method of connecting a cradle to a housing to provide a rotatably disengaged connection. In a first step, the standoff is press-fit into the housing and the threaded nut is slid over the housing (fig. 3A). In the next step, the nut is aligned with the external groove in the housing (fig. 3B). In a final step, the end of the nut is crimped to the housing to provide free rotation of the nut about the abutment, which moves only in the axial direction as the nut rotates (fig. 3C).

Fig. 4 schematically illustrates a conventional needle-holder type back pressure regulator. The supports used in this conventional BPR are within the scope of the prior art and are not compatible with the present technology.

FIG. 5 is a cross-sectional view of an embodiment of an elastomeric mount in accordance with the present technique. The carrier of FIG. 5 has a surface 550 that forms a face seal with an adjacent component and a deformable surface 520 that has less elastic deformation than the surface 550 when the carrier is axially compressed. The mount of fig. 5 also has a geometry designed to reduce the internal fluid volume.

FIG. 6 schematically illustrates a finite element analysis of the total deformation of a mount in accordance with the present technique. The outer black border 800 shows the undeformed state.

FIG. 7 schematically illustrates a finite element analysis of seal pressures on the inlet and outlet outer surfaces of a carrier in accordance with the present technique.

Fig. 8 schematically illustrates a needle-holder type back pressure regulator that is not configured to reduce internal volume.

Fig. 9 schematically illustrates a needle-holder type back pressure regulator configured to reduce internal volume.

Figure 10 provides three chromatograms illustrating the banding of various systems.

Detailed Description

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. Features illustrated or described in connection with one exemplary embodiment may be combined with 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 relate to improved sealing between two surfaces in a pressurized system (e.g., a system environment in excess of 1000 psi). In some embodiments, the improvement is achieved by removing or minimizing torque applied to a compliant member positioned at the sealing joint. In some embodiments, the compliant member is a seat within the back pressure regulator. In other embodiments, the compliant member is a sealing ring located between two metal faces in the injector of the chromatography column.

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

Referring to fig. 1, embodiments of the present technology relate to a method of installing a mount between a first surface and a second surface in a pressurized system. The method 100 shown in fig. 1 may be used to install a seat or other seal between two regions in a pressurized system, such as, for example, between a high pressure region and a low pressure region in a Back Pressure Regulator (BPR), or between two metal surfaces within a sample injector of a chromatography column. Because the method 100 utilizes a compliant or press-fit member disengaged from the housing as a sealing element, the installation method 100 eliminates the use of torque on the compliant seal. That is, when the abutment is disengaged from a fixed structure (e.g., a nut or threaded groove on the outside of the housing), the abutment moves in the axial direction only when the nut is rotated and secured in place. Accordingly, at least a portion of the method 100 may be repeated multiple times (e.g., step 140). The seal can be unloaded and reinstalled multiple times without shearing or damaging the seal.

The method 100 includes four steps to install a mount between a first surface and a second surface in a pressurized system. In step 110, a carrier or seal is press fit into a housing that is capable of being attached to a first surface. Next, in step 120, the threaded nut is slid over the housing. The end of the nut is crimped to the housing in step 130 to provide a rotatably disengaged connection between the housing and the nut that allows the nut to rotate freely about the abutment. Finally, the nut is secured to the second surface in step 140. The securing of the threaded nut to the second surface forms a pressure-tight seal between the first surface and the second surface by rotation of the nut due to the rotatably disengaged connection. That is, because the connection is disengaged, no (or very little) torque is applied to the abutment during rotation of the nut. The seat does not undergo shear but only axial compression to form a high pressure seal.

Fig. 3A-3C illustrate a method 100 applied to mount an elastomeric mount within a BPR. For context, fig. 2 is provided as a reference to components and regions of the BPR. Note that fig. 2 shows an embodiment of the present technology. That is, FIG. 2 shows the connection portion of the BPR200 after the installation method 100 has been performed to form a pressure-tight seal between the first surface and the second surface.

In particular, fig. 2 shows an enlarged view of the connection between the head portion 240 (high pressure portion) and the outlet 230 (located in the low pressure portion). Generally, the outlet 230 is located in the housing 260. Fluid flow within the BPR200 enters through the inlet port 205, is controlled by movement of a needle 210 positioned within the seal 204 through the seat 215, and exits the BPR through the outlet 230. To form a pressure tight seal within the regulator 200 and maintain the seal, the nut 265 is rotatably secured (i.e., torqued) to the head 240 (e.g., the second surface in the BPR) until the housing 260 contacts the second surface on the head 240. In prior art devices and methods, the standoff between the high pressure section and the low pressure section is coupled directly to the nut or the threaded housing. When the outlet portion is secured in the head of a conventional apparatus, the housing and the support rotate together, creating high shear forces acting at the end of the support. Therefore, the conventional mount deteriorates during installation.

However, the mount 215 shown in fig. 2 is not coupled to the nut 265. That is, the seat 215 is rotatably disengaged from the nut 265, allowing for a more direct connection between the head 240 and the outlet 230 (e.g., minimizing internal volume) and preventing undesired shearing of the seat during an installation event. Comparing fig. 4 with fig. 2, a conventional BPR400 connection using a mount 415 directly connected to a housing 460 is shown. In fig. 4, the head 440 is secured directly to the threaded housing 460 to provide a connection to the outlet 430 located in the low pressure portion of the system. Fluid flows through the BPR400 through the inlet 405. The flow of fluid is controlled by the axial movement of a needle 410 located in the seal 404, with the tip 406 positioned in a seat 415. The mount 415 is located within a housing 460 having a threaded outer surface 465 that is directly connected to the head 440. Ends 416 and 417 of mount 415 are sheared as housing 460 is twisted into head 440 to form a seal.

In particular, the components of the BPR200 may be constructed and installed using the following techniques to minimize internal volume and reduce shear forces on the mount 215, as compared to conventional mounts installed in conventional BPRs or other pressurized equipment. One method of installation is shown in fig. 3A-3C, in which the carrier 215 is first press-fit into the housing 260. See mount 215 having a press fit connection with an opening in housing 260. That is, the seat 215 has an interference fit with the opening in the housing 260. The threaded nut 265 slides over the housing 260 as shown in fig. 3A. To provide a rotatably disengaged connection between the housing and the nut, the nut is positioned over one or more external grooves 262 in the housing 260, as shown in fig. 3B, and an end 270 of the nut 265 is crimped to the housing 260, as shown in fig. 3C. This type of connection allows the nut 265 to rotate freely about the housing 260. Thus, when the housing 260 containing the outlet 230 is mounted in the head portion 240 (see fig. 2), it can be secured/fixed by rotation as required without any shearing effect on the carrier 215. That is, as the nut 265 is rotated and tightened to form a pressure seal with the head 240, the seat 215 does not rotate but rather moves axially toward the needle 210. This mounting and standoff design allows for a more robust connection because the standoff 215 does not experience shear. Thus, the housing 260 may be removed and reinstalled multiple times without damaging the mount 215. For example, scratches and particles (if any) generated during installation are minimized as compared to support 415 during installation. Both scratches and particles can cause seal degradation or poor performance because the gap is created by scratches (removed material) in the carrier and particles that collect and accumulate along the sealing surface.

In general, the present technology also relates to elastomeric mounts or seals that can provide improved pressure-resistant connections between two different pressure regions (e.g., a high-pressure portion and a low-pressure portion) within a system. Embodiments of elastomeric mounts or seals may be used with the methods of the present technology. Further, elastomeric seats or seals may be used to improve sealing by tailoring the geometry, shape, and/or material of the seat/seal to meet environmental requirements. For example, because the support/seal is typically located at the interface between the high pressure zone and the low pressure zone, each end of the support and seal of the present technology is configured in view of its environmental placement. That is, in the embodiment used in conjunction with a BPR, one end of the seat interacts with the tip of the needle 210 and is exposed to high pressure, while the opposite end of the seat interfaces with the outlet 230 and is on the low pressure side of the regulator. To address these needs and eliminate redundant fluid paths within the carrier, the carrier 215 has a custom geometry as shown in FIG. 5. The first end 520 of the seat 215 at the end that interfaces with the needle (the high pressure side) is formed with a compliant surface that is angled and sized to be within a range of axial positions that allow the needle 210 to be positioned therein. In certain embodiments, this portion of the internal geometry of the holder comprises a surface 525 that closely matches the profile of the needle 210 to provide a tight connection and allow the flow path F-F to be customized for the range of needle displacement through this first portion of the holder. First end 520 is compliant and deformable, particularly during installation, to allow seat 215 and head portion 240 to be properly positioned. The internal geometry of the seat transitions from a conical or angled volume to a narrower custom right circular cylinder at point 530 to meet the low pressure side requirements. The opposite end 550 of the support, which is the side of the support that interfaces with the outlet 230, includes a small flange (e.g., chamfer) 540 with a face seal. Using finite element analysis, it has been found that a small flange or chamfer 540 on the end 550 helps to control deformation within the inside diameter of the seat during use. In this embodiment, the flange 540 has an angled (i.e., non-rounded) profile and extends from the outlet outer sealing surface 550. In other embodiments, the flange 540 may be rounded. As the seat 215 is axially compressed, the angled profile of the flange 540 deflects inwardly from the outlet outer seal surface 550 toward the fluid flow path (F-F) extending between the surfaces 520 and 550.

Using finite element analysis, the stress state around the end of the standoff 215 was studied and the local stress state was found to be at an acceptable level. Fig. 6 shows the result of the deformation on the support caused by the mounting. As can be seen in fig. 6, the outlet outer sealing surface 550 forming the top face seal undergoes the greatest degree of deformation. Without being bound by theory, it is believed that the shape or amount of material present on the outlet outer surface 550 creates a rigid seal, resulting in deformation coaxial with the load and not into the fluid flow path of the seat. It should be noted that changing the angle of the inner chamfer on the surface changes the degree of deformation into the flow path during FEA. The inlet outer surface 520 shows a change in shape in response to an applied axial deformation. The outer black border 800 shows the undeformed state, while the inner shaded portion shows the shape of the pedestal after a load is applied. As can be seen in fig. 6, surface 520 deforms such that material overflows outside of its original boundaries. Without being bound by theory, it is believed that surface 520 changes shape because it is more flexible than surface 550 because it is free of material (e.g., see gap 810, forming rounded lip/flange 527). The flange 527 deforms outwardly toward the surface 580. By varying the angle of the inner chamfer defining the opening to the fluid flow path, the degree of outward deformation can be varied. That is, in this embodiment, if the inner chamfer has a steep angle (e.g., vertical), the deformation outward to the edge 580 will be less than the deformation outward to a gradual angle (e.g., more horizontal). Fig. 7 shows the results obtained using FEA with respect to the sealing pressure. In particular, the sealing pressure on the raised structure 540 on the surface 550 and the rounded lip 527 on the surface 520 were studied. Both the raised structure 540 and the lip 527 are capable of sealing up to 31,307psi for the boundary conditions applied.

Generally, outlet outer seal surface 550 is configured to have a greater elastic deformation than inner outer seal surface 520 when the carrier is axially compressed. That is, the material, shape configuration, and/or thickness of the features extending from the outlet external sealing surface provide less resistance to deformation than the inlet external sealing surface. For example, the outlet outer sealing surface 550 may include an angled flange 540 that will deflect inward and will deform more than a flange 525 extending from the inlet outer sealing surface 520. The flange 525 extends outwardly from the fluid flow path (see the angled edges of the fluid flow paths F-F near the end 520 that extend outwardly toward the lateral outer surface 580). In addition to flaring outward, the flange 525 also includes a rounded outer profile 527. The rounded outer profile 527 readily deforms and will deform outwardly from the inlet outer seal surface 520 toward the outer surface 580 and away from the interior of the fluid flow path F-F when the seat 215 is axially compressed. While the carrier 215 shown in fig. 5 has a rounded profile flange extending from its inlet outer surface to provide a deformation member for the carrier, other structures or materials may be used in addition to or in place of the rounded profile flange. For example, rather than including a rounded profile, a different material that is more deformable than the interior portion of surface 520 may be used on a portion of surface 520 corresponding to the location of 527. Additionally or alternatively, different sized rounded flanges or protrusions extending from the surface 520 may be used as the deforming member. Indeed, any deforming member configured to deform outwardly toward the outer or lateral outer surface 580 and away from the internal fluid flow path F-F may be used.

In addition to the deformation and sealing features, the seat 215 of the present technology may include other structures or features on the outer surface. For example, the holder 215 in fig. 5 includes a protrusion 560 on its lateral outer surface 570. The protrusions 560 extend radially and improve the interference fit of the carrier 215 in the holder 260. In addition to the protrusions, the lateral outer surfaces may also contain visual aids to aid in the placement of the mount within the holder. In fig. 5, the seat 215 includes a visual aid 580 (e.g., a notch) that corresponds in this embodiment to the location of the transition 530. The visual aid 580 in fig. 5 indicates the end inserted into the housing (e.g., to aid the user in proper placement of the mount 215). Although the embodiment shown in fig. 5 uses notches or cut-out grooves, other visual aids are possible. For example, a color change or a color band or stripe may be used instead of the notch. Furthermore, other patterns besides notches may also be used to visually mark the desired orientation or position of the stand-off.

The support 215 may be made of a single material, graded materials, or multiple materials. That is, the support 215 may be formed from a single piece (e.g., a single material or graded material), or it may be a two-piece structure in which each piece is formed from a different material and bonded together. In the embodiment shown in fig. 5, the standoffs 215 are a unitary piece formed from a single compliant material such as polyimide-based plastic (e.g., Vespel). The difference in elastic deformation between the inlet and outlet external sealing surfaces results from the structures and features on those surfaces. In other embodiments, the difference in elastic deformation is caused by grading the material (inlet surface 520 has less elastic deformation than outlet 550). That is, additives may be incorporated into the material forming the standoffs such that surface 520 has less elastic deformation characteristics than surface 550. In other embodiments (not shown), the standoffs 215 may be made of two different materials that are bonded together, such as at the location of the transition 530, to provide a difference in elastic deformation characteristics between the surfaces 520 and 550. The one or more materials forming the seat 215 are typically compliant materials that are resilient under axial compression. The seat 215 will be compressed between the metal or rigid surfaces defining the high and low pressure regions when installed. Further, in embodiments within a BPR, the seat will be exposed to the needle 210, which moves in, out, and along the flow path F-F, with its tip possibly encountering the transition 530 to control the flow of fluid therethrough. To provide resiliency under these operating conditions, the material forming the elastomeric mount will typically have a lower modulus of elasticity than the material forming the needle. Furthermore, to ensure the resiliency of the mount 215 during multiple installation events, the material used to form the mount will have a lower modulus of elasticity than the housing material and a lower modulus of elasticity than the material forming the head of the back pressure regulator.

Generally, the seat/seal and method of installation within a pressurized system described herein provide enhanced pressure sealing capabilities. Thus, the present techniques can be robustly employed in high pressure systems (e.g., in conjunction with 1000psi or greater). This advantage is particularly attractive for use within BPRs for controlling pressure variations in chromatographic systems. The mount of the present technology also increases or enhances the performance of pressure control by reducing the internal volume to help eliminate unswept volume. The unswept volume is the accessible portion of the fluid stream, but not within the main solvent flow path used in chromatographic separations. Portions of the solvent stream may diffuse into or out of the unswept volume at irregular rates, resulting in band broadening. Band broadening reduces the quality of the separation and can result in broad and potentially overlapping chromatogram peaks. In the present technique, the standoffs within the BPR may be customized to reduce the internal volume within the BPR. For example, at least a portion of the fluid flow path F-F extending through the support may be precisely customized to the exterior shape of the needle within the BPR. Another portion of the fluid flow path F-F (the portion above the transition 530) is sized to provide a narrower restriction, which may also reduce the length of the fluid path, thereby eliminating the internal volume. Examples 1 and 2 below show the improved performance of BPR using standoffs according to the present technology.

Example 1

Fig. 8 illustrates a back pressure regulator 1300 that has not been configured to reduce internal volume (i.e., standard commercial raw BPR). The back pressure regulator 1300 includes an inlet 1305, a seal 1304, a needle 1310, a seat 1315, and an outlet 1330. The needle 1310 and the support 1315 define a restriction 1316 at which the needle 1310 will meet the support 1315 at one extreme of the range of motion of the needle 1310. The back pressure regulator 1300 also contains an internal volume that can be occupied by the mobile phase fluid stream when the back pressure regulator is used for chromatographic separations. The head volume 1306(55.0 μ L) contains the portion of fluid flow from the inlet up to the seal 1304, along the needle 1310, and to the seat 1315. Seal volume 1307(25.0 μ L) is adjacent to seal 1304. A seat volume 1318(34.1 μ L) is located within the seat 1315. An outlet volume 1335(19.8.1 μ L) is located downstream of the support 1315 at outlet 1330. The total internal volume of these components was 134 μ L (109 μ L excluding the sealed volume 1307).

Fig. 9 shows a back pressure regulator 1400 that has been configured to reduce internal volume. The back pressure regulator 1400 contains the same basic components: the back pressure regulator 1400 includes an inlet 1405, a seal 1404, a needle 1410, a support 1415, and an outlet 1430. The needle 1410 and the seat 1415 define a restriction 1416 where the needle 1410 will meet the seat 1415 at one extreme of the range of motion of the needle 1410. The back pressure regulator 1400 also contains an internal volume that may be occupied by the mobile phase fluid stream when the back pressure regulator is used for chromatographic separations. The head volume 1406 contains the portion of fluid flow from the inlet up to the seal 1404, along the needle 1410, and to the seat 1415. The sealed volume 1407 is proximate to the seal 1404. The seat volume 1418 is within the seat 1415. The outlet volume 1425 is downstream of the support 1415 at the outlet 1430.

The back pressure regulator 1400 is configured to reduce the internal volume. That is, the relationship and positioning of the various BPR components has been customized to reduce internal volume (e.g., minimize unswept volume). It should be understood that while the BPR shown in FIG. 9 has been customized in a variety of ways, the BPR need not be customized in each of the ways shown in FIG. 9 to achieve at least some advantages over commercially available BPRs. By positioning the inlet 1405 near the seat 1415 and providing a reduction in the length of the flow path of the needle 1410 perpendicular to the inlet 1405 of the needle 1410, the head volume 1406 has been reduced to 39.4 μ L (28% reduction). The seal 1404 is positioned closer to the support 1415. The sealing volume 1407 is not reduced in the back pressure regulator 1400 as shown. The carrier volume 1418 has been reduced to 9.3 μ L (73% reduction) by reducing the length of the carrier 1415 and shaping the carrier 1415 so that its internal volume is closer to the shape of the needle 1410. The restraint 1416 is configured to define a sharp point at the interface of the conical portion and the cylindrical portion of the mount 1415. The outlet volume 1430 has been reduced to 1.9 μ L (90% reduction) by connecting the outlet 1430 directly to the flow path from the support 1415. Comparison of fig. 8 with fig. 9 also provides an example of reducing the volume by reducing the cross-sectional area at the interface between BPR components. The support 1418 and outlet volume 1425 are reduced by minimizing the cross-sectional area at the outlet 1430, and the support 1415 is configured such that it is no larger than the size of the flow path. The total internal volume of the back pressure regulator 1400 was 76 μ L, a 44% reduction compared to the back pressure regulator 1300, or no seal volume included, 51 μ L (53% reduction). In general, the interfaces between components in an unmodified back pressure regulator may have larger areas than the flow paths within the components, and reducing these areas may reduce the volume within the back pressure regulator.

Example 2

Fig. 10 shows the significant reduction in band distortion effects achieved using the BPR 1400. Fig. 10 provides chromatograms of three different BPR designs and shows the effect on peak broadening and tailing. Trace 1501 is a peak measured from a sample that has not passed through a single flow path that contains both a back pressure regulator and a detector. That is, trace 1501 is the peak measured from a sample measured in a system with a split interface design, where the BPR is provided with supplemental solvent, and the detector is split from a flow line extending directly from the column. Since the sample associated with the split interface design is not affected by the amount of unswept volume in the BPR, the sample associated with trace 1501 does not experience any sample band diffusion — see region 1510. Trace 1501 is sharp and symmetrical, having a half width of about 1.22. Trace 1502 is the peak measured in the same way, except that the sample passed through a back pressure regulator without the present technique (i.e., using the system shown in fig. 8). That is, the back pressure regulator is a standard commercial material that is not customized to reduce internal volume and is not a flow splitting interface as used by the sample provided in trace 1501, which is a BPR interface flow design where the BPR is positioned on the same flow path between the column and the detector. Trace 1502 shows a peak that is significantly widened compared to trace 1501 (compare half width 1.22 of trace 1501 to half width 3.22 of trace 1502) and exhibits a substantial tail and some shoulders in region 1515. Trace 1503 is also a peak measured in a system using a BPR interface design but containing a BPR 1400 (fig. 9, and described in example 1) configured with a reduced internal volume in accordance with the present techniques. Trace 1503 is a sharp symmetrical peak, is more closely aligned with trace 1501 (compare half width 1.22 of trace 1501 to half width 1.65 of trace 1503), and has significantly less widening and shoulder in region 1520 than in trace 1502.

Embodiment 2 demonstrates that embodiments of the present technology significantly reduce or eliminate band broadening caused by back pressure regulators, allowing for separation quality comparable to that performed in split interface designs. Thus, a user may achieve advantages associated with a back pressure regulator, such as good pressure control at a reasonable cost and robust and wear-resistant operation, without sacrificing separation quality by implementing the methods, apparatus, and mounts of the present technology.

One of ordinary skill in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the invention is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.