Apparatus and method for forming plastic preforms into plastic containers with wear check of valves

A valve device, wherein said valve device has a media inlet for a flowable medium and a media outlet for the flowable medium and a linearly movable piston device which is movable between at least two positions of the valve device, wherein in one of the two positions a media flow of the flowable medium from the media inlet to the media outlet is enabled and in the other of the two positions a media flow of the flowable medium from the media inlet to the media outlet is prevented, and having a housing within which the piston device is movable,

• wherein
• at least a portion of the piston device and/or a valve seat can be observed by an optical detection device through a region of the housing.

A method for forming plastic preforms into plastic containers, wherein a movable carrier, on which a plurality of forming stations for forming the plastic preforms into the plastic containers is arranged, transports these plastic preforms, wherein these forming stations each have valve arrangements by which a flowable medium is applied to the plastic preforms in order to expand them, and wherein each of these valve arrangements has at least two controllable valve devices, wherein these valve devices having movable piston devices which switch the valve devices between at least two valve positions,

• wherein
• a monitoring device is provided for checking a state of wear of at least one of the valve devices, wherein this monitoring device has at least one detection device which optically detects at least one element of the valve device in order to detect and/or determine the state of wear of the valve device optically and without contact.