Gas mass flow products are used in applications such as coating, semiconductor processes, petrochemical work, gas generation and mixing, and analytical equipment. The archived article describes the design principles of higher-flow thermal products.
Main features and operating principle
- Thermal sensing provides a mass-flow-related measurement under the agreed calibration conditions.
- A split-flow arrangement directs an appropriate part of the gas through the sensing passage.
- Different configurations can be supplied for specified low- or high-pressure operating conditions.
- Warm-up, zero stability, accuracy and reliability must be evaluated against the actual model's documented limits.
- Electronic interfaces allow a compatible display or host system to read the instrument and, for a controller, send a flow command.
An MFC includes a flow sensor, a flow-splitting element, a regulating valve and control electronics. In a bypass thermal design, gas flow changes heat transfer and the temperature distribution along a small sensing passage. The electronics process that signal, compare measured flow with the command, and drive the valve to reduce the difference.
An MFM performs the flow measurement without active valve regulation. Thermal mass-flow sensing does not mean unlimited independence from pressure or temperature: gas, temperature, pressure and calibration conditions must remain within the specification.
See the current flow-control and flow-measurement pages for the agreed series bands and model details.
Flowmethod designs, develops, manufactures and supports gas mass flow controllers, meters and custom gas-control and mixing systems. Configurations are matched to the customer's process and operating requirements.
For selection, installation or technical enquiries, contact Flowmethod: Mr. Dou, +86 180 3818 3381; doufeijin@hotmail.com. See Contact for the full contact list.