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3. EchoSmart Sensor (ESS)
The EchoSmart Sensor is a microprocessor controlled piezoelectric transducer designed
specifically for operation under water (submerged in the process liquid).
3.1.
General Overview
The EchoSmart Sensor generates an ultrasonic sound wave that propagates through a
liquid medium and is reflected back from material that is present in the vessel (typically
settled solids, suspended solids, and/or the tank bottom). The sound wave travels at
known velocities providing the ability to convert elapsed time into Range and Level
measurements.
The EchoSmart Sensor does more than just produce a raw signal. It is equipped with
an advanced programmable microprocessor and dynamic memory. Through these
facilities, the sensor provides all signal control, enhancement and interpretation, and
determines the final process measurement. The Smart Sensor communicates with an
EchoSmart Controller via digital communication. The sensor also generates a 4-20 mA
proportional current loop signal. Customer connections are provided at the Controller.
If a Smart Sensor is part of a field network, connections are made at the Controller or
Power Supply Unit that is supplying power to the sensor.
Sensors with a 90
◦
surface back-scatter turbidity meter integrated into the ESS are
available. This option can be beneficial and cost effective in applications where a
turbidity measurement at the location of the sensor is desired. It is often used in
secondary clarifiers and similar applications to alert process upset conditions. It is also
employed in water and wastewater treatment media filters as part of an effective
conditional backwash control system.