A level sensor is used to measure or detect levels or amounts of fluids in pipes, containers, or other systems, both open and sealed. The fluids are often liquids, but can be solid materials that behave as fluids, such as sand or grain, for example. Level sensors are found in a number of different designs, depending on the intended application. Sensors of this type are manufactured by many companies around the world and are generally designed for some specific application, rather than general use.
Sensors for monitoring levels in containers or other closed systems can take many forms. A level sensor may be as simple as a window for viewing contents directly, with a printed gauge indicating the amount of material present. This is not technically a true level sensor as much as a level gauge, however. A true sensor is something that can sense changes in fluid level and communicate those changes in some way. A fuel indicator in an automobile is a good example of a simple level sensor and gauge pairing.
A typical level sensor can detect even small changes in fluid levels in a container or other vessel. Most sensors of this type are linked to some type of output system for the purpose of sending notifications to a technician at a monitoring station or for sounding an alarm. Level sensors are often used for detecting dangerous levels of fluid build-up within a closed system, and when a certain level is reached, an alarm will sound, alerting workers or technicians of the danger.
Many sensors of this type are designed to monitor conditions at locations that are either not easily accessible to workers, such as in elevated water tanks, or where conditions are hazardous. In these cases, transmission capability is a must for the sensor and may be accomplished with standard wiring techniques or with wireless transmission. Newer technologies allow sensors to transmit data wirelessly to monitoring systems or even to mobile devices. Sensors of this type may be hard wired into a power grid or operate on battery power.
Depending on the application, level sensors can employ a wide range of means for performing their task. Mechanical sensors often employ a float system to detect and measure liquid levels. Some level sensors employ electrodes and a very weak electric current to measure changes in levels of conductive liquids. Ultrasonic sensors are capable of monitoring many liquids remotely without the need for any part of the sensor to actually contact the liquid. Other types of level sensors include magnetic, pressure, and even gamma ray radiation sensors that measure levels of molten metals in foundries.