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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