Bypass valves are used if valves are exposed to high differential pressures. They help to avoid water hammers. A simple rule defines that the main valve must not be operated unless the bypass valve is completely opened. Two Auma actuators with integral bypass management ensure that this rule is observed. The actuator on the main valve is directly connected to the actuator on the bypass valve. During normal operation, the bypass management consists of a simple interlock, i.e. an operation command to the main valve will only be executed if the bypass valve is opened. Otherwise a fault signal will be sent to the control room. In case of emergency operation, e.g. emergency-close, the actuators automatically co-ordinate their operations. The bypass valve will be opened first and after the main valve has been closed, the bypass valve will be closed.
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