Water Level Sensors

Ott PLS

Accurate water level and temperature measurement for demanding monitoring applications

The Ott PLS is a rugged, vented pressure and level probe designed for precise water level measurement in surface water and groundwater environments. Its ceramic capacitive measuring cell delivers excellent accuracy, long term stability and reliable performance under demanding field conditions.

An integrated temperature sensor provides simultaneous water temperature measurements. Standard SDI-12, SDI-12 via RS-485 and 4 to 20 mA output options allow the probe to connect easily with compatible dataloggers and monitoring systems.

Applications

• Surface water level monitoring
• Stream and river gauging
• Flood warning systems
• Stormwater monitoring
• Lakes and reservoirs
• Tidal monitoring
• Hydropower applications
• Groundwater observation wells
• Boreholes and aquifer studies
• Mine water monitoring
• Drinking water applications
• Managed aquifer recharge
• Dam seepage monitoring

Proven ceramic measurement technology

The Ott PLS uses a ceramic capacitive pressure cell to measure the hydrostatic pressure above the probe. This pressure is converted into an accurate water level value.

Unlike some membrane based technologies, the robust ceramic measuring cell is designed to resist deformation over time. This supports dependable long term measurements and reduces the risk of drift during extended monitoring installations.

The pressure cell can withstand overloads of up to five times the selected measuring range without permanent mechanical damage.

Automatic compensation for changing conditions

The built in microcontroller compensates for temperature effects and applies correction values for water density and gravitational acceleration.

A vented capillary inside the probe cable allows the sensor to compensate automatically for changes in atmospheric pressure. This enables the Ott PLS to provide water level measurements without requiring a separate barometric sensor for standard vented installations.

Integrated temperature measurement

In addition to water level, the Ott PLS measures water temperature using an integrated NTC temperature sensor.

The temperature channel has a measuring range from −25°C to +70°C, a resolution of 0.1°C and a stated accuracy of ±0.5°C.

Collecting level and temperature data from one probe can simplify station design and reduce the number of instruments required at the monitoring location.

High accuracy and long term stability

For SDI-12 configurations, the Ott PLS provides a water level resolution of 0.001 m, or 1 mm.

The stated pressure measurement accuracy is ±0.05% of full scale. For the 0 to 4 m and 0 to 10 m ranges, the supplied specification also states water column accuracy of ±10 mm across a temperature range of 10°C.

Long term stability is specified at no more than ±0.1% of full scale per year.

Multiple measuring ranges

The Ott PLS is available in several water column measuring ranges:

• 0 to 4 m
• 0 to 10 m
• 0 to 20 m
• 0 to 40 m
• 0 to 100 m

Accuracy =  ± 0.05% FS.

Available interfaces

• SDI-12
• RS-485 using the SDI-12 protocol
• 4 to 20 mA analogue output

Construction & Cables

Designed with continuous deployment in mind, this Logger incorporates a ceramic pressure sensor within a salt water resistant 904L stainless steel housing.

All PLS units are manufactured with custom cut vented cables.

Users to specify cable length upon order.

This product is manufactured by Ott and proudly represented by Aqualab Scientific.