A valve door for a seal cylinder comprises a lid having first and second surfaces and a connecting means connecting the lid with an actuating mechanism, the connecting means distributes forces from the actuating mechanism across a portion of the first lid surface in order to bias the lid to a closed position. A force directing member is attached to the first lid surface, the force directing member being adapted to distribute force from the connecting means over a portion of the lid surface, thereby maintaining a positive seal and reducing lid deflection.