Device or instrument designed to detect and measure a variable.
A sensor (also called detector) is a converter that measures a physical quantity and converts it into a signal which can be read by an observer or by an (today mostly electronic) instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass tube. A thermocouple converts temperature to an output voltage which can be read by a voltmeter. For accuracy, most sensors are calibrated against known standards.
A sensor capable of providing a signal (output) that is related to the volumetric flow of liquid through the sensor.
A sensor, located in the liquid circuit, which is capable of producing a signal (output) that is related to the temperature of the sensor.
Temperature Differential Sensor
A sensor system, composed of two temperature sensors, which is capable of providing a signal that is related to the temperature differential of the two sensors.