Apparatus and methods for restricting flow in a bore

摘要

Apparatus (10) for restricting a flow of fluid through a bore (14) comprises a bore sealing member (12a) and an actuation assembly for moving the bore sealing member (12a) between first and second configurations. The actuation assembly is configured to isolate first and second end portions (46, 48) of the activation member (12a) from a bore fluid (50). The apparatus (10) provides for moving the bore sealing member (12a) between the first and second configurations without a bore fluid (50) pressure acting on an end portion (46, 48) of the activation member (12a).