Image Number 4 for United States Patent #4213545.
A positive expulsion tank incorporates an expanding bladder in the form of a metal bellows, which is adapted to undergo elastic deformation during a product storage condition to provide for thermal cycling of a stored product, and plastic deformation, during a product expulsion operation to achieve high efficiency expulsion of product from the tank. Convolution crests of the bellows are internally reinforced by rings, whereby plastic deformation of the bellows is caused to occur primarily in the root areas during the expulsion operation. As a result, the root areas are displaced radially outwardly towards the wall of the tank incident to axially directed extension of the bellows to lie in essential alignment with their adjacent crests when the bellows has been fully extended to complete the expulsion operation, thereby providing for expulsion efficiencies in excess of 97 percent.
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