RCHM Current Meter

Main components

• Propeller (rotor)
  A lightweight, well-balanced propeller whose rotation speed is proportional to water velocity.

• High-sensitivity shaft and bearings
  Minimize friction to measure low velocities with high accuracy.

• Current meter body
  Designed to be mounted on a rod, cable, net frame, or immersion arm.

• Pulse sensor
  Each rotation generates a pulse (reed switch, magnet, or inductive sensor) recorded by a counter or datalogger.

• RCHM calibration curve
  Provides the relationship between the number of pulses and actual velocity (m/s), necessary for reliable hydraulic data.

Operation

1. The current meter is positioned steadily in the flow.

2. The moving water makes the propeller rotate.

3. Pulses are counted over a known time interval.

4. Velocity is computed using the calibration curve.

5. Flow rate can be calculated if the cross-section is known.

Typical characteristics

• Accurate measurement from very low velocities (≈ 0.03 m/s) to higher speeds depending on the model

• Robust construction for field or laboratory

• Simple and reliable mechanical design, little affected by electrical noise

• Compatible with plankton nets, concrete channels, pipes, and natural streams

Applications

• Velocity measurement in rivers, ditches, canals

• Flow characterization in plankton nets

• Velocity measurement in concrete channels or test flumes

• Flow control in hydraulic or aquaculture systems

• Hydrodynamic studies in natural or industrial environments