Patent ID: 8434511

Claim:
A gate valve comprising: a valve housing including a passageway arranged along a passage axis from a first axial side to an opposed second axial side of the valve housing; and an expandable gate member movable within the housing from a retracted position displaced from and not blocking the passageway to a blocking position disposed in the passageway, the expandable gate including: a sealing member configured to seal a sealing surface disposed on the first axial side when the gate member is expanded, an opposed member configured to abut an abutting surface facing the sealing surface and disposed on the second axial side when the gate member is expanded, a pneumatic cavity having movable expandable sides disposed inside the gate member such that positive gaseous pressure applied to the pneumatic cavity activates the gate member to a compressed state, a compression spring disposed inside the pneumatic cavity and biasing the gate member to an expanded state, and first and second flexible side walls forming walls of the pneumatic cavity.