Patent ID: 6761063
Filing Date: 2004-07-13
Classification: F16K,G01D

Abstract:
An arrangement for measuring the true position of a diaphragm membrane within a diaphragm valve, said diaphragm valve including a valve body having at least a pair of reservoirs controlled by said diaphragm membrane and actuator for moving said membrane between an open position and a closed position, the arrangement comprising:a thin conductive member disposed between the diaphragm membrane and the actuator, said thin conductive member comprised of essentially the same dimensions as said diaphragm membrane; and a capacitive measuring arrangement connected between said thin conductive member and said valve body for measuring the capacitance from said valve body, through said diaphragm membrane and to said thin conductive member, the capacitance having a first value when the diaphragm membrane is in the closed position and in contact with said valve body and a second value when the diaphragm membrane is in the open position and separated from said valve body, the capacitive measuring arrangement comprising a first lead coupled to the thin conductive member, a second lead coupled to the valve body, a timing circuit coupled to the first and second leads for converting the measured capacitance into a frequency signal, and a microprocessor coupled to the timing circuit for translating the frequency signal into a signal indicative of the true position of the diaphragm membrane with respect to the valve body.