Submersible hydrostatic level transmitters for depths of 200m

Paul Boughton
Impress Sensors & Systems is introducing a new range of submersible hydrostatic level transmitters for use in depths of up to 200m. The transmitter features an SDI-12 digital output and an inbuilt high accuracy temperature sensor.
The SDI-12L range of submersible level transmitters uses either a stainless steel silicon-based pressure sensor or a ceramic pressure sensor in marine-bronze. Both versions use piezoresistive technology, which provides long-term stability and measurement repeatability.
Highly versatile, the transmitter is suitable for a wide range of applications, including the monitoring of: river and reservoir levels; tanks and vessels in process plants; seawater and estuary levels; borehole water levels; wave height; and V-notch weir flow measurement instruments.
The stainless steel version offers a higher resolution of pressure measurement to around 12-13 Bit and has a much lower signal-to-noise ratio, providing a very smooth and accurate method of level measurement. On the other hand, the ceramic pressure sensor version is better suited to marine use, where standard devices may suffer from corrosion.
Measurement ranges are available from 0.5mWG up to 200mWG. The output units can easily be adjusted to mmWG, cmWG, inHg and all the standard engineering units required via the SDI-12 interface and command structure. Temperature range of the transmitter is from -20 up to +60 degrees C. Accuracy of the inbuilt temperature sensor is less than +/-0.1 per cent of full-scale output.
Due to its SDI-12 (serial data interface at 1200 baud) compatibility, the transmitter can be corrected according to the specific density of the media being measured and local gravity can be set within the device, adding further to the accuracy of the unit.
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