Nucon zander [india] pvt. Ltd offers a wide range of valve accessories. These are highly reliable and provide efficient service. As part of that the company offers zs/520 range of non-return valves, which are widely used as protective devices in air circuits. They come with following salient features:
Non-return valves permit free flow of air in one direction only
Non-return valves protect down stream side in the event of air supply failure