DIAPHRAGM VALVE WITH PLASTIC DIAPHRAGM

Abstract

The technologies are described for diaphragm valves with a plastic diaphragm and a backing pad with reduced or no elastomer, where all sealing or peripheral forces can be applied directly to the diaphragm of the valve assembly; in several examples, the valve assemblies may include a pressure ring to apply sealing force to a diaphragm surface with a reduced size or no backing pad, allowing a twofold or more increase in the pressure capacity of the valve assembly; in other examples, a metallic or elastomeric spring positioned above a projection of the central diaphragm may provide center-to-edge distensibility for the passage seal.

Description

DIAPHRAGM VALVE WITH PLASTIC DIAPHRAGM CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of United States Patent Application Serial Number 16 / 912,864 filed June 26, 2020. The descriptions in the prior application are incorporated herein by reference for all purposes. BACKGROUND OF THE INVENTION Unless otherwise stated in this description, the materials described in this section are not prior art with respect to the claims in this application and are not admitted to be prior art by inclusion in this section. Diaphragm valves (or membrane valves) consist of a valve body with two or more ports, a diaphragm, and a weir or seat against which the diaphragm seals the valve. A peripheral diaphragm seal (which seals the valve assembly to prevent external leakage) and a weir seal rely on the distensibility of the elastomer in the sealing components. The peripheral seal may also rely on an elastomer spring load to accommodate the thermal expansion and contraction of the valve assembly. BRIEF DESCRIPTION OF THE INVENTION The present description generally describes diaphragm valves with a plastic diaphragm and a backing pad with reduced or no elastomer, where sealing or peripheral forces can be applied directly to the diaphragm of the valve assembly. According to some examples, a diaphragm valve assembly may include a valve body having an inner wall, a first port defined by a first portion of the inner wall, a second port defined by a second portion of the inner wall, and a controllable flow path defined by a third portion of the inner wall between the first port and the second port; a plastic diaphragm positioned over an opening along the third portion of the inner wall, the diaphragm configured to provide a peripheral seal along a periphery of the opening and a passage seal along a diametric weir within the opening; a pressure ring in contact with a peripheral surface of the diaphragm configured to provide a pressure load to the diaphragm to provide the peripheral seal;a reduced elastic backing pad that is substantially ring-shaped and configured to fit over the diaphragm within the pressure ring; a compressor within the pressure ring and in partial contact with the reduced backing pad, the compressor configured to selectively engage a central portion of the diaphragm effective in forming the passage seal; and a spindle coupled to the compressor, wherein the spindle is configured to actuate a position of the compressor between a closed position and an open position such that the diaphragm forms the passage seal in the closed position or releases the passage seal in the open position. According to other examples, the diaphragm valve assembly may include a handwheel configured to actuate a spindle position between the open and closed positions; and a bonnet to house the pressure ring, compressor, and spindle. The diaphragm valve assembly may further include a cover that fits over a portion of the bonnet and is slidably engaged with the handwheel, wherein the cover comprises threads on an inner surface that engage corresponding threads on an outer surface of the bonnet, and the cover is configured to allow the handwheel to be rotated to actuate the spindle position.The diaphragm valve assembly may also include a plurality of pins configured to receive pressure load from the cover; a load plate positioned in contact with the plurality of pins and configured to receive the pressure load from the plurality of pins; and one or more springs positioned in contact with the load plate and configured to receive the load pressure from the load plate; and provide peripheral sealing thrust to the pressure ring. According to additional examples, the diaphragm valve assembly may also include a diaphragm pin mechanically coupled to the compressor and inserted into a central portion of the diaphragm to engage the diaphragm when the passage seal is released due to a reverse thrust from the compressor. The central portion of the diaphragm may be a raised diaphragm protrusion, and the reduced backing pad may be configured to fit around the diaphragm protrusion. According to some examples, a diaphragm valve assembly may include a valve body having an inner wall, a first port defined by a first portion of the inner wall, a second port defined by a second portion of the inner wall, and a controllable flow path defined by a third portion of the inner wall between the first port and the second port; a plastic diaphragm positioned over an opening along the third portion of the inner wall, the diaphragm configured to provide a peripheral seal along a periphery of the opening and a passage seal along a diametric weir within the opening; a pressure ring in contact with a peripheral surface of the diaphragm configured to provide a pressure load to the diaphragm to provide the peripheral seal;a compressor within the pressure ring and in contact with the diaphragm, the compressor configured to selectively engage a central portion of the diaphragm effective in forming the passage seal; and a spindle coupled to the compressor, wherein the spindle is configured to actuate a position of the compressor between a closed position and an open position such that the diaphragm forms the passage seal in the closed position or releases the passage seal in the open position. According to other examples, the diaphragm valve assembly may further include a handwheel configured to actuate a spindle position between the open and closed positions; and a bonnet to house the pressure ring, the compressor, and the spindle. The diaphragm valve assembly may further include a cover that fits over a portion of the bonnet and is slidably engaged with the handwheel, wherein the cover comprises threads on an inner surface that engage corresponding threads on an outer surface of the bonnet, and the cover is configured to allow the handwheel to be rotated to actuate the spindle position.The diaphragm valve assembly may also include a plurality of pins configured to receive pressure load from the cover; a load plate positioned in contact with the plurality of pins and configured to receive the pressure load from the plurality of pins; and one or more springs positioned in contact with the load plate and configured to receive the load pressure from the load plate; and provide peripheral sealing thrust to the pressure ring. According to additional examples, the diaphragm valve assembly may also include a diaphragm pin mechanically coupled to the compressor and inserted into a diaphragm projection to engage the diaphragm when the passage seal is released due to a reverse thrust from the compressor. The pressure rating of the valve assembly may range from approximately 2300 psi to approximately 4400 psi. The orifice may be substantially circular, and the diaphragm may be substantially rectangular. According to some examples, a diaphragm valve assembly may include a valve body having an inner wall, a first port defined by a first portion of the inner wall, a second port defined by a second portion of the inner wall, and a controllable flow path defined by a third portion of the inner wall between the first port and the second port; a plastic diaphragm positioned over an opening along the third portion of the inner wall, the diaphragm comprising a diaphragm membrane and a diaphragm projection rising from a central portion of the diaphragm membrane, wherein the diaphragm is configured to provide a peripheral seal along a periphery of the opening and a passage seal along a diametric weir within the opening;a pressure ring in contact with a peripheral surface of the diaphragm membrane configured to provide a pressure load to the diaphragm membrane to provide the peripheral seal; a compressor within the pressure ring configured to selectively engage the diaphragm projection effectively to form the passage seal; a diaphragm pin mechanically coupled to the compressor and inserted into the diaphragm projection to engage the diaphragm membrane when it releases the passage seal based on a reverse thrust of the compressor; a spring located between the diaphragm projection and the compressor surrounding the diaphragm pin, the spring configured to provide relative distensibility for the height of the diaphragm projection;and a spindle coupled to the compressor, wherein the spindle is configured to actuate a position of the compressor between a closed position and an open position such that the diaphragm membrane forms the passage seal in the closed position or releases the passage seal in the open position. According to other examples, the diaphragm valve assembly may further include a handwheel configured to actuate a spindle position between the open and closed positions; and a bonnet to house the pressure ring, the compressor, and the spindle. The diaphragm valve assembly may further include a cover that fits over a portion of the bonnet and is slidably engaged with the handwheel, wherein the cover comprises threads on an inner surface that engage corresponding threads on an outer surface of the bonnet, and the cover is configured to allow the handwheel to be rotated to actuate the spindle position. According to additional examples, the diaphragm valve assembly may also include a plurality of pins configured to receive pressure load from the cover; a load plate positioned in contact with the plurality of pins and configured to receive the pressure load from the plurality of pins; and one or more springs positioned in contact with the load plate and configured to receive the load pressure from the load plate and provide peripheral sealing thrust to the pressure ring. The pressure capacity of the valve assembly may range from approximately 2300 psi to approximately 4400 psi. The spring may be made of elastomer or metal. The orifice may be substantially circular. The preceding summary is for illustrative purposes only and is not intended to be exhaustive in any way. In addition to the illustrative aspects, modalities, and characteristics described above, further aspects, modalities, and characteristics will become apparent through reference to the figures and the following detailed description. BRIEF DESCRIPTION OF THE FIGURES The foregoing and other features of this description will become more evident from the following description and accompanying claims, taken in conjunction with the accompanying figures. It should be understood that these figures represent only various embodiments according to the description and, therefore, are not considered to limit its scope. The description will be described with further specificity and detail through the use of the accompanying figures, in which: Figures 1A and 1B illustrate the top and bottom exploded views of a valve assembly with a full flanged backing pad and a raised diaphragm flange on the weir seal and peripheral seal; Figures 2A and 2B illustrate the process flow and weir cross-sections of the valve assembly of Figures 1A and 1B in a closed valve position, where the peripheral and weir seals are engaged; Figures 3A and 3B illustrate the top and bottom exploded views of a valve assembly with a contact ring concentrated on the backing pad and the removal of the raised diaphragm flange on the peripheral seal; Figures 4A and 4B illustrate the process flow and weir cross-sections of the valve assembly in Figures 3A and 3B; Figures 5A and 5B illustrate the top and bottom exploded views of a valve assembly, where a peripheral sealing force is applied directly to the diaphragm; Figures 6A and 6B illustrate the process flow and weir cross-sections of the valve assembly in Figures 5A and 5B; Figures 7A and 7B illustrate the top and bottom exploded views of a valve assembly, where all sealing forces are applied directly to the diaphragm; Figure 8 illustrates the cross-section of the weir of the valve assembly of Figures 7A and 7B; and Figure 9 illustrates the weir cross-section of the valve assembly of Figure 7A and 7B with a spring above a central diaphragm projection to provide center-to-edge distensibility for the passage seal, some of which is arranged according to at least some modalities described herein. DETAILED DESCRIPTION OF THE INVENTION In the following detailed description, reference is made to the accompanying figures, which form part hereof. In the figures, similar symbols typically identify similar components, unless the context otherwise indicates. The illustrative embodiments described in the detailed description, figures, and claims are not intended to be limiting. Other embodiments may be used, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. The aspects of this description, as generally described herein and illustrated in the figures, may be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein. This description generally applies, among other things, to methods, apparatus, systems and / or devices associated with diaphragm valves with plastic diaphragms and backing pad with reduced or zero elastomer, where all sealing or peripheral forces can be applied directly to a diaphragm of the valve assembly. In short, the technologies described apply to diaphragm valves with a plastic diaphragm and a backing pad with reduced or no elastomer, where all sealing or peripheral forces can be applied directly to the valve assembly's diaphragm. In some examples, the valve assemblies may include a pressure ring to apply sealing force to a diaphragm surface with a reduced size or no backing pad, allowing for a twofold or greater increase in the valve assembly's pressure capacity. In other examples, an elastomeric or metallic spring positioned above a central diaphragm projection can provide center-to-edge distensibility for the passage seal. Figures 1A and 1B illustrate the top and bottom exploded views of a valve assembly with a full flanged backing pad and a raised diaphragm flange on the weir seal and peripheral seal. Figures 1A and 1B include the handwheel 102, a cap 104, the backing pad 106, the diaphragm assembly 108, and the body 110. The body 110 may include an inner wall, a first portion of which may define a first valve port and a second portion of the inner wall may define a second valve port. In some examples, the valve ports may be designated as inlet and outlet ports. The inner wall of the body 110 and the valve ports may define a controllable flow path that extends along the inner wall between the first and second valve ports. The flow of liquids or gases through the controllable flow path may be controlled by the diaphragm assembly 108, which may provide a peripheral seal as well as a weir cross-section seal to restrict the flow. The illustrative configurations are shown and discussed with specific components and configurations, which should not be interpreted as limitations on the configurations. For example, several example valve assemblies with a handwheel actuator are shown. Other forms of mechanical drive for the valve spindle / compressor, such as pneumatic (with or without springs) or electric motors, or even hydraulic drives, may also be used in illustrative implementations. Similarly, other parts may be replaced or configured differently depending on the implementation specifications by using the principles described herein. Conventional diaphragm valves with a plastic diaphragm have an elastomer member between the plastic diaphragm and the component that provides the sealing load. Both the peripheral seal and the weir seal rely on the elastomer's distensibility to overcome imperfections in the components and assembly. The peripheral seal also depends on the elastomer's spring load to compensate for the differential thermal expansion and contraction of the assembly components. Without the elastomer, the plastic diaphragm can be crushed by the metal components during heating and can loosen upon cooling, thus negating the peripheral seal. Figures 2A and 2B illustrate the process flow and weir cross-sections of the valve assembly of Figures 1A and 1B in a closed valve position, where the peripheral and weir seals are engaged. In the process view of Fig. 2A, the valve assembly is shown with the handwheel 202, bonnet 204, elastomer backing pad 206, diaphragm assembly 208, and body 210. In the process flow cross-section, the body 210 is shown along a cross-section of the valve ports. The inner wall of the body is shaped so that a liquid or gas is directed from an inlet port to an outlet port through a raised central portion (diaphragm valve), where the diaphragm assembly 208 makes contact with the raised portion when pressed down and seals the passage, preventing the liquid or gas from passing through. In addition to sealing the passage through the body, the diaphragm assembly 208 also seals a periphery of the central portion, preventing leakage from the inside of the valve assembly to the outside. The cap 204 houses the spindle 212, which, through a movement of the handwheel 202, is pressed down on the compressor 216. The compressor 216, in turn, presses against a surface of the diaphragm assembly 208 (above the spout flange and the diaphragm projection 219) to seal the passage. A diaphragm pin 218 can be used to provide mechanical force from the compressor to the center of the diaphragm assembly 208 when it is pulled upward to open the passage. O-rings 214 can be used to seal an inner wall of the cap 204 and an outer surface of the compressor 216, as well as an outer wall of the cap 204 and an inner surface of the handwheel 202. A lower portion of the cap 204 can press down on a peripheral surface of the diaphragm assembly 208, allowing sealing of the periphery of the raised portion of the body 210. The elastomeric backing pad 206 is positioned between the diaphragm assembly 208 and the bottom of the cap 204, providing the sealing load. Both the peripheral seal and the weir seal rely on the elastomer's extensibility to compensate for imperfections in the components and assembly. The peripheral seal also depends on the elastomer's spring load to adjust for thermal expansion and contraction of the assembly. Without the elastomer, the plastic diaphragm could be crushed by the metal components during heating and could loosen upon cooling, thus negating the peripheral seal. In the cross-section of the weir in Figure 2B, the diaphragm assembly 208 is shown in the pressed-down state, where, activated by spindle 212, the compressor 216 pushes down on the diaphragm surface above the weir flange and the diaphragm projection 219 and, consequently, presses the central portion of the diaphragm assembly 208 onto a raised metal surface of the valve body, preventing the passage of liquid or gas through the valve assembly. Figures 3A and 3B illustrate the top and bottom exploded views of a valve assembly with a pressure ring on the backing pad and the removal of the raised diaphragm flange on the peripheral seal. Figures 3A and 3B include handwheel 302, cap 304, pressure ring 312, backing pad 306, diaphragm assembly 308, and body 310. Body 310 includes an inner wall, a first portion of which can define a first valve port and a second portion of the inner wall can define a second valve port. The inner wall of body 310 and the valve ports define a controllable flow path that extends along the inner wall between the first and second valve ports and includes the center portion with the raised body flange to contact the diaphragm assembly 308 and provide a peripheral seal (through the circumference of the substantially circular center portion) and a weir seal (through the asymmetrical linear portion of the center portion). The configurations shown in Figures 3A and 3B provide parallelism between the peripheral sealing surfaces of the body flange and the pressure ring, including the allowable distensibility for diaphragm thickness variations on the non-parallel upper / lower diaphragm flange surfaces. The pressure ring surface, used for peripheral sealing, can be a flat, highly controlled machined surface. The body flange or lip surface, also used for peripheral sealing, can be a flat, highly controlled machined surface. Figures 4A and 4B illustrate the process flow and weir cross-sections of the valve assembly of Figures 3A and 3B in a closed valve position, where the peripheral and weir seals are engaged. In the process view of Fig. 4A, the valve assembly is shown with the handwheel 402, cover 403, cap 404, elastomer backing pad 406, diaphragm assembly 408, and body 410. In the process flow cross-section, the body 410 is shown along a cross-section of the valve ports. The inner wall of the body is shaped so that a liquid or gas is directed from an inlet port to an outlet port through a raised central portion (diaphragm valve), where the diaphragm assembly 408 makes contact with the raised portion when pressed down and seals the passage, preventing the liquid or gas from passing through. In addition to sealing the passage through the body, the diaphragm assembly 408 also seals a periphery of the central portion, preventing leakage from the inside of the valve assembly to the outside. Cap 404 houses spindle 412, which, through a rotary motion of handwheel 402, is pressed down on compressor 416. Compressor 416, in turn, presses a surface of diaphragm assembly 408 (above the spout flange and the diaphragm projection 419) to seal the passage. A diaphragm pin 418 can be used to provide mechanical force from the compressor to the center of diaphragm assembly 408 when it is pulled upward to open the passage. Cover 403 locks cap 404 to body 410 and is secured to an upper part of the body via a threaded coupling. The cap 404 also contains springs 424 to provide a peripheral sealing load and a load plate 426. Pins 432 transfer the load from the cap to the load plate 426, which transfers the load to the springs 424, via the pressure ring 434, applying the peripheral sealing force to the diaphragm 408. O-rings 414 can be used to seal an inner wall of the cap 404 and an outer surface of the pressure ring 434, the load plate 426 to an inner surface of the cap 404, as well as an outer wall of the cap 404 and an inner surface of the cover 403. The pressure ring 434 described above provides the force for the peripheral seal between the diaphragm and the body, and the thrust of the spindle / compressor makes the weir seal, pressing the central projection of the diaphragm above the weir. The configuration shown in Figure 4A (and 4B) uses 424 springs to provide peripheral sealing thrust throughout the service life, compensating for mechanical and thermal cycles. Furthermore, the configuration provides excellent centering and position control of all components, including superior positioning control of body-to-upper body parts, and ensures parallelism between the peripheral sealing surfaces of the body flange and the pressure ring. This includes accommodating diaphragm thickness variations on the non-parallel upper / lower diaphragm flange surfaces. The pressure ring surface, used for peripheral sealing, can be a highly controlled, flat machined surface.The surface of the flange or body lip, used for peripheral sealing, can also be a flat, highly controlled machined surface. The compressor surfaces, used for sealing passages, are also highly controlled machined surfaces. In the cross-section of the valve weir in Figure 4B, the diaphragm assembly 408 is shown in the pressed-down state. Actuated by spindle 414, the compressor 416 pushes down the diaphragm projection 419, consequently pressing the center portion of the diaphragm assembly 408 against a raised metal surface of the valve body. This prevents the passage of liquid or gas through the valve assembly. With peripheral seal pressure transmitted through the elastomer backing pad, the pressure is limited to approximately 2200 psi. Above this pressure, the elastomer experiences extreme and unacceptable deformation and shearing. Figures 5A and 5B illustrate the top and bottom exploded views of a valve assembly, where a peripheral sealing force is applied directly to the diaphragm, arranged according to at least some of the modalities described herein. Figures 5A and 5B include the handwheel 502, cover 503, cap 504, pressure ring 512, reduced backing pad 506, diaphragm assembly 508, and body 510. Body 510 includes an inner wall, a first portion of which can define a first valve port and a second portion of which can define a second valve port. The inner wall of body 510 and the valve ports define a controllable flow path that extends along the inner wall between the first and second valve ports and includes the central portion to contact the diaphragm assembly 508 and provide a peripheral seal (through the circumference of the substantially circular central portion) and a weir seal (through the asymmetrical linear portion of the central portion). Due to the parallelism provided between the peripheral sealing surfaces of the body flange and the pressure ring, where a pressure ring surface and a body flange or flange surface can be a highly controlled flat machined surface, the backing pad can have a substantially reduced ring shape, allowing for higher pressure capabilities for the valve assembly. Figures 6A and 6B illustrate the process flow and weir cross-sections of the valve assembly of Figures 5A and 5B in a closed valve position, where the peripheral and weir seals are coupled, arranged according to at least some of the modalities described herein. In the process view of Figure 6A, the valve assembly is shown with the handwheel 602, cover 603, cap 604, elastomer backing pad 606, diaphragm assembly 608, and body 610. In the process flow cross-section, the body Figure 610 is shown along a cross-section of the valve ports. The inner wall of the body is shaped such that a liquid or gas is directed from an inlet port to the outlet port through a central portion (diaphragm valve), where the diaphragm assembly 608 makes contact with the periphery of the central portion when installed and makes contact with an asymmetrical linear portion when pressed down to seal the passage, preventing the liquid or gas from passing through. The cap 604 houses the spindle 612, which, through a rotary motion of the handwheel 602, is pressed down on the compressor 616. The compressor 616, in turn, presses a surface of the diaphragm assembly 608 (above the spout flange and the diaphragm projection 619) to seal the passage. A diaphragm pin 618 can be used to provide mechanical force from the compressor to the center of the diaphragm assembly 608 when it is pulled upward to open the passage. The cover 603 locks the cap 604 to the body 610 and is secured to an upper part of the body via a threaded coupling. O-rings 614 can be used to seal an inner wall of the cap 604 and an outer surface of the pressure ring 512, the load plate 626 to an inner surface of the cap 604, as well as an outer wall of the cap 604 and an inner surface of the cover 603. A lower portion of the pressure ring 512 can press down on a peripheral surface of the diaphragm assembly 608, allowing sealing of the periphery of the raised portion of the body 610. Due to the spring force provided by the 624 springs on the 512 pressure ring, the Central America 606 backing pad has a substantially ring-like shape that does not cover the contact area between the pressure ring and the diaphragm along the periphery. Eliminating the elastomer backing pad above the diaphragm's peripheral seal allows the use of high, concentrated sealing pressures (e.g., up to 4400 psi) to provide improved peripheral sealing capabilities, even on flat flanges with poor surface finishes, and even under extreme thermal and mechanical cycling conditions. The reduced 606 backing pad can be a simple, washer-shaped stamping of sheet material that is easy to install over the diaphragm overhang and may not require a special orientation procedure. In the cross-section of the weir in Figure 6B, the diaphragm assembly 608 is shown in the pressed-down state. Activated by spindle 614, the compressor 616 pushes down the diaphragm projection 619, consequently pressing the center portion of the diaphragm assembly 608 against a metal surface of the valve body, thus preventing the passage of liquid or gas through the valve assembly. The valve assembly configuration with a reduced backing pad can have an improved pressure capacity, for example, from 2300 psi to approximately 4400 psi. When providing a peripheral seal of a diaphragm over a flawed body surface, the seal pressure may need to be increased to allow the plastic diaphragm to conform to the surface imperfections. Having a layer of elastic material (elastomer backing pad) between the compression structure and the diaphragm helps to distribute the load over a larger area, thus reducing the pressure. If the required pressure is very high, such as that needed to mold the plastic to the flange imperfections, the elastomer may experience compressive shear, fracturing, and reduced service life. Simple elastomer backing pads, manufactured from a cut sheet, have a cutout on the inside for the diaphragm connection to the compressor and around the periphery.When an embedded fabric is required for strength, these fibers also create a passage that negates the sealing cap's ability. Having an elastomer layer beneath the compressor allows the system to accommodate part variation and misalignment of parts and assemblies. However, the elastomer layer also dilutes the actuator load over a larger area, reducing the passage seal pressure and, consequently, the seal efficiency. Some, but not all, losses can be recovered by using a diaphragm flange as described in Figures 3A and 3B. Using a backing pad also adds a component to the valve assembly and requires control and guidance of that component. This added cost and complexity are experienced not only with the initial valve offering but also with each diaphragm assembly replacement. Figures 7A and 7B illustrate the top and bottom exploded views of a valve assembly, where all sealing forces are applied directly to the diaphragm, arranged according to at least some of the modalities described herein. Figures 7A and 7B include the handwheel 702, cover 703, cap 704, pressure ring 712, diaphragm assembly 708, and body 710. Body 710 includes an inner wall, a first portion of which can define a first valve port and a second portion of which can define a second valve port. The inner wall of body 710 and the valve ports define a controllable flow path that extends along the inner wall between the first and second valve ports and includes the central portion to contact the diaphragm assembly 708 and provide a peripheral seal (through the substantially circular circumference of the central portion) and a weir seal (through the asymmetrical linear portion of the central portion). In the configuration shown in Figures 7A and 7B, the elastomer backing pad has been completely removed. Therefore, the required pressure load can be met with reduced force. Removing the elastomer backing pad from the valve assembly can be done in systems that incorporate the advantages of the pressure ring and internal springs described above. In these systems, the compressor thrust distensibility requirement can be significantly reduced. Figure 8 illustrates the cross-section of the weir of the valve assembly of Figures 7A and 7B in a closed valve position, where the peripheral and weir seals are coupled, arranged according to at least some of the modalities described in this description. In the weir cross-section view of Figure 8, the valve assembly is shown with the handwheel 802, cover 803, cap 804, diaphragm assembly 808, and body 810. In the process flow cross-section, the body 810 is shown along a cross-section of the valve ports. The inner wall of the body is shaped such that a liquid or gas is directed from an inlet port to an outlet port through a central portion (diaphragm valve), where the diaphragm assembly 808 makes contact with the periphery of the central portion when installed and contacts an asymmetrical linear portion when pressed down to seal the passage, preventing the liquid or gas from passing through. The cap 804 houses the spindle 812, which, through a rotary motion of the handwheel 802, is pressed down on the compressor 816. The compressor 816, in turn, presses a surface of the diaphragm assembly 808 (above the spout flange and the diaphragm projection 819) to seal the passage. A diaphragm pin 818 can be used to provide mechanical force from the compressor to the center of the diaphragm assembly 808 when it is pulled upward to open the passage. The cover 803 locks the cap 804 to the body 810 and is secured to an upper part of the body via a threaded coupling 822. O-rings 814 can be used to seal an inner wall of the cap 804 and an outer surface of the pressure ring 712, the load plate 828 to an inner surface of the cap 804, as well as an outer wall of the cap 804 and an inner surface of the cover 803. A lower portion of the pressure ring 712 can press down on a peripheral surface of the diaphragm assembly 808, allowing sealing of the periphery of the body 810. Due to the spring force provided by springs 824 on pressure ring 712, the elastomeric backing pad is completely eliminated. Eliminating the elastomeric backing pad above the peripheral seal and diaphragm passage seal allows the use of high, concentrated sealing pressures (e.g., up to 4400 psi) to provide improved peripheral sealing capabilities, even on flat flanges with poor surface finishes, even under extreme thermal and mechanical cycling conditions. This also allows for increased valve capacity or the option of using a smaller, less expensive actuator. Figure 9 illustrates the cross-section of the weir of the valve assembly of Figure 7A and 7B with a spring over a central diaphragm projection to provide center-to-edge distensibility for the passage seal in a closed valve position, where the peripheral and weir seals are engaged, arranged according to at least some of the modalities described herein. In the weir cross-section view of Figure 9, the valve assembly is shown with the handwheel 902, cover 903, cap 904, diaphragm assembly 908, and body 910. In the process flow cross-section, the body 910 is shown along a cross-section of the valve ports. The inner wall of the body is shaped such that a liquid or gas is directed from an inlet port to an outlet port through a central portion (diaphragm valve), where the diaphragm assembly 908 makes contact with the periphery of the central portion when installed and contacts an asymmetrical linear portion (weir) when pressed down to seal the passage, preventing the liquid or gas from passing through. The cap 904 houses the spindle 912, which, through a rotary motion of the handwheel 902, is pressed down on the compressor 916. The compressor 916, in turn, presses a surface of the diaphragm assembly 908 (above the spout flange and the diaphragm projection 919) to seal the passage. A diaphragm pin 918 can be used to provide mechanical force from the compressor to the center of the diaphragm assembly 908 when it is pulled upward to open the passage. A spring (elastomeric or metallic) 932 can provide relative sensitivity for the overhang height, in place of the elastomeric backing pad under the compressor 916. The cover 903 locks the cap 904 to the body 910 and is secured to an upper part of the body via a threaded coupling 922. The cap 904 also contains springs 924 to provide peripheral sealing load and a load plate 926. O-rings 914 can be used to seal an inner wall of the cap 904 and an outer surface of the pressure ring 712, the load plate 928 to an inner surface of the cap 904, as well as an outer wall of the cap 904 and an inner surface of the cover 903. A lower portion of the pressure ring 712 can press down on a peripheral surface of the diaphragm assembly 908, allowing sealing of the periphery of the body 910. As mentioned previously, a small elastomeric or metallic spring (932) can be used above the diaphragm overhang to provide relative distensibility for the overhang height, instead of the elastomer below the compressor. With the removal of the backing pad, some other form of passage seal distensibility may be required. Placing a distensible material above the diaphragm overhang can help ensure even distribution of the actuator thrust between the seal below the overhang and the rest of the passage seal. As discussed earlier, the methods are not limited to steering wheel actuation. Pneumatic (with or without springs) or electric motors, or even hydraulic actuation, can also be used in illustrative implementations without departing from the principles described herein. The benefits of the valve assembly devices described herein are numerous. For example, the valve assemblies with reduced or eliminated elastomer backing pads described herein can allow for increased and / or concentrated loading of the peripheral seal so that a seal can be achieved and maintained when using plastic diaphragms on poor body flange surface finishes. The example systems can also allow for concentrated loading of the passage seal so that a seal can be achieved and maintained with reduced actuator thrust. This efficiency can further allow for a reduction in actuator size and cost, while also increasing cycle life.Another benefit of valve assembly examples may include simplifying the plastic diaphragm assembly to eliminate components and / or component complexity while adding control with improved seal reliability. The present description should not be limited to the particular embodiments described herein, which are intended to illustrate various aspects. Many modifications and variations may be made without departing from its spirit and scope. Functionally equivalent methods and apparatus within the scope of the description, in addition to those listed herein, are possible based on the preceding descriptions. Such modifications and variations are intended to be within the scope of the appended claims. The present description should be limited only by the terms of the appended claims, together with the full scope of equivalents to which such claims are entitled. The terminology used herein is intended to describe particular embodiments only and is not intended to be limiting. The subject matter described herein sometimes illustrates different components contained within or connected to other components. These depicted architectures are merely examples, and many other architectures can be implemented to achieve the same functionality. Conceptually, any arrangement of components to achieve the same functionality is effectively associated with each other to achieve the desired functionality. Therefore, any two components from this description combined to achieve a particular functionality can be seen as associated with each other to achieve the desired functionality, regardless of the architectures or intermediate components.Similarly, any two components associated in this way can also be seen as operationally connected, or operationally coupled, to achieve the desired functionality, and any two components capable of being associated in this way can also be seen as operationally coupled to achieve the desired functionality. Specific examples of operationally coupled components include, but are not limited to, physically connectable and / or physically interacting components and / or wirelessly interacting components and / or wirelessly interacting components and / or logically interacting and / or logically interactive components. With regard to the use of any plural and / or singular term in this description, those skilled in the art may translate from plural to singular and / or from singular to plural as appropriate to the context and / or application. Various singular / plural permutations may be expressly stated in this description for clarity. In general, the terms used herein, and especially in the appended claims (e.g., appended claim bodies), are generally intended to be open-ended terms (e.g., the term "includes" should be interpreted as including, but not limited to; the term "has" should be interpreted as having at least; the term "includes" should be interpreted as including, but not limited to, etc.). It shall further be understood by those skilled in the art that if a specific number of introduced claim references is intended, such intention shall be explicitly stated in the claim, and in the absence of such a statement, such intention is not present. For example, as an aid to understanding, the following appended claims may contain the use of at least one introductory phrase and one or more to introduce the claim references.However, the use of such phrases should not be interpreted as implying that the introduction of a claim mention by the indefinite articles a or an limits any particular claim containing such introduced claim mention to modalities containing only one of such mention, even when the same claim includes the introductory phrases one or more or at least one and indefinite articles such as a or an (for example, a and / or an should be interpreted as at least one or one or more); the same applies to the use of definite articles used to introduce claim mentions.Furthermore, even if a specific number of an introduced claim mention is explicitly mentioned, those skilled in the art will recognize that such mention should be interpreted as at least the mentioned number (e.g., the mere mention of two mentions, without any other modifiers, means at least two mentions, or two or more mentions). Furthermore, in those cases where a convention analogous to at least one of A, B, and C, etc., is used, such an interpretation generally means the sense in which a person skilled in the art would understand the convention (for example, a system having at least one of A, B, and C would include, but not be limited to, systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). It shall further be understood by those skilled in the art that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, claims, or figures, should be understood to encompass the possibilities of including one of the terms, any one of the terms, or both terms. For example, the phrase A or B shall be understood to include the possibilities of A or B or A and B. For all purposes, such as providing a written description, all intervals described herein also encompass all possible subintervals and combinations thereof. Any enumerated interval can be readily recognized as a sufficient description, allowing the interval to be divided into at least equal halves, thirds, quarters, fifths, tenths, and so forth. By way of non-limiting example, each interval described herein can be easily divided into a lower third, a middle third, and an upper third, and so forth. As will also be understood by someone skilled in the art, all language such as up to, at least, greater than, less than, and the like includes the number mentioned and refers to intervals that can be subsequently divided into subintervals as described above. Finally, an interval includes each individual member.Therefore, for example, a group that has 1-3 cells refers to groups that have 1, 2, or 3 cells. Similarly, a group that has 1-5 cells refers to groups that have 1, 2, 3, 4, or 5 cells, and so on. While several aspects and modalities have been described herein, other aspects and modalities are possible. The various aspects and modalities described herein are for illustrative purposes and are not intended to be limiting, with the true scope and spirit indicated by the following claims.

Claims

1. A diaphragm valve assembly comprising: a valve body having an inner wall, a first port defined by a first portion of the inner wall, a second port defined by a second portion of the inner wall, and a controllable flow path defined by a third portion of the inner wall between the first port and the second port; a plastic diaphragm positioned over an opening along the third portion of the inner wall, the diaphragm configured to provide a peripheral seal along a periphery of the opening and a passage seal along a diametric weir within the opening; a pressure ring in contact with a peripheral surface of the diaphragm configured to provide a pressure load to the diaphragm to provide the peripheral seal;a reduced elastic backing pad that is substantially ring-shaped and configured to fit over the diaphragm within the pressure ring; a compressor within the pressure ring and in partial contact with the reduced backing pad, the compressor being configured to selectively engage a central portion of the diaphragm effectively to form the passage seal; and a spindle coupled to the compressor, wherein the spindle is configured to actuate a position of the compressor between a closed position and an open position such that the diaphragm forms the passage seal in the closed position or releases the passage seal in the open position.

2. The diaphragm valve assembly of claim 1, further comprising: a handwheel configured to actuate a spindle position between the open position and the closed position; and a cap for housing the pressure ring, the compressor, and the spindle.

3. The diaphragm valve assembly of claim 2, further comprising: a cover that fits over a top portion of the bonnet and is slidably coupled to the handwheel, wherein the cover comprises threads on an inner surface that match corresponding threads on an outer surface of the bonnet, and the cover is configured to allow the handwheel to be rotated to actuate the spindle position.

4. The diaphragm valve assembly of claim 3, further comprising: a plurality of pins configured to receive pressure load from the cover; a load plate positioned in contact with the plurality of pins and configured to receive the pressure load from the plurality of pins; and one or more springs positioned in contact with the load plate and configured to: receive the load pressure from the load plate; and provide a peripheral sealing thrust to the pressure ring.

5. The diaphragm valve assembly of claim 1, further comprising: a diaphragm pin mechanically coupled to the compressor and inserted into a central portion of the diaphragm to engage the diaphragm when the passage seal is released as a function of a reverse thrust of the compressor.

6. The diaphragm valve assembly of claim 5, wherein the central portion of the diaphragm is a raised diaphragm projection and the reduced backing pad is configured to fit around the diaphragm projection.

7. A diaphragm valve assembly comprising: a valve body having an inner wall, a first port defined by a first portion of the inner wall, a second port defined by a second portion of the inner wall, and a controllable flow path defined by a third portion of the inner wall between the first port and the second port; a plastic diaphragm positioned over an opening along the third portion of the inner wall, the diaphragm configured to provide a peripheral seal along a periphery of the opening and a passage seal along a diametric weir within the opening; a pressure ring in contact with a peripheral surface of the diaphragm configured to provide a pressure load to the diaphragm to provide the peripheral seal;a compressor within the pressure ring and in contact with the diaphragm, the compressor configured to selectively engage a central portion of the diaphragm effectively to form the passage seal; and a spindle coupled to the compressor, wherein the spindle is configured to actuate a position of the compressor between a closed position and an open position such that the diaphragm forms the passage seal in the closed position or releases the passage seal in the open position.

8. The diaphragm valve assembly of claim 7, further comprising: a handwheel configured to actuate a spindle position between the open position and the closed position; and a cap for housing the pressure ring, the compressor, and the spindle.

9. The diaphragm valve assembly of claim 8, further comprising: a cover that fits over an upper portion of the bonnet and is slidably engaged with the handwheel, wherein the cover comprises threads on an inner surface that match corresponding threads on an outer surface of the bonnet, and the cover is configured to allow the handwheel to be rotated to actuate the spindle position.

10. The diaphragm valve assembly of claim 9, further comprising: a plurality of pins configured to receive pressure load from the cover; a load plate positioned in contact with the plurality of pins and configured to receive the pressure load from the plurality of pins; and one or more springs positioned in contact with the load plate and configured to: receive the load pressure from the load plate; and provide a peripheral sealing thrust to the pressure ring.

11. The diaphragm valve assembly of claim 7, further comprising: a diaphragm pin mechanically coupled to the compressor and inserted into a diaphragm projection to engage the diaphragm when the passage seal is released as a function of a reverse thrust of the compressor.

12. The diaphragm valve assembly of claim 7, wherein a pressure capacity of the valve assembly is in a range of approximately 2300 psi to approximately 4400 psi.

13. The diaphragm valve assembly of claim 7, wherein the opening has a substantially circular shape and the diaphragm has a substantially rectangular shape.

14. A diaphragm valve assembly comprising: a valve body having an inner wall, a first port defined by a first portion of the inner wall, a second port defined by a second portion of the inner wall, and a controllable flow path defined by a third portion of the inner wall between the first port and the second port; a plastic diaphragm positioned over an opening along the third portion of the inner wall, the diaphragm comprising a diaphragm membrane and a diaphragm projection rising from a central portion of the diaphragm membrane, wherein the diaphragm is configured to provide a peripheral seal along a periphery of the opening and a passage seal along a diametric weir within the opening;a pressure ring in contact with a peripheral surface of the diaphragm membrane configured to provide a pressure load to the diaphragm membrane to provide the peripheral seal; a compressor within the pressure ring configured to selectively engage the diaphragm projection effectively to form the passage seal; a diaphragm pin mechanically coupled to the compressor and inserted into the diaphragm projection to engage the diaphragm membrane when the passage seal is released by a reverse thrust of the compressor; a spring situated between the diaphragm projection and the compressor around the diaphragm pin, the spring configured to provide relative distensibility for the height of the diaphragm projection;and a spindle coupled to the compressor, wherein the spindle is configured to actuate a position of the compressor between a closed position and an open position such that the diaphragm membrane forms the passage seal in the closed position or releases the passage seal in the open position.

15. The diaphragm valve assembly of claim 14, further comprising: a handwheel configured to actuate a spindle position between the open position and the closed position; and a cap for housing the pressure ring, the compressor, and the spindle.

16. The diaphragm valve assembly of claim 15, further comprising: a cover that fits over an upper portion of the bonnet and is slidably engaged with the handwheel, wherein the cover comprises threads on an inner surface that match corresponding threads on an outer surface of the bonnet, and the cover is configured to allow the handwheel to be rotated to actuate the spindle position.

17. The diaphragm valve assembly of claim 16, further comprising: a plurality of pins configured to receive pressure load from the cover; a load plate positioned in contact with the plurality of pins and configured to receive the pressure load from the plurality of pins; and one or more springs positioned in contact with the load plate and configured to: receive the load pressure from the load plate; and provide a peripheral sealing thrust to the pressure ring.

18. The diaphragm valve assembly of claim 14, wherein a pressure capacity of the valve assembly is in a range of approximately 2300 psi to approximately 4400 psi.

19. The diaphragm valve assembly of claim 14, wherein the 5 spring is elastomeric or metallic.

20. The diaphragm valve assembly of claim 14, wherein the opening is substantially circular in shape.

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