Thin-film thermal mass flow sensor for liquid and gas
0 - 100 m/s, -20 - 150 °C | FS5
IST AG
Thermal Mass Flow Sensor for all-purpose use in Gases:
The flow Sens FS5 is successor of the proven FS1 and is characterised by a thermally more efficient sensor
structure, which exhibits with same electrical connected loads a higher chip temperature and is thus more
sensitive.
The Flow sensor element consists of two temperature depending platinum-resistors, both deposited on one chip.
The low-ohm resistor with a small area is used as a heater, whereas the other high-ohm resistor serves to
measure the reference temperature. Using a bridge circuit, the differing resistance value of two elements leads to
different (self) heating. The (self) heating is dependent upon the applied voltage, the mass flow, and the media in
which the sensor is located. Higher voltage increases self heating, a higher flow rate increases cooling. If the self
heating is kept constantly by a suitable controller, the voltage increases with higher flow rates and therefore
becomes a measure for the mass flow. As a result of his little thermal mass, this sensor has fast heating and
cooling response times. The measuring principle of the sensor can be used for large operation ranges, from
0...0.1m/s up to 100m/s. The Flow Sens is also available with a plastic housing of Æ 6mm. This option provides
the user with ideal opportunities to incorporate the element into custom-built applications or specific housings, e.g.
into a T-piece.
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