Flowmeters are devices that measure the amount of fluid (liquid, gas or vapour) that passes through them, usually through a pipeline. Some flowmeters measure flow as the amount of volumetric fluid passing through the flowmeter during a time period (such as 100 litres per minute – volumetric flow). Other flowmeters measure the totalized amount of fluid that has passed through the flowmeter (such as 100 litres – quantity in volume). Yet other flowmeters measure the amount of mass flow passing through a flowmeter (such as 100 Kg per min – mass flow).