AEROSOL CONTAINER TESTING APPARATUS

Abstract: The apparatus comprises a conveyor (16) having an open mesh endless belt (12) for transporting arriving aerosol containers (8) through a heating station (2). The heating station (2) comprises an array of shower heads (22) which rain heated water down onto the containers (8) carried by the conveyor (6) until the temperature of the containers (8) and their contents are substantially stabilised at a predetermined level. Thereafter, the conveyor (6) carries the containers (8) through a drying station (4) where they are subjected to blow drying.

Description: AEROSOL CONTAINER TESTING APPARATUS The present invention relates to aerosol container testing apparatus In the manufacture of aerosol cans, the cans are filled with a product to be dispensed and with a propellant, pressurised and then sealed with a valved cap Before these containers can be packaged and shipped out, they are required to be tested to eliminate any cans with leaks or weak spots It is a requirement that the cans be heated until they and their contents reach an equilibrium temperature of 50°C This increases the pressure of the propellant within the can to a point at which any significant weaknesses should manifest themselves To effect this test, a conveyer system was provided to gπp each can of a row of cans arriving in single file at the testing station, by its head, and to draw it through a tank of water heated to a temperature of 55°C The length of the tank is such that each can remains submerged for around 3 minutes to allow the temperature of the can and contents to equalise The cans are then withdrawn from the water in the tank, dπed and tested for leaks The conveyor remains proud of the surface of the water in the tank and keeps all but the head of each can submerged as it travels over the tank This system suffers from a number of disadvantages Firstly, the tank is filled with a high volume of water which must be constantly circulated and heated to a temperature of 55°C Secondly, the conveyor system is adapted to draw only a single row of cans through the water tank with the cans being spaced at regular intervals from each other To feed a second row of cans requires a second conveyor system It is an object of the present invention to provide an improved aerosol container testing apparatus. According to the present invention there is provided aerosol container testing apparatus comprising a heating station and a drying station, a conveyor for carrying an array of approaching containers in succession through said heating station and said drying station, said heating station including means providing a shower curtain of heated liquid to shower said containers as they are carried by the conveyor through said heating station, the length of the shower curtain, in relation to the speed of the conveyor, being such that the temperature of each container and its contents become substantially stabilised at a temperature approaching that of the liquid. An aerosol testing apparatus embodying the present invention, will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a side elevation of the testing apparatus; and Figure 2 is a fragmentary plan view, to an enlarged scale, of part of the conveyor travelling through the testing station. The testing apparatus comprises a heating station 2, a drying station 4 downstream of the heating station and a leak detecting station (not shown) located downstream of the drying station. A conveyor 6 conveys filled aerosol cans 8 received from a feed conveyor 10 successively through the heating station 2 and the drying station 4. The conveyor 6 consists of an endless belt 12 extending around a pair of rollers 14 and 16. The endless belt 12 is of open mesh material, for example stainless steel, which allows the passage of any water therethrough. Located below the belt 6 is a wide trough 18 to collect any water passing through the belt. The trough 18 is thermally insulated to minimise heat loss. The heating station 2 includes a housing 20 supporting, in its upper region, an array of shower heads 22 which provide a shower curtain to envelop any aerosol cans being conveyed through the heating station on the conveyor 12. Instead of an array of show headers, other means can be provided to generate the shower curtain. A pump 24 pumps water drawn from an outlet at the bottom of the trough 18 and feeds it through a heater 26 connected to a power source 28. A pipe 30 delivers the heated water from the heater 26 to the shower heads 22. The heater 26 heats the water in the range of from 55°C to 65°C. The heated water, which is then showered on the cans 8, heats the cans and their contents to an equilibrium temperature of around 50°C. The speed of the conveyor 6, in relationship to the length of the shower curtain in the direction of travel of the cans, is such as to allow each can to dwell in the shower curtain for around 2.5 to 3.00 minutes to achieve equilibrium at 50°C. Typically, the conveyor 6 may move the cans 8 at a speed of lm/minute and the shower curtain may be 3m in length. The air knife 32 is located at the downstream end of the housing 20 to drive excess water from the outer surface of the cans. The air knife may be located above and/or below the cans. The conveyor 6 then carries the cans through the drying station 4. The drying station 4 includes a housing 36 supporting an array of air jets 38 which blow hot or warm air at the cans 8 to complete the drying process. The jets 38 are supplied by a fan heater 40 located on top of the housing. In a modification, instead of the shower heads 22 being located above the conveyor 6, they can be located between the upper and lower runs of the belt 12 and directed upwardly through the upper run of the belt to provide a shower curtain in the form of a shower fountain. The advantage of this arrangement, is that the water will initially impinge on the underside and lower portions of the cans 8 which is generally where the higher heat capacity product to be dispensed is located and so temperature equilibrium will be achieved much sooner. The speed at which hot liquid flows along the sides of the cans is considerably faster than the speed of the conveyor 6 and so heating takes place much faster and more efficiently than when the cans are being dragged through a bath of hot water, as in the prior art. In a modification, the shower heads may be arranged to produce water streams which intersect one another at the point at which the cans pass therethrough to effect more efficient heating of the cans. As can be seen in Figure 2, the provision of a wide belt 12 allows the cans to arrive and pass through the heating station 2 in a random manner without the need to slow down and deliver the cans in single file and at spaced intervals, as required by the prior art. The heater 26 can comprise a heat exchanger and be provided with a filter to filter the water entering or leaving the heater 26.

Claims: CLAIMS 1. Aerosol container testing apparatus comprising a heating station and a drying station, a conveyor for carrying an array of approaching containers in succession through said heating station and said drying station, said heating station including means providing a shower curtain of heated liquid to shower said containers as they are carried by the conveyor through said heating station, the length of the shower curtain, in relation to the speed of the conveyor, being such that the temperature of each container and its contents become substantially stabilised at a temperature approaching that of the liquid. 2. Apparatus according to Claim 1, wherein said conveyor comprises an endless belt of porous material. 3. Apparatus according to Claim 1, wherein said conveyor comprises an endless belt of open mesh material. 4. Apparatus according to any preceding claim, wherein said shower curtain is provided by a plurality of shower heads located above the conveyor. 5. Apparatus according to any one of Claims 1 to 3, wherein said shower curtain is produced by a plurality of shower heads located below the upper surface of the conveyor. 6. Apparatus according to any preceding claim, wherein said heating station includes a trough located below said conveyor to collect the liquid from said shower curtain, heating means for reheating the collected liquid and pump means for recycling the reheated liquid to said shower curtain. 7. Apparatus according to any preceding claim, including an air knife located at the downstream end of the heating station to remove excess liquid on each container as it emerges from the heating section. 8. Apparatus according to any preceding claim, wherein said drying station includes an array of warm air jets for drying said containers as they pass therethrough. 9. Apparatus according to Claim 4 or to Claim 5, wherein said shower heads are arranged to provide two shower curtains inclined to one another at a predetermined angle. 10. Apparatus according to any preceding claim, wherein said liquid comprises water. 11. Aerosol container testing apparatus, substantially as hereinbefore described, with reference to the accompanying drawings.

Inventors: BOYLE RICHARD JOHN, BOYLE, RICHARD, JOHN
Applicants: BOYLE RICHARD JOHN, BWI PLC, BOYLE, RICHARD, JOHN
Application year: 2000
Main classification: G01M3
IPC codes: G01M3