Flow Switch

Written by Jerry Ratzlaff on . Posted in Flow Instrument

Flow switch, abbreviated as FS, provides a discrete input to the PLC.  The flow switch is typically used as a method of control in tanks, vessels, pumps and other types of process equipment.

Note that like a pressure switch, a flow switch is different than a flow transmitter in that a flow switches sole function is to provide a binary TRUE or FALSE into the PLC.  This approach simplifies programming.


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Flow Switch Types

Flow switches can be solid state or electro=mechanical.  They can be mass flow switches or volumetric flow switches and measure gas or liquids.


Configuration and Alarms

Alarms in the PLC can be:

  • Flow
    • High - FSH
    • Low - FSL
    • High/Low - FSHL