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Submersion Turbidity Transmitter for Clean Water Applications

Submersible Turbidity Transmitter for Clean Water

The TU8325 is a Turbidity Sensor with integrated electronics designed to output a 4-20mA signal proportional to the turbidity measurement. The TU8325 is designed to be screwed into a riser tube for submersion into streams, weirs, pits, tanks or other unpressurised vessels.

The TU8325 uses an infrared light emitting source and a 90° photo-receptor to measure back scattering in accordance with ISO 7027EN 27027.

Manufactured in PVC with IP68 rating, the TU8325 is designed to be submersed into an open vessel, stream or pit to give continuous turbidity measurements.

4-20mA Submersion Turbidity Transmitter

The TU8325 is a unique piece of equipment.  It combines a nephelometric turbidity sensor and is offered complete with integrated electronics to provide an isolated 4-20mA output proportional to the turbidity measurement.

The industry standard 4-20mA output signal is isolated into 600Ω and designed to give easy integration with a wide range of control equipment. The 4-20mA signal is simple to connect to a PLC, digital Chart Recorder, universal controller or even our online Data Logger.

The 4-20mA output is loop powered, which means that the same two wires which carry the 4-20mA signal are also the same two wires which power the device. This makes integration with PLC's and other control equipment incredibly straightforward.

Turbidity Transmitter with NTU Ranges

The TU8325 is designed for water quality analysis and is suitable for drinking water applications, raw water applications and water treatment applications. The ranges available with the TU8325 are as follows:-

Please note:- Nephelometric Turbidity Units are shown as NTU

Turbidity RangeTurbidity Resolution
0 - 4.000 NTU 0.001 NTU
0 - 40.00 NTU 0.01 NTU
0 - 400.0 NTU 0.1 NTU

As a microprocessor driven device the TU8325 can communicate with a personal computer using a hyper-terminal client and serial interface. By accessing the device the ranges can be adjusted in the instrument software, allowing the same device to measure from as low as 0.001 NTU through to 400.0 NTU. We're also able to factory calibrate the measuring range of the instrument prior to it being despatched.

The TU8325 also offers a digital RS485 output which can be used to connect to a supported device.

Submersion Turbidity Transmitter

The TU8325 has a 2" thread at the rear of the device to allow it to be screwed into a riser tube (such as our model TU90s or TU90-ATC-S) for continuous or online turbidity measurements.

The TU8325 is designed to continuously monitor the turbidity in a stream or tank and is used in applications such as water treatment monitoring, raw water monitoring and other water quality analysis in industrial or municipal environments.

In addition to the rear mounting thread, the TU8325 has an optional auto-clean nozzle, which can be connected to a suitable compressed air system.  The auto-clean system can be called for via a PLC or on an auto-clean relay from of our universal controllers (BC7635-AC or BC7685-AC). The auto-clean system then uses the compressed air to remove any contaminating agent or detritus from interfering with the lens of the turbidity transmitter, thus reducing the requirement for human involvement in preventative maintenance and prolonging continuous operation.

The auto-clean air-nozzle is rated for use with a maximum air pressure of 3 Bar.

Submersible Turbidity Transmitter Features & Benefits

The TU8325 is a genuinely unique instrument. It is designed to be permanently mounted into the flow of a weir, stream or into an open tank, to provide continuous turbidity readings. It outputs a 4-20mA signal proportional to the turbidity measurement.

Designed to offer precision measurements, even when measuring very low turbidities, the TU8325 can measure as low as 0.001 NTU or as high as 400.0 NTU in the same cell.  Using a personal computer hyper terminal, the serial interface allows the range to be changed from 0 4.000 NTU to 0 - 40.00 NTU or 0-400.0 NTU.

The PVC body and IP68 rating allows the cell to be permanently mounted into a dip tube or riser tube, and with the optional auto-clean system enabled, gives continuous turbidity readings with minimal maintenance.  The isolated industry standard 4-20mA can interface with a wide arrange of PLC's and other control instruments which can easily be connected using just 2 wires.

The turbidity measurements follow the standard nephelometric back scattering methodology (ISO 7027 - EN27027) and the infra-red light is not affected by the colour of the sample.

TU8325 Sumbersible Turbidity Transmitter Specifications

  • Specifications


    Submersible Turbidity Transmitter

    Model No:- TU8325

    Turbidity Range & Resolution:- 0-4.000 NTU with 0.001 NTU resolution

    Turbidity Range & Resolution:- 0-40.00 NTU with 0.01 NTU resolution

    Turbidity Range & Resolution:- 0-400.0 NTU with 0.1 NTU resolution

    Zero NTU:- ±0.400 NTU all ranges.

    Sensitivity:- 70% / 130%

    Materials and Rating:- Manufactured in PVC to IP68

    Analogue Output:- 4-20mA isolated into 600Ω

    Digital Output:- RS485

    Operating temperature:- 0-50°C

    Operating Pressure:- 1 Bar at 25°C

    Autoclean:- by air pressure max 3 Bar

    Power supply:- 9 / 36 VDC

    Weight:- 800 grams

  • Features


    • Submersion Turbidity Sensor for installation into a riser tube, which allows the TU8325 to give to continous or online Turbidity measurements from inside a tank, pit, weir, stream or other unpressurised vessel.
    • Nephelometric Turbidity measurements (ISO 7027 - EN 27027) give results in NTU. Ideal for water quality analysis.
    • Exceptional accuracy even at very low ranges, a resolution of just 0.001 NTU and a maximum scale of 400.0 NTU all in the same compact design.
    • Simple to install and connect to measurement and control equipment - the 4-20mA current output is loop powered, meaning that the same two wires that transmit the signal also transmit the measurement signal.
    • Optional auto-clean nozzle, means that when paired with a suitable auto-clean system, and build up of material around the sensing lens of the TU8325 can be removed, reducing the requirement for human intervention outside scheduled preventative maintenance.
    • The TU8325 has no moving parts and requires minimal periodic calibration and maintenance.
    • Factory set or configurable via computer - the TU8325 can be periodically calibrated using a personal computer and the instrument can be re-ranged for alternative applications as required.
    • Designed specifically for precision measurements in drinking water analysis, raw water measurement, and for water treatment applications.
  • Data Sheets

    Data Sheets


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