OTT PLS – Pressure Level Sensor

Robust ceramic pressure transducer for water level measurement

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The OTT PLS measures water level, depth to water, or pressure by means of an integrated controller and ceramic pressure-measuring cell. Design features such as multiple communication outputs (SDI-12 or 4 … 20 mA), stainless steel housing, and a rugged cable make this sensor ideal for monitoring water level in a variety of applications.

  • Surface water, Groundwater
  • Vented pressure cell
  • Water level, Pressure, Temperature
  • Water level and temperature measurement – for use with external data logger
  • 0 … 4, 10, 20, 40, and 100 m
  • ± 0.05% FS
  • No
  • SDI-12, RS-485 (using SDI-12), or 4 … 20 mA


The robust ceramic pressure cell offers industry-leading accuracy and does not deform over time like membrane technology, providing long-term measurement stability

  • Rugged design: Ceramic pressure cell resistant to physical force (5 x burst pressure) and enclosure made of high-quality saltwater resistant steel for use in coastal environments
  • Built-in microcontroller – compensates for temperature effects and applies correction values for gravitational acceleration and water density
  • Vented pressure probe, automatically compensates for changes in barometric pressure
  • Robust cable with Kevlar core for length stabilization and capillary tube for venting
  • Simple setup and connection to external dataloggers using SDI-12 or 4 … 20 mA interfaces
  • Optimized resolution is achieved by assigning the 4 … 20 mA to that part of the measuring range that is actually required
  • Water temperature output in addition to water level (for SDI-12 output)

Examples of Use

Measuring water level in surface and groundwater, including:

  • Stations with sloping bottom, e.g. water banks
  • Small diameter pipes or holes (from 1″ Ø)
  • Dams, weirs, irrigation systems
  • Waterways that occasionally ice over
  • Brackish water, saltwater
  • Waterways that do not contain water throughout the year (e.g. retaining basins)


White Paper – OTT ecoLog Guidance: Remote communication via mobile networks
OTT PLS – CE Konformitätserklärung | Declaration of Conformity | Declaration de Conformité
Supplement to operating instructions Pressure Probe OTT PLS – Plug-in pressure probe cable
Operating instructions Pressure Probe OTT PLS
Leaflet – Pressure Probe OTT PLS
Technical Note – Sensor Selection Guide Groundwater
Technical Note – Sensor Selection Guide Surface Water
Brochure – OTT Water level measurement
White Paper – OTT ecoLog Guidance: Remote communication via mobile networks
netDL Templates – Configuration – for OTT Data Logger Operating Program
Templates for netDL Configuration shown in the OTT netDL configuration videos
OTT netDL – Configuration – OTT PLS via OTTSDI – Video EN

Technical Data

Water level measurement
Measurement range 0 … 4 m, 10 m, 20 m, 40 m, 100 m
 SDI-12 ±0.05 % FS (linearity and hysteresis)
 4 … 20 mA ±0.1 % FS (linearity and hysteresis)
10 ppm/°C at 20 °C
Resolution (SDI-12) 0.001 m; 0.1 cm; 0.01 ft; 0.1 mbar; 0.001 psi
Temperature compensated working range  -5 °C … +45 °C (ice-free)
Temperature measurement range –-25 °C … +70 °C (ice-free)
Resolution 0.1 °C / 0.1 °F
Accuracy ±0.5 °C / ±0.9 °F
Electrical data
Available interfaces (use as required) 4 … 20 mA, SDI-12, RS485 (via SDI-12 protocol)
Supply voltage +9.6 … +28 V DC, typically 12/24 V DC
Power consumption (SDI-12)
Sleep <600 µA
Active <3.6 mA
Pressure sensor (capacitive pressure sensor) ceramic, temperature compensated, overload safe for up to 5 times the measuring range without permanent mechanical damage
Temperature sensor NTC
Dimensions 195 mm x 22 mm
Weight approx. 0.3 kg
Environmental conditions
Operating temperature –-25 … +70 °C
Storage temperature –-40 … +85 °C
Housing stainless steel 1.4539 (904L) resistant to sea water
Seals Viton
Cable jacket PUR
Protection type IP68
Mechanical Strength meets the mechanical shock tests of IEC 68-2-32
EMC limits CE conformity; EN 61000-4-2/3/4/5/6 and EN 61000-6-3 Class B are adhered to

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