Flow control bladders for zone control apparatus

Claim 1

A flow control bladder for controlling flow through a conduit, comprising: a flexible walled body having a hollow interior; and fluid passage means for passing an inflation fluid in and out of said hollow interior thereby transforming said body between an inflated condition for restricted flow through a conduit and a deflated condition for relatively unrestricted flow through a conduit; and wherein said body includes first and second panel walls, which normally are generally parallel when said body is in said deflated condition, and opposite side walls connected to the first and second panel walls at respective peripheral side folds, each side wall includes an inner fold which opens in a direction opposite the peripheral side folds when said body is in said deflated condition, said peripheral side folds extend between and converge towards one another at opposite ends of said body, said opposite ends of said body are movable towards one another upon inflation of said body, and said body is formed, at least in the regions thereof containing said side and inner folds, of a material that is flexible without permanent deformation during inflation and deflation of said body between said inflated and deflated conditions, whereby said body may resume its former shape when deflated.