ELECTRONIC MOISTURE SENSING SYSTEM

摘要

A system for sensing the level of moisture contamination of refrigerant material flowing in a flow circuit of a heat transfer apparatus, such as an automobile air conditioner, includes a sensor (10). The sensor has a body (12) housing a light emitting diode (30), a sensing photo diode (32), and a reference photo diode (34). The sensor further includes a sight glass (20). A substrate (58) which is coated with a dye treated cobalt bromide salt, is positioned in the refrigerant material adjacent to the sight glass. The substrate changes color responsive to the degree of moisture contamination in the refrigerant material. The light emitting diode produces a red light which is reflected off the substrate and is sensed by the sensing photo diode. The difference in intensity sensed by the sensing photo diode, and the reference photo diode which senses the intensity of the light emitting idode on a direct path, is determined by electrical circuitry which produces an output signal representative of the degree of contamination.