OTT CBS – Compact Bubbler Sensor

Non-contact, bubbler sensor for longterm surface water level monitoring

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The OTT CBS is a compact, accurate, and low power bubbler sensor for surface water level monitoring. The OTT CBS meets or exceeds USGS standards for accuracy, and will not drift over time. It features outputs for SDI-12 and 4…20 mA.

  • Surface water, Groundwater
  • Bubbler-in
  • Drift-free water level measurement – no pressure sensor or electronics in the water
  • 0 to 15 m or 0 to 30 m
  • ± 3 mm (high accuracy version); ± 5 mm (standard and 30 meter versions)
  • No
  • SDI-12, RS-485 (using SDI-12), or 4 …20 mA

Examples of Use

For water level measurement of:

  • Streams, rivers, channels, or canals
  • Groundwater wells
  • Reservoirs, lakes, and wetlands

Ideal for monitoring:

  • Continuous water level networks
  • Lightning prone areas
  • Channels with long, flat embankments


Accurate—Meets and exceeds USGS guidelines for water level accuracy, and will not drift over time

  • Complete Solution—Combining the CBS with an EPS-50 bubble chamber reduces the influence of wave action and prevents unnecessary noise in your data
  • Low Maintenance—No desiccant, pump maintenance, or lubrication required
  • Easy-to-Start/Install—All programming can be completed using DIP switches; connect into existing platforms using 3/8′ O.D. or 4mm O.D. measuring tube (no adapters required)
  • Compact Size—small and powerful pump motor generates the required volume of air to perform measurement.
  • Low Power—Intelligent pumping strategy compares the previous measurement to the actual pressure at the current measurement, and optimizes the pumping time depending on the difference (i.e., small changes in level are measured with very short pump cycles)


OTT CBS – CE Konformitätserklärung | Declaration of Conformity | Declaration de Conformité
Operating instructions Bubble Sensor OTT CBS
Installation instructions Air drying unit for Bubble Sensor OTT CBS
Leaflet – Compact Bubble Sensor OTT CBS
Technical Note – Sensor Selection Guide Surface Water
Brochure – OTT Water level measurement
OTT CBS White Paper

Technical Data

Water level measurement
Measuring range
Version ”Standard” and ”USGS specification” 0 … 15 m (0…50 ft)
Version ”30 m measuring range” 0 … 30 m (0…100 ft)
Resolution 1 mm (0.01 ft)
Version ”Standard” and ”30m measuring range” ±5 mm
Version ”USGS specification” 0 … 15 ft: ±0.01 %
15 … 50 ft: ±0.065 % of measurement value or 0.02 ft, whichever if less
Units m, ft, bar, PSI
Electrical data
Interfaces 4 … 20 mA, SDI-12, SDI-12 via RS-485
Power supply 10 … 30 V DC, typ. 12/24 V DC
Current consumption
Measuring interval 1 min typ. 320 mAh/day
Measuring interval 15min typ. 25 mAh/day
Housing material ABS
Dimensions L x W x H 165 mm x 205 mm x 115 mm
Weight approx. 1,500 g
Protection class IP43
Environmental conditions
Operating temperature -20 … +60 °C
Storage temperature – 40 … +85 °C
Relativ air humidity 10 … 95 %; not condensing
Measuring tube inner diameter typ. 2 mm or 4 mm
EMV – limit values According to IEC61326 and EN61326

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Application Example