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Changeover valves, also called Switch valves, are designed to connetc two safety valves to a single pressurized system, acting as the three ways devices for flow seletcion in a pipeline.
Through these Changeover valves, one of the two safety valves is in operation and ensures the protetcion of the system, the other safety valve is in "stand by" ready to come into operation if the first one must be changed or removed to maintenance. Changeover valves are often required for the continuous production.