Tank for transport and storage of semisolid and fluid materials

Abstract From the Canadian patent

An elongate tank for transport or for storage in bulk of semisolid and fluid materials, such as grease and oil. This tank has an outlet for the material contained therein at one end thereof, and is of generally cylindric internal cross section. It has a generally cylindric piston sized to slide therein which is adapted to be moved in a direction toward the outlet thereby forcing the material in the tank through the outlet. An elastic annular seal is carried in a circumferential channel around the piston adjacent one end of the piston. The seal is hollow and expandable and has a pressurizing device for varying the pressure within the seal between atmospheric pressure and a pressure higher …