How Do Flow Meters Work – Mass And Volumetric Flow Rates
The need to measure the flow rate in a pipe or tube has many aaplications for individuals and in business. Generally, gases and liquids need to be measured. there are two ways to do this. The volumetric flow rate is a measure of the volume of the medium by time. The mass flow rate is a measure of the mass of the medium by time.
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 the most varied applications are in the manufacturing industries or water management processes where precise measurements are vital for successful operations. This article will touch on how flow meters work in industry and for individuals.
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.
Two other examples of flow meters that analyze and calculate changes in waves to reach a measure for a flow rate are the ultrasonic flow meter and the Doppler shift flow meter.
In the case of the ultrasonic flow meter, two transmitters of ultrasonic sound waves are placed at the ends of a pipe where the measure is to take place. Each transmitter sends a pulse of sound.
The transmitters also act as a receiver of the wave sent by the other transmitter. One pulse of sound is sent in the direction of the flow and the other is sent against the flow.
The flow rate can be determined by the difference in the timings of each ultrasonic wave provided information on the material of the pipe and some details on the medium being measured are known.
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 variable area flow meter is a more straightforward meter. It consists of a calibrated tube in which a liquid or gas passes through. In the tube is a float that is displaced by the substance.
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.
Filed under: Computers & Technology