This article explains the main difference between mass flow meter and volumetric flow meter, and when we should use one or the other. As an engineer, getting repeatable and accurate measurements from your flow monitoring device is critical. However, this may not happen if wrong type of flow meter is used. Therefore, it is important to know the types of flow meter you are using and determine if your application requires a mass flow meter or a volumetric flow meter.

What is volumetric flow?

Volumetric flow refers to a volume of medium moving per unit time. Common units for volumetric flow are m3/hr, m3/min, CFM or ACFM. The volume is a substance occupying a three-dimensional space.

What is mass flow?

Mass flow refers to the measure of a mass moving per unit time. Mass flow rate can be expressed by kg/hr and lb/min. It can obtain the mass directly without conversion from volume.

Should we use a volumetric flow meter or a mass flow meter?

There are a lot of volumetric flow meter types. Some examples of devices that measure volumetric flow rates includes a positive displacement flow meter, a vortex flow meter, and a turbine flow meter. They are recommended if high accuracy is not required. Mass flow meters have higher accuracy and reliability and more often used in custody transfer. A typical example of such device is Coriolis mass flow meter.

It is clear that different flow meters have their own advantages. There are more volumetric flow meter applications in the industry probably because historically most measuring instruments measure in volumetric flow and the volumetric flow meter price is lower than that of the mass flow meter. And mass flow meters are used in specific industries or applications where direct mass measurement with high accuracy is required.