A valve combination for flame photometers particularly for a rapid and secure switching over from one to another fuel gas comprises a switching valve and a subsequent safety valve which either obstructs or lets pass a fuel gas emitted therefrom. Both valves are contained in a housing at a considerably short distance. Each of said valves has at least two entrance openings and one exit opening for the fuel gas.The exit opening of the switching valve is at the same time the entrance opening of the safety valve, the latter opening being closely located relative to the exit opening of the safety valve.