GB1412688A - Method in vacuum packing of compressible material eg foodstuffs and similar products and an arrangement for the execution of said method - Google Patents

Abstract

1412688 Packaging granulated or powder materials CHRISTENSSONS MASKINER & PATENTER AB 13 March 1973 11900/73 Heading B8C In a method for use in vacuum packing of compressible material, e.g. food stuff and similar products, in which method the material to be packed is precompressed in a package and then the package is introduced into a vacuum chamber for evacuation and final closing, the precompression takes place by means of a tool, e.g. a piston 23, Fig. 3, introduced into the interior of the package under pressure applied from outside, the said pre-compression taking place to such a degree that the material to be packed will assume, at least approximately, the volume which the material would have assumed if no mechanical compression had existed and the only compression had been that occurring when the package, after closure in the evacuation chamber, were again brought out into the outer atmosphere. The product may be subjected to the usual short-duration, shaking, or vibration. to reduce its volume to between 2 and 3% before the mechanical pre-compression which further reduces the volume from between 15, and 20%. For the required amount of precompression the degree of increase of volume of the product, due to resilient recovery, is considered to be negligible, the pre-compression providing a bond between the granules of the product instead of breaking off their outer fibres as is stated to be the case when the product is subjected to an intensive shaking to provide an equivalent reduction of volume. As shown in Fig. 3, a plastics-lined cardboard package 11 is placed in a casing 10 with its closure flaps 12- 14, and lining 15, extending above the upper edge of the casing 10, the product, after aninitial light shaking, being at level 16. A resilient skirt 20, carried by a vertically movable frame 17, is lowered into the mouth of the package with its lower edge 21 above the level 16. A piston 24, operated by a pneumatic motor 25, is lowered through the skirt 20 to compress the product by an amount which would have been obtained by the evacuation process without pre-compression. The piston 24 is provided with spring- loaded valves 32 which open when the piston 24 is withdrawn. After pre-compression the piston 24 and skirt 20 are withdrawn upwardly and the package is transferred to an evacuation chamber, not shown. In a somewhat similar arrangement, Fig. 4, small and larger pistons 40, 41, successively compress the product. The pressure is increased in steps up to its maximum value.