Dispensing – Automatic control – Of dispensers with fluid pressure discharge assistance
Patent
1979-02-26
1984-05-29
Skaggs, H. Grant
Dispensing
Automatic control
Of dispensers with fluid pressure discharge assistance
222 64, 222639, 137209, B67D 508
Patent
active
044509812
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates generally to material filling systems, and more particularly relates to precision filling systems capable of filling containers within tolerance limits of .+-.0.1% to .+-.0.5%. The system is applicable for the precise dispensing of fluid materials through a wide range of viscosity including creams, but is also usable for the dispensing of powdered and particulate materials.
BACKGROUND ART
Filling accuracies in various packaging fields have been expected only within the range of 2% to 5%, and in such cases it has been necessary to overfill the package or container in order not to be underfilled within the filling tolerance limits. Particularly in the pharmaceutical field, with some substances costing on the order of $50.00 to $100.00 per ounce, the savings in product cost achievable with equipment capable of accuracies within the 0.1% to 0.5% range is very high and can effect such cost savings as to pay for the equipment according to the invention within extremely short times, sometimes within a matter of weeks.
Presently used filling systems use pumping devices such as piston pumps or rotary pumps, both of which have moving parts which cause abrasion and the generation of fine particles which can and do enter into the product being dispensed, thereby causing particulate contamination. The system according to the invention has no moving parts during the dispensing process and is free of particulate contamination.
Further, in the pharmaceutical field, sterilization is sometimes extremely important, and pharmaceutical companies when running some products operate a third eight hour shift each day solely to dismantle, autoclave the system parts, and reassemble the system. Even with such sterilization techniques there is the continuing possibility of recontamination of the equipment due to handling in reassembly. The system according to the invention is sterilizable without disassembly and in a small fraction of the time required by the present day conventional sterilization techniques for such systems.
Finally, the pumping fill systems presently used create two additional problems when dispensing certain types of materials. One problem is foaming which can take place because the materials are not handled in a gentle fashion due to the high peak pressures developed by pumping type dispensing systems. The second problem is that of molecular shear which causes damage to protein substances, and which occurs in conventional piston type filling equipment as a result of the piston walls being wiped by the piston seals as the substance flows through the pump.
DISCLOSURE OF INVENTION
The filling systems according to the invention utilize pneumatic pressure maintained within closely held tolerance limits to impose a constant dispensing force upon the material being dispensed, thereby avoiding foaming by providing a lower average and constant flow rate to the substance being dispensed. Additionally, since the material being dispensed is not in contact with moving parts during the dispensing operation, there is no abrasion and particulate contamination, nor is there molecular shearing damage to the products being dispensed. Also inherent in the system is the ability to steam or gas sterilize the entire system without dismantling any part of it by introducing steam or gas at various points in the system and allowing it to flow through the system out through the dispensing head. The invention in one embodiment utilizes a buffer tank system, and in a second embodiment utilizes a pressure balancing system.
The buffer tank system minimizes the effect of high gravity head pressure found in conventional deep supply tanks. Such gravity head pressure reduces as the level in the tank drops, and can significantly change the amount of product passing through the dispensing head if not compensated for. In order to minimize this effect so as to maintain an acceptable accuracy tolerance, the product to be dispensed is transferred from the supply tank to the buffer tank where the desired press
REFERENCES:
patent: 2660336 (1953-11-01), Coffey et al.
patent: 3394847 (1968-07-01), Garrard
patent: 3499580 (1970-03-01), Smith
patent: 3612090 (1971-10-01), Kassel
patent: 3976222 (1976-08-01), Spagnolo
patent: 4090526 (1978-05-01), Witt et al.
Jacobs Abe
Skaggs H. Grant
Udell Walter B.
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