Thermal gas mass flow instruments infer flow from heat transfer between a sensing element and the gas. One design uses a temperature-measuring element and a heater: electrical input maintains a defined temperature difference, and the power needed changes with the heat removed by the gas.
As flow changes, the relationship between thermal transfer and mass flow is used to calculate the reading. Other thermal sensor arrangements use a temperature difference along a bypass passage; the exact implementation depends on the instrument.
A controller adds a regulating valve and feedback operation to the flow measurement. A meter provides the measurement without active valve regulation. Thermal products can offer a useful flow range, repeatability and compact integration, but their actual pressure loss, accuracy and gas compatibility are model-specific.
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.