Flow sensor
Encyclopedia
A flow sensor is a device for sensing the rate of fluid flow. Typically a flow sensor
is the sensing element used in a flow meter, or flow logger, to record the flow of fluid
s.
As is true for all sensors, absolute accuracy of a measurement requires a functionality for calibration
.
There are various kinds of flow sensors and flow meters, including some that have a vane that is pushed by the fluid, and can drive a rotary potentiometer, or similar devices.
Other flow sensors are based on sensors which measure the transfer of heat caused by the moving medium. This principle is common for microsensors to measure flow.
Flow meters are related to devices called velocimeters
that measure velocity
of fluids flowing through them. Laser-based interferometry
is often used for air flow measurement, but for liquids, it is often easier to measure the flow. Another approach is Doppler
-based methods for flow measurement. Hall effect sensor
s may also be used, on a flapper valve, or vane, to sense the position of the vane, as displaced by fluid flow.
Sensor
A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an 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...
is the sensing element used in a flow meter, or flow logger, to record the flow of fluid
Fluid
In physics, a fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
s.
As is true for all sensors, absolute accuracy of a measurement requires a functionality for calibration
Calibration
Calibration is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device....
.
There are various kinds of flow sensors and flow meters, including some that have a vane that is pushed by the fluid, and can drive a rotary potentiometer, or similar devices.
Other flow sensors are based on sensors which measure the transfer of heat caused by the moving medium. This principle is common for microsensors to measure flow.
Flow meters are related to devices called velocimeters
Velocimetry
Velocimetry is the measurement of the velocity of fluids, as often used to solve fluid dynamics problems, or to study fluid networks, as well as in industrial and process control applications, or in the creation of new kinds of fluid flow sensors...
that measure velocity
Velocity
In physics, velocity is speed in a given direction. Speed describes only how fast an object is moving, whereas velocity gives both the speed and direction of the object's motion. To have a constant velocity, an object must have a constant speed and motion in a constant direction. Constant ...
of fluids flowing through them. Laser-based interferometry
Interferometry
Interferometry refers to a family of techniques in which electromagnetic waves are superimposed in order to extract information about the waves. An instrument used to interfere waves is called an interferometer. Interferometry is an important investigative technique in the fields of astronomy,...
is often used for air flow measurement, but for liquids, it is often easier to measure the flow. Another approach is Doppler
Photoacoustic Doppler effect
The photoacoustic Doppler effect, as its name implies, is one specific kind of Doppler effect, which occurs when an intensity modulated light wave induces a photoacoustic wave on moving particles with a specific frequency. The observed frequency shift is a good indicator of the velocity of the...
-based methods for flow measurement. Hall effect sensor
Hall effect sensor
A Hall effect sensor is a transducer that varies its output voltage in response to a magnetic field. Hall effect sensors are used for proximity switching, positioning, speed detection, and current sensing applications....
s may also be used, on a flapper valve, or vane, to sense the position of the vane, as displaced by fluid flow.