Industry's Broadest Selection of Electro-Optic Sensors! Compact, Electro-Optic Liquid Level Switches and Controllers     Small size Economically priced Built-in, solid-state electronics No moving parts Simple, one-unit installation    Typical Applications Medical laboratory Food & beverage systems Pharmaceuticals Petrochemicals Leak detection Hydraulic reservoirs Machine tools ELS Series Level Switches are low cost, compact, optical level sensors with built-in switching electronics. With no moving parts, these small units are ideal for a variety of point level sensing applications — especially where dependability and economy are a must. Level switches 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 offers ±1mm repeatability and broad liquid compatibility. They are not recommended for use in any liquid that crystallizes or leaves a solid residue.          Simple Operating Principle 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 reflected 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 unit to operate an external alarm or control circuit.          Liquid below the sensing prism Liquid immersing the sensing prism