As the name suggests, a flow meter is a device or an instrument used to measure linear, nonlinear, mass or volumetric flow rate of a liquid or a gas. Different types of flow meters are available for different application and depending upon the requirement, a careful selection of flow meter is made. For e.g., a Turbine type flow meter cannot be used for measuring the flow in an unclear liquid (waste water or corrosive liquids).

Basic types of digital flow meters commonly applied in the industry:

• Turbine Flow meter
• Electromagnetic Flow meter
• Metal Tube Rotameter
• Mass Flow meter
• Differential Pressure Flow meter
• Venturi meter
• Orifice meter
• Ultrasonic Flow meter
• Vortex Flow meter

Selection Criteria

Before selecting a flow meter for an application, certain queries must be answered:

• Application: Liquid or gas
• Type of Liquid : Corrosive / Non Corrosive
• Viscosity of Liquid :
• Flow rate : Min / Max
• Material of construction of wetted parts :
• Liquid type : Clear / Corrosive etc.
• Operating Temperature :
• Operating Pressure :
• Line Size :
• Indicator : Remote or Local

Necessary conditions:

There are however certain necessary conditions for any flow meter to work properly to its expectations:

• The pipeline must be completely filled. If the flow passes through incompletely filled pipe lines then erratic readings may occur.
• The flow should be streamlined at the inlet and outlet of the flow meter failing which turbulence may occur thereby the display reading may fluctuate and may incur loss of accuracy to a noticeable extent.