Comparison of Different Types of Flow Meters

Image Credits : toshiba.co.jp

Comparison of Flow Meters

Flowmeter	Pipe/size	Gas/Liquid	Accuracy	Ideal for measuring	Principle
Orifice	1” – 48”	Liquid/Gas	1%	Mass flow / velocity	Diff. Pressure
Venturi	6” – up	Liquid/Gas	0.50%	Mass flow / velocity	Diff. Pressure
Turbine	0.5” – 2”	Liquid/Gas	0.30%	Mass flow / velocity	Rotating blades produce pulses
Positive Displacement	1” – 24”	Liquid	0.50%	Mass flow	Traps a specific volume
Magnetic	1” – 120”	Liquid	0.2 – 1 %	Mass flow	Faraday’s Law
Ultrasonic	0.5” – 48”	Liquid/Gas	1%	Mass flow	Speed of sound
Vortex	0.5” – 16”	Liquid/Gas	1%	Velocity	Eddies produce pulses
Variable area	0.5” – 3”	Liquid/Gas	1%	Velocity	Diff. Pressure
Coriolis	2” – 150”	Liquid	0.50%	Mass flow	Coriolis principle
Pitot	3” – up	Liquid/Gas	2%	Mass flow / velocity	Diff. Pressure

Note :

1. Pipe/Size may vary from make to make, Above shared details are for reference only.
2. For measuring Mass Flow, appropriate Temperature/Pressure compensation, Density Factors etc… to be considered in calculations of the Mass Flow, if the instrument primarily a volumetric flow measuring device.

Comparison between Turbine meter and Positive Displacement meter

Turbine Flow meter	Positive Displacement Flow meter
Indirect measurement	Direct measurement
Requires upstream/downstream straight lengths	No straight lengths required
Affected by fluid viscosity	Free from viscosity effect
For a given small range, a smaller size compared to PD meter	Larger size required to achieve a given flowrate range
Lower operating/maintenance/investment costs	Higher operating/maintenance/investment costs

Credits : N Asyiddin