How Do Flow Meters Work - Mass And Volumetric Flow Rates

Flow meters are devices that are used to measure the flow rate of a certain liquid or gas. They can measure these substances in terms of the volumetric flow rate or the mass flow rate. The volumetric flow rate is generally given in m3/second. The mass flow rate is given in kg/second.

Flow meters have many applications. For individuals, a peak flow meter can measure the lung capacity. This is also used by people with asthma and can be used to determine if an asthma attack is imminent.

However they are most commonly used in industry, notably in machines or processes that require precise amounts of a certain gas or liquid to be applied or added during the manufacturing of an item. This article will cover how some flow meters work.

Flow meters are generally classified by the principal that governs their operation or possibly by their applications. For instance, mass flow meters measure the flow rate of a medium in terms of it's mass.

The Coriolis flow meter in an example of the principle determining the name. The Coriolis effect is the force that a liquid experiences in a circular motion. In the flow meter, vibrating pipes cause the liquid to move in a circular motion. If the wave motion of the vibrating pipes is known before the liquid passes through the pipes then the flow rate of the liquid can be determined.

Ultrasonic and Doppler shift flow meters also use the changes caused to sound waves to correlate a rate of flow for the medium passing through the meter.

The ultrasonic flow meter transmits two ultrasonic waves in opposite directions of a pipe where a liquid or gas is flowing.

The ultrasonic waves are recorded by receivers at opposite ends of the pipe. One wave is sent in the direction of the flow of the liquid to be measured. The other wave is sent in the opposite direction to the flow.

Provided some information is known about the type of pipe used and a few constants for the liquid or gas, then the flow rate can be determined from the time difference of each wave.

Doppler shift flow meters use the changes in the frequency and amplitude of a sound wave when it bounces off particulate matter in the liquid that is being measured to determine the flow rate.

A more traditional type of flow meter is the variable area flow meter that uses a float in a calibrated tube. When a substance passes through the tube, the float is displaced by the flow.

By taking the reading from the calibrated tube an indication of the flow rate can be determined. This is the principle of the peak flow meter used for lung capacity and asthma.

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Learn more about flow meters, specifically on portable flow meters at http://www.flowmetermatters.com.