US3866804A

US3866804A - Aerosol valve with pressure relief vent

Info

Publication number: US3866804A
Application number: US446408A
Authority: US
Inventors: Silvester William Stevens
Original assignee: Precision Valve Corp
Current assignee: Precision Valve Corp
Priority date: 1973-03-07
Filing date: 1974-02-27
Publication date: 1975-02-18
Anticipated expiration: 1992-02-18
Also published as: GB1429466A; AU472208B2; AU5299173A; CA988893A

Abstract

The valve of a pressurized aerosol dispenser is modified to vent excessive internal container pressure by providing the movable valve member with a vent passage and with the ability to be displaced outwardly of the valve housing by excessive pressure thereby causing the vent passage to communicate the interior of the container with the atmosphere.

Description

[111 3,866,804 [4 1 Feb. 18,1975

United States Patent [19] Stevens W s m e H V H C "u" e "mm R w mm e n B 10 3 0L h d r. w m m r( MBR o R 0003 677 r WWW M UN m a x 029 LL 75 y m awn m ,5 n 333 P m E w W s & S w S e E N R "m P s m h a n w H mFm w wwu E m V s L sqe T w AN a mmMw V m 0m m RL 6 EE M AR 1 M H 5 7 [73] Assignee: Precision Valve Corporation, Assistant EXamierDaVid Scheme Yonkers, NY.

Feb. 27, 1974 Attorney, Agent, or FirmDavis, Hoxic. Faithful] & Hapgood {22] Filed:

Appl. No.: 446,408

ABSTRACT [30] Foreign Application Priority Data Mar. 7, I973 Australian.....t................ 52991/73 The valve of a pressurized aerosol dispenser is modified to vent excessive internal container pressure by providing the movable valve member with a vent pas- [52] U.S. 222/396, ZZZ/402.24 [51] Int.

B65 33/ 4 sage and with the ability to be displaced outwardly of 251/353 the valve housing by excessive pressure thereby caus- 222/396, 397, 402.24

[58] Field of Search............................

ing the vent passage to communicate the interior of the container with the atmosphere.

References Cited UNITED STATES PATENTS 4 Claims, 5 Drawing Figures 2,631,814 Abplanalp...v..............t.... 222/320 X AEROSOL VALVE WITH PRESSURE RELIEF VENT BACKGROUND OF THE INVENTION This invention relates generally to spark gap devices, and more particularly to an adjustable spark gap which can be controlled to provide a wide range of breakdown voltages.

Adjustable spark gaps are useful in many high voltage devices for purposes such as switching high voltage pulses in test equipment, and for use in such devices as pulsers, Marx generators and high voltage protective devices. In these devices the gap functions as an on-off switch which becomes conductive when the voltage across it exceeds a preset value. These spark gaps must therefore usually be adjustable to set the breakdown voltage at the desired value. The breakdown voltage can be varied by changing the electrode spacing of the gap and by changing the Pressurized aerosol dispensers comprise a sealed container provided with a dispensing valve forac'cess to the container contents. The product to be dispensed is packaged in the container along with a propellant which vaporizes to provide the pressure used to force the product from the container when the valve is opened. Abplanalp U.S. Pat. No. 2,631,814 describes such an aerosol dispenser in more detail. The propellant is usually a material having a vapor pressure of between 25 and 70 psig. at room temperature. Fluorinated hydrocarbons are commonly used as propellants.

When pressurized aerosol dispensers are exposed to high temperatures, the internal pressure may rise to an extent sufficient to cause the container to explode. Even when considered to be empty by the consumer, sufficient propellant and product may remain to create dangerous pressures if the container is incinerated. Much attention has been devoted to providing means to vent excessive internal pressure, but none of the proposed solutions are entirely satisfactory from the aspects of cost, reliability, and freedom from premature venting. Some of the general approaches to solution have been fusible plugs or inserts, fusible sealing material beneath the mounting cup or in an end seal, pressure relief valves, frangible areas in a wall of the container and weakened areas or notches which are intended to fracture when internal pressure distorts the container. Fusible means are not pressure responsive and fail to provide adequate protection if the melting point is not attained. Pressure relief valves separate from the dispensing valve are expensive and create a problem of selecting a suitable location on the container. Weakened or frangible areas are prone to premature failure due to impact and do not always function at low enough pressures. Aerosol valves having a stem provided with a second transverse orifice and a second biased spring are known. Such a valve is shown in Bruce U.S. Pat. No. 3,519,172. The second orifice is normally wholly interior of the container, but under excessive pressure the valve stem is forced against the second spring to expose the second orifice. This double mode venting concept necessitates replacement of conventional valves with an entirely new valve, requires more parts, does not permit use of a sealing shoulder or tapered neck on the valve stem for reliable sealing.

The present invention provides a safety relief for excessive internal container pressure which reliably functions at a predetermined and precise pressure, has no tendency to prematurely function, requires no modification of the container and only minor modification of a standard dispensing valve, adds no parts, is compatible with other standard aerosol dispenser components, does not affect the normal reliable operation of the dispenser, adds no additional cost to the valve, and appears to be unlimited in its applications.

The present invention is a modification of the movable valve member of a standard aerosol dispensing valve such as that shown in U.S. Pat. No. 2,631,814 to provide the valve member with at least one duct or groove which provides a venting passage past the valve sealing gasket when internal pressure rises sufficiently to outwardly displace the valve member from its normal operative position to a venting position. The diam eter of the lower portion of the valve member may be reduced somewhat from the dimension of the standard unmodified valve member and the diameter of the valve stem aperture in the mounting cup pedestal may be slightly enlarged to promote the outward displacement of the valve member at a predetermined relief pressure well within the margin for safety, but above those pressures which aerosol dispensers encounter in normal use situations. A flange stands proud of the valve member to prevent ejection of the member.

The size of the valve stem aperture in the mounting cup pedestal, the degree of flexibility of the valve sealing gasket and the configuration of the movable valve member are factors which may be varied to affect the relief pressure at which the safety vent means actuates. The valve manufacturer can, within a reasonably broad range accurately adjust the safety relief pressure for valves according to the present invention by selecting the size of the valve stem aperture as well as by selecting gaskets of an appropriate flexibility by choosing gasket thickness or hardness.

The modifications of the molds required to change from manufacture of standard valve members to valve members according to the present invention is simple and inexpensive.

FIG. 1 is an elevational view in section of an aerosol dispenser according to the present invention shown in the normal operative condition,

FIG. 2 is a view similar to FIG. 1, but showing the valve member in the safety venting condition as a result of excessive internalpressure,

FIG. 3 is an enlarged elevational view of the movable valve member of FIGS. land 2,

FIG. 4 is a sectional view taken along plane IVIV of FIG. 3, and

FIG. 5 is an enlarged elevational view of a movable valve member according to a second embodiment of the invention.

FIG. 1 shows a conventional aerosol dispenser similar to that disclosed in U.S. Pat. No. 2,631,814, but including the modifications of the present invention. The dispenser includes a container 50 for holding the product to be dispensed and a suitable propellant such as the fluorinated hydrocarbon propellants sold under the trademarks FREON and GENETRON. The container 50 is closed by a valve mounting cup 52 which may be affixed to the container by a conventional rolled seam bead 53. A valve mounting pedestal portion 54 of the valve mounting cup 52 retains a dispensing valve assembly 40 by means of a crimp 55. An aperture 56 central of the valve mounting cup and pedestal accommodates the upstanding stem portion 12 of the movable valve member. A valve actuating button 60 or other valve actuator may be frictionally fitted to the upstanding stem 12.

The valve assembly, discussed in detail in U.S. Pat. No. 2,831,814, comprises a valve housing 44 having a nipple 48 at its lower end for receiving a dip tube 42. Captured between the upper rim of the valve housing and the upper wall of the valve mounting pedestal is a resilient annular washer or gasket 70. The valve housing 44 contains a movable valve member and a biasing spring 46 to bias the valve closed. The movable valve member 10 is illustrated enlarged in FIGS. 3 and 4.

Referring now to FIG. 3, the movable valve member 10 includes a valve stem portion 12 which protrudes through the aperture 56 in the valve mounting cup pedestal. The medial portion of the member 10 is reduced in diameter to form a neck 14 which includes a valve orifice 18 for controlling flow through the valve. Valve orifice 18 communicates with the hollow interior 13 of the upstanding valve stem 12 and is blocked or sealed by the inner margin of the resilient gasket 70 when the valve is closed. A tapered transition 16 interposed between the stem portion 12 and the neck 14 aids in reliable operation of the valve. The upper surface of the main body portion 30 of the valve member includes a shoulder 32 which bears against the lower surface of the gasket 70 to insure a good seal when the valve is closed. A radial flange 34 located at a lower portion of the body portion 30 prevents the valve member from passing through the aperture 56 of the valve mounting cup pedestal when the valve member is displaced outwardly by excessive pressure. One or more longitudinal channels or grooves 36 are provided in the body portion of the movable valve member 10 to form ducts which serve as safety vent passages. The lower extremity of the movable valve member 10 may include a spring retaining nipple 38 or other means to retain the biasing spring 46.

The movable valve member 10 of the present invention differs from the conventional valve member in having vent passages 36 arranged longitudinally of body portion 30, and a radial flange 34. The diameter of the body portion 30 may be reduced from that of conventional movable members to reduce the force required for relief actuation. These relatively minor modifications of the conventional movable valve member are easily effected in the molds and require no substantial changes in assembly techniques or apparatus.

Under normal conditions, the valve of the present invention operates identically with the standard valves of this type. Depression of the valve actuating button 60 forces the valve member 10 inwardly of the valve assembly 40. The tapered portion 16 ofthe valve member 10 causes the inner margin of the resilient gasket 70 to peel away from the neck portion 14 to expose the valve orifice 18 to the pressurized product in the valve housing 44. The pressurized product flows through the valve orifice 18 into the hollow interior 13 of the valve stem portion 12 and thence through the discharge passages in the button 60. Pressurized product is forced up the dip tube 42 into the interior of the valve housing 44.

FIG. 2 shows the valve of the present invention in the safety venting condition. Excessive internal pressure in the container, such as may occur at high temperatures, has acted on the movable valve member 10 with sufficient force to cause the valve member to pop up or be displaced outwardly of the valve assembly 40. The body portion 30 has been forced partially through the aperture of the gasket thereby bringing the vent passages 36 into a position where they establish a bypass about the inner margin of the gasket 70 to vent the excessive pressure. Radial flange 34 is large enough in diameter to prevent ejection of the valve member through aperture 56 in the valve mounting cup pedestal 54.

FIG. 5 shows another embodiment of the movable valve member of the present invention. The movable valve body 10A of FIG. 5 differs from that of FIGS. 1-4 in having no enlarged body portion such as 30 of FIG. 4. Gasket engaging shoulder 32 is the upper surface of a flange 38 of smaller diameter than stop flange 34a.

It has been found by testing that the internal pressure at which the valve member pops up to the venting position can be accurately preselected over a fairly broad range by selecting the flexibility of the gasket 70 or the diameter of the aperture 56 in the valve mounting cup pedestal 54 or both. More resilient elastomer or thinner gaskets provide lower relief pressures as do increasingly larger stem apertures in the mounting cup and diminished body diameters. Buna-N elastomers are relatively hard, generally on the order of 67-77 Shore A Durometer units, whereas softer elastomer gaskets are on the order of 50-60 Shore A Durometer units. Dispensers made with these variables preselected and fixed have been found to very reliably vent at pressures within a close tolerance of the preselected desired pressure. Nearly full, full and nearly empty dispensers will vent at substantially the same pressure. Because the actuation pressure can be predicted with considerable accuracy, the dispensers can be made to actuate at lower pressures just above those which the dispenser can be expected to encounter under normal conditions of use.

Because the relief pressure depends in part upon the flexibility of the gasket 70 and the relative diameters of aperture 56 and body portion 30, the manufacturer can easily preselect actuation pressures by choice of gasket material and thickness of aperture size. Thus, he can offer a reasonably wide selection of relief pressures with identical valve parts by choice of gasket or aperture size. If the product affects the resilience of the gasket, the resilience of the gasket should be chosen to take into consideration this effect.

Standard valves of the type manufactured here and abroad by PRECISION VALVE CORPORATION and its affiliates, and modified in accordance with the present invention to have a smaller movable valve member body diameter of 0.174 inches and two vent grooves of 0.06 by 0.02 inches in cross section. Mounting cup valve stem apertures between 0.203 and 0.234 inches have been employed. Of course, other dimensions are within the scope of this invention.

Valves employing the present invention have been tested with containers full and nearly empty in fire, on hot plates, and in hot water with various typical product formulations and a typical fluorinated propellant. Soldered side seam, welded side seam and seamless standard commercial containers were tested. The test specimens, when set at relief pressures between I50 and 200 psi, mounted in commercial containers safety vented excepting some of the nearly empty soldered side seam cans. As presently constructed, soldered side seam cans sometimes undergo side seam failure when empty because the solder melts and the seam lock unfolds at a pressure below the relief pressure. Higher melting point solders or stronger seam lock folds or both result in containers having sufficient strength and fire resistance to withstand the pressure minimums chosen for relief venting. Lowering the selected relief pressure to less than, 100 psi results in reliable venting of nearly empty fire exposed soldered side seam containers. Other container constructions reliably vent under all conditions.

Although the present invention has been described in the context of a particular type of dispenser valve, it is apparent that the invention is applicable to other types of dispenser valve for example, movable valve members having a socket for receiving a post on the button rather than having an upstanding hollow valve stem can be modified in a fashion substantially similar to that described.

What is claimed is:

1. In a valve for a pressurized aerosol dispenser comprising a product container having an apertured end closure including means for supporting the valve; the valve comprising:

a valve housing;

a movable valve member in said housing and having a body portion includinga shoulder normally interior of the dispenser, a product outlet passage for conveying product through the end closure aperture and a transverse valve orifice in communication with the outlet passage;

a resilient annular gasket blocking the transverse orifice and overlying said shoulder; and means to bias the movable member toward closure of the valve;

the excessive internal pressure relief improvement which comprises a size relationship between the movable member body portion and the end closure aperture which will allow the body portion and shoulder to distort the annular gasket and be forced partially through the annular gasket and end closure aperture against the resistance provided by the gasket and the end closure aperture by excessive internal pressure and a duct formed in the exterior surface of the body portion, the uppermost portion of the duct extending through the end closure past the distorted gasket to vent excessive internal pressure only when the body portion has been forced through the aperture.

2. The improvement of claim 1 wherein the duct comprises at least one longitudinal groove in the exterior of the body portion, said groove terminating interior of the dispenser from the transverse valve orifice.

3. The improvement of claim 1 wherein the lower portion of the body portion includes a radial flange of a size incapable of passing through the end closure aperture to prevent ejection of the movable member through the end closure aperture.

4. The improvement of claim 1 wherein the product trudes through the aperture.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PAIENI N(jr 3,866,804 DATED- F ruary 18, 1975 rNvENTORrS) Silvester William Stevens It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below" Column 1, line 3 through line 19, should be deleted. Column 1, line 57, "biased" should be -biasing.

Signed and sealed this 27th day of May 1975.

Attest:

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks

Claims

1. In a valve for a pressurized aerosol dispenser comprising a product container having an apertured end closure including means for supporting the valve; the valve comprising: a valve housing; a movable valve member in said housing and having a body portion includIng a shoulder normally interior of the dispenser, a product outlet passage for conveying product through the end closure aperture and a transverse valve orifice in communication with the outlet passage; a resilient annular gasket blocking the transverse orifice and overlying said shoulder; and means to bias the movable member toward closure of the valve; the excessive internal pressure relief improvement which comprises a size relationship between the movable member body portion and the end closure aperture which will allow the body portion and shoulder to distort the annular gasket and be forced partially through the annular gasket and end closure aperture against the resistance provided by the gasket and the end closure aperture by excessive internal pressure and a duct formed in the exterior surface of the body portion, the uppermost portion of the duct extending through the end closure past the distorted gasket to vent excessive internal pressure only when the body portion has been forced through the aperture.

4. The improvement of claim 1 wherein the product outlet passage is the bore of a hollow stem which protrudes through the aperture.