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The probe is a 1" (25mm) in diameter
cylinder which can be used in wells as small as 1-1/8" (29mm) in diameter. The probe contains two different sensor units, one for detecting the liquid/air interface, and one for for distinguishing between water and hydrocarbon. The liquid sensor is an optical prism located on the end of the probe. This sensor detects liquid by reacting to the differences in the indices of refraction of air and liquids. An infrared light source is internally reflected to an unfired detector by a prism on the face of the sensor.
When the prism becomes immersed in liquid, the light beam is refracted away from the detector. To determine if the liquid is conductive (water) or nonconductive (hydrocarbon), a small Intrinsically Safe electrical cable is passed between two electrodes on the sensor. Current flow will occur only in conductive fluids such as water. The Interface probe is capable of measuring oil slicks less than 1/16 of an inch (1.6mm) in thickness. |