Ball Valves Ball valves are the best method of shutting off gas supplies. They stay permanently leak-tight without maintenance for many years. WITT ball valves are available in a variety of models, materials and seals to suit all applications. WITT ball valves are designed in accordance with the DIN standards. Ball valves for oxygen for working pressures up to 40 bar (580.1 psi) are burn-out safe. They have been tested and approved for this purpose by the Federal Institute for Materials Research and Testing in Germany (BAM).