US3625403A

US3625403A - Aerosol-type dispenser for dispensing a powdered material

Info

Publication number: US3625403A
Application number: US813642A
Authority: US
Inventors: Felix Rousselot
Original assignee: Ciba Geigy Corp
Current assignee: Novartis Corp
Priority date: 1968-04-05
Filing date: 1969-04-04
Publication date: 1971-12-07
Anticipated expiration: 1988-12-07
Also published as: DE1916422B2; DE1916422A1; DE1916422C3; IL31957A0; FR1602651A; CH509107A; NO131412C; BE730924A; LU58374A1; NL6905164A; SE344402B; NO131412B; AT305685B; DK130328C; IL31957A; GB1216616A; OA03338A; DK130328B

Abstract

An aerosol-type dispenser for dispensing a powdered material. The dispenser has a propellant container, valve means operatively associated with said propellant container for controlling release of propellant from said propellant container, and a productcontaining chamber for containing the powdered material to be dispensed. A fluidization chamber is mounted on one end of said product-containing chamber and said product-containing chamber opens into it. The propellant container is mounted on said fluidization chamber and said valve means discharges into said fluidization chamber. The fluidization chamber has an outlet orifice therein, the propellant container is mounted on said fluidization chamber with the axis thereof at an oblique angle to the axis of said product-containing chamber, whereby when the dispenser is held with the product-containing chamber above the propellant-containing container, the powdered material is fed to the fluidization chamber by gravity.

Description

1 llnnte States atent [72] Inventor Felix Rousselot St. Benoit, France [21] Appl. No. 813,642 [22] Filed Apr. 4, 1969 [45] Patented Dec. 7, 1971 73] Assignee Ciba-Geigy Corporation Ardsley, N.Y.

[32] Priority Apr. 5, 1968 [33] France [31 147102 [54] AEROSOL-TYPE DISPENSER FOR DISPENSING A POWDERED MATERIAL 13 Claims, 6 Drawing Figs.

[52] U.S.Cl 222/193 [51] Int. Cl 867d 5/54 [50] Field of Search 222/193;

[56] References Cited UNlTED STATES PATENTS 2,560,093 7/1951 Doble 222/193 2,615,693 10/1952 Matirko 222/193 X 3,237,805 3/1966 Stogner 222/193 X Primary Examiner-Samuel F. Coleman Attorney-Wenderoth, Lind & Ponack ABSTRACT: An aerosol-type dispenser for dispensing a powdered material. The dispenser has a propellant container, valve means operatively associated with said propellant container for controlling release of propellant from said propellant container, and a product-containing chamber for containing the powdered material to be dispensed. A fluidization chamber is mounted on one end of said product-containing chamber and said product-containing chamber opens into it. The propellant container is mounted on said fluidization chamber and said valve means discharges into said fluidization chamber. The fluidization chamber has an outlet orifice therein, the propellant container is mounted on said fluidization chamber with the axis thereof at an oblique angle to the axis of said product-containing chamber, whereby when the dispenser is held with the product-containing chamber above the propellant-containing container, the powdered material is fed to the fluidization chamber by gravity SHEET 1 OF 5 FIG] INVENTOR FELIX ROU SSELOT ATTORNEYS PATENTEU DEC 7 I97! SHEET 2 BF 5 INVENTOR FELIX ROU SSELOT Zak ATTORNEYS PATENTEI] HEB 7L9?! 3.625403

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ATTORNEYS PATENTEUnEc H971 3.625403 sum 5 OF 5 INVENTOR FELIX R-OUSSELOT ATTOR NEYS AEROSOL-TYPE DISPENSER FOR DISPENSING A POWDEREI) MATERIAL This invention relates to an aerosol-type dispensing device especially for dispensing powder, and in which a liquefied gas, constituting a propellent, and the powder to be dispensed are held in separate storage containers. Such a dispenser may be easily held in the hand and can be operated manually.

Mixing insoluble powders with a propellant in a conventional aerosol-type dispenser causes problems of valve clogging, of maintenance of the powder in suspension, etc., so that a ratio of percent powder to 85 percent propellant is hardly ever exceeded. In a so-called double aerosol having separate containers for powder and propellant, a spray nozzle with a Venturi is used, and it is possible to dispense powders with a yield that may go as high as 70 percent powder to 30 percent propellant.

However, all known systems eventually produce clogging in the relatively narrow tubes or bores through which the powder is conducted at low speeds.

Numerous types of easy to handle and portable powder dispensers are already known which have two separate storage compartments, one for the liquefied gas used as the propellant and the other for the powder. During their operation, these units spray a cloud of powder fluidized by the propellant. However, in these known dispensers, there are often difficulties in obtaining regular sprays. This is remedied by resorting to attachments which are frequently complex and costly. For example, the outlet for the fluidized powder has a valve that opens only a certain timelag after the opening of the liquefied gas outlet valve so as to create an overpressure favorable to the discharge of the powder in the powder storage container. Likewise, the tube or bore carrying the fluidized powder to the outlet hole may have one or more propellant gas inlets to prevent the possibility of its clogging or to facilitate the discharge of the fluidized powder.

The purpose of the present invention is to provide an aerosol-type dispenser for powders in which there is no need to resort to attachments, the dispenser being a simply designed portable dispenser.

According to the invention, the powder dispenser has two storage containers, one for the liquified gas under pressure which is to be used as a propellant, and the other for the powder to be dispensed. The propellant storage container has a valve controlling the flow of the propellant to an admission tube directed toward the powder storage container. The dispenser has a fluidization chamber where the mixture of the propellant and powder takes place. This chamber is located at the top of the powder storage container, being separated from a powder storage chamber therein by an annular neck and in which the end of the propellant admission tube opens. The fluidization chamber has an outlet hole. The fluidization chamber is supplied with powder by gravity when the powder storage container is in an upside down position. The propellant storage container is mounted in relation to the fluidization chamber in such a way that its axis is oblique to the axis of the powder storage container.

When the powder storage container is in the upside down position and as a consequence the fluidization chamber is filled with powder, the jet of propellant gas comes out of the admission tube tangentially to the wall of this chamber flowing along said wall. Therefore the whirling pattern of gas fluidizes the powder encountered during its flow. After being mixed in the fluidization chamber, the powder and gas mixture is discharged through the outlet hole.

Preferably, the fluidization chamber has an area in which at least a portion of the wall is cone-shaped, at the tip of which said outlet hole is located. The powder storage chamber opens into said area between the tip and base of said cone-shaped wall and itself has a cone-shaped wall. The propellant storage container is connected to the base of said cone-shaped wall. The extremity of the propellant admission tube is preferably located in said area near the base of said cone-shaped wall.

In another form of the dispenser according to the invention, the fluidization chamber has a second area, generally in the shape of a bulb or a truncated ellipsoid, which lies between the aforesaid area with a cone-shaped wall and the powder storage chamber. In this embodiment, the extremity of the propellant admission tube preferably opens into fluidization chamber adjacent the region of transition between the cone-shaped wall area and the bulb, and is therefore located on the same side as the outlet hole.

In the forms of the powder dispenser according to the invention which have been described above, the fluidization chamber is placed at the extremity of the powder storage container, and on the side opposite the hole into said storage container is a handle for the purpose of holding the dispenser and turning it upside down.

The dispensers according to the invention have many favorable features. They are based on the principle of speeding the propellant gas directly into a fluidization chamber where it is mixed with the powder. The powder is fed into this chamber by gravity rather than by suction. The volume of the fluidization chamber is much smaller than that of the powder storage container as a whole and is separated from the latter by a section that narrows down to form a neck and yet is sufficiently wide to allow the powder to pass by gravity without holding it back. The fluidization chamber has an outlet hole for the mixture of gas and powder that opens directly to the outside, so that the gas and powder mixture does not have to go through tubes or bores.

In this way, maximum use is made of the propellant gas. It still has a high rate of flow at the time it is mixed with the powder, and the mixing of the gas and powder in the fluidization chamber is very energetic. The powder does not have any long and narrow conduit to go through, and the risks of clogging are practically nil.

The yields obtained range between 98 percent powder to 2 percent propellant gas and percent powder to 15 percent propellant gas.

Depending on the shape of the chamber, the path followed by the gas in the fluidization chamber may be more or less rectilinear or more or less circular or spiral. The advantage of a circular or spiral path is that the gas may go around the same circuit a number of times before escaping to the outside. The gas has a higher velocity in the fluidization chamber and it is mixed more energetically with the powder than when it goes in a straight line. It has also been found that the forms of dispensers which produce a circular path for the gas in the fluidization chamber produce maximum propellant efficiency. Yields of 98 percent powder to 2 percent propellant gas can be obtained, calculated on the basis of the total weight of the mixture, leaving the dispenser. The jet nevertheless remains regular, with good dispersion and has a good range.

This type of unit is of particular interest in cases where it is desired to have a dispenser with which large quantities of powder can be dispensed while retaining a small volume propellant storage container. However, in practice the delivery rate of powder which is obtained, for example between 4 and 8 gram molecule per second, is too high for many types of applications. For instance, when it is desired to treat garden plants by means of powder, these delivery rates are too high. In that case, it is preferable to adopt a rectilinear path for the gas through the fluidization chamber. Lower powder delivery rates of 1 to 2 gram molecule per second can thus be obtained, and still very worthwhile propellant yields on the order of 92 percent powder to 8 percent propellant gas, can be obtained.

The different characteristics of the fluidization chamber, determined on the basis of a liquefied gas storage container of regular capacity, i.e., of 300 ml. or less, are: the volume of the fluidization chamber is preferably less than one-third the volume of the powder storage chamber, and the annular neck section preferably has an area between 2 and 30 cm. With a dispenser having these specifications, a powder storage chamber can advantageously be made with a capacity as high as 10 times the volume of the liquified gas storage container.

In the embodiments of the invention described above, the dispenser has a hollow handle extending obliquely to the axis of the powder storage container and mounted on the fluidization chamber. This handle serves to house the liquefied gas storage container and has a valve-control trigger for controlling the valve means on said storage container. The valve means can be integral with a movable screen inside the handle. This screen can partition the fluidization chamber from the rest of the space inside the handle in which the liquified gas container is housed. The trigger and the valve are connected through the admission tube mounted on the valve atomizer and integral with the screen.

With this system, since the fluidization chamber has to be at the base of the unit during the operation, the following elements are grouped together in the immediate proximity of said chamber:

the valve control button the outlet from the propellant storage chamber valve the outlet hole for the gas-powder mixture the system for opening and closing this hole.

The use of pipes is therefore avoided, thus greatly simplifying the manufacturing. Only the units that are to be turned upside down can have these elements grouped together. This makes for an unusually compact unit, which can be produced for a very low price.

Some further special advantages of the dispenser include:

a propellant storage container that does not require an immersed dip tube,

the elimination of the risk that the operator will use it the wrong way,

it is easily held in the hand, in a natural position, when it has to be used for some time.

To make the unit easier to hold in the hand and minimize sharp angles along the path of the gas or the gas-powder mixture, the propellant storage container is preferably positioned with its axis at an angle of approximately 135 with the axis of the powder storage container.

Other features of the invention will be brought out in the following detailed description taken with the accompanying drawings, in which:

FIG. 1 is a sectional elevational view of an embodiment of the dispenser according to the invention showing the liquefied gas storage container partially in section, and with the parts in the nondispensing positions;

FIG. 2 is a sectional elevation view of the upper part of the dispenser of FIG. 1;

FIG. 3 is a sectional view taken along line IIIIII of FIG. 2;

FIG. 4 is a view similar to FIG. 2 showing the dispenser in operation;

FIG. 5 is a sectional elevational view similar to FIG. 1 of another embodiment of the dispenser according to the invention in the upside down or operating position; and

FIG. 6 is a perspective view, partly broken away, of the dispenser of FIG. 5.

Referring to FIG. 1, the powder dispenser includes a powder container 1 for the storage of powder B and a hollow handle 2 mounted on the collar 8 of the container 1. The handle 2 houses a storage container 3 for liquefied gas C, and has a valve therein actuated by a trigger 4, for the controlled release of a flow of gas into an admission tube 5 directed generally toward powder storage chamber 1.

Powder storage container 1, which is a one-piece container, is a solid of revolution and comprises two superimposed chambers, a fluidization chamber A and a chamber 6 for powder B, separated by an annular neck 7 having an opening 7a therethrough. Fluidization chamber A, located just beneath the opening through collar 8 of powder storage container 1, is bulb-shaped and is coaxial with powder chamber 6. The powder chamber 6, which is cylindrical in the vicinity of bottom 9 of powder storage container 1, then narrows down in the direction of neck 7, at which point its walls roughly form a cone having an angle at the apex in the neighborhood of 90.

The hollow handle 2, mounted obliquely to the axis of powder storage container 1, is at an angle of approximately l35 with this axis and has a grip 10 mounted on a cylindrical sleeve 11. Sleeve 11 has a ferrule 12 on the end thereof which is force-fitted into opening in collar 8 of powder storage container 1. On the end where sleeve 11 is located, the handle 2 has a control trigger 4 which can move along the plane of symmetry of the dispenser and which has an extension extending through an opening 13 in sleeve 11. Handle 2 also has an outlet hole 14 for the fluidized powder, which hole 14 is located at the extremity of sleeve 11 and is cut diametrically by the aforementioned plane of symmetry. Also, the handle 2 has, on grip 10, a plurality of recesses 15 perpendicular to the plane of symmetry and positioned at intervals along the grip 10 and where the operator can place his fingers to facilitate gripping the dispenser.

As seen clearly in FIG. 2, the valve on the propellant container 3 includes a valve body 16 mounted in cap 17 of propellant storage container 3. A gasket 18 is positioned between the valve body 16 and cap 17 and an atomizer 19 is urged outwardly by a spring 21 resting against the bottom of valve body 16. The tubular atomizer 19 has an admission tube 5 mounted on the end thereof. Atomizer 19 has a hole 22 opening into propellant storage container 3, said hole 22 normally being obturated by gasket 18.

Admission tube 5 is connected with control trigger 4 through a circular-shaped flange 23, see FIG. 3, articulated on shaft 24 mounted on ferrule 12 on sleeve 11. Flange 23 is urged outwardly of container 3 by a return spring 25 resting against cap 17 of liquefied gas storage container 3. Said admission tube 5 has at its free end 27 a calibrated nozzle opening into fluidization chamber A at an angle roughly tangential to the wall of the chamber A.

Flange 23 has a shutter 26 on the peripheral edge thereof and slidable inside of sleeve 11, which obturates a fluidized powder outlet hole 14 and an opening 13 through which trigger 4 projects. Flange 23 forms a separating member between fluidization chamber A and the interior of handle 2 that houses storage container 3 for liquefied gas C.

When in the nondispensing condition (FIGS. 1 and 2), the powder dispenser according to the invention has the powder storage chamber 6 at the bottom of storage container I which is in a vertical position, and powder B is stored in the bottom part of chamber 6. Hollow handle 2, inclined at about 45 from the horizontal carrying trigger 4 is on top of powder container 1. In this position, the gas phase of liquefied gas C gathers at the bottom of storage container 3 which is at the upper end thereof, while its liquid phase is in contact with the outlet valve.

This dispenser is used manually, and when in a dispensing position as shown in FIG. 4, the operator holds it by grasping handle 2, with the last three fingers of his hand placed in recesses 15 of grip 10, and the index finger near trigger 4. Storage container 1, still in vertical position, is turned completely upside down and the powder B that it contains shifts to the end opposite the bottom 9 and fills fluidization chamber A. Trigger 4 juts out under handle 2 and is located above the operators hand. In addition, the gas phase of liquefied gas C now comes in contact with body 16 of the outlet valve in such a way that the discharge can take place from this gas phase.

This working position is adopted naturally by the operator after gripping handle 2 because he is forced to have the unit well in hand and has to pull on trigger 4 to make it operate. Referring to FIG. 4, it can be seen that this operation accomplished easily by pulling downward on trigger 4 in the direction of arrow F.

As trigger 4 is pulled, atomizer 19 is moved into propellant storage container 3 so that hole 22 communicates with the gas phase of the liquefied gas in storage container 3. As a result, there is a flow of pressurized gas into admission tube 5 and out through the calibrated nozzle 27 in the form of a jet directed tangentially to the wall of fluidization chamber A. This pressurized jet advances (as shown by arrows G), and while so doing it expands. It flows along the fluidization chamber wall,

being given a whirling pattern, and mixes with the powder B that lies in its path. Then this mixture of gas and powder under high-pressure as compared with the ambient air pressure is directed toward outlet hole 14 that was opened by movement of shutter 26 when trigger 4 was moved, and comes out of hole M as a cloud.

The powder 8 forced out through hole 14 is progressively replaced by new powder fed by gravity through annular neck 7 The operation of the dispenser is stopped by releasing trigger 4. The latter is returned to its initial position by the action of return spring 25, causing atomizer 19 to go back to its previous position, the inlet opening 22 being obturated by gasket 18.

In a most preferred embodiment according to the invention, as shown in FIGS. 5 and 6 in which like parts bear like reference numbers to the parts in the preceding FIGS. a portion of the fluidization chamber designated by the numeral 28 is defined by a cylindrical wall portions, 36, and end wall 29. The powder container 1 is provided with a frustoconical or funnel-shaped outlet neck 30 which is mounted on the side wall of turbulence chamber 28, so that an opening 31 provided in this sidewall registers with the opening of neck 30 of the powder container.

The propellant admission tube 5 ends in a mouth or nonle 32 which directs a jet of propellant emerging therefrom when the handle t is actuated generally toward the gas-and-powder mixture discharge orifice M. This mouth 32 is located during actuation of the dispenser a short distance behind the central axis of the powder cone entering the turbulence chamber 28 through the opening 31, which axis is indicated by arrow P. No flange, such as flange 23 of FIGS. [-4, need be provided on the lever 33 actuated by the trigger 4 and pivotally mounted on a pin 24. The lever 33 engages a shoulder 34 or a like projection provided on the propellant admission tube 5, and ef fects propellant release in exactly the same manner as in the embodiments shown in the preceding figures. The trigger also engages shutter 26 which is guided between projections 35 on the inner surface of cylindrical wall 36.

In this embodiment of the invention, with a storage container 3 for liquefied gas at a normal capacity and having a volume of not over 300 ml. there may advantageously be used as a propellant gas those liquefied gases, either pure or mixed, that have a boiling point of between 0 and 45 c.

The following are preferred: Boiling point Chlorodifluorornelhane (F22) 40.8 C. Dichlorodifluoromethane (F12) 27.8 C. Propane 42.2 C. lsobutane l 1.7 C. lsobutylcne 6 C. Butane -0.5 C. Methyl oxide 23.7 C. Vinyl chloride l4" C.

With such a liquefied gas storage container 3, the rate of discharge should preferably not exceed l/ 100 gram molecule per second, because the cooling of the container, which follows accelerated evaporation of the liquefied gas, causes rapid reduction in the rate of flow. This rate advantageously ranges between 1 100 and l/ 1,000 gram molecule, and is preferably l/200. For example, with dichlorodifluoromethane, these limits correspond to 1.2 and 0. l 2 gram molecule.

Numerous experiments have shown that certain relationships between various parameters of the dispenser wild insure optimum operating conditions, both as regards quality of spraying and propellant economy. These relationships are as follows: 1. the volume of fluidization chamber A must be less than one-third of the volume of the storage chamber for powder B; and 2. the cross-sectional area of annular neck 7 must be between 2 and 30 cm.

With dispensers having these characteristics, it was found that the entrainment of powder B was regular at all times and that the gas and powder mixture contained between 75 and 90 percent powder or even more.

The particle size of powder 8 to be dispensed can vary within wide limits depending on the applications desired. Preferably, particles of powder B have a great dimension less than 0.15 mm.

By virtue of the remarkable effectiveness of the fluidization chamber, dispensers according to the invention can have a powder storage chamber with a volume of up to 3 liters.

Practical embodiments of the dispenser according to the invention are in the form of a unit with a simple design which has no attachments. This is because fluidization chamber A is a part of powder storage container 1 into which only propellant gas admission tube 5 emerges. There is no tube for delivery of the fluidized powder, the latter being directed to outlet hole M by flange 23 which is positioned so as to serve both for delimiting this fluidization chamber A and for controlling the admission of propellant gas into the latter.

This unit makes it possible to dispense large quantities of powder economically because powder storage container ll has a large capacity, and at the same time the entire mass of powder stored in this storage container 1 can be dispensed. lndeed, the wall of powder chamber 6 which is cone-shaped in the vicinity of fluidization chamber A allows the powder to flow through continuously even if there is an accidental or intentional variation in the ideal position of the unit as shown in FIG. 4. In addition, the gas flow that circulates tangentially to the wall of fluidization chamber A empties the latter of all the powder it may contain, even in the vicinity of flange 23.

The position in which the unit is held may vary by as much as 45 in one direction or another without any problem. Thus, powder can be sprayed at will, upward, downward or horizontally.

Furthermore, when the unit is turned upside down, which occurs when it is grasped by handle 2, the powder is loosened so that both clogging and nonclogging powders can be sprayed.

Furthermore, powder outlet hole 14 is obturated during storage and when not in use by obturating shutter 26, which prevents any loss of powder through this hole.

Lastly, the fact that storage container 3 for liquefied gas C is located inside handle 2 which is held in the operator's hand facilitates the warming of said storage container 3 when it is has been cooled as a result of the evaporation of the liquefied gas.

It is quite obvious that there can be modifications in the powder dispenser according to the invention. Thus, flange 23, which is pivot-mounted, could also be slidably mounted in sleeve 1! of handle 2.

Experiments have shown that there are four main factors affecting the performance of powder dispensers according to the invention: 1. the cross'sectional area of the gas inlet nozzle; 2. the cross-sectional area of the outlet hole for the gas and powder mixture; 3. the cross-sectional area of the passage between the powder storage chamber and the fluidization chamber; and 4. the position of the gas admission nozzle in relation to powder admission opening.

Within practical limits, the shape of the fluidization chamber and the shape of the powder storage container seem to have only a negligible influence on operating efficiency.

In dispensers having propellant and powder storage containers of 300 ml. and 3 liters, respectively, the other preferred characteristics mentioned above, and gas inlet nozzles with a diameter of 0.25 to 0.40 mm. the range and regularity of powder flow are optimum.

On the other hand, if the nozzle has a smaller diameter, for example 0.15 or 0.20 mm. the range and regularity of the powder jet are markedly reduced as a result of the reduction in the quantity of gas. Also, if we change to nozzles with a larger diameter, for example 0.70 or 1.0 mm., the performance and regularity of operation are reduced. As a result of the preexpansion of the gas, the chamber is supplied with the same quantity of gas but at a lesser rate of speed.

However, very small diameter nozzles (0.15 or 0.20 mm.) are of interest for very short range powder applications, other than the treatment of garden plants.

It was also noted, that under the same conditions, that the efficiency, range and regularity are optimum with an outlet orifice of L to 2.5 mm. and preferably about 2 mm. in diameter. Below this size, the gas is inhibited in its flow, and there is no longer enough whirling in the fluidization chamber to mix the powder and gas effectively.

However, if the shape of the chamber is convergent, for example, is cone-shaped toward the outlet end, smaller outlet holes of 1.7 and even l.5 mm. in diameter will still give a good range and a good regularity of powder flow, making it possible at the same time to reduce the average powder rate of flow.

Other tests have shown that a hole of L5 mm. was a minimum below which it was not possible to go without risking a clogging of powder in said hole.

in the particular case of an aerosol dispenser for spraying plants in private gardens, since a low rate of powder flow is an important factor, and outlet hole of L5 mm. is recommended.

it was further noted that efficiency, range and regularity were a direct function of size of the opening from the powder hopper of the powder storage container. It appears that it is an advantage to have this opening as large as possible. However, it there is no neck at all between the hopper and the fluidization chamber, the results are mediocre or poor. The whirling instead of continuing in the chamber, becomes dispersed in the powder storage container and becomes less energetic.

Under the conditions described above, the optimum hopper opening is between 35 and 40 mm. in diameter. Openings with a diameter of 25 mm. or less do not allow the powder to come down normally by gravity and can only be used in conjunction with powders that have high flowability without any tendency to form bridges, or else with the use of energetic propellants such as propane.

In the most preferred embodiment according to the invention, the orifice of the gas inlet nozzle is located a short distance, 5 to 20 mm., and preferably to mm., behind the axis of the powder delivery opening. Actually, in this most preferred embodiment, which has no intermediate bulbshaped chamber between the powder storage chamber and the zone that has a convergent shape toward the outlet orifice, it is imperative that the gas admission be spaced from the axis of the powder admission hopper.

Preferably, the propellant gas admission orifice is so oriented toward the inside of the fluidization chambers convergent zone having a partially cylindrical wall that the axis of the jet is below the outlet hole when the unit is in operation.

Normally, the powder should not obstruct the outlet hole if it does not contain any uncrushed granules or impurities larger than the outlet orifice in any of its dimensions, and if it does not contain relatively hard lumps.

Nevertheless, if clogging of the orifice should occur accidentally and if the inexperienced user continues to press on the propellant valve, the unit as a whole gets in a state of over pressure which could ultimately lead to an explosion of the plastic unit.

For this reason, a slot has been provided which extends for example over a distance of 8 to 10 mm. from the outlet hole, in the convergent part of the fluidization chamber wall. Under normal conditions, this slot is closed ofi and no gas flows along it. in case of accidental overpressure, the plastic material begins to flex and the edges of the slot are able to open up widely enough to leave a large orifice and reduce the pressure within the unit.

What is claimed is:

l. A hand-held powder dispenser comprising a propellant container for holding a propellant gas liquefied at a pressure above atmospheric, a powder container for holding a powder to be dispensed in a spray and having a bottom surface on which the dispenser stands when not being hand held in an inverted position for dispensing a turbulent chamber connected between the top of the powder container remote from the bottom surface and the propellant container, said powder container and said turbulence chamber having an opening therebetween and the internal surfaces of the walls of the powder container adjacent said opening having a shape for causing powder to flow through the opening into said turbulence chamber in the form of a cone with the apex within the turbulence chamber a valve-controlled propellant gas flow tube being directed into said turbulence chamber in a direction to flow laterally across the opening between the powder container and the turbulence chamber for fluidizing the powder in the cone of powder falling into the fluidizing chamber, the axis of the gas flow tube intersecting the axis of the cone formed by the powder dropping into said turbulence chamber in an obtuse angle, said turbulence chamber having an outlet for the powder and propellant positioned laterally of said opening between said powder container and said turbulence chamber, and trigger means operatively associated with said valve means for controlling the flow of gaseous propellant from said propellant container, whereby only when the dispenser is inverted can powder flow from the powder container into the turbulence chamber in a cone to be mixed with the propellant from the propellant container released by actuation of said trigger means.

2. A powder dispenser as claimed in claim 1 wherein said angle is about 3. A powder dispenser as claimed in claim 1 wherein said turbulence chamber has a curved wall curving from a position generally in alignment with said gas flow tube to a direction across said opening between said powder container and said turbulence chamber.

4. A powder dispenser as claimed in claim 1 further comprising a hollow handle attached to said turbulence chamber and extending obliquely to the axis of the powder container.

5. A powder dispenser as claimed in claim 4 in which said propellant container is positioned inside said hollow handle.

6. A powder dispenser as claimed in claim 1 in which said turbulence chamber has a generally pointed extension therein in which said outlet is positioned.

7. A powder dispenser as claimed in claim 1 wherein said turbulence chamber is a hollow truncated right circular cylinder with the powder container connected to the base thereof.

8. A powder dispenser as claimed in claim 1 wherein said trigger means comprises a trigger, lever means on which said trigger is mounted and pivoted in said turbulence chamber adjacent said valve means and being engaged with said valve means for moving said valve means by movement of the trigger to move said lever means.

9. A powder dispenser as claimed in claim 8 further comprising a slider slidable along the wall of said turbulence chamber over said outlet and engaged by said lever means to be moved to uncover said opening when said trigger is actuated to open said valve means.

10. A powder dispenser as claimed in claim 8 wherein said gas flow tube is mounted on said lever means and is integral therewith.

11. A powder dispenser as claimed in claim 8 further comprising spring means engaged with said lever means urging said lever means to the valve-closed position.

12. A powder dispenser as claimed in claim 1 wherein said opening between said powder container and said turbulence chamber has an area of from 2 to 30 cm., and said propellant container has a volume of about 300 ml.

13. A hand-held powder dispenser comprising a propellant container for holding a propellant gas liquefied at a pressure above atmospheric, a powder container for holding a powder to be dispensed in a spray and having a bottom surface on which the dispenser stands when not being hand held in an inverted position for dispensing a turbulence chamber connected between the top of the powder container remote from the bottom surface and the propellant container, said powder container and said turbulence chamber having an opening therebetween and the internal surfaces of the walls of the powder container adjacent said opening having a shape for causing powder to flow through the opening into said turbulence chamber in the form of a cone with the apex within the turbulence chamber, valve means on said propellant container including a gas flow tube directed into said turbulence chamber for directing a flow of gas from said propellant container into said turbulence chamber for fluidizing the powder flowing into the turbulence chamber, said turbulence chamber having an outlet for the powder and propellant positioned laterally of said opening between said powder container and said turbulence chamber, the portion of said turbulence chamber adjacent to the powder container and into which the opening between the powder container and the turbulence chamber opens being generally bulb-shaped, and the part of the turbulence chamber having said outlet therein being on the side of the turbulence chamber remote from the powder container, said gas flow tube extending into said bulb-shaped portion of the turbulence chamber and being directed generally along the wall of the bulb-shaped portion adjacent the portion thereof nearest the outlet, and trigger means operatively associated with said valve means for controlling the flow of gaseous propellant from said propellant container, whereby only when the dispenser is inverted can powder flow from the powder container into the turbulence chamber in a cone to be mixed with the propellant from the propellant container released by actuation of said trigger means.

Claims

1. A hand-held powder dispenser comprising a propellant container for holding a propellant gas liquefied at a pressure above atmospheric, a powder container for holding a powder to be dispensed in a spray and having a bottom surface on which the dispenser stands when not being hand held in an inverted position for dispensing a turbulence chamber connected between the top of the powder container remote from the bottom surface and the propellant container, said powder container and said turbulence chamber having an opening therebetween and the internal surfaces of the walls of the powder container adjacent said opening having a shape for causing powder to flow through the opening into said turbulence chamber in the form of a cone with the apex within the turbulence chamber a valve-controlled propellant gas flow tube being directed into said turbulence chamber in a direction to flow laterally across the opening between the powder container and the turbulence chamber for fluidizing the powder in the cone of powder falling into the fluidizing chamber, the axis of the gas flow tube intersecting the axis of the cone formed by the powder dropping into said turbulence chamber in an obtuse angle, said turbulence chamber having an outlet for the powder and propellant positioned laterally of said opening between said powder container and said turbulence chamber, and trigger means operatively associated with said valve means for controlling the flow of gaseous propellant from said propellant container, whereby only when the Dispenser is inverted can powder flow from the powder container into the turbulence chamber in a cone to be mixed with the propellant from the propellant container released by actuation of said trigger means.

2. A powder dispenser as claimed in claim 1 wherein said angle is about 135*.

3. A powder dispenser as claimed in claim 1 wherein said turbulence chamber has a curved wall curving from a position generally in alignment with said gas flow tube to a direction across said opening between said powder container and said turbulence chamber.

12. A powder dispenser as claimed in claim 1 wherein said opening between said powder container and said turbulence chamber has an area of from 2 to 30 cm.2 and said propellant container has a volume of about 300 ml.