Fluids are substances that immediately yield to any force that changes their shape, thus conforming to the configuration of a vessel that contains them. Fluids are either gas or liquid. Sometimes it is difficult to distinguish fluids and solids, because even solids and plasma flow under favorable conditions. A flow meter is used to measure how fast a fluid could move within the constraints of a container for a given pressure. It could also provide information regarding the fluid's measurement in linear, mass, nonlinear and volumetric rates.
Many engineers use a flow meter to apply the concepts of fluid mechanics to a certain system in diverse fields. Although experienced professionals have certain partiality to what kind of flow meter they tend to use for such measurements, a greenhorn has a myriad of choices and would need advice on how to choose a flow meter.
The following are some essential criteria to help one choose a flow meter:
- Which kind of fluid will be measured? Flow meters are highly specific as to which kind of fluid is to be measured. Flow meters designed for gases will not tolerate the presence of liquids in their chambers, likewise with flow meters for liquids.
- What kind of information is needed? Some flow meters will measure the relationship of pressure to velocity of the fluid in a container. Others are designed to show how much fluid is in the container. An additional variable to consider would be the fluid's density or its specific gravity.
- Would viscosity matter? This is actually for liquids that are to be measured with the exemption of water. Flow rates are a little sluggish when the liquid is a little viscous, and this would cause erroneous readings if calculated on a flow meter that does not bear viscosity's drag.
- Is the fluid being measured clean? Flow meters have additional features depending on their purpose. The more besmirched the fluid, the more often you need to inspect, clean and calibrate the flow meter.
- What are the upper and lower limits of the variables? You would have to consider the range of the flow rate and pressure that had to be exerted in the process of measurement. Many flow meters in the markets are designed with settings that had to be calibrated before actual capacity is determined.
- How is its calibration? A regularly calibrated flow meter will definitely provide accurate replication of process control. Choose a flow meter that can be easily calibrated to your standards. Many suppliers will supply technicians to perform such calibration at a price.
- What are its piping requirements? Flow meters need pipes to define the space that it needs to measure. Certain fluids have specific requirements that could not be mixed up.
Over 83% of the flow meters in use in the industry today are either poorly chosen or do not perform satisfactorily. One needs to know exactly what this instrument is supposed to do to gain full benefit of the data provided by the flow meter.