Many industrial and commercial practices will need switches that engage depending on the different conditions of a liquid that is being worked with. It could be dependent upon liquid level, pressure, flow or temperature. In some cases, it could be necessary to have switching or monitoring for more than one of these factors. Very commonly, a process will need switching or monitoring in relation to both temperature and liquid level. For these situations, it can be ideal to use a combination sensor switch that manages both operations.
A liquid level temperature sensor will monitor both the level of the liquid and the temperature. Depending on the need, it can be configured to perform a variety of functions for different situations. They could be used to provide feedback on temperature and liquid level, they can be used to control circuits that operate different components and they can be used to send an alarm signal.
A liquid level temperature sensor is really two different sensors in one device. The first is the sensor that operates on the liquid level and the other is for operating in relation to the temperature. Depending on the purpose, you could use different float switch technologies for the liquid level in combination with different types of temperature sensors.
For monitoring and managing operation based on liquid level, the magnetic reed switch is a popular form of float switch and it can be combined with different temperature sensors depending upon the need. Common types of temperature switches that can be combined for these applications include thermistors, thermocouples and resistance temperature detectors (RTDs). The exact combination of float switch and temperature sensor will depend on the specific application.
A thermocouple works by measuring the voltage change in a junction of two pieces of wire made from dissimilar metals. As the temperature at the probe end changes, it creates an electrical charge that runs to the other end of the thermocouple. This change in voltage can then be measured to determine the temperature.
Thermistors and RTDs both measure resistance to detect the temperature. Both contain a conductive element through which a current flows. As the temperature changes, the level of resistance in the conductor will change. This change in resistance correlates to the temperature for which the element is exposed. The level of resistance on the element can then be translated into a temperature reading.
The difference between a thermistor and an RTD generally comes down to the material from which the conductive element is made. An RTD will usually have a metal conductor and a thermistor will use an element made from ceramic or a polymer. This difference in material provides a different temperature response and that can make these different types of temperature sensors good for different applications.
If you need to measure both liquid level and temperature, then it is important to make sure that you are using the right combination of sensors. Many of the sensors and switches are designed to be fitted together and it is possible to find combination liquid level temperature sensors that come in a range of different configurations. Short of that, they can also be custom made to meet the specific needs of different industrial and commercial practices.