Accurate surveillance of sanitary single acting valves with large mechanical tolerances

摘要

Sanitary valves are typically fitted with a control top unit to have surveillance of the dosed position of the valve. It is considered a critical error in a sanitary process if a valve is not sufficiently closed as the resulting leakage can cause contamination. The closed position (or positions) is typically taught into the control top unit. The control top unit is typically configured with a tolerance threshold for when the position is considered out of bounds and when this condition occurs the control system is alerted, and actions can be taken. The sensor system of most control top units is fitted to the actuator of the sanitary valve and some sanitary valves can have larger mechanical tolerances in the actuators than in the valve member itself. This is typically addressed by increasing the tolerance threshold symmetrically around the stored position, thus sacrificing some of the accuracy of the surveillance to avoid false errors.