Thermal Mass Flow Meters

Working Principle :  A thermal mass flow meter is a precision instrument that measures gas  & air mass flow and is used in various industries with a wide range of applications.

The thermal mass meter measures flow based upon the concept of convective heat transfer.

One of the sensors is heated by an integrated circuit and functions as the flow sensor, while a second detector acts as the reference sensor, and determines the gas temperature. The Sage proprietary circuitry maintains a continuous overheat between the flow and reference sensor. As gas flows by the heated sensor, flowing gas molecules transport heat away from the sensor and as a result, the sensor cools and the energy is lost. The circuit balance is disrupted, and the temperature difference (ΔT) between the heated RTD and the reference sensor has been altered. Within a second, the circuit restores the lost energy by heating the flow sensor, to adjust the overheat temperature.

The electrical power required to sustain this overheat denotes the mass flow signal.

Either in-line flow bodies or insertion-style probes of the meter support two sensors that interface with the gas being measured.

Features :

• No moving parts, which reduces maintenance and permits the use in demanding application areas, including saturated gas.
• Calculate mass flow rather than volumetric flow and do not require temperature or pressure correction, which means there is no additional expense for the purchase and installation of additional equipment.
• Provide excellent accuracy and repeatability over a wide range of flow rates with valve function.
• It can measure flow in large pipes also.