Optical Level Switch
Optical level switches are measurement control devices that operate using optical sensors in order to use the light transmittance, reflective or refractive properties of the material being measured to determine its level. Optical level switches operate using either visible, infrared or laser light, depending on what type of light is best-suited for the intended application.
Able to measure the levels of clear, translucent, reflective and opaque materials, optical level switches can have either a contacting or non-contacting design. As a result of the wide-ranging capabilities of the optical level switch, the applications and industries in which it is utilized are numerous and include chemical processing, for material level control in aggressive and harsh environments; industrial manufacturing, for measurement purposes in many high temperature and high power processing applications; medical, for level sensing of materials requiring extremely precise measurements; and commercial, for diverse applications such as restaurants, fishing and satellite communications.
Some examples of materials that optical level switches are commonly used to measure and control include sediments, liquids with suspending solids and aqueous, organic and corrosive liquids such as water or food items.
Optical level switches operate without moving parts, instead depending on light emitting diodes (LEDs). LEDs used in optical level switches produce infrared light that used in the measurement of the material. Optical level switches mainly consist of an optical sensor, an LED, a probe and a photocell. In general, optical level switches react to their physical state and will change depending on whether they are wet or dry (at least, if the probe is wet or dry).
When wet, the amount of light that is reflected back to the level switch is reduced significantly as it is being reflected into the liquid material. As a result, if it is dry the amount of reflected light is increased significantly, thus signally a change in the level of the material. The additional reflected light is then detected by the photocell (which itself does not come into contact with the materials it measures) and then alerts the reaction of the level switch.
Able to operate at temperatures up to 125°C (257ºF) and at pressures of up to 500 PSI, optical level switches are incredibly accurate, cost-efficient and provide a rapid response time. Additional parts can be utilized such as fiber optic cable and a conductivity-type level sensor in order to widen the capabilities of the optical level switch.