When do you use mass flow meter and volume flow meter?

Mass flow meters are used when it's essential to measure the mass of a fluid flowing through a system, regardless of temperature or pressure changes, making them ideal for applications in industries like pharmaceuticals and food processing. In contrast, volume flow meters are suitable for applications where the fluid's density is consistent and the measurement of flow rate in terms of volume is sufficient, such as in water supply and HVAC systems. The choice between the two depends on factors like the nature of the fluid, accuracy requirements, and process conditions.