The AT-OPSEN Optical liquid detection sensor has been designed for instant detection of fuel oils and any other none aggressive liquids. The optical sensor can be used with any of the TraceTek and AquiTron leak detection panels and is fully compatible with all TT1000, TT1100, TT3000, TT5000 and TT7000 system components. The electro-optic sensor contains an infrared LED and a light receiver. Light from the LED is directed into a prism which forms the tip of the sensor. With no liquid present, light from the LED is re?ected within the prism to the receiver. When rising liquid immerses the prism, the light is refracted out into the liquid, leaving little or no light to reach the receiver. Sensing this change, the receiver actuates electronic switching within the AT-OPSEN to operate a red LED for visual alarm and operates a relay which initiates an alarm on the TraceTek or AquiTron™ alarm panel. AT-OPSEN can also be used as level switches, and are suitable for high, low or intermediate level detection in practically any tank, large or small. Installation is simple and quick through the tank top, bottom or side. Solid state-switching ensures dependability over long service life. The sensor o?ers ±1mm repeatability and broad liquid compatibility. They are not recommended for use in any liquid that crystallizes or leaves a solid residue.