US 3299960 A
Description (OCR text may contain errors)
Jan. 24, 1967 G. F. STERN 3,299,960
VALVE Filed O01?. 30, 1964 Elite tats dice 3,299,960 VALVE Gottfried lF. Stern, 7 Broadview Road, Woodstock, N.Y. 12498 Filed Oct. 30, 1964, Ser. No. 407,646 17 Claims. (Cl. 169-23) In the well known and Widely used aerosol containers the materials to be dispensed (eg. aqueous or nonaqueous liquids such as shaving cream, paints, insecticides, cleaning compositions, deodorants, etc.) are mixed with propellant. The propellants employed (for example fluorocarbons, e.g. uorochlorohydrocarbons, or low boiling hydrocarbons, such as propane) are gaseous at atmospheric pressure at normal temperatures but are liquids at the pressures, say to 100 p.s.i.g., prevailing in the closed container. When the push button of the container valve is depressed the material to be dispensed is forced out through that valve by the pressure generated by vaporization of the propellant.
Aerosol containers explode when they are exposed to excessive heat, which raises the pressure above the limit the sheet metal, glass, or plastic container is designed to withstand. This may occur even in the rear deck of an automobile left in strong sunlight on a hot summer day. Fatal explosions have taken place when used aerosol containers, still containing some propellant, have been incinerated with rubbish or garbage.
While pressure-relieving devices for aerosol containers have been proposed previously, these have involved relatively expensive modications of the low-priced valves or have been inoperative until distortion of the container has occurred.
It is therefore an object of this invention to provide an economical and effective aerosol container valve capable of relieving excess pressure and thereby preventing explosions.
Another object of this invention is the provision of an aerosol container valve in which the pressure-relieving function is accomplished without drastic or expensive changes in the construction of the conventional valve elements.
Still another object is to provide an economical pressure-relieving valve which will relieve excess pressures by permitting a portion of the contents to escape without destruction of the valve, so that the valve will be operative repeatedly to relieve such excess pressure again if necessary.
A further object of this invention is the provision of a novel valve for a fire alarm device.
In the accompanying drawing which illustrates several aspects of this invention:
FIGURE l is an overall view of an aerosol container of conventional construction;
FIGURE 2 is a cross-sectional View of a conventional aerosol container, showing details of the valve construction;
FIGURE 3 is a similar View showing the valve of FIG. 2 modified in accordance with one .aspect of this invention; and
FIGURE 4 is a View of a modification of the valve of FIG. 3 in which the push button is in the fo-rm of an alarm device.
In one conventional construction, shown in FIGS. l and 2, there is mounted at the top 8 of the aerosol can 9 a valve 11 having a body 12, a reciprocable core 13, a push button 14- having a discharge opening 16, a spring 17 biasing the core 13 to closed position, an annular resilient sealing gasket 18, and a dip tube 19 extending down below the level of the liquid in the container. The top 8 of the can is usually crimped or otherwise shaped about the Valve body 12 and sealing gasket 18 as to hold these elements in a ixed position relative to the can. The dip tube 19 is mounted on a depending axially bored extension 21 of the valve body. The spring 17 and the lower portion 22 of the core 13 are disposed within the hollow of the valve body 12, with the bottom of the helical spring 17 abutting against a shoulder 23 of the valve body; in the conventional construction, the top of the spring presses against a face 24 of the core 13.
The `core 13 has an axial bore 26 extending part way down its length .and communicating with a radial inlet passage 27 whose outer end is normally sealed by contact with the inner portion of the gasket 18. The core 13 may also have a depending skirt 28 for housing the upper end of the spring 17. Except for the orices 16 and 27, the parts are radially symmetrical.
In operation, a downward pressure on the push button moves the core 13 against the force of the spring 17 to a position where the outer end of the radial inlet passage 27 is no longer sealed by its contact with the gasket 18. The contents of the can are then forced, by the pressure in the can, up through the dip tube 19 and valve body 12, through the radial passage 27, the axial bore 26 and the discharge opening 16. The core may have circumferential tapered cam surfaces (not shown) to deflect the inner portion of the gasket away from the end of the passage 27 during the downward movement of the core 13.
In the embodiment of this invention illustrated in FIG. 3, the parts are the same as those shown in FIG. 2 except that the axial bore 26a extends through the core 13a to the face 24a against which there is pressed a resilient disc 31 having a tiny perforation 32 terminating at the bore 26a. The perforation 32 is so small that it is normally effectively closed and no leakage of the contents, whether gaseous or liquid, occurs at the normal aerosol can pressures. If the pressure in the can should rise to dangerously high levels, the perforation will be forced open, venting the interior of the can to the atmosphere until the pressure decreases to below the danger level, at which time the can may be used again in the usual fashion. If, however, there is a sudden surge of pressure which cannot be Vented gradually through the opened perforation, the pressure will start a rip in the resilient material at the perforation, thus enlarging the opening and permitting a quick release of the pressure. In this case, of course, the can will generally not be suitable for reuse after the pressure has declined, since the sealing effect at the perforation will be destroyed or diminished.
The disc 31 is preferably made of a rubbery material, `advantageously one which is resistant to any deteriorating effects of the contents of the can. Silicone rubber, rubbery butadiene-acrylonitrile copolymers, and polychloroprene are some examples of suitable materials.
While the aperture 32 may be produced mechanically, as by penetrating the disc 31 with a ne steel needle, it is preferably produced by an electroperforating process. Electroperforation is `a known technique in which a hole is burnt through a dielectric material by the passage of a current (usually forming a spark) between two electrodes disposed at opposite sides of the material. By using very small currents, for short times, microscopic holes can be produced. The conditions employed in the electroperforation operation will, of course, be determined by routine experimentation, varying the voltage, the current, .and the time to produce a hole that will open or bleed when the disc is subjected to the selected pressure or range of pressures.
The disc 31 may be held in place, rmly against the face 24a of the core 13a, solely by the action of the spring 17 reinforced by the pressure of the contents of the can against the lower face of the disc. If desired, the disc 31 may be force-fitted within the skirt 28 or may have its edges cemented to the face 24a. The face 24a may have an annular ridge to serve as a seat against which the disc 31 is pressed and the disc may have a rigid annular backing member, below it, to more uniformly distribute the pressure exerted by the helical spring. The open portion of such an annular backing is preferably small and aligned with the perforation of the disc. There may also be present a rigid annular Washer between the disc and the face 24a to limit the deflection of the disc under the normal pressures in the container. A
In the embodiment of the fire alarm device, shown in FIG. 4, the conventional push button is in the form of a signal producing device such as a whistle 36 secured, like the push button 14, to the top of the core 13a. The whistle 36, of -conventional design, has a port 37, leading from the bore 26a, for the passage of the gas escaping from the interior of the container when the pressure in the container exceeds the limit which the perforated disc 31 is designed to withstand. Suitable designs for whistles or other alarms for this purpose will readily suggest themselves to those skilled in the art (e.g. the whistles shown in U.S. Patents 2,697,999; 2,842,088; 2,865,320 and 2,798,452). A non-inflammable cap 38 placed over the valve serves to shield the valve from heat and flame; the valve usually is made in whole or in part of plastic and is not heat resistant. The cap 38, which may 'be a cylindrical cup-like metal member of such size and shape as to be snapped over any appropriate portion of the upper part of the container, also serves to guard the valve against dirt, grease, etc. and thus helps to assure the reliable functioning of the device in the event of a fire. The cap preferably has side openings, such as the narrow vertical slits 39, to help transmit the sound made by the whistle.
In the re alarm device of FIG. 4, the container will generally be lled merely with a non-inflammable compressed gas such as carbon dioxide, or With a non-inammable propellant liquid, such as a conventional fluorocarbon propellant (e.g. dichlorodiuoromethane). The device is intended to be placed in any position Where a lire warning device is employed, for example, above the head of the stairs of a dwelling house. In the event of a re, the heating of the contents of the container causes an increase in the pressure in the container until the perforation in the` disc is forced open, and the resulting stream of gas actuates the whistle 36 to warn the occupants of the building. The gas in the container may also comprise an odoriferous substance, readily noticeable on discharge to give an additional alarm to the occupants.
The re alarm device of this invention lends itself to easy demonstration and test. Thus, the sound of the whistle may be demonstrated to a prospective purchaser merely by manually depressing the whistle 36 and the attached core 13a, to permit gas under pressure to flow through the passage 27, the bore 26a and the whistle 36. The container may be heated (as by placing it in very hot water) to demonstrate and test the operativeness of the alarm device without the need for destroying the device.
The lire alarm device may also serve as an automatic re extinguisher, particularly when it is used in a confined space, such as a furnace room. In this case the stream of gas, such as carbon dioxide, released from the container will form a dense blanket over the burning material. For the same purpose there may also be present in the container such re extinguishing materials as carbon tetrachloride or chlorobromomethane to form a fog when discharged with the carbon dioxide or fiuorocarbon propellant.
Returning now to the general operation of the perforated disc 31, this need not be of resilient material, such as a soft rubber. For example, it may be made of a more or less rigid plastic such as linear polyethylene or isotactic polypropylene. When the perforation is in a rigid material, the advantageous rapid bleeding effect Will generally not be obtained, since the material surrounding the perforation will not reversibly deform in response to the excess pressure. Instead the material will tend to break at the perforation when the unsafe pressure is reached and thereby tend to allow the entire contents of the can to be discharged through the valve. In either case, by proper choice of hole size, the excess pressure can be vented well before any deformation of the can takes place (eg. at a pressure of less than 125 p.s.i.g., for example at about -110 p.s.i.g.) for a sheet metal aerosol container.
If desired, there may be a number of perforations in a single disc. Thus there may be used a microporous material such as the known microporous artificial leather having a multitude of meandering pores, which may if desired be coated with a suitable lacquer to reduce the effective size of the pores. Or there may be employed a disc having a series of perforations arranged in a circle with lines of lesser thickness than the remainder of the disc joining the perforations to facilitate rupture if there is a sudden buildup of very high pressure. Also, the disc need not be of uniform thickness; it may, for example, be concave on one or both of its faces, and the perforation may Ibe situated in the thin portion of the disc.
It is to be understood that the foregoing detailed description is given merely by way of illustration, and that variations may be made therein without departing from the spirit of this invention.
The embodiments of the invention in which an exclusive property or privilege is claimed are dened as follows:
1. A valve for a container having therein a normally gaseous liquid, said valve having means for permitting the discharge of at least part of the contents of said container through said valve to dispense said material from said container as desired, said valve having a portion having a microscopic perforation impermeable to discharge of the contents of the container through said perforation under the normal pressures in said container but permeable to discharge through said perforation when the pressure in the container exceeds said normal pressure and approaches a level at which rupture of said container occurs.
2. A valve as set forth in claim 1 in which said valve has a push button and a member movable with said push button to a dispensing position permitting discharge of at least part of the contents of the container through said valve to dispense said material from said container as desired, said member having a wall one side of which is positioned to be subjected to the superatmospheric pressure of the contents of the container and the opposite side of which is positioned to be at the substantially atmospheric pressure in said valve, said Wall having said microscopic perforation.
3. A lled aerosol container having therein a normally gaseous liquid under a superatmospheric pressure, which container is sufliciently strong to retain said pressure, said container being subject to rupture when the pressure therein is raised, as by heating of said container, to a higher level which distorts the walls of said container, said container having a dispensing valve as set forth in claim 2, said perforation being formed in a rubbery material.
4. A valve as set forth in claim 2 in which said member comprises a hollow core having a normally sealed passage and being movable with said push button to said dispensing position permitting the discharge of at least part of the contents of said container through said passage and thence through said core to the atmosphere, a spring biasing said core away from said dispensing position, said wall being part of said core and comprising a resilient material having said microscopic perforation therein.
S. A valve as set forth in claim 4, said core having an opening at the lower end thereof, sealing means at said lower end to block the ow of the contents of the can through said opening, a spring pressing against said sealing means to urge said core away from said dispensing position, said sealing means being part of said wall and having said microscopic perforation therein.
6. A valve as set forth in claim 5 in which said sealing means comprises a flat member of rubbery material pressed against said lower end of said core by said spring.
7. A filled aerosol container having therein a normally gaseous liquid under a superatmospheric pressure, which container is sufficiently strong to retain said pressure, said container being subject to rupture when the pressure therein is raised, as by heating of said container, to a higher level which distorts the walls of said container7 said container having a dispensing valve as set forth in claim 4.
8. A filled aerosol container having therein a normally gaseous liquid under a superatmospheric pressure, which container is suiiiciently strong to retain said pressure, said container being subject to rupture when the pressure therein is raised, as by heating of said container, to a higher level which distorts the walls of said container, said container having a dispensing valve as set forth in claim 6.
9. A filled container as set forth in claim 8, said container being of sheet metal and said perforation being permeable to the contents of said container when the pressure is in the range of about 80 to 125 p.s.i.g.
10. A lled aerosol container having therein a normally gaseous liquid under a rst superatmospheric pressure, which container is sufficiently strong to retain said pressure, said container being subject to rupture when the pressure therein is raised, as by heating of said container, to a higher level which distorts the walls of said container, said container having a dispensing valve as set forth in claim 1.
11. A filled aerosol container as set forth in claim 10, said permeability and impermeability being reversible whereby, when the pressure is reduced to said first pressure after rising to a level at which said perforation is permeable, said perforation continues to be impermeable to said first pressure.
12. A push button operated valve adapted for use in an aerosol container, said valve having a push button, a hollow core having a normally sealed passage and being movable with said push button to a position permitting the discharge of at least part of the contents of said .container through said passage and thence through said core to the atmosphere so as to dispense said material from said container as desired, said core having an opening at the lower end thereof, sealing means at said lower end to block the ow of the contents of the can through said opening, a spring pressing against said sealing means to urge said core away from said dispensing position, said sealing means having a microscopic perforation in a resilient material, said microscopic perforation being of such size as to prevent passage of said contents through said perforation under the normal pressures in said container but permitting discharge through said perforation when the pressure in the container exceeds said normal pressure and approaches a level at which rupture of said container occurs.
13. An alarm device comprising a container having therein under superatmospheric pressure a material which is a gas at atmospheric pressure and having a valve as set forth in claim 12, the push button of said valve having a whistie for producing a signal when there is a discharge of the contents through said core,
14. An alarm device as set forth in claim 13 and having a protective cap over said valve, said cap having openings in its walls for transmitting the sound of said Whistle, and said container having therein a fire extinguishing composition.
15. A fire alarm device comprising gas actuatable alarm means, a container having therein under superatmospheric pressure a material which is a gas at atmospheric pressure, manually -operable valve means normally in closed position for preventing said gas from actuating said alarm means and movable to an open position to permit said gas to actuate said alarm means, and means sensitive to the change in conditions produced by the heat of a re for permitting said gas to actuate said alarm means when said valve means is in closed position.
16. A fire alarm device comprising gas actuable alarm means, a container having therein under superatmospheric pressure a material which is a gas at atmospheric pressure, pressure responsive means normally preventing said gas from actuating said alarm means, said pressure-responsive means having a microscopic perforation impermeable to said gas under the normal pressures in said container lbut permeable to said gas when the pressure in the container is increased owing to the heat of a fire.
17. A fire extinguisher comprising a container having therein under superatmospheric pressure a re extinguishing composition whose pressure increases with temperature, and pressure-responsive means for preventing discharge of said composition from said container, said pressure-responsive means having a microscopic perforation impermeable to said composition under the normal pressures in said container but permeable to said composition when the pressure in the container is increased owing to the heat of a lire.
References Cited by the Examiner UNITED STATES PATENTS 2,757,964 8/1956 Both et al. 222-397 2,933,222 4/1960 Waldherr 222-394 FOREIGN PATENTS 642,898 6/ 1962 Canada. 338,382 11/1959 Switzerland.
EVERETT W. KIRBY, Primary Examiner.