Scientists’ Tip: To understand how Aqua Data’s probes work remember; water contains charge carriers.

Equation 2
E = F/q 

Where: 

E = electric field strength
F = Force acting on the charge
q = Charge

Image 2: The “Right-Hand Rule” is used to determine the direction of the created electric field.

Scientists’ Tip: The magnetic field generated by the coil in Aqua Data probes is (approximately) pointing upwards - as shown in Image 3. Using the Right Hand Rule, we can deduce that the electric field must be pointing in the direction indicated by the green arrow (Image 3).

Scientists’ Tip: Aqua Data probes contain two electrodes that you align in the known electric field direction. These electrodes measure voltage caused by the electric field.

Equation 3
U = E*x 

Where: 

U = Measured voltage
E =electric field strength
x = distance between electrodes

 Equation 4
U= B*v*x 

Where: 

U = measured voltage
B =magnetic field strength
V = velocity of water flow
X = distance between electrodes

Scientists’ Tip: In a nutshell, since both the magnetic field strength and the distance between the electrodes are constant, the water flow velocity can be deduced from the voltage measurement.

FloStick RC4 WaterVelocity Meter
Product code: FloStick-RC4

The Aqua Data FloStick RC4 Water Velocity Meter is a stand-alone instrument comprising a velocity probe, wading rod and rugged display housing, combined in a single integrated package.

 The RC4’s advanced analogue and digital electronics offer an accurate, robust, low-cost method for measuring and logging water velocity data.

  Key Features

• Calibrated from 0.000 to 2.000m/s with a resolution of 0.001m/s. Exceptional sensitivity makes this meter ideal for measurements in shallow and sluggish flows.
• Indicates both reverse or saturated flow.
• User-selectable averaging periods of 2, 5, 10, 30, 60 seconds are available.
• Velocity measurements are not influenced by water quality. Readings are just as accurate in clean or dirty water.
• Small probe permits measurement close to fluid surface and channel beds or pipelines in walls.
• Unaffected by temperature variations and changes in water density or suspended sediment.
• The probe’s unique design results in low vulnerability to fouling by weeds in rivers or ragging-up in sewers.
• No moving parts - maintenance-free design.
• If maintained correctly, the unit retains its calibration for life.
• Accuracy of 2% of reading, typically ± 30mm/sec.
• Losing the meter in deep water is not an issue – the Aqua Data FloStick RC4 will float if dropped.

Fluvia RC3 Electromagnetic Velocity Meter
Product code: FluviaRC3B

The Fluvia RC3 is Aqua Data’s flagship velocity meter. This portable device measures the velocity of water electromagnetically to determine its flow.

 The RC3 features a hydrodynamic shape, small probe, and no moving parts – so you won’t accumulate debris, which guarantees accuracy and reliability.

 The FLUVIA’s user interface is designed for simple, quick and accurate velocity measurements. Settings can be tailored to individual needs, including data logging methods, units of measure, date, time and language.

Key Features

• The electromagnetic sensor is unaffected by temperature variations, density changes, sediment and water clarity.
• IP67 Environmental Rating with robust stainless steel electrodes.
• Users enjoy reliable, straightforward, and completely hands-free operation.
• The rechargeable battery allows for up to 20 hours of continuous use.
• GPS, Bluetooth and GSM (Cellular network) support.
• Measured velocity records are stored on the device up to a total of 12,000 points.
• The menu-driven meter makes it quick and easy to configure the device, allowing the user to set unit measurements, time filters and recording preferences.
• Measures and records real-time velocity readings with timestamps attached. Recording can be enabled and disabled as required.
• User-adjustable zero offset to ensure accuracy in measurements.
• Features an easy to interpret, on-screen graphical representation of velocity reading.
• Flow calculation from dimensions, water height and velocity points are calculated according to ISO748:2007.
• The “River profile” setting assists the operator in taking up to 30 vertical sections containing up to 6 different readings, which can be exported.
• Reading data: Displays saved velocity readings with the ability to transfer them to a PC via RS-232 or SDI 12. 

Pros

Cons

Electromagnetic velocity meters

• Performance is not impacted by temperature, viscosity or pressure.
• Able to handle rapid flow changes
• Measure flow horizontally or vertically
• No maintenance required
• Typically have a high accuracy than ultrasonic meters

Cannot measure other non-conductive fluids such as oils and steam.

Ultrasonic Meters

Measure both conductivity and non-conductive fluids

• Fluids containing debris, soils or air bubbles may impact the accuracy
• May require temperature compensation