The DUNGS VDK 200A is a valve proving system for safety shutoff valves. It checks that both safety shutoff valves in a gas train are fully closed before a system startup or after system shutdown when wired and interlocked to a suitable flame safeguard control. The VDK 200 will halt the startup sequence to a burner if it detects an open safety shutoff valve, thus preventing ignition under undesirable conditions.