Blocking apparatus for a fire damper, blocking apparatus system and method for blocking a drive direction

Various embodiments include a blocking apparatus comprising: a holding apparatus; a receiving element mounted in the holding apparatus about an axis of rotation, defining a through-opening with a through-axis parallel to the axis of rotation; a wrap spring mechanically prestressed in the holding apparatus, with a winding arranged around the receiving element; and a thermocouple made of a material having a lower melting temperature than the holding apparatus and/or the wrap spring. The thermocouple holds at least one end of the wrap spring with respect to the holding apparatus in the prestressed state in such a way that the receiving element can be freely rotated in both drive directions about the axis of rotation. The receiving element is blocked in one of the two drive directions in the relaxed state of the wrap spring and in the triggered state of a thermal fuse.