Choice Between Flowmeters for Particular Applications
Choosing the correct flowmeters for measurements
The number of relevant factors to be
considered when specifying a flowmeter for a particular application is
very large. These factors include the temperature and pressure of the
fluid, its density, viscosity, chemical properties and abrasiveness,
whether it contains particles, whether it is a liquid or gas, etc. This
narrows the field to a subset of instruments which are physically
capable of making the measurement. Next, the required performance
factors of accuracy, rangeability, acceptable pressure drop, output
signal characteristics, reliability and service life must be considered.
Finally, the economic viability must be
assessed and this must take account not only of purchase cost, but also
of reliability, installation difficulties, maintenance requirements and
service life.
Where only a visual indication of flow rate is needed, the most popular
instrument is the variable area meter. This requirement is common enough
for this type of instrument to account for 20% of all flowmeters sold.
Where a flow measurement in the form of an electrical signal is
required, the choice of available instruments is very large. The orifice
plate is extremely common for such purposes and accounts for almost 50%
of the instruments currently in use in industry.
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