A pressure control device for isolating a section of a conduit is described. The device comprises a support member, a flexible cup member mounted to the support member, a first swellable element, the first swellable element adapted, upon activation by an activation fluid, to urge a first portion of the cup member outwards into engagement with a conduit surface and at least one bypass arranged to permit the activation fluid to bypass the swellable element and build up behind a second portion of the cup member.