Pressure-relief device for a medium- and/or high-voltage switchgear installation, comprising a pressure-conducting device , wherein the pressure-conducting device has one or more gas inlet regions and one or more gas outlet regions , and comprising a pressure-conducting device closure , wherein the pressure-conducting device closure closes the pressure-conducting device and thus the gas outlet region or regions in a first position and wherein the pressure-conducting device closure does not close the pressure-conducting device and thus the gas outlet region or regions in a second position , wherein the pressure-conducting device has - one or more receiving elements , - and one or more blocking elements , wherein the pressure-conducting device closure has one or more fastening elements and one or more blocking agents , wherein the fastening element or elements each have a receiving mating piece element , characterized in that the receiving mating piece element and the respective receiving element are connected in such a way that the pressure-conducting device closure is movably connected to the pressure-conducting device and the pressure-conducting device closure can be arranged displaceably and rotatably relative to the pressure-conducting device along a pressure propagation direction , in that the blocking element or elements with the blocking agents prevent a rotation of the pressure-conducting device closure relative to the pressure-conducting device in the first position and permit a rotation of the pressure-conducting device closure relative to the pressure-conducting device starting with a transitional position up to and including the second position , wherein the pressure-conducting device closure can be moved from the first position to the transitional position by the displacement of the pressure-conducting device closure relative to the pressure-conducting device and the blocking agent is released from the blocking element by the displacement of the pressure-conducting device closure from the first position to the transitional position . the pressure-conducting device has - one or more receiving elements , - and one or more blocking elements , - one or more receiving elements , - and one or more blocking elements , wherein the pressure-conducting device closure has one or more fastening elements and one or more blocking agents , wherein the fastening element or elements each have a receiving mating piece element , characterized in that the receiving mating piece element and the respective receiving element are connected in such a way that the pressure-conducting device closure is movably connected to the pressure-conducting device and the pressure-conducting device closure can be arranged displaceably and rotatably relative to the pressure-conducting device along a pressure propagation direction , in that the blocking element or elements with the blocking agents prevent a rotation of the pressure-conducting device closure relative to the pressure-conducting device in the first position and permit a rotation of the pressure-conducting device closure relative to the pressure-conducting device starting with a transitional position up to and including the second position , wherein the pressure-conducting device closure can be moved from the first position to the transitional position by the displacement of the pressure-conducting device closure relative to the pressure-conducting device and the blocking agent is released from the blocking element by the displacement of the pressure-conducting device closure from the first position to the transitional position . <EOS>