Patent ID: 6678584
Filing Date: 2004-01-13
Classification: F15B,G05B,G05D

Abstract:
A positioner system for controlling a pneumatic actuator coupled to a throttling element, the actuator having at least a first control chamber, the positioner system comprising:an I/P converter delivering a pressure signal; second stage pneumatics including a housing with an inlet port in fluid communication with a control fluid supply and a first outlet port in fluid communication with the first control chamber, and a control fluid valve assembly disposed in the housing and responsive to the pressure signal for controlling flow of control fluid from the inlet port to the first outlet port; an inlet pressure sensor in fluid communication with the housing inlet port for measuring an inlet port pressure; a first outlet pressure sensor in fluid communication with the first outlet port for measuring a first outlet port pressure; a displacement sensor for detecting a control fluid valve assembly position; and a diagnostics unit communicatively coupled to the inlet pressure sensor, first outlet pressure sensor, and displacement sensor, the diagnostics unit including a processor having a stored routine adapted to determine a first outlet port mass flow rate of control fluid based on the inlet port pressure, the first outlet port pressure, and a first outlet port area of restriction.