What type of sensor is commonly used for flow measurement of gases?

Thermal mass flow sensors are commonly used for flow measurement of gases due to their ability to provide accurate readings across a wide range of flow rates and gas types. These sensors operate based on the principle of heat transfer. When a heated element is placed in the flow of gas, the amount of heat carried away by the gas is proportional to the mass flow rate of that gas. By measuring the temperature difference between the heated element and the gas, the thermal mass flow sensor can effectively determine the flow rate.

This type of sensor is particularly advantageous for gases because it is less affected by changes in pressure and temperature compared to other flow measurement technologies. Additionally, thermal mass flow sensors can provide direct mass flow measurements, which is essential in many industrial applications.

Other types of sensors, like capacitive, optical, or magnetic sensors, are not typically effective for measuring gas flow due to their design and operational principles which cater more towards different applications or media. Capacitive sensors are usually used for detecting levels or proximity; optical sensors are often employed for detecting light or imaging applications; and magnetic sensors are favored for magnetic fields and have limited application in gas flow measurement.