RSS-2-300 WL Flow Meter

Product Highlights
  • Contactless flow measurement
  • Instrument combined from two sensors:
    surface velocity radar and
    radar level sensor
  • Integrated discharge calculation in the instrument
  • Wide velocity measurement range from 0,02 m/s to 15 m/s
  • Distance measurement range from 0,5 m to either 15 m or 30 m, depends on device model
  • Compact, low-power design
  • Wide input voltage range, suitable for solar applications
  • IP68 aluminum casing
  • Supports variety of communication interfaces (RS-232, RS-485, CAN, Alarm open-drain outputs)
  • Optional SDI-12 support
  • Automatic mounting angle compensation (cosine correction)
  • Easy pole, wall or enclosure mounting
  • Operating temperature range from -40 °C to +85 °C (-40 °F to +185 °F)
Product Description
The Geolux RSS-2-300 WL flow velocity and level meter uses radar technology to provide precise, contactless measurement of surface flow velocity, and to measure the distance from the sensor to the water level. Contactless radar technology enables quick and simple sensor installation above the water surface, and requires minimum maintenance.
The integrated discharge calculation module uses the two measurements together with a pre-configured river channel geometry profile to calculate the total water discharge in real-time. The discharge calculation module is included in the price of RSS-2-300 WL instrument.
RSS-2-300 WL flow meter is used to monitor flow velocity and water level in open channels such as rivers, irrigation channels or sewer systems, and for monitoring and controlling hydropower plants and wastewater treatment plants. The flow meter is also suitable for various mass flow metering applications in mining processing plants, industrial installations, and, due to operation without moving parts and robust mechanical design, is ideal for measurement of flammable fluids and harsh chemical applications.
The surface velocity radar operates in the K-band (at 24.125 GHz), and provides 20 flow speed readings per second over serial (RS-232, RS-485) and CAN interfaces. The level radar sensor operates in the W-band, between 77 GHz and 81 GHz.
A variety of supported communication interfaces and protocols enable easy integration with existing telemetry equipment and SCADA systems. The integrated tilt sensor measures inclination angle of the sensor and the flow velocity measurement is automatically cosine-corrected according to the measured mounting tilt angle.
Geolux RSS-2-300 WL instrument is certified according to both European and American standards, and is being used worldwide.

Open Channel Flow Measurement

RSS-2-300 WL is a non-contact flow sensor that provides precise measurement of surface flow velocity and water level. The flow sensor is immune to air temperature and air density changes. The unit is enclosed inside an IP68-rated waterproof enclosure,which makes it suitable for measuring open channel flow. The instrument supports multiple communication interfaces and protocols, which makes it easy to integrate in an existing SCADA system.

Industrial Flow Measurement

RSS-2-300 WL flow meter can be used for precise flow measurement in all kinds of outdoor and indoor industrial facilities. Geolux RSS-2-300 WL flow meter is also perfectly suited for use in various water and sewage processing facilities, hydro power plants, etc.
Detailed Specifications


Surface Velocity Radar Type
K-band 24.125 GHz Doppler radar, 21 dBm EIRP
Surface Velocity Radar Beam Angle
12° Azimuth
24° Elevation
Level Radar Type
W-band 77-81 GHz FMCW radar
Level Radar Beam Angle
Detection Distance
15 m / 30 m
Speed Range
0,02 m/s to 15 m/s
Speed Resolution
0,001 m/s
Speed Accuracy
Level Resolution
0,5 mm
Level Accuracy
+/-2 mm
IP Rating

Electrical & Mechanical

Power Input
9 to 27 VDC
Power Consumption
1,3 W operational; 0,235 W standby
Maximal Current
< 750 mA
Temperature Range
-40°C to +85°C
(without heating or coolers)
Device Outer Dimensions
150mm x 200mm x 250mm


Serial Interface
1 x serial RS-485 half-duplex
1 x serial RS-232 (two wire interface)
Baud Rate
1200 bps to 115200 bps
Serial Protocols
Modbus/RS-485, GLX-NMEA, ASCII-S
other available on request
SDI-12 Interface
Analog 4-20 mA Interface


EN 50293:2000
EN 61000-6-2, EN 61000-6-4:2007
EN 61000-3-2:2006+A1:2009+A2:2009, EN 61000-3-3:2008
EN 300 440-1, EN 300 440-2
FCC Part 15 Subpart C