Patent ID: 7905099

Claim:
Apparatus for use in a heating, ventilation, air-conditioning or refrigeration system including a compressor, a condenser, an expansion valve and an evaporator interconnected by a line having an interior within which a refrigerant fluid circulates, said apparatus comprising: an optical aperture formed in said line at a location between said condenser and said expansion valve; an emitter operative to direct radiant energy through said optical aperture into said interior of said line at a wavelength that can be transmitted through said refrigerant flowing through said line without being completely absorbed; a detector operative to produce a first signal upon sensing said radiant energy that is not absorbed by said refrigerant fluid when said refrigerant fluid is in liquid phase, said detector being operative to produce a second signal upon sensing said radiant energy that is not absorbed by said refrigerant fluid when said refrigerant fluid is in both liquid phase and gaseous phase; a controller coupled to said detector and to said emitter, said controller being effective to provide a warning indication upon receipt of said second signal from said detector.