massflowcontrolled

Massflowcontrolled refers to devices and methods that regulate the mass flow rate of a fluid, typically a gas, in a process. The most common implementation is a mass flow controller (MFC), an integrated unit comprising a flow sensor, a valve or actuator, and control electronics that maintain a user-set mass flow rate, largely independent of inlet pressure and temperature within specified ranges.

Most MFCs use a thermal mass flow sensor: a heated element's temperature rise or cooling effect is related to flow rate, allowing the controller to infer mass flow. Other designs may use differential pressure sensors across an orifice. A closed-loop control system continuously compares the measured flow to the setpoint and adjusts the valve to keep the target. Typical readouts are in mass flow units such as standard cubic centimeters per minute (sccm) or standard liters per minute (slpm); some meters report kg/s. MFCs are available for single gas or for gas mixtures, with performance specified for particular gases.

Applications include semiconductor fabrication, chemical vapor deposition, plasma processing, analytical instrumentation, and laboratory gas delivery systems. Advantages include precise, repeatable control, rapid response, and reduced gas usage. Limitations include sensitivity to gas composition, pressure, and temperature; need for gas-specific calibration; potential drift over time; and sensitivity to contamination or upstream leaks. Proper selection, installation, and regular calibration are essential for accuracy.