Abstract: The invention refers to an explosion protection system for electrical apparatuses and machineries, such as manipulators or industrial robots, located in hazardous environments, i.e. environments containing explosive concentrations of inflammable gases, dusts or vapours, comprising an air supply that applies internal pressurized air into an explosion proof enclosure. The invention is achieved by a flow- and pressure sensor arranged as an integrated unit and designed to stand high dynamic forces by having low inertia, balanced arrangement of moving parts and a movement guide, e.g. an axle with a support guide, with low friction.