Abstract: An energy conversion device, a removable assembly for use with the energy conversion device and an associated methods. The energy conversion device comprises a flexible diaphragm configured to be located between a first fluid and a second fluid and being moveable in response to variations in at least one of the first and second fluids to permit energy transfer between said fluids; and a limit apparatus configured to limit movement of the diaphragm at a limit position, wherein the limit apparatus defines a contoured contact surface configured to be engaged by the diaphragm when in its limit position.