The invention relates to a functional medical device (900) with a valve seat (803) for a non-return valve (1). In addition to a first position which is suitable for sterilizing gas, the non-return valve (1) is designed to assume a second functional position, in which the non-return valve (1) exerts a non-return function, by applying a force onto a portion of the non-return valve (1) and/or by moving the non-return valve. The non-return valve (1) is designed to remain in the second position after being successfully converted into the second position after the force and/or the moving element has been removed.
