What are the two main categories of flow meters?

Flow meters are essential instruments used to measure the flow rate of liquids and gases, and they can be classified into two primary categories: volumetric flow meters and mass flow meters.

Volumetric flow meters measure the volume of fluid that passes through the meter over a defined period. This type of meter provides readings in units such as liters per minute or gallons per hour, which directly relates to the physical amount of fluid being measured. They operate based on principles that can involve displacement, turbine, or other methods that focus on volume.

Mass flow meters, on the other hand, measure the mass of the fluid flowing through the meter rather than just the volume. By taking into account the fluid's density, these meters provide highly accurate readings of mass flow in units such as kilograms per second. This is particularly important in industries where precise measurements of mass are critical, such as in chemical processing.

The other options listed, while they may describe types or classifications of flow meters, do not encompass the primary distinction based on measurement principle—volume versus mass. For example, circular and elliptical do not represent broad categories of flow meters in the way that volumetric and mass do, as these terms refer to specific shapes rather than measurement methodologies. Similarly, standard and digital describe