FIELD: measurement equipment.
SUBSTANCE: invention relates to methods for determining variation of a valve parameter for valve control. According to a diagnostic method of a control valve, data on position, which indicates position of the control valve, and data on pressure, which indicates pressure drop on the valve actuator, and unnecessarily direction of stroke of the control valve is measured (41) during online operation of the control valve. Data on position and data on pressure drop is processed (42) so that it can contain data near initial points of a variety of individual movements of stroke of the control valve during normal online operation of the control valve. Finally, a chart of variation of the valve parameter of the control valve is determined (44) based on processed data on position and on pressure drop, which are collected in the variety of points along the stroke range of the control valve during online operation of the control valve.
EFFECT: improvement of accurate diagnostics of valves in online modes.
16 cl, 10 dwg
