NZ233906A - Dispensing head for pressurised container; ratio of actuator port area to valve port area when using compressed gas propellant - Google Patents

Abstract

Dispensing arrangements, comprising a gas-pressurized container for a material to be dispensed with a valve actuable to open a discharge passage through the valve and through a valve and a valve actuator to an actuator discharge outlet, are well known in the art. The invention proposes a non-liquefied gas-pressurized dispensing arrangement capable of being used with relatively low initial gas pressures, and of discharging a relatively high percentage of the dispenser contents with an acceptable spray pattern. The proposed dispensing arrangement attains these advantages by arranging the cross-sectional area of the valve port (17c) to be many times greater than the cross-sectional area of the actuator outlet (22a). In one recited embodiment the actuator outlet has a cross-sectional area in the region of 0.049 mm<2> whilst the total cross-sectional area of the valve ports, the valve having four ports, is some sixteen times greater.

Description

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NEW ZEALAND PATENTS ACT, 1953 P^2EA^D - pat£i^T office "1JUN/99Q received o No.: Date: COMPLETE SPECIFICATION IMPROVEMENTS IN OR RELATING TO DISPENSERS //We, RECKITT & COLMAN PRODUCTS LIMITED, a British company of One Burlington Lane, London, United Kingdom, W4 2RW hereby declare the invention for which t/ we pray that a patent may be granted to we/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - (followed by page la) 233906 - 1 a - "IMPROVEMENTS IN OR RELATING TO DISPENSERS" This invention relates to dispensers and, more specifically, to the dispensing of flowable materials from gas-pressurized containers.

It is well known in the art to dispense flowable materials from a container having a valve-controlled outlet by charging the container with the flowable material and a pressurizing gas, whereupon the gas forms a head space above the liquid. To dispense the flowable material the container is placed in a position where the inlet to the valve opening is below the material/gas interface whereupon, when the valve is opened, the pressurized gas propels the flowable material through the valve to discharge.

When the container is to be used erect the valve is conveniently located in the upper regions of the container and a dip tube within the container extends from the valve to the lower regions of the container so that, whilst the container is erect, the dip tube inlet is below the material/gas interface until substantially the whole of the material content of the container has been dispensed.

In one well known and widely used dispensing arrangement the valve is opened by depressing an actuator and the valve port opens to a chamber within the actuator from which the material is dispensed through a discharge outlet in the actuator.

Such a material dispensing arrangement is, hereinafter, referred to as "a dispensing arrangement of the type defined".

It should be noted that in a dispensing arrangement of the type defined the material flowing through the dip tube passes through a first restriction, defined by the valve port, and then through a second restriction defined by the actuator discharge outlet. Other restrictions may be imposed by the valve housing, the tail-piece and the dip-tube.

In some constructions for dispensing arrangements of the type defined the valve may include more than one valve port and/or the actuator may have more than one discharge outlet. Throughout this specification the term " cross-sectional area of the valve port" shall mean the cross-sectional area of the valve port in a single valve port arrangement and the sum of the cross-sectional areas of all the valve ports in a multi-port valve port arrangement and the term "cross-sectional area of the actuator outlet" shall mean the cross-sectional area of the actuator outlet in a single actuator outlet arrangement and the sum of the cross-sectional areas of all the actuator outlets in a multi-outlet arrangement.

One inherent problem with dispensing arrangements of the type defined resides in providing a pressurizing gas capable of maintaining sufficient pressure throughout the life of the container as to propelling at least the greater part of the material content from the container.

The above problem appeared to have been overcome by the use of the so-called "liquefied gases", that is to say gases at normal temperature and pressures which condense at relatively low pressures above atmosphere, generally between one and twelve atmospheres gauge. This is often reduced to the order of three atmospheres gauge by the presence of other components in the formulation.

When such liquefied gases are used in a dispensing arrangement of the type defined vaporization of the liquefied gas establishes the gas space at a pressure sufficient to propel the material contents out of the container and, as material content is discharged and the volume of the gas space increases, the liquefied gas vaporizes within the container, thus to maintain a substantially uniform material-propelling gas pressure in the head space until substantially all the material content has been discharged.

. The liquefied gases in being readily usable with a wide range of products, in allowing containers to be charged with material contents often in excess of 70% of the container volume and in allowing the use of relatively cheap low pressure containers in a wide variety of materials, have substantially dominated the dispensing industry for the past forty years.

Serious disadvantages in the commercial usage of the liquefied gases arise from the special plant, equipment and apparatus necessary for the safe transportation, storage and handling of such gases and in implementing and supervising the special precautions and regulations applicable thereto. r, • "2 5W<W92 233 - if - Further, the liquefied gases, and in particular the chlorofluorocarbons (CFCs), have now been recognised as harmful to the environment or having other undesirable features and the dispensing arrangement industry has been forced to seek alternative systems, essentially using compressed gases virtually all of which remain in their gaseous phase for all operating parameters of the dispensing arrangement and which gases are, hereinafter, referred to as "non-liquefied gases".

Gases obey the gas laws, at stable temperature the pressure reduces proportional with increase in volume and for non-liquefied gases the initial gas content must be sufficient to maintain a pressure adequate to propel an acceptable volume of the material content of the dispensing arrangement up the dip tube and through the valve arrangement.

As the gas pressure depends upon the volume of the material content in the dispensing arrangement the dispensing arrangement with its valve and actuator arrangement must be designed to safely withstand the initial high gas pressure as will exist when the dispensing arrangement is charged with its prescribed material content.

It is however believed that by careful design of the dispensing arrangement and by reducing the prescribed charge of material content to not more than 70%, and more preferably not more than 65%, of the volume of the dispensing arrangement, a dispensing arrangement can be designed to meet the above propellant requirements with the initial gas pressure little more than 100 p.s.i. (0.703 kg/cm^).

However, the liquefied gases used with certain material contents, solvents for material contents or additives, offer a further advantage in that the said liquefied gases can be dispersed through the material content in the dispensing arrangement. As the material content passes through the actuator outlet the entrained liquefied gas vaporizes, breaking up the discharging material into discrete particles a 2339 and blowing the particles apart to form a relatively constant spray pattern. This advantage is particularly useful when the material content is a liquid, whereupon vaporization of the liquefied gas leaving the actuator outlet breaks the liquid 5 material content into fine droplets, particularly advantageous for many applications such as hair sprays, air fresheners and liquid insecticides. Additional breakup can be achieved by bleeding propellant gas into the liquid stream from the vapour phase.

It will now be appreciated that whilst, as stated 10 above, it is possible to design a dispensing arrangement of the type defined to allow non-liquefied gases to propel an acceptable part of the material content to discharge such a design cannot, with the current state of the art, provide acceptable discharge pattern characteristics of the material 15 content propelled through the actuator outlet.

The reasons for this are, as will be apparent from the foregoing description, that the pressure of the non-liquefied gas propellant will be continuously reducing as material content is discharged from the dispensing arrangement and 20 without liquefied gas in the material being dispensed there can be no "blowing apart" of the material being dispensed. The reduction in pressure within the dispensing arrangement, with use, also reduces the flow rate of the material being dispensed.

The present invention seeks to provide a dispensing arrangement of the type defined capable of affording substantially constant discharge characteristics for a material being dispensed for the greater part of the life of the dispensing arrangement.

According to the present invention there is provided a dispensing arrangement of the type defined for use with non-liquefied gases, characterized in that the cross-sectional area r> £33 of the valve port is greater than the cross-sectional area of the actuator outlet.

Preferably the cross-sectional area of the valve port is greater than twice the cross-sectional area of the actuator 5 outlet, more preferably the cross-sectional area of the valve port is greater than five times the cross-sectional area of the said actuator outlet and most preferably the said cross-sectional area of the valve port is greater than ten times the cross-sectional area of the actuator outlet.

Preferably the actuator outlet has a cross-sectional 7 ? area of from 0.02 mm to 0.126 mm and, more preferably, from 0.04 mm^ to 0.071 mrn^.

In a preferred embodiment the actuator has a single outlet having a diameter of 0.25 mm.

Preferably the cross-sectional area of the valve port 9 9 2. is from 0.196 mm to 1.57 mm more preferably from 0.2 mm to 0.8 mm^.

In a preferred embodiment the valve has more than one port and in a more preferred embodiment the said valve has four 20 ports.

When the valve has more than one port the said valve ports are preferably of the same diameter and most preferably the diameters of the valve ports are in the region of 0.5 mm.

The invention also envisages dispensing arrangements, 25 of the type defined, having the actuator outlet/valve port relationship according to the invention, charged with a non-liquefied gas.

Preferably the said non-liquefied gas, comprises air, nitrogen or carbon dioxide.

The invention will now be described further, by way of example, with reference to the accompanying drawings in which, Fig. 1 shows a vertical cross-section through a valve system for a dispensing arrangement in accordance with the present invention, Fig. 2 shows a view of the valve port arrangement, on an enlarged scale with respect to Fig 1, with the valve port open, Fig. 3 shows, graphically, how the discharge rates through a fixed valve port differ with different actuator outlets for a liquid material having a viscosity of 510 c.p.s. (mPa s) using nitrogen as the non-liquefied gas.

Fig. 4 shows, graphically, the results of an experiment, identical to that illustrated in Fig. 3 but using air as the non-liquefied gas, and Fig. 5 shows, graphically, the results of an experiment identical to that shown in Fig. 4, for a liquid material having a viscosity of 20 c.p.s. (mPa s) Referring to Figs 1 and 2 a dispensing arrangement generally comprises a valve system, supported by a conventional cup 11 intended to close the opening in a container C, generally comprising a body 12, rigidly crimped into the cup 11 within the container C, with an actuator/valve assembly supported by the body 12 and axially displaceable relative thereto. ~N r °* -/ 5MAU1992 £3390 The body 12 is a body of revolution defining a large bore 13 with a small through bore 14, axially aligned with and opening to the bore 13.

A dip-tube T is attached to the outer cylindrical surface of the wall defining the bore 14 and extends into the container C to open in the lower regions of the said container C.

The body 12 includes an annular flange 15 at that opposite axial end to which the bore 14 opens and an annular, flexible, resilient gasket 16 has its radially outermost parts clamped between the flange 15 and the cup 11.

A valve stem 17, with a blind bore 17a^ extends through a clearance bore in the cup 11, through the bore in the gasket 16 and terminates in an integral annular block 17b, within the bore 13, having a diameter larger than the diameter of the bore in gasket 16. A coil compression spring 18 acts on the block 17b and continuously urges the block 17b against the gasket 16. The valve stem 17 has an actuator button 19 secured thereon.

The valve stem is a friction fit in the bore of the gasket 16 and includes a valve port, defined by a radial opening' 17c_ in the wall of the valve stem 17 opening to the bore 17au The valve port 17c^ is so located from the block 17b that said valve port I7_c is closed by the gasket 16 when the gasket is unflexed (as shown in Fig 1) and is open to the bore 13 when the actuator button 19 is depressed, thereby forcing the valve stem 17 into the body 12 and flexing the gasket 16 inwardly of the container as shown in Fig 2.

At its end entered into the actuator button 19 the bore 17ja of valve stem 17 opens to a chamber 20, which may include a conventional swirl block 21, and an exit passage 19a. from the chamber 20 is closed by an insert plate 22 in the actuator which has an aperture 22a_ therethrough defining^ the^^ • I EN/* actuator discharge outlet. V* The valve arrangement described thus far is of a conventional design, with the actuator button 19 released the spring 18 urges the valve block 17b and stem 17 upwardly to the position shown in Fig. 1 where the gasket 16 is sealing the valve port 17£.

When the actuator button 19 is depressed the block 17b is displaced downwardly away from the gasket 16, the gasket 16 deflects into the bore 13 exposing the valve port 17£ and, under the action of the propellant pressure gas in container C, container contents are driven up the dip tube T into the bore 13 and therefrom through the valve port 17c_, up the blind bore 11a to the chamber 20 and therefrom along the passage 19a_ and through the actuator outlet 22a to discharge.

In the conventional arrangement for non-liquefied gases the cross-sectional area of the valve port 17£ would be similar to the cross sectional area of the actuator outlet 22a_ but, for a material dispensing arrangement of the type defined in accordance with the present invention, this relationship is disregarded and the actuator outlet has a very much smaller cross-sectional area than the valve port.

Thus, for the illustrated example using a non-liquefied gas such as nitrogen, a liquid material content charging 50% to 60% of the container volume and the gas space n charged to an initial pressure of 100 p.s.i. (7.03 kg/cnr) the actuator outlet 22ja may conveniently have a diameter of 0.25 9 9 mm, giving a cross-sectional area of 0.049087 mm (0.049 mm ), and the valve port, conveniently four ports 17_c on a common plane at right angles to the axis of the stem 17, may have each port 0.5 mm in diameter, giving a cross-sectional area of 0.7854 mm^ (0.79 mm^).

As will become evident hereafter, such proportions have been shown in practice to allow a substantially uniform discharge rate throughout substantially the whole of the life of the container, with a relatively fine droplet size in a wide - spread distribution spray pattern compatible with that obtainable by a liquefied gas dispensing arrangement.

EXPERIMENT I Six dispensing arrangements were used for each trial, 5 each container was charged to 55% of its volume with a furniture polish having a viscosity of 510 c.p.s.(mPa s) and the remaining volume in each container was charged with O nitrogen to a pressure of 100 p.s.i. (7.03 kg/cm"6). All six dispensing arrangements had a valve port arrangement comprising 10 four 0.5 mm diameter ports, giving a cross-sectional area of 0.79 mm^.

The dispensing arrangements differed only in the cross-sectional areas of their respective actuator outlets and Table II shows the different actuator outlet sizes for the six 15 dispensing arrangements.

""N TABLE II DISPENSING NUMBER OF ARRANGEMENT OUTLETS DIAMETER CROSS-SECTIONAL OUTLET AREA OF OUTLET AREA OF OUTLET RELATIVE TO VALVE PORT AREA A B C D E F mm 0.6 0.5 0.45 0.4 0.3 0.25 mm 0.283 0.196 0.159 0.126 0.071 0.049 0.36 0.25 0.2025 0.16 0.09 0.0625 * 23 3 - n - Each dispensing arrangement was discharged in a series of 10 second sprays and the material discharged in each spray was measured and noted. r~*) On average the containers discharged some 94% of their polish charge.

The trial was repeated and Fig. 3 illustrates, graphically, the mean values obtained for the different actuator outlets under trial, the discharge in grams being plotted vertically and the number of 10 second sprays being ^ 10 plotted horizontally.

Fig. 3 clearly shows that as the cross-sectional area of the actuator outlet was reduced the rate of distribution became more uniform and, contrary to what one would expect with a continuously falling propellant gas pressure, the dispensing 15 arrangements E and F illustrated substantially uniform rates of discharge for more than 90% of the material contents.

EXPERIMENT II The above described Experiment I was repeated, simply substituting air for nitrogen as the propellant gas, and Fig. 20 4 shows, graphically, the results of the air trials. For Fig. ^ 4 the different actuator outlet cross-sectional areas are identified in Table II.

TABLE II CROSS- SECTIONAL AREA GRAPH ^ 25 OF ACTUATOR OUTLET mm 0.283 a 0.196 b 0.159 c 0.126 d 0.071 e 0.049 f A comparison of the results illustrated in Figs. 3 and 4 clearly shows that the substitution of air for nitrogen had little effect, if any, on the results obtained and such minor variations as did occur are due to the minor differences in the discharge characteristics of the different dispensing arrangements, attributable to the valve housing, the tail piece and the dip-tube as defined hereinbefore.

It was also observed that as the cross-sectional area of the valve port increased relative to the cross-sectional area of the actuator outlet the more consistent became the area covered by the spray pattern throughout the life of the dispensing arrangement.

EXPERIMENT III Six substantially identical dispensing arrangements, each having an actuator outlet with a cross-sectional area of 0.049 mm^, were charged with furniture polish to 55% of their volumes and then charged to 100 p.s.i. (7.03 kg/cm ) with nitrogen.

The containers varied only in the cross-sectional area of their respective valve ports as shown in Table III; TABLE III DISPENSING CROSS-SECTIONAL ARRANGEMENT AREA OF VALVE PORT (mm^ ) a 0.071 b 0.159 c 0.196 d 0.283 e 0.392 f 0.783 m 233 n o The dispensing arrangements were then successively subjected to a standard test wherein each dispensing arrangement to be tested was supported above a horizontal target plane with its axis inclined at an angle of 40 degrees to the horizontal (the actuator being uppermost) and with the centre of the dispensing arrangement 200 mm above the target plane. The container was then discharged for 4 seconds and the area of the target plane covered by the dispensed material was measured and noted.

The dispensing arrangements were then each discharged to \ full and again subjected to the above test and the area of the target plane covered by the dispensed material was again measured and noted.

Table IV shows the results of one such experiment.

TABLE IV CROSS-SECTIONAL SPRAY AREA SPRAY AREA % SPRAY AREA AREA OF VALVE PORT mm 0.071 0.159 0.196 0.283 0.392 0.783 COVERED BY COVERED BY OF FULL CONTAINER FULL cm 422 638 540 651 596 798 1/4 FULL CONTAINER CONTAINER cm 110 220 300 460 410 580 COVERED BY 1/4 FULL CONTAINER 26 34 56 72 70 73 It will be noted from Table IV that the percentage of the area of the full container spray pattern covered by the quarter full container increased with increase in the difference between the " " 23 39 0 6 cross-sectional areas of the valve port and the actuator outlet. As the area covered can be taken as indicative of the spray distribution, the reisults obtainable by utilizing valve port cross-sectional areas many times larger than the actuator outlet are closely comparable with the results obtainable by liquefied gas dispensers.

In all the above described experiments the contents of the dispensing arrangements was a furniture polish having a viscosity of 510 c.p.s. (mPa s) and Experiment IV was carried out to ascertain what effects, if any, viscosity may have on the dispensing arrangement proposed by the present invention.

EXPERIMENT IV Six dispensing arrangements were used for each trial, each container was charged to 55% of its volume with a laundry spray material having a viscosity of in the region of 20 c.p.s.(mPa s)and the remaining volume in each container was charged with air to a pressure of 100 p.s.i. (7.03 kg/cm^).

All six dispensing arrangements had a valve port arrangement comprising four 0.5 mm diameter ports, giving a cross- 9 sectional area of 0.79 mm.

The dispensing arrangements differed only in the cross-sectional areas of their respective actuator outlets and Table V shows the different actuator outlet sizes for the six dispensing arrangements. 233906 TABLE V DISPENSING NUMBER DIAMETER CROSS-SECTIONAL OUTLET AREA ARRANGEMENT OF OUTLETS OF OUTLET AREA OF OUTLET RELATIVE TO 2 VALVE PORT AREA mm mm A' 1 0.6 0.283 0.36 B1 1 0.5 0.196 0.25 C' 1 0.45 0.159 0.2025 D' 1 0.4 0.126 0.16 E' 1 0.3 0.071 0.09 F' 1 0.25 0.049 0.0625 Each dispensing arrangement was discharged in a series of 10 second sprays and the material discharged in each spray was measured and noted.

The results of this experiment are graphically illustrated in Fig. 5, the material dispensed in grams being plotted vertically and the number of 10 second sprays being plotted horizontally.

A comparison of the results obtained and illustrated by Figs. 4 and 5, in which the only differences were in the product type, the viscosity of the material being dispensed and such minor variations in the flow characteristics of the dispensing arrangements as has been described above, clearly shows that the differences in product type and viscosity had little effect on the dispensing characteristics of the dispensing arrangement proposed by the present invention and, therefore, the dispensing arrangement proposed by the present invention appears to be capable of dispensing virtually all the materials dispensable by liquefied gas dispensing arrangements.

Claims (1)

1. «p*s £ j j 9 0 6;■ — 16 —;WHAT //WE CLAIM IS:;1. A dispensing arrangement of the type defined for use r~~} with non-liquefied gases, characterized in that the cross-;sectional area of the valve port is greater than twice the ^ cross-sectional area of the actuator outlet.;n;10 2- A. dispensing arrangement according to claim 1,;characterized in that the cross-sectional area of the valve port is at least five times greater than the cross-sectional area of the actuator outlet.;3- A dispensing arrangement according to claim 1 or 2, 15 characterized in that the cross-sectional area of the valve port is at least ten times greater than the cross-sectional area of the actuator outlet.;4- A dispensing arrangement according to any one of the preceding claims, characterized in that the actuator outlet has a cross-sectional area of from 0.02 mm^ to 0.126 mrn^.;5* A dispensing arrangement according to any one of the preceding claims, characterized in that the actuator has a single outlet having a diameter of 0.25 mm. "2 5 MAR 1992 " - 17 - 6. A dispensing arrangement according to any one of the preceding claims, characterized in that the cross-sectional area of the valve port is from 0.196 mm^ to 1.57 mm^. 7. A dispensing arrangement according to any one of the preceding claims, characterized in that the arrangement includes four valve ports, each having a diameter of 0.5 mm. 8. A dispensing arrangement of the type defined according to any one of the preceding claims, charged with a non-liquefied gas. 9- A dispensing arrangement according to claim 8, characterized in that the gas comprises nitrogen. 10 • A dispensing arrangement according to claim 8, characterized in that the gas comprises carbon dioxide. 11- A dispensing arrangement according to claim 8, characterized in that the gas comprises air. 12. A dispensing arrangement as defined in claim 1 substantially as herein described with reference to any example thereof or to the accompanying drawings. By jskc/Ttioir aui'noriood Agent A.J. PARK & SON Per: