Nivetec Echo Smart Series, Руководство по эксплуатации и установке, Страница: 61 / 73

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11. System Options
11.1.
Self-Cleaning Wiper Sensor with Turbidity Measurement
This sensor incorporates a scattered light turbidity meter into the EchoSmart Wiper
Sensor to provide continuous Level and Turbidity measurements.
11.1.1. Application
This sensor is recommended for use in applications in which there is need for a
Level and Turbidity measurements at the location of the sensor. It is specifically
recommended for use in water and wastewater treatment clarifiers and thickeners
to continuously monitor sludge level and to provide an indication of turbidity at the
location of the sensor – typically near the effluent weir.
The Level and Turbidity Sensor is also recommended to measure Media Level,
Backwash Expansion and Backwash Turbidity in granular media filters. It may be
used separately or in conjunction with the available in-air Water Level Sensor for
effective conditional control of filter backwashing.
11.1.2. Principle of Operation
Sludge level measurements use the EchoSmart ultrasonic time-in-flight
measurement technique as with all EchoSmart interface level sensors.
Turbidity measurements are provided by a 90º scattered-light turbidity meter
located in the combined sensor housing. Sensors are factory calibrated from 0 – 50
NTU. Power to the sensor is provided by an EchoSmart Controller or Power Supply
Unit to which it is connected. The measurement indication is displayed on the
Controller. Output signals include a 4-20mA proportional signal and RS-485
Modbus RTU digital.
11.1.3. Sensor Cleaning
Sensing surfaces of the sludge level and turbidity sensor are automatically cleaned
by a fully integrated wiper system with a replaceable rubber wiper blade. The wiper
is operated by an internal motor powered by the EchoSmart Controller or Power
Supply Unit.
11.1.4.
Installation
The sensor has a ¾ in. NPT female threaded connection to provide simple
attachment to a user supplied mounting pipe. The connection is a direct replacement
for the standard EchoSmart sensor. In general, locate the sensor in accordance with
instructions for ultrasonic sensors as otherwise described in Section 6. Additionally,
the sensor may be located near an effluent weir to optimize the effluent turbidity
measurement without adversely affecting sludge level measurements.
In filter applications, sensors are located immediately below the top of the
backwash trough to secure measurements during active backwashing and while the