Patent ID: 8042334

Claim:
An apparatus comprising: a structural frame; a generally vertical fluid container containing a fluid supported on the frame; an endless chain of gas containing capsule elements having a portion of the elements passing through the fluid in the fluid container; a wheel rotatably fastened to the frame outside the container, the endless chain of elements passing over the wheel; the capsule elements being in complementary relationship with each other about the perimeter of each capsule so as to provide a straight line outer surface of the chain of capsule elements around the perimeter of the chain, and wherein each capsule element comprises: a hollow tubular wall; a curved concave top cap closing an upper end of the tubular wall; a bottom convex cap closing a bottom end of the tubular wall; such that the concave top fits in the convex bottom in complementary relationship and a linkage pin supported in the bottom cap engaging a portion of an adjacent element.