How Do Flow Meters Work - Flowmeter Types And Principles
July 31, 2008 – 6:22 pmFlow 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.
There are a wide variety of types of flow meters. They are generally classified by what they do or how they operate. For instance, a mass flow meter is a general classification of flow meter that determines the flow rate of a medium in terms of mass even though the operating principles for each meter may be different.
One example of a principle governing the name of a meter is the Coriolis flow meter. It uses the Coriolis effect to determine the mass of a fluid passing through two vibrating tubes or pipes. The idea being that by understanding the change in the characteristics of the wave patterns in the vibrating tubes, you can correlate the flow rate of the substance passing through.
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.
For an ultrasonic flow meter, flow rate is measured by contrasting the measurements of two ultrasonic waves. These two waves are set off at the same time as each other but from different directions.
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.
Tags: Computers And Technology
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