Thermal Mass Flowmeters

Thermal Mass Flowmeters

Thermal mass flowmeters provide direct mass flow measurement for gases using a heat-transfer principle. Two temperature sensors are used: one measures the actual gas temperature, while the other is heated to maintain a defined temperature difference. As gas flows past the heated sensor it removes heat; the electrical power required to hold the temperature differential is proportional to mass flow.

This method is well suited where high turndown, excellent low-end sensitivity, and minimal pressure loss are required. High turndown ratios (often on the order of 100:1) enable one meter to cover both standby and peak demand conditions without sacrificing stability. Because mass flow is measured directly and the device also reports gas temperature, additional pressure or temperature compensation is often unnecessary for many control and monitoring duties.

Thermal meters are commonly used for compressed air consumption and distribution monitoring, carbon dioxide service in beverage production and chilling, inert gases such as argon in steel production and nitrogen/oxygen in production networks, and natural gas measurement for burner and boiler feed control. Air and biogas measurement in wastewater treatment is another frequent application, including aeration optimization, digester gas tracking, and leak detection on low-pressure headers.

Device configurations include inline meters for smaller lines and insertion meters for very large pipes or rectangular ducts. Insertion designs extend thermal technology into high-capacity networks where clamp-on or full-bore meters may be impractical, and they can often be installed with limited interruption. Proper installation focuses on sensor positioning, profile effects, and ensuring the meter’s calibration range and gas composition assumptions remain valid over time.

Thermal mass measurement supports energy management and asset performance initiatives by providing reliable, repeatable gas flow data for dashboards, alarms, and optimization routines. Quick response to fluctuations improves control of combustion air and process gas supply, while stable measurement at low flow increases confidence in leakage studies and standby-load quantification. Modern communication options and diagnostics streamline commissioning, verification, and condition-based maintenance.

Instrumentation and Controls., an exclusive authorized representative of sales and service for Endress+Hauser.