Mass flow controller
A mass flow controller (MFC) is a device used to measure and control the flow of liquids and gases.[1] A mass flow controller is designed and calibrated to control a specific type of liquid or gas at a particular range of flow rates. The MFC can be given a setpoint from 0 to 100% of its full scale range but is typically operated in the 10 to 90% of full scale where the best accuracy is achieved. The device will then control the rate of flow to the given setpoint. MFCs can be either analog or digital. A digital flow controller is usually able to control more than one type of fluid whereas an analog controller is limited to the fluid for which it was calibrated.
![](../I/m/MFC_en.svg.png)
![](../I/m/Massflow_gas_flow_controller.jpg)
All mass flow controllers have an inlet port, an outlet port, a mass flow sensor and a proportional control valve. The MFC is fitted with a closed loop control system which is given an input signal by the operator (or an external circuit/computer) that it compares to the value from the mass flow sensor and adjusts the proportional valve accordingly to achieve the required flow. The flow rate is specified as a percentage of its calibrated full scale flow and is supplied to the MFC as a voltage signal.
Mass flow controllers require the supply gas or liquid to be within a specific pressure range. Low pressure will starve the MFC of fluid and cause it to fail to achieve its setpoint. High pressure may cause erratic flow rates.
See also
References
- Tison, S. A. (1996). "A critical evaluation of thermal mass flow meters" (PDF). Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. 14 (4): 2582–2591. Bibcode:1996JVSTA..14.2582T. doi:10.1116/1.579985. ISSN 0734-2101.
External links
- How a Mass Flow Controller works video
- Thermal Mass Flow Meter / Controller (Principle of operation) video
- MEMS-based thermal mass flow controller video