Kofloc Small Karman Vortex Flow Meter FM31 Series


The Model31 Karman Vortex Flow Meter employs the following principle for measurement of flows:

When a columnar object (object that generates vortices) is placed in the flow path of a fluid, regular channels of vortices, called Karman vortex channels, are generated at the back of the object.
Since the frequency of a vortex generated is linearly proportional to the flow velocity within a given range, the flow amount can be measured by counting the number of vortices.
When the frequency of each vortex generated is detected by the incorporated vortex detector (piezoelectric device), the signal processing circuit outputs a signal which is linearly proportional to volume flow.


  • Because of no moving part, the meter has superior reliability and durability and no error in mounting position is produced.
  • Simple construction (its flow path of fluid contains a columnar object and a vortex detector only) ensures low-pressure loss and low liquid leak. In addition, the detector does not get into contact with the fluid running through the path, therefore, it is ideal for process monitoring of various liquids.
  • Two types of particle-free body materials (PPS and PFA) are available for choice according to your needs.
  • Global specifications (Certification for CE Marking already acquired)
  • Since Teflon is the material for the entire wetted part and no O-ring is in use, the Model31 Series Karman Vortex Flow Meter is optimum for monitoring liquid flows in the manufacturing process of semiconductors.


  • FA instruments
  • Semiconductor manufacturing
  • LCD
  • Housing material production
  • Medicine production
  • Chemical industry
  • Biomedical applications
  • Environment systems
  • Food processing
  • Agricultural/Botanical applications


Flow range (L/min)0.4-42-205-5010-100
Pipe end
Pipe end
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Fluids for measurementUltrapure water, chemicals, and other liquids
Measuring accuracy±3.0%+ 1 digit
RepeatabilityWithin ±0.5% F.S.
Liquid temperature range0-90℃ (No bedewing, no boiling)
Amb. temperature range0-50℃
OutputsWith indicatorLED display in 3 digits
Current output: 4-20 mA (linear)
Alarm output: Open collector (2 LEDs; 80 mA, 30 VDC max.)
W/o indicatorCurrent output: 4-20 mA (linear)
Pulse output: Open collector (10 mA, 30 VDC max.)
Supply voltage12-24VDC
MaterialsBodyAll Teflon® (PFA), without O-rings
CoverPolybutylene terephthalate (PBT) resin
Cable2 meters long; Conductor: Tinned bare annealed copper wire;
Sheath: Heat-/cold-resistant polyvinyl chloride (POC)

Download Datasheet: Kofloc FM31 small vortex flowmeter

For more info and price please contact sales@wmablog.com