Chinese
Spanish
French
Russian
German
Portuguese
Indonesian
Thai
Vietnamese
Arabic
Direct Answer: Radar or Doppler for Water Flow Velocity?
Choose non-contact radar when debris, floodwater, corrosion or unsafe access make submerged hardware difficult; choose submerged Doppler when the water contains suitable acoustic scatterers and the sensor can remain correctly installed in the flow. Neither method produces defensible discharge from velocity alone: water level, channel geometry and the velocity-to-flow calculation must be part of the scope.
The buyer should submit low and flood conditions, channel section, sediment and debris, surface condition, mounting access, power, telemetry and the required acceptance method before selecting a meter.
Buyer Risk: Comparing Only the Velocity Range
A wide stated range does not prove that the site will produce a usable signal. Radar depends on a representative moving surface and mounting geometry. Doppler depends on acoustic scatterers, submergence and a stable sensor position. Channel geometry, datum and conversion assumptions can dominate the final flow error.
| Selection factor | Non-contact radar | Submerged Doppler | Buyer evidence |
|---|---|---|---|
| Sensor contact | Mounted above water | Installed in the water | Flood clearance, debris and maintenance access |
| Measured velocity | Surface velocity | Velocity from acoustic scatterers in the water | Document conversion to mean velocity or discharge |
| Site dependency | Surface return, angle and beam footprint | Particles or bubbles, depth and mounting stability | Photos and low/high condition data |
| Maintenance exposure | No submerged probe | Probe can collect sediment or debris | Cleaning and safe retrieval plan |
| Hydraulic input | Level and channel section required for discharge | Level and channel section required for discharge | Survey, datum and recheck responsibility |
Verified YexSensor Flow-Meter Evidence
The following published values apply to the named models only. Confirm the ordered revision and the complete station design before purchase.
| Model | Published velocity evidence | Published integration evidence | Selection boundary |
|---|---|---|---|
| YEX-HY-RFMS-01 | Radar velocity range 0.1-20 m/s; published accuracy ±2% | Integrated level evidence and RS485 Modbus RTU | Requires representative surface, mounting geometry and configured channel section |
| YEX-HY-DFM-01 | Ultrasonic Doppler range 0.03-10 m/s; published accuracy ±1.0% plus 1 cm/s in stated range | Water level input and RS485 Modbus RTU; IP68 | Requires submergence, suitable scatterers and protected mounting |
| YEX-HY-DFM-02 | Ultrasonic Doppler range 0.03-5 m/s; published accuracy ±1.0% plus 1 cm/s | Water level input and RS485 Modbus RTU; IP68 | Base-mounted submerged installation; confirm sediment and access |
Hydraulic Data Required for Discharge
Velocity must be combined with water level and a defined channel section. For radar, document the surface-to-mean velocity relationship. For Doppler, document the meter algorithm and configured section. Natural channels require survey evidence and a recheck trigger after flood, scour, sediment or civil work.
Store raw velocity and level with calculated flow so reviewers can diagnose whether a change came from the water, the geometry or the conversion.
Installation and Site Constraints
Radar needs a rigid bracket, clear beam, stable angle and clearance above maximum water level. Avoid bridge vibration, bank eddies and obstructed surfaces. Doppler needs firm orientation, continuous submergence, cable protection and a location that limits burial and debris impact.
For both methods, define datum, low-flow and flood access, lightning and surge protection, enclosure, solar or mains power, grounding, telemetry and safe maintenance responsibility.
Modbus, RTU and SCADA Integration
Confirm power, address, baud rate, parity, registers, data type, byte order, units, scaling and status behavior from the exact manual. Transmit raw velocity, level, calculated flow, data quality, battery or supply status and communication age where available.
When communication fails, the station should preserve local data or clearly mark the gap. Test power recovery, time synchronization, alarms and backlog behavior during commissioning.
Commissioning and Acceptance
Acceptance should prove alignment, sensor position, datum, configured section, raw velocity, level, calculated flow, units, timestamps, communication and fault recovery. Compare with an agreed reference method across more than one condition when practical.
Handover should include survey, installation drawings and photos, exact model manuals, channel configuration, coefficients, register map, power budget, alarm tests, maintenance plan and re-survey triggers.
Request a Flow Velocity Recommendation
Send application, channel type and dimensions, low and high depth and velocity, surface condition, suspended matter, sediment, debris and ice risk, flood level, mounting photos, power, cable distance, RTU/SCADA platform, telemetry, quantity and acceptance method.
Review the YEX-HY-RFMS-01 radar flow meter, YEX-HY-DFM-01 Doppler flow meter and RS485 Modbus integration FAQ, then Send Your Project Requirements for method confirmation.
FAQ
Q1. Does radar measure the whole water column?
No. It measures surface velocity, so the station needs a validated relationship to mean velocity and the configured channel section.
Q2. What does Doppler need in the water?
It needs suitable acoustic scatterers and correct submergence and orientation. Very clear water or changing sediment can affect signal quality.
Q3. Which method is better for flood debris?
Non-contact radar avoids a submerged obstruction, but the surface and mounting must still provide a usable return through the flood range.
Q4. Can velocity be reported as flow directly?
Only after applying water level, channel geometry and the approved conversion. Store the raw inputs with the calculated result.
Q5. When is a mechanical current meter useful?
It can support surveys or reference checks when the site and procedure are suitable, even if continuous monitoring uses radar or Doppler.
Q6. Can both meters connect to a PLC or RTU?
The named YexSensor models publish RS485 Modbus RTU. Confirm the exact power and register map for the ordered revision.
Q7. Why can flow be wrong when velocity looks reasonable?
Check water-level datum, channel section, coefficient, sensor position and sediment or civil changes before adjusting the velocity sensor.
Q8. How often should channel geometry be rechecked?
Set triggers after floods, dredging, deposition, vegetation or civil changes and an interval based on channel stability and consequence.
Q9. What belongs in the RFQ?
Include hydraulics, geometry, surface and water conditions, mounting, power, telemetry, Modbus, survey, commissioning and acceptance.
Q10. How should lifecycle cost be compared?
Compare civil work, brackets, power, telemetry, cleaning, re-survey, spare parts, data platform and field access, not only the sensor price.
Summary
Radar and submerged Doppler meters fit different water-velocity conditions. Select from surface, scatterers, depth, debris, mounting and maintenance, then engineer level, channel geometry and conversion with the sensor. Verify Modbus/RTU data, hydraulic configuration and fault recovery and include survey, station and acceptance scope in the RFQ.
