<p>A conduit stopper (10) used for interrupting the flow of fluid through an elongated conduit (12) comprises a nozzle (20) sealingly mounted on the conduit in communication therewith through an aperture (18). A deformable sealing element (92) having opposed substantially flat sides is movably mounted in the nozzle and is engageable with the interior of the conduit to interrupt the flow of fluid through the conduit. A carrier (110) is sealingly connected to the sealing element and an actuator (80) is connected to the carrier for moving the carrier into sealing communication with the nozzle and then to deform the sealing element into sealing engagement with the interior of the conduit while the carrier and the nozzle are in sealing communication. <IMAGE> <IMAGE></p>
