Feed connection part, wherein the feed connection part comprises connection means for connecting the feed connection part to a feed device for gaseous media, wherein the feed connection part comprises receiving means for receiving a mating connection part, wherein the feed connection part comprises at least one actuating element, wherein the receiving means comprise blocking means, wherein, in a first position of the at least one actuating element, the blocking means of the receiving means of the feed connection part prevents a mating connection part that is inserted into the receiving means from becoming mechanically detached by means of retaining the mating connection part in a positive-locking manner, wherein in this first position furthermore passage means are open (5, 18, 16) so as to discharge the gaseous medium by way of the feed connection part into an inserted mating connection part, wherein, in a second position of the at least one actuating element, the feed connection part is blocked against discharging the gaseous medium (5, 6, 9, 10) and the blocking means of the receiving means are released (12, 13, 301; 12, 501, 502; 12, 601, 602; 12, 801, 802; 12, 1101; 12, 1401, 1402, 1403), wherein the at least one actuating means comprises an intermediate position in which the feed connection part is blocked against discharging the gaseous medium (5, 6, 9, 10), wherein furthermore the blocking means of the receiving medium of the feed connection part prevents a mating connection part that is inserted into the receiving means from becoming mechanically detached by means of retaining the mating connection part in a positive-locking manner (12, 302; 12, 1404; 12, 1102) and wherein a mating connection part that is inserted into the receiving means is connected to the surrounding atmosphere (16, 18, 17, 19, 20), wherein the feed connection part comprises at least one venting duct (16, 18, 17, 403, 2203, 2501), wherein in the said intermediate position a mating connection part that is inserted into the feed connection part is connected by way of the at least one venting duct (16, 18, 17, 403, 2203, 2501) to the surrounding atmosphere, wherein this at least one venting duct (16, 18, 17, 403, 2203, 2501) extends in part between the inner face of the receiving device of the mating connection part in the feed connection part and the mating connection part that is inserted into the feed connection part and/or extends in part between the outer surface of the feed connection part and the at least one actuating element and/or extends in part through the at least one actuating element, wherein at least a further blocking means is provided that in the case of a pressure above a threshold value in the mating connection part is maintained at least in the intermediate position in a positive-locking manner and/or non-positive locking manner in a securing position (2001, 2004) with the result that a movement of the at least one actuating element out of this intermediate position into the second position is prevented, wherein the pressure above the threshold value holds the blocking means in the securing position against a spring force, wherein, in the case of a pressure below the threshold value of the pressure in the mating connection part, the blocking means is moved by means of the spring force out of the securing position with the result that a movement of the at least one actuating element out of the intermediate position into the second position is rendered possible, wherein the further blocking means is embodied as a differential piston that comprises two surface areas that are of different sizes, lie opposite one another and are influenced with the same pressure in the mating connection part. extends in part between the inner face of the receiving device of the mating connection part in the feed connection part and the mating connection part that is inserted into the feed connection part and/or extends in part between the outer surface of the feed connection part and the at least one actuating element and/or extends in part through the at least one actuating element,