A safety valve includes an inlet, an outlet, two shut-off valves arranged behind one another, and a discharge valve with a discharge outlet. The two shut-off valves and the discharge valve are connected by an inlet and outlet respectively. The safety valve has a housing main body, relative to which a piston is guided movably, and which has a housing cover guided movably on a side lying opposite the housing main body. The inlet is arranged on the piston, the outlet is arranged on the housing cover, each of which merges into a bore closeable by one sealing surface arranged on the piston and the housing cover respectively. The housing cover and the housing main body form a cavity, in which the bores end. A circumferential gap formed when the housing cover is lifted off produces the discharge outlet.