Valve assembly with flow streamline element to prevent oscillatory flow effects

Abstract

A valve assembly for controlling the flow rate of a fluid. The valve assembly includes a valve plunger and a protective member. The valve plunger forces a fluid with a certain flow rate to flow between an inlet and an outlet in response to an applied actuation force. The actuation force is applied to a first side, and a fluid is applied to a second side of the valve plunger. The protective member minimizes or eliminates the unstable force caused by static pressure generated by the interaction of the fluid on the second side. The protective member is connected to the valve plunger, or formed in the valve plunger, or suspended below the valve plunger, and extends a length into the outlet. The valve assembly further includes an orifice between the inlet and the outlet, wherein the orifice includes at least one flat surface and at least one non-flat surface. The protective member protects a section of the second side from the influence of the fluid.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 784,197, filed on December 21, 2018, and U.S. Non-Provisional Application No. 16 / 719,772, the entire disclosures of which are expressly incorporated herein by reference. Background Art

[0003] For example, the valve assembly used in a mass flow controller (MFC) is designed to transmit fluid at a desired rate, which can depend on the specific application. It is generally beneficial to minimize the power consumption of the control valve to reduce the heat generated by the valve and minimize the total power draw of the MFC. However, since the fluid force may become a significant part of the force acting on the valve, the low power / low force valve may be affected by control problems. Therefore, the combination of a low force valve and a simplified control system presents a special problem to engineers because the resulting MFC must still operate within acceptable standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] For a more complete understanding of the features and advantages of the present disclosure, reference is now made to the detailed description and accompanying drawings, in which corresponding reference numerals in the different drawings represent corresponding parts, and in which:

[0005] Figure 1 is a diagram of an MFC having a valve assembly designed to mitigate or eliminate the buildup of stagnant fluid and pressure, according to certain example embodiments;

[0006] Figure 2A is an illustration of graphs of flow rate, absolute pressure, and differential pressure versus time for a valve of an MFC that does not include a guard according to certain example embodiments;

[0007] Figure 2B is the static pressure (F) under the plunger, orifice, and inlet according to certain example embodiments s ) concentrated illustration;

[0008] Figure 3A and Figure 3B shows cross-sectional views of valves having different guard configurations according to certain example embodiments;

[0009] Figure 4 is an illustration of an isometric view of a tube passage, a plunger, a plunger housing, a guard, and an orifice according to certain example embodiments;

[0010] Figure 5A is an illustration of a cross-sectional cutaway view of a tube passage, a plunger, and an orifice, wherein the orifice has at least one non-planar surface (NPS), according to certain example embodiments;

[0011] FIG. 5B to FIG. 5C is an illustration of a cross-sectional cutaway view of a tube passage, a plunger, a guard, and an orifice, wherein the orifice has at least one non-planar surface (NPS), according to certain example embodiments;

[0012] 6A to 6H is an illustration of a plurality of different cross-sectional views of a tube passage, a plunger, a protector, and an orifice, wherein the plunger and an NPS on at least one of the tube passage and the orifice have a plurality of different configurations, according to certain example embodiments;

[0013] Fig. 7A is an illustration of a graph of fluid flow rate, absolute pressure, and differential pressure versus time for a valve of an MFC including a protector according to certain example embodiments;

[0014] Figure 7B is an illustration of a corresponding simulation (eg, a CFD simulation) in which the plunger has been modified to include a guard to dissipate an inward radial jet with a relatively larger diameter, according to certain example embodiments; and

[0015] FIG. 8A to FIG. 8B , FIG. 9A to FIG. 9B as well as FIG. 10A to FIG. 10B is a velocity contour map generated from a CFD (computational fluid dynamics) simulation showing the fluid velocity under the plunger with and without a guard. DETAILED DESCRIPTION

[0016] Although the manufacture and use of various embodiments of the present disclosure are discussed in detail below, it should be understood that the present disclosure provides many applicable inventive concepts that can be embodied in many special contexts. The specific embodiments discussed herein are illustrative only and do not limit the scope of the present disclosure. For the sake of clarity, all features of the actual implementation may not be described in the present disclosure. Of course, it should be understood that in the development of any such actual embodiment, many decisions specifically for the implementation must be made to achieve the specific goals of the developers, such as complying with system-related and business-related constraints, which will vary from implementation to implementation. In addition, it should be understood that such development work may be complex and time-consuming, but it will be a routine task for those of ordinary skill in the art who benefit from the present disclosure.

[0017] A particular challenge in reducing the production cost of the MFC model is how to develop a valve assembly that can be used with a limited amount of force (F a ) or power valves, can reliably maintain the desired fluid flow rate without advanced diagnostic and control systems. It has been found that in some MFC applications, the flow-induced force (F fl) can become an important part of the force balance on the valve, that is, F fl Relative to F o Become important.

[0018] Flow-induced valve forces arise from changes in static pressure at the base of the plunger. Changes in static pressure are usually caused by changes in the flow pattern near the plunger, i.e., the flow attachment point moves from the plunger to the sidewall (or vice versa) as the plunger moves up and down. These flow changes can lead to a situation where a plunger held in the same position has different fluid forces acting on it at different times, resulting in oscillatory behavior.

[0019] Disclosed herein is a valve assembly designed to mitigate or eliminate F by providing a flow path that keeps fluid flow lines consistent beneath a plunger and, in some embodiments, isolates the plunger from fluid forces beneath the plunger. fl changes.

[0020] Reference now Figure 1 , showing a design that is designed to reduce or eliminate the plunger below F fl FIG. 1 is a diagram of an MFC of a valve assembly with a variation of the MFC. The MFC includes a base platform 10, a tube channel 12 having volumes 14, 16, valve assemblies 18, 20, and a control unit 22 communicatively connected to the valve assemblies 18, 20. Each valve assembly 20, 22 includes an electrically controlled actuator 18A, 20A, a plunger 18B, 20B (coupled to the corresponding actuator 18A, 20A via a valve stem), and a plunger housing 18C, 20C. A protective member 18D, 20D (i.e., a fluid guide) is arranged in the tube channel 12 so that the F under its corresponding plunger 18B, 20B is fl In an embodiment, the guards 18D, 20D may be coupled to or formed with their respective plungers 18B, 20B. In another embodiment, the guards 18D, 20D may be suspended below their respective plungers 18B, 20B, such as by coupling the guards 18D, 20D to a section of the tube channel 12.

[0021] In certain applications, such as semiconductor manufacturing, the base platform 10 is connected to an upstream fluid source and to a downstream processing chamber via a fluid pipeline. The fluid flows through the tube channel 12 and the MFC operates to maintain the desired fluid flow rate. The control unit 22 can use measurements from multiple temperature sensors and pressure sensors (not shown) to maintain the desired fluid flow rate. The fluid dynamics of the fluid traveling through the tube channel 12, the volume design of the plunger housing 18C, 20C, and the position of the plunger 18B, 20B may cause the fluid to concentrate under the plunger 18B, 20B. When the plunger 20A, 22B is adjusted in response to the control signal, the fluid force (F) generated by the static pressure on the bottom of the plunger fl) may overcome or cause the valve force (F o However, the introduction of the guards 18D, 20D in the pipe passage 12 can eliminate or significantly reduce the static pressure variation oscillations that cause valve vibration.

[0022] Reference now Figure 2A , shows a graph of flow rate, absolute pressure, and differential pressure versus time for a valve of an MFC that does not include a protective member according to certain example embodiments. As shown, when the valve is opened or closed (i.e., when the valve is adjusted), noise, for example in the form of vibrations or valve oscillations, is introduced, which makes the responding valve unstable, resulting in a disturbance in the desired flow rate. In practice, for sensitive applications, such as controlling the flow of fluids entering a semiconductor processing chamber (which requires very precise flow rates), this can significantly affect product yield. As previously described, changes in the flow (or more precisely, changes in the flow attachment point) under the plungers 18B, 20B cause F fl This may result in valve oscillations in response to manipulation of plungers 20B, 22B. Figure 2B It is shown how the flow pattern under the plunger changes as the plunger moves according to an existing example embodiment without a guard.

[0023] Figure 2A A graph of normalized N2 flow rate (short dashed line), absolute pressure (solid line), and LFE (laminar flow element) pressure drop (dashed line) versus time is shown as the valve input voltage changes from 0.0 to maximum voltage and then to 0.0 volts via a triangular ramp over a 60 second window (from about 30 seconds to about 90 seconds). In the graphs, a flow value of 1.0 corresponds to a flow rate of 50 slpm N2, an absolute pressure value of 1.0 corresponds to a N2 inlet pressure of 100 psia, and a dP value of 1.0 corresponds to a N2 pressure drop of 1.0 psid for a given N2 (nitrogen) flow rate and inlet pressure. Figure 2AAs shown, once the valve is opened, the flow becomes unstable, and the flow remains unstable until about 50 seconds. In response, the following oscillation mechanism is assumed: when the valve is operated at a low height (i.e., low flow), radial jet acceleration occurs due to the reduction in area when the jet is directed toward the radial center. Then, since the speed must change direction, this jet stagnates at the center of the orifice, resulting in an increase in pressure (stagnation and downward turning causes an increase in the static pressure below the plunger). This static pressure exerts an upward force, which causes the valve plunger to be lifted to a higher position, that is, the upward fluid force formed by the static pressure exceeds the downward force (the sum of the spring force and other forces, such as the actuation force on the plunger). When the plunger moves upward, the flow separates from the plunger and the resulting radial jet velocity decreases, thereby reducing the static pressure. At the same time, this movement (displacement) causes the spring force to increase. The reduction in static pressure and the increase in spring force (or other forces, such as changes in the actuation force) reduce the total force on the plunger 20. This makes the total downward force now greater than the upward force, which causes the plunger to move back downward. The above physical phenomena are the cause of the plunger movement. Subsequent experiments and CFD simulations verified the basic assumption that providing a small solid cylinder at the center of the bottom side of the plunger 20 reduces the interference force. FIG. 8A to FIG. 8B , FIG. 9A to FIG. 9B as well as FIG. 10A to FIG. 10B ] is a velocity contour map generated from a CFD (Computational Fluid Dynamics) simulation, which shows the fluid velocity under the plunger with and without the guard, clearly showing that the guard has a dissipative effect on the radial jet.

[0024] Reference now Figure 3A , Figure 3B , shows a cross-sectional view of a valve 20 with different protection member 20D configurations according to certain example embodiments. The protection member 20D is designed to have a radius and a length, wherein the radius is smaller than the radius of the plunger and the length extends into the section of the tube channel 12. The length and radius of the protection member 20D may be based on Figure 2B The simulation of the valve assembly for a specific MFC application is used to determine the Figure 3A In the embodiment, the protective member 20D is connected to the plunger 20B or formed therewith (e.g., the actual manufacturing of the plunger 20B). Figure 3B In the embodiment of the present invention, the plunger 20B includes a cavity 26 configured to receive a protector 20D. The protector 20D can be attached to the wall of the cavity 26. Nevertheless, the cavity 26 is optional, that is, the protector 20D can be connected to the tube channel 12 and suspended under the plunger 20B. The spacing between the plunger 20B and the protector 20D can be, for example, about 0.010 inches. The protector 20D protects the bottom side of the plunger 20C by acting as a fluid guide, so that the change of the fluid streamline under the plunger 20D is minimized.

[0025] Reference now Figure 4, shows an isometric view of the tube passage 12, plunger 20B, plunger housing 20C, guard 20D, and orifice 24 according to certain example embodiments. As shown, guard 20D protects the area below plunger 20B (i.e., the surface area below plunger 20B) and serves as a guide to direct fluid down tube passage 12 and prevent fluid from stagnating under plunger 20B. Figure 5A is a cross-sectional view of the tube passage 12, plunger 20B, and orifice 24 for a standard valve embodiment subject to oscillation. Figure 5B FIG. 1 is a cross-sectional view of a tube passage 12, a plunger 20B, a guard 20D, and an orifice 24 according to certain exemplary embodiments, wherein the orifice has at least one non-planar surface (NPS). The NPS streamlines the flow path and provides a more constant flow attachment point under the plunger, thereby reducing F fl This more constant F fl A more constant delivery flow is provided. It should also be understood that the NPS may also be formed on the surface of the tube passage 12. 6A to 6H Shown in FIG. 1 are various different cross-sectional views of the tube passage 12 , the plunger 20B, the protector D, and the orifice 24 , wherein the plunger 20B and the NPS on at least one of the tube passage 12 and the orifice 24 have various different configurations.

[0026] Fig. 7A is an illustration of a graph of fluid flow rate, absolute pressure, and differential pressure versus time for a valve of an MFC including a guard, according to certain example embodiments. Figure 2B , Figure 7B The flow attachment point shown is more constant throughout the plunger stroke. Figure 2B The noise present in the curve graph of is eliminated or negligible and clean noise (ie, no noise) is delivered to downstream processing. The use of the column eliminates or minimizes the F fl changes, which produced Fig. 7A A steady flow rate versus time curve is shown for a triangular voltage wave. Figure 7B A corresponding simulation (e.g., CFD simulation) is shown in which the plunger has been modified to include a post to dissipate the inward radial jet with a relatively large diameter (e.g., a guard diameter of 0.063 inches and an orifice diameter of approximately 0.100 inches). Alternatively, the test showed that a post of 0.040 inches in diameter would also work as a 0.063 inch post, but would provide the same flow as the original design under choked conditions (35 psia input and 2 psia output at x = 0.015 inches).

[0027] As used herein, the singular forms "one", "an" and "the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should be further understood that the terms "include" and / or "comprise" used in this specification specify the presence of stated features, wholes, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, parts, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more items in the associated listed items. As used herein, phrases such as "between X and Y" and "between about X and Y" should be interpreted as including X and Y. As used herein, phrases such as "between about X and Y" refer to "between about X and Y". As used herein, phrases such as "from about X to Y" refer to "from about X to about Y".

[0028] The embodiments of the above disclosure have been given for the purpose of illustration and to enable one of ordinary skill in the art to practice the disclosure, but the disclosure is not intended to be exhaustive or limited to the forms disclosed. Many insubstantial modifications and variations will be apparent to one of ordinary skill in the art without departing from the scope and spirit of the disclosure. The scope of the claims is intended to broadly cover the disclosed embodiments and any such modifications. In addition, the following clauses represent additional embodiments of the disclosure and should be considered within the scope of the disclosure:

[0029] Item 1, a valve assembly for controlling a flow rate of a fluid, the valve assembly comprising: a valve plunger configured to force a fluid having a certain flow rate to flow between an inlet and an outlet, the valve plunger causing an actuation force to be applied to a first side and causing the fluid to be in fluid communication with a second side; and a guard configured to minimize or eliminate an unstable force caused by a static pressure generated by fluid interaction on the second side;

[0030] Clause 2. The valve assembly of clause 1, wherein the valve plunger further comprises a recessed section on the second side, the recessed section being configured to receive the guard;

[0031] Clause 3, the valve assembly of clause 2, wherein the guard is one of coupled to the valve plunger, formed in the valve plunger, and suspended below the valve plunger and extends a length into the outlet;

[0032] Clause 4. The valve assembly of clause 1, wherein the valve assembly further comprises an orifice between the inlet and the outlet, wherein the orifice comprises at least one planar surface and at least one non-planar surface;

[0033] Clause 5. The valve assembly of clause 1, wherein the protective member protects a section of the second side from the fluid;

[0034] Clause 6, the valve assembly of clause 1, wherein the guard allows fluid to pass from the section of the second side and into the outlet;

[0035] Clause 7. The valve assembly of clause 1, wherein the inlet is a plurality of inlets; wherein the valve plunger further comprises an orifice between the plurality of inlets and the outlet, wherein the orifice comprises at least one planar surface and at least one non-planar surface; wherein the guard protects a portion of the second side from the fluid; and wherein the guard allows fluid to pass from a first section of the second side and a second section of the second side and into the outlet; wherein the guard is one of a flow path formed by the plunger, coupled to the plunger, and disposed under the plunger;

[0036] Item 8, a mass flow controller for controlling a flow rate of a fluid, the mass flow controller comprising: an electrically controlled actuator controllable in response to a change in a set flow rate to generate an actuation force; a valve assembly communicatively connected to the electrically controlled actuator, the valve assembly comprising a valve plunger, the valve plunger being configured to force a fluid having a certain flow rate to flow between an inlet and an outlet, the valve plunger causing the actuation force to be applied to a first side and causing the fluid to be in fluid communication with a second side; and a protective member configured to minimize or eliminate destabilizing forces caused by static pressure generated by fluid interaction on the second side;

[0037] Clause 9, the mass flow controller of clause 8, wherein the valve plunger further comprises a recessed section on the second side, the recessed section being configured to receive the guard;

[0038] Clause 10, a mass flow controller as described in Clause 8, wherein the guard is one of coupled to the valve plunger, formed in the valve plunger, and suspended below the valve plunger and extends a length into the outlet;

[0039] Clause 11. The mass flow controller of clause 8, wherein the valve assembly further comprises an orifice between the inlet and the outlet, wherein the orifice comprises at least one planar surface and at least one non-planar surface;

[0040] Clause 12. The mass flow controller of clause 8, wherein the protective member protects a section of the second side from the fluid;

[0041] Clause 13, a mass flow controller as described in Clause 8, wherein the guard allows fluid to pass from the section of the second side and into the outlet;

[0042] Clause 14. A mass flow controller as described in clause 8, wherein the inlet is a plurality of inlets; wherein the valve plunger further includes an orifice between the plurality of inlets and the outlet, wherein the orifice includes at least one planar surface and at least one non-planar surface; wherein the guard protects a portion of the second side from the fluid; and wherein the guard allows fluid to pass from a first section of the second side and a second section of the second side and into the outlet; wherein the guard is one of a flow path formed by the plunger, coupled to the plunger, and disposed under the plunger;

[0043] Item 15, a method for controlling a fluid flow rate, the method comprising: generating an actuation force; communicatively coupling the actuation force to a valve assembly; forcing a fluid having a flow rate to flow between an inlet and an outlet using a valve plunger of the valve assembly, wherein forcing the fluid to flow between the inlet and the outlet further comprises: applying the actuation force to a first side of the valve plunger; acting on the fluid with a second side of the valve plunger; and using a protective member to minimize or eliminate destabilizing forces caused by static pressure generated by fluid interaction on the second side;

[0044] Clause 16, the method of clause 15, wherein the valve plunger further comprises a recessed section on the second side, the recessed section being configured to receive the guard;

[0045] Clause 17, the method of clause 15, wherein the guard is one of coupled to the valve plunger, formed in the valve plunger, and suspended below the valve plunger and extends a length into the outlet;

[0046] Clause 18, the method of clause 15, wherein the valve plunger further comprises an orifice between the inlet and the outlet, wherein the orifice comprises at least one planar surface and at least one non-planar surface;

[0047] Clause 19. The method of clause 15, wherein the guard protects a section of the second side from the fluid; and wherein the guard allows the fluid to pass from the section of the second side and into the outlet; and

[0048] Item 20, a method as described in Item 15, wherein the inlet is a plurality of inlets; wherein the valve plunger further includes an orifice between the plurality of inlets and the outlet, wherein the orifice includes at least one flat surface and at least one non-flat surface; wherein the protective member protects a portion of the second side from the fluid; and wherein the protective member allows the fluid to pass from a first section of the second side and a second section of the second side and into the outlet; wherein the protective member is one of a flow path formed by the plunger, connected to the plunger, and arranged under the plunger.

Claims

1. A valve assembly for controlling a flow rate of a fluid, the valve assembly comprising: a valve plunger configured to force a fluid having a flow rate to flow between an inlet and an outlet in a flow path, the valve plunger causing an actuation force to be applied to a first side of the valve plunger and causing the fluid to be in fluid communication with a second side of the valve plunger, the valve plunger being located within at least a portion of the flow path in a direction perpendicular to the valve plunger; an orifice located between the inlet and the outlet, wherein the orifice includes at least one planar surface and at least one concave surface defined within the portion of the flow path perpendicular to the direction of the valve plunger, an actuator configured to apply the actuation force to the first side of the valve plunger, the actuation force operable to move the valve plunger toward a tubular member forming a portion of the flow path; and A guard member is configured to reduce a destabilizing force applied by the fluid to the second side, wherein the guard member is a cylindrical protrusion extending from a bottom of the valve plunger.

2. The valve assembly of claim 1, wherein: The valve plunger further includes a recessed section on the second side configured to receive the guard.

3. The valve assembly of claim 2, wherein: The guard is one of coupled to the valve plunger, formed in the valve plunger, and suspended below the valve plunger and extends a length into the outlet.

4. The valve assembly of claim 1, wherein: The protector protects a section of the second side from the fluid.

5. The valve assembly of claim 1, wherein: The guard allows the fluid to pass from a section of the second side and into the outlet.

6. The valve assembly of claim 1, wherein: The inlet is a plurality of inlets; wherein the valve plunger further includes the orifice between the plurality of inlets and the outlet; wherein the guard protects a portion of the second side from the fluid; and wherein the guard allows the fluid to pass from a first section of the second side and a second section of the second side and into the outlet; wherein the guard is one of a flow path formed with the plunger, coupled to the plunger, and arranged under the plunger.

7. A mass flow controller for controlling the flow rate of a fluid, the mass flow controller comprising: an electrically controlled actuator controllable to generate an actuation force in response to a change in a set flow rate; a valve assembly communicatively coupled to the electrically controlled actuator, the valve assembly comprising a valve plunger configured to force a fluid having a flow rate to flow at least partially through a tubular member between an inlet and an outlet, the valve plunger causing the actuation force to be applied to a first side of the valve plunger and causing the fluid to be in fluid communication with a second side of the valve plunger, the valve plunger being located within at least a portion of a flow path in a direction perpendicular to the valve plunger; an orifice located between the inlet and the outlet, wherein the orifice includes at least one planar surface and at least one concave surface, the concave surface defined within the portion of the flow path perpendicular to the direction of the valve plunger; as well as A guard member is configured to reduce destabilizing forces applied to the second side, wherein the guard member is a cylindrical protrusion extending from a bottom of the valve plunger.

8. The mass flow controller according to claim 7, wherein: The valve plunger further includes a recessed section on the second side configured to receive the guard.

9. The mass flow controller according to claim 7, wherein: The guard is one of coupled to the valve plunger, formed in the valve plunger, and suspended below the valve plunger and extends a length into the outlet.

10. The mass flow controller according to claim 7, wherein: The protector protects a section of the second side from the fluid.

11. The mass flow controller of claim 7, wherein: The guard allows the fluid to pass from a section of the second side and into the outlet.

12. The mass flow controller of claim 7, wherein: The inlet is a plurality of inlets; wherein the valve plunger further includes the orifice between the plurality of inlets and the outlet; wherein the guard protects a portion of the second side from the fluid; and wherein the guard allows the fluid to pass from a first section of the second side and a second section of the second side and into the outlet; wherein the guard is one of a flow path formed with the plunger, coupled to the plunger, and arranged under the plunger.

13. A method for controlling a fluid flow rate, the method comprising: Generate actuating force; applying the actuation force to the valve assembly; A fluid having a certain flow rate is forced to flow in a tubular member between an inlet and an outlet using a valve plunger of the valve assembly, the valve plunger being located in at least a portion of a flow path perpendicular to a direction of the valve plunger, the valve assembly further comprising an orifice located between the inlet and the outlet, wherein the orifice comprises at least one flat surface and at least one concave surface, the concave surface being defined in the portion of the flow path perpendicular to a direction of the valve plunger, wherein forcing the fluid to flow between the inlet and the outlet further comprises: applying the actuation force to a first side of the valve plunger, the actuation force being a mechanical force applied to the first side; acting upon the fluid with a second side of the valve plunger; and The destabilizing force applied to the second side is reduced using a guard member, wherein the guard member is a cylindrical protrusion extending from the bottom of the valve plunger.

14. The method of claim 13, wherein: The valve plunger further includes a recessed section on the second side configured to receive the guard.

15. The method of claim 13, wherein: The guard is one of coupled to the valve plunger, formed in the valve plunger, and suspended below the valve plunger and extends a length into the outlet.

16. The method of claim 13, wherein: The guard protects a section of the second side from the fluid; and wherein the guard allows the fluid to pass from the section of the second side and into the outlet.

17. The method of claim 13, wherein: The inlet is a plurality of inlets; wherein the valve plunger further includes the orifice between the plurality of inlets and the outlet; wherein the guard protects a portion of the second side from the fluid; and wherein the guard allows the fluid to pass from a first section of the second side and a second section of the second side and into the outlet; wherein the guard is one of a flow path formed with the plunger, coupled to the plunger, and arranged under the plunger.

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