Bonetti’s bellows seal valves are zero emission and maintenance free. The valves are particularly suitable for dangerous, inflammable, lethal and explosive media: an uninterrupted metallic barrier is positioned between the piping and the environment. Hence these valves are suitable for any fluid and are recommended when zero emission characteristics are required to protect the environment and the health of the workers from pollutive leaks, to prevent expensive wastes due to loss of energy and fluid, and to eliminate the not negligible cost of replacement of the packing.