Polyethylene film sack for beer inside pressure vessel - is of two films below critical thickness for leakage

摘要

Two films are used to form a sack to be filled with a fluid, esp. beer, inside a pressure tank. The thickness of each film is selected so that it is below the critical thickness at which pressure loading tends to reveal points of leakage. A connection for the inlet and outlet of the fluid is bonded to a laminated arrangement forming the sack from film. The sack consists of a tubular centre section, to which the inlet section carrying the connection is attached. The bottom closing section is similarly attached by welding. The sack is simple to produce and overcomes the problems of leakage caused by incompletely melted granular material in single films of polyethylene, which increases with the thickness of the film.