AEROSOL VALVE ASSEMBLY

Abstract

A valve assembly is provided that includes a cup having a hub with an end wall and an opening therein. The valve assembly includes an annular seal interconnected to a cylindrical valve element by resilient radial ribs extending therebetween that provide for axial movement of the cylindrical valve element relative to the annular seal. The annular seal and cylindrical valve element are disposed within the hub with the top surface seated against the end wall in the hub. The cylindrical valve element is offset above the top surface such that when the annular seal is seated against the end wall the cylindrical valve element is axially displaced and compressed against the end wall to provide a minimum pre-load force effective for sealing off the opening. An actuator having a sleeve is disposed over the hub, and includes a plunger tip projecting eccentrically through the opening for unseating the cylindrical valve element.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/310,156, filed on Mar. 3, 2010. The entire disclosure of the above application is incorporated herein by reference.

FIELD

The present disclosure relates to valves for aerosol containers, and more specifically to dispensing valves for aerosol containers.

BACKGROUND

This section provides background information related to the present disclosure which is not necessarily prior art.

The present application relates to aerosol valves, and more specifically to dispensing valves in aerosol containers for dispensing product.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

Exemplary embodiments of the present disclosure include a valve assembly for an aerosol container. The various embodiments of a valve assembly include a cup having a hub including an end wall therein, and an opening in the endwall. The valve assembly includes an annular seal interconnected to a cylindrical valve element by resilient radial ribs extending between the annular seal and an outside diameter of the cylindrical valve element, which provide for axial movement of the cylindrical valve element relative to the annular seal. The annular seal and cylindrical valve element are disposed within the hub with a top surface of the annular seal seated against the end wall in the hub. The cylindrical valve element is offset a predetermined distance above the top surface such that when the annular seal is seated with the top surface against the end wall the cylindrical valve element is axially displaced and compressed against the end wall to provide a minimum pre-load force that is effective for substantially sealing off the opening in the end wall. The various embodiments of a valve assembly further include an actuator having a sleeve disposed over the hub, and a plunger tip projecting through the opening for displacing and unseating the cylindrical valve element from the opening. In the various embodiments, the ratio of the outside diameter of the cylindrical valve element to the opening diameter is between about 1.1 to 2.0, whereby the ratio allows the resilient radial ribs to have sufficient radial length to permit unseating of the cylindrical valve element with less than a predetermined force.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is an exploded view of a first embodiment of a valve assembly with a cup, annular seal and actuator according to the disclosure;

FIG. 2 is a cross-sectional view of the valve assembly of FIG. 1;

FIG. 3 is a front and top view of an annular seal of the valve assembly of FIG. 1;

FIG. 4 is a cross-sectional view of a conventional valve with an inwardly projecting valve seat opening; and

FIG. 5 is a cross-sectional view of an alternate construction of an annular seal in accordance with the present disclosure.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings.

In the various exemplary embodiments, an improved valve assembly for an aerosol container is provided. The various embodiments of a valve assembly include a cup having a hub including an end wall and an opening therein of a predetermined diameter. The valve assembly includes an annular seal with a top surface, being interconnected to a cylindrical valve element by resilient radial ribs extending between the annular seal and an outside diameter of the cylindrical valve element, which provide for axial movement of the cylindrical valve element relative to the annular seal. The annular seal and cylindrical valve element are disposed within the hub with the top surface seated against the end wall in the hub. The cylindrical valve element is offset a predetermined distance above the top surface such that when the annular seal is seated with the top surface against the end wall, the cylindrical valve element is axially displaced and compressed against the end wall to provide a minimum pre-load force that is effective for substantially sealing off the opening in the end wall. The various embodiments of a valve assembly further include an actuator having a sleeve disposed over the hub, and a plunger tip projecting eccentrically through the opening for displacing and unseating the cylindrical valve element from the opening. In the various embodiments, the ratio of the outside diameter of the cylindrical valve element to the opening diameter is between about 1.1 to 2.0, whereby the ratio allows the resilient radial ribs to have sufficient radial length to permit unseating of the cylindrical valve element with less than a predetermined force. Further aspects of the various embodiments will be understood from the following description.

In one aspect of the present disclosure, a first embodiment of a valve assembly 100 for an aerosol container is provided as shown in FIGS. 1-2. The valve assembly 100 for an aerosol container includes a cup 104 having a hub 108 including an end wall 110 therein. The hub 108 has an opening 112 in the end wall 110 of a predetermined diameter D1.

The valve assembly 100 further includes an annular seal 120 that is interconnected to a cylindrical valve element 130 by resilient radial ribs 126 extending therebetween, which provide for axial movement of the cylindrical valve element 130 relative to the annular seal 120. Specifically, the resilient radial ribs 126 extend between the annular seal 120 and an outside diameter D2 of the cylindrical valve element 130 to form spokes therebetween, and may include between three and eight ribs, for example. The annular seal 120 further includes a top surface 122 thereon, and an inside diameter from which the radial ribs 126 extend. The annular seal 120 and interconnected cylindrical valve element 130 are disposed within the hub 108 with the top surface 122 seated against the end wall 110 in the hub 108. As shown in FIG. 3, the cylindrical valve element 130 is offset a predetermined distance X above the top surface 122 of the annular seal 120. The cylindrical valve element 130 is offset such that when the annular seal 120 is seated with its top surface 122 against the end wall 110 in the hub 108, the cylindrical valve element 130 is axially displaced and compressed against the end wall 110 over the opening 112, as shown in FIG. 2. This axial displacement of the cylindrical valve element 130 (i.e., compression resulting from bending of the ribs 126) establishes a minimum pre-load force of the cylindrical valve element 130 against the end wall 110 of the hub 108 that is effective for sealing off the opening 112.

The valve assembly 100 further includes an actuator 140 having a sleeve 142 slidably disposed over the hub 108. The actuator 140 includes a plunger tip 144 projecting eccentrically through the opening 110 for displacing and unseating the cylindrical valve element 130 from the opening 112 to establish a flow path P through the valve and to an exit. The actuator 140 may include a plunger tip 144 that is angled to provide a relatively sharp point, for eccentrically engaging the cylindrical valve element 130 along a perimeter portion of the cylindrical valve element 130. Accordingly, a user may depress the actuator 140 with a finger to displace and unseat the cylindrical valve element 130 from the opening 112 in the end wall 110 of the hub 108, to allow product within the aerosol container to be dispensed through the valve assembly 100.

Some aerosol containers have dispensing valves as shown in FIG. 4, in which a cup 110 is formed to have an inwardly projecting valve seat 114 with a narrow landing surface 116 against which a valve 130 seats. This inwardly projecting valve seat design, which may entail more complex manufacturing, minimizes the required force against the valve that will provide an effective seal. Moreover, the internal pressure in the container has an added effect in acting against the valve element, to provide bias for urging the valve element against the valve seat and maintaining a seal. Accordingly, it would follow that a valve element of a larger diameter would be best for purposes of utilizing the internal pressure to increase the force applied against the valve element to the opening to provide for better sealing. A larger valve element diameter would also result in shortening of any support members attached to the valve element, which would increase stiffness of the supports to provide additional bias for sealing off the opening.

In the first embodiment, however, the opening does not project inwardly to form a valve seat (the opening may project outwardly), and the size of the valve element is not enlarged. Rather, the ratio of the outside diameter D2 of the cylindrical valve element 130 to the opening diameter D1 in the end wall 110 is between about 1.1 to about 2.0. Specifically, in the first embodiment, the opening 112 is preferably about 0.125 inches in diameter. Also, the cup 104 preferably has an outwardly projecting opening flange with a bending radius R adjacent the opening 112 of between about 0.010 inches and about 0.035 inches. Relative to the opening diameter D1, the cylindrical valve element 130 has an outside diameter D2 of about 0.200 to about 0.220 inches. This ratio (about 1.6) of the outside diameter D2 of the cylindrical valve element 130 to the opening diameter D1 allows the resilient radial ribs 126 to have sufficient radial length L for resilient bending that permits unseating of the cylindrical valve element 130 with a minimal amount of force. In the first embodiment, the predetermined amount of force required for unseating the cylindrical valve element 130 from the opening 112 was found to be about 1.9 pounds of force, as applied by the plunger tip 144 to a peripheral side on the top of the cylindrical valve element 130 within an aerosol container pressurized to about 120 psi.

In the first embodiment, the resilient radial ribs 126 are preferably configured to permit the cylindrical valve element 130 to be axially displaced relative to the annular seal 120 at least a predetermined distance (X) by application of a minimum pre-load of about 2.6 pounds of force. To achieve this, the first embodiment comprises four resilient radial ribs 126 that each have a radial length L of at least 0.047 inches, and more preferably have a modulus of elasticity of about 775 psi at 300%. Additionally, the resilient radial ribs 126 have a thickness of about 0.035 inches, and a depth of about 0.090 inches. The resilient radial ribs 126 are preferably formed of an elastic material such as a rubber or Thermoplastic Elastomer (TPE). Such an elastic material may comprise a natural or synthetic rubber such as Acrylonitrile-butadiene rubber, Ethylene propylene diene rubber, Polychloroprene rubber, Fluorocarbon Rubber, Chloroprene rubber, Silicone rubber, Fluorosilicone rubber, Polyacrylate rubber, Ethylene Acrylic rubber, Styrene-butadiene rubber, Polyester urethane/Polyether urethane, and combinations thereof. With the select number of radial ribs 126, the radial ribs 126 are configured to have a minimum radial length, cross-sectional area and suitable modulus of elasticity to provide a bending moment sufficient to permit axial movement of the cylindrical valve element 130 relative to the annular seal 120 for unseating the cylindrical valve element 130 with a force of not more than 1.9 pounds of force, as applied by the plunger tip 144 to a peripheral side on the top of the cylindrical valve element 130 within an aerosol container pressurized to about 120 psi.

It should be noted that the annular seal 120, resilient radial ribs 126 and cylindrical valve element 130 may be integrally formed of an elastic material. In the first embodiment, the annular seal 120, resilient radial ribs 126 and cylindrical valve element 130 are integrally formed of a rubber having a hardness of about 70 durometer, and more preferably about 78 durometer. Additionally, the cylindrical valve element 130 in the first embodiment is preferably offset above the top surface 122 of the annular seal 120 by a predetermined distance X of at least 0.036 inches. This offset distance, and the radial ribs 126 configured as above, provide for sufficient resilient displacement of the resilient radial ribs 126 to establish a minimum preload of about 2.6 pounds of force. Accordingly, in the first embodiment, the resilient radial ribs 126 each have a minimum radial length L and a modulus of elasticity sufficient to permit axial movement of the cylindrical valve element 130 relative to the annular seal 120 for unseating the cylindrical valve element 130 with a force of not more than 1.9 pounds.

In a second embodiment of a valve assembly, the valve assembly includes a hub similar to the first embodiment, with an opening of about 0.125 inches in diameter (D1). However, as shown in FIG. 5, the second embodiment includes an annular seal 220 with a cylindrical valve element 230 having an outside diameter D2 of about 0.267 inches. In the second embodiment, the ratio of the outside diameter D2 of the cylindrical valve element 230 to the opening diameter D1 is about 2.1. The annular seal of this second embodiment has a diameter of sufficient size to provide an effective seal against the cup end wall, which also allows the resilient radial ribs to have sufficient radial length and elasticity to permit axial movement of the cylindrical valve element for unseating from the opening with a force of not more than 1.9 pounds. Accordingly, the first and second embodiments establish a range of between about 1.6 to about 2.1, for a diametric ratio of the cylindrical valve element diameter to an outwardly projecting opening diameter, where the cylindrical valve element may be of any diameter falling within this diametric ratio range. This ratio range of the outside diameter D2 of the cylindrical valve element 230 to the opening diameter D1, when applied in combination with the preload from the offset of the valve element, was found to exceed the expected result of the preload and minimum valve diameter in providing a sealing function. Specifically, the combination of preloading the valve element, with the constraint of a diametric ratio limiting the valve element diameter allowed the resilient radial ribs 226 to have a radial length L sufficient to permit bending and/or axial movement of the cylindrical valve element 230 relative to the top surface 222 of the annular seal 220 for unseating the cylindrical valve element with a lower than expected opening force. While sealing function may be provided by valve element diameters outside of this range, such valve diameters do not provide sufficient radial length L for resilient bending to permit unseating of the cylindrical valve element 230 with minimal force provided by the disclosed embodiments, as explained below.

For both the first and second embodiments, the minimum pre-load force required to provide an effective seal was found to be at least 2.6 pounds of force, as shown in Table 1 below.

TABLE 1
PRE-LOAD FORCE
Pre-Load Test Data
	Sample 1	2.6 lb. pre-load force	No leakage
	Sample 2	1.6 lb. pre-load force	Slight leakage
	Sample 3	.75 lb. pre-load force	Unacceptable leakage

In addition to the sealing aspects provided by the above valve assemblies having an offset valve element of a size limited by the disclosed ratio of the outside diameter D2 to the opening diameter D1, the first and second embodiments also exhibited additional synergistic effects. Specifically, the combination of an offset valve element and limited valve element diameter exceeded what each would have provided individually, because the diametric ratio limiting the valve element size allowed the resilient radial ribs to have a radial length sufficient to permit bending and/or axial movement of the cylindrical valve element relative to the annular seal for unseating the cylindrical valve element with a lower than expected opening force. The first and second embodiments having the above diameter ratio were found to have an opening force of less than 1.9 pounds, which is significantly less than conventional spring-type valves, as shown in the table below.

TABLE 2
OPENING FORCE
Conventional spring-
Type Valve	First embodiment	Second embodiment
7 lb. opening force	1.9 lb. opening force	1.9 lb. opening force

In the first embodiment (and other embodiments) the valve assembly 100 may comprise an actuator 140 that further includes a tamper evident portion 150. Specifically, the actuator 140 may include a tamper evident removable portion 150 that is formed integrally with the actuator 140 (see FIG. 1), which is defined by lines of weakness between the actuator 140 and the removable portion 150. An opening force exerted on the removable portion 140 causes the removable portion 150 to at least partially separate from the actuator 140, to provide a tamper evident condition.

The above described embodiments of valve assemblies for aerosol containers include valve elements offset from an interconnected annular seal that provides a pre-load to establish sufficient sealing force, and a valve element diametric ratio that allows the resilient radial ribs to have sufficient radial length and elasticity for bending to permit axial movement of the cylindrical valve element relative to the annular seal for unseating the cylindrical valve element with a force of not more than 1.9 pounds.

Accordingly, the present embodiments are distinguished over conventional valves by providing improved sealing and opening forces not found in aerosol containers having valve elements without the essential offset for pre-load, and without the valve element diametric ratio that allows the resilient radial ribs to have sufficient radial length and elasticity for bending to permit a reduced opening force of not more than 1.9 pounds.

The example embodiments above are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

When an element or layer is referred to as being “on”, “engaged to”, “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to”, “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.

Claims

1. A valve assembly for an aerosol container, comprising:

a cup having a hub including an end wall therein, and opening in the endwall of a predetermined diameter, wherein the endwall portion around said opening does project inwardly;

an annular seal with a top surface, being interconnected to a cylindrical valve element by resilient radial ribs extending between the annular seal and an outside diameter of the cylindrical valve element that provide for axial movement of the cylindrical valve element relative to the annular seal, the annular seal and cylindrical valve element being disposed within the hub with said top surface seated against the end wall in the hub, the cylindrical valve element being offset a predetermined distance above said top surface such that when the annular seal is seated with said top surface against said end wall the cylindrical valve element is axially displaced and compressed against the end wall over the opening to provide a minimum pre-load force that is effective for sealing off the opening in the end wall of the hub; and

an actuator having a sleeve disposed over the hub, and a plunger tip projecting eccentrically through the opening for displacing and unseating the cylindrical valve element from the opening.

2. The valve assembly of claim 1, wherein the ratio of the outside diameter of the cylindrical valve element to the opening diameter is between about 1.6 to 2.1, whereby the ratio allows the resilient radial ribs to have sufficient radial length to permit unseating of the cylindrical valve element with less than a predetermined force.

3. The valve assembly of claim 1, wherein the resilient radial ribs are configured to permit the cylindrical valve element to be axially displaced relative to the annular seal in an amount of said predetermined distance by application of a minimum pre-load force.

4. The valve assembly of claim 1, wherein the resilient radial ribs each have a radial length of at least 0.047 inches.

5. The valve assembly of claim 1, wherein the resilient radial ribs each have a minimum radial length and a minimum modulus of elasticity that are sufficient to permit axial movement of the cylindrical valve element relative to the annular seal for unseating the cylindrical valve element with a force of not more than 1.9 pounds.

6. The valve assembly of claim 1, wherein the minimum pre-load force is a minimum of about 2.6 pounds.

7. The valve assembly of claim 1, wherein the cylindrical valve element is offset above said top surface by a predetermined distance of at least 0.035 inches, to provide sufficient elastic displacement of the resilient radial ribs to establish the minimum preload force.

8. The valve assembly of claim 1, wherein the annular seal, resilient radial ribs and cylindrical valve element are integrally formed of an elastic material selected from the group consisting of Acrylonitrile-butadiene rubber, Ethylene propylene diene rubber, Polychloroprene rubber, Fluorocarbon Rubber, Chloroprene rubber, Silicone rubber, Fluorosilicone rubber, Polyacrylate rubber, Ethylene Acrylic rubber, Styrene-butadiene rubber, Polyester urethane/Polyether urethane, Natural rubber, thermoplastic elastomers, and combinations thereof.

9. The valve assembly of claim 1, wherein the annular seal, resilient radial ribs and cylindrical valve element are integrally formed of an elastomer having a hardness of at least 70 durometer.

10. The valve assembly of claim 1, wherein the actuator further includes a tamper evident removable portion that is formed integrally with the actuator and is defined by lines of weakness between the actuator and the removable portion, wherein an opening force exerted on the removable portion causes the removable portion to at least partially separate from the actuator, to provide a tamper evident condition.

11. A valve assembly for an aerosol container, comprising:

a cup having a hub including an end wall therein, and an opening in the endwall of a predetermined diameter;

an annular seal with a top surface, being interconnected to a cylindrical valve element by resilient radial ribs extending between the annular seal and an outside diameter of the cylindrical valve element that provide for axial movement of the cylindrical valve element relative to the annular seal, the annular seal and cylindrical valve element being disposed within the hub with said top surface seated against the end wall in the hub, the cylindrical valve element being offset a predetermined distance above said top surface such that when the annular seal is seated with said top surface against said end wall the cylindrical valve element is axially displaced and compressed against the end wall over the opening to provide a minimum pre-load force of at least 1 lb. that is effective for substantially sealing off the opening in the end wall of the hub; and

an actuator having a sleeve disposed over the hub, and a plunger tip projecting eccentrically through the opening for displacing and unseating the cylindrical valve element from the opening;

wherein the ratio of the outside diameter of the cylindrical valve element to the opening diameter is between about 1.6 to about 2.1, whereby the ratio allows the resilient radial ribs to have sufficient radial length to permit unseating of the cylindrical valve element with less than a predetermined amount of force.

12. The valve assembly of claim 11, wherein the resilient radial ribs are configured to permit the cylindrical valve element to be axially displaced relative to the annular seal in an amount of said predetermined distance by application of said minimum pre-load force.

13. The valve assembly of claim 11, wherein the resilient radial ribs each have a radial length of at least 0.047 inches.

14. The valve assembly of claim 11, wherein the resilient radial ribs each have a minimum radial length and a minimum modulus of elasticity that are sufficient to permit axial movement of the cylindrical valve element relative to the annular seal for unseating the cylindrical valve element with a force of not more than 1.9 pounds.

15. The valve assembly of claim 11, wherein the cylindrical valve element is offset above said top surface by a predetermined distance of at least 0.050 inches, to provide sufficient elastic displacement of the resilient radial ribs to establish the minimum preload force.

16. The valve assembly of claim 11, wherein the annular seal, resilient radial ribs and cylindrical valve element are integrally formed of an elastic material selected from the group consisting of Acrylonitrile-butadiene rubber, Ethylene propylene diene rubber, Polychloroprene rubber, Fluorocarbon Rubber, Chloroprene rubber, Silicone rubber, Fluorosilicone rubber, Polyacrylate rubber, Ethylene Acrylic rubber, Styrene-butadiene rubber, Polyester urethane/Polyether urethane, Natural rubber, thermoplastic elastomers, and combinations thereof.

17. The valve assembly of claim 11, wherein the annular seal, resilient radial ribs and cylindrical valve element are integrally formed of an elastomer having a hardness of at least 70 durometer.

18. The valve assembly of claim 11, wherein the actuator further includes a tamper evident removable portion that is formed integrally with the actuator and is defined by lines of weakness between the actuator and the removable portion, wherein an opening force exerted on the removable portion causes the removable portion to at least partially separate from the actuator, to provide a tamper evident condition.

19. The valve assembly of claim 11, wherein the tamper evident removable portion further includes a projection thereon to permit gripping of the removable portion to cause the removable portion to dislodge from the actuator.

20. A valve assembly for an aerosol container, comprising:

a cup having a hub including an end wall therein, and an opening in the endwall of a predetermined diameter, wherein the endwall portion around said opening does project inwardly;

an annular seal with a top surface, being interconnected to a cylindrical valve element by resilient radial ribs extending between the annular seal and an outside diameter of the cylindrical valve element that provide for axial movement of the cylindrical valve element relative to the annular seal, the annular seal and cylindrical valve element being disposed within the hub with said top surface seated against the end wall in the hub, the cylindrical valve element being offset a predetermined distance above said top surface such that when the annular seal is seated with said top surface against the said end wall the cylindrical valve element is axially displaced and compressed against the end wall over the opening to provide a minimum pre-load force of at least 2.6 pounds that is effective for substantially sealing off the opening in the end wall of the hub; and

an actuator having a sleeve disposed over the hub, and a plunger tip projecting eccentrically through the opening for displacing and unseating the cylindrical valve element from the opening;

wherein the ratio of the outside diameter of the cylindrical valve element to the opening diameter is between about 1.6 to about 2.1, whereby the ratio allows for the resilient radial ribs to each have a minimum radial length to provide sufficient bending to permit axial movement of the cylindrical valve element relative to the annular seal for unseating the cylindrical valve element with a force of not more than 1.9 pounds.