US2517555A - Aerosol dispensing nozzle - Google Patents

Description

Aug. 8, 1950 R. A. FULTON ETAL AEROSOL DISPENSING NOZZLE Filed July 8, 1947 INVENTOR5. RA. FULTON/W0 J. H. FALES 14 7' TORNEY PatentedAug. 8, 1950 AEROSOL DISPENSING NOZZLE Robert A. Fulton and John H. Fales, Silver Spring, I

Md.; dedicated to the free use of the People in the territory of the United States Application July 8, 1947, Serial No. 759,681

(Granted under the m of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) 2 Claims.

This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described and claimed, it patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

We hereby dedicate the invention herein described to the free use of the people in the territory of the United States to take efi'ect on the granting of a .patent to us.

This invention relates to the production of aerosols and is more particularly concerned with devices used to produce aerosols by the liquefied gas propellant method. See United States Patent No. 2,321,023.

In accordance with the liquefied gas propellant method, the material to be dispersed as an aerosol is dissolved in a liquefied gas under pressure and the solution sprayed into the air. The liquefied gas boils violently, thereby breaking up the spray droplets into even smaller droplets with the result that when evaporation is completed, the material remains suspended in the air in very mi. nute particles on the order of a colloidal suspension.

In using this method as heretofore practiced, it is important to utilize low boiling point gas propellants which, when liquefied, have relatively high vapor pressures on th order of 50 to 100 pounds per square inch. Such pressures require the use of specially constructed containers. 'The cost of these containers is very high relative to the cost of their contents. Consequently, the ultimate consumer fails to obtain full value for the price he pays for such an aerosol producing solution when he purchases it in such expensive containers. Moreover, it is difllcult to handle liquefied gas solutions at such high pressures. This difiiculty involves additional increases in the cost of manufacture.

To obviate these deficiencies, attempts have been made to employ lower pressure propellants, thereby permitting the use of inexpensive containers, such as ordinary beer cans, which cost only a fraction of that of the regular aerosol containers. However, the use of ordinary spray devices is insuflicient to create a satisfactory aerothe provision of a spray nozzle for the purpose indicated whichcan be used to create aerosols from solutions of propellants having very low vapor. pressures and which are substantially as efiective as aerosols created by the use of ordinary propellants having vapor pressures of 60 to pounds per square inch. 0

In general, the objects-oi this invention are attained by the provision of a nozzle having two aligned apertures separated by a chamber which permits a preliminary expansion of the propellant before it is finally discharged into the atmosphere. In particular, the nozzle comprises a tubular member having a discharge end and another end adapted to be attached to the outlet of a container, this tubular member having a chamber section. There are further provided axially disposed walls at the ends of the chamber section, which walls have apertures therethrough, the apertures through the wall at the discharge end bein larger than the other aperture, the areas of these respective apertures being in the approximate ratio of 3 to 2. The diameter of the aperture in the wall at the discharge end is in the range of 0.016 to 0.024 inch, while the diameter of the other aperture is in the range of 0.0135'to 0.020 inch.

Two embodiments of this invention are illustrated in the accompanying drawing, in which Fig. 1 is an elevational view of an adjustable embodiment with a quarter section cut away:

Fig. 2 is also an elevational view with a quarter section cut away of a fixed embodiment; and Fig. 3 is a vertical section of the upper part of the tubular nozzle member of Fig. 1 illustrating the relative sizes of the apertures in the walls thereof.

Referring with more .particularity to Fig. l, the embodiment illustrated comprises a series oftubular members l5, l6, and 26. The tubular member 15 is provided with threads I3 at its lower end that engage corresponding threads of a head piece H, the latter bein integral with the container ID in which the aerosol solution is disposed. The usual dip tube I2 is connected to the tubular member l5 and extends to the bottom (not shown) of the container.

The tubular member l6 comprises a lower section in the form of a hollow needle I! that fits within the top part of the member l5 and is threadedly engaged therewith. The connection is pressure-sealed by means of a gasket 23 secured in position by means of a cap22 on threads M.

The objects of the present invention include 66 The bottom 0! the needle is closedand is prowardly from the wall of the member it. When the needle is seated in this position on the shoulder 9, the contents of the container it are sealed. The tubular member II is provided with thumb grips 24 to facilitate turning it. When turned in one direction, the beveled edge I 8 is forced against the shoulder 9. when turned in the opposite direction, it is moved out of contact with the shoulder, thereby permitting the passage of liquid within the container past this ,point into an annular space It between the lower section oi the needle and the inner wall of the member II. From this point it passes inwardly through radial apertures l9 and 20 and then into the hollow core of the needle, from whence it passes into the upper chamber 25 of the member IS. The tubular member 26 is engaged with the exterior of the upper section of the member l6 by means of threads 21.

The member 26 contains two removable walls 29 and 3|, one above the other, separated by a removable hollow cylinder 30 which cylinder comprises the expansion chamber. The walls, which are axially disposed at the ends of the cylinder, are provided with a central aperture 34 having a diameter in the range of 0.0135 to 0.020 inch, and another central aperture 35 having a diameter in the range of 0.016 to 0.024 inch. Aperture 35, which is in the wall at the discharge end, is larger than aperture 34, the areas of these respective apertures being in the approximate ratio of 3 to 2. The liquid under pressure passes from the upper chamber 25 through the first aperture 34 and then into the expansion chamber 30 where a small pressure drop is effected, with partial boiling of the propellant. This results in part of the propellant being converted to a gaseous phase and the formation of droplets of the remaining portion of the solution.

The residual pressure forces these droplets out through the aperture 35 where the final pressure drop causes further boiling oi the liquefied gas propellant in -each droplet, thereby causing the droplets to break up into still finer particles which assume aerosol or near aerosol proportions when all the liquefied gas evaporates.

The walls 29 and 3|, together with the expansion chamber 30, are held in place by means of a cap 32 removably engaged with the top of the member 26 by means of threads 28. The cap is provided with a wide outwardly flared passage 33 to permit escape of the material from the aperture 35 and to guide it into a conicallike pattern.

In operation, it is important that the pressure drop eilfected in the expansion chamber 30 be not too great but still great enough to obtain the desired effect explained above. A pressure drop just suflicient to form the droplets without waste ing or expending any unnecessary energy represented by the liquefied gas is important so as to reserve as much of this energy as possible for the final pressure drop into the atmosphere where a breaking up of the droplets must take place. This condition is a function of the size of the apertures 34 and 35. If the apertures are too large, the desired effects will not be obtained. Instead, only a wet mist will result.

Under the conditions of aperture sizes set forth above, we have found that a satisfactory volume of the expansion chamber is 0.008 to 0.01 cubic inch, although it is not indispensable that the volume be restricted to this range. In general,

4 I I what is desired is the establishment of conditions which will provide for a proper pressure drop in accordance with the requirements set forth.

. These requirements may be translated into specihe pressure drops for specific initial pressures which have been determined empirically to be as follows, all values being in pounds per square inch:

Initial Pressure to to to The arrangement of the aperture walls 29 and 3| and the intervenin expansion chamber is such that they may be removed and substituted with chambers and walls having, apertures 01 diiferent sizes to suit any particular conditions. Such substitution may be effected by removing the cap 32, then the walls 29 and ii with expansion chamber 30, reinserting other combinations of walls and expansion chambers having the desired dimensions and replacing the cap 32.

However, when such flexibility is not necessary and it is suilicient to employ a nozzle having fixed dimensions, the embodiment of Fig. 2 may be employed. In this embodiment all parts are fixed or integral. The threads 46 at the base of the nozzle are adapted to fit the threads 21 on the tubular member IS. The tip ll of the nozzle is provided with an aperture 43. Between the tip 4| and the base of the home, a partition 42 is provided having an aperture 44. The space 45 between the tip II and the partition 42 constitutes the expansion chamber. The size of the expansion chamber and of the apertures 43 and 44 conform, of course, to the requirements set forth above in order to obtain satisfactory aerosols and to avoid dripping onseparatory action of the aerosol. The inner wall 41 of the section between the base of the nozzle and the partition 42 is preferably streamlined to avoid any unnecessary heat losses through eddy currents.

Although this invention has been described as being particularly useful for use in dispensing aerosol solutions of low vapor pressure, it is to be understood that it may also be used for dispensing aerosol solutions of high vapor pressure. Havin thus described our invention, we claim: 1. An aerosol dispensin nozzle comprising a tubular member having a discharge end and another end adapted to be attached to the outlet of a container, said member having a chamber section, axially disposed walls at the ends of the chamber section, said walls having apertures therethrough, the diameter of the aperture in the 7 wall at the discharge end being in the range of 0.016 to 0.024 inch and the diameter of the other aperture being in the range of 0.0135 to 0.020 inch, the area of said aperture through the wall at the discharge end being to the area of the other aperture in the approximate ratio of 3 to 2.

2. An aerosol dispensing nozzle comprising a tubular member having a discharge end and another end adapted to be attached to the outlet of a container, said member having a chamber section, a removable cylinder in said chamber section having a volume in the range of 0.008 to 0.01 cubic inch, axially disposed removable walls at the ends of the cylinder, said walls having each an aperture therethrough, the diameter of 8 the aperture in the wall at the discharge end being in the range of 0.016 to 0.024 inch and the diameter of the other aperture being in the range of 0.0135 to 0.020 inch, the area. of said aperture through the wall at the discharge end being to 5 the area of the other aperture in the approximate ratio of 3 to 2.

ROBERT A. FULTON.

JOHN H. FALES.

REFERENCES CITED 0 UNITED STATES PATENTS Number Name Date Palmer Mar. 22, 1887 Battelle Dec. 27, 1904 Green Nov. 29, 1910 Koerting July 25, 1916 Rotheim Jan. 3, 1933 Vensel June 19, 1945 Gebauer et al May 14, 1946

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