ColTechw² Sensor

Sensor for Apparent Colour Monitoring

The ColTechw² Sensor has been specifically designed to monitor Apparent Colour in applications where a broad indication of the colour of the water is required. Organic materials such as Humic Acid or metals like Iron and Manganese dissolved in water will appear as an unacceptable yellow tinge. If discoloured water is allowed to enter the water supply network customers will quickly become aware of the problem.

Measurement of colour is therefore an important element of potable water treatment control, the ColTechw² Sensor in combination with the 7300w² Monitor will provide a reliable, repeatable indication of colour levels allowing online adjustment of coagulation control packages. A high residual colour reading is a clear indicator of a coagulation control system that is not functioning correctly, and will allow the process to be optimised ebabling significant savings to be made in usage of dosing chemicals.

The sensor requires very little maintenance, with no special tools or training required. Calibration can be carried out against either a wet Turbidity standard or using the dry calibration reference cell that is supplied with every sensor. The reference cell provide an extremely easy, repeatable method of checking the performance of the sensor without the cost and inherent errors associated with chemical standards.


  • Raw Water
  • Filtered Water
  • Coagulation Control


  • Automatic Self Cleaning
  • Low Cost of Ownership
  • No Reagents

Technical Specification


Dimensions370 mm x 280 mm x 200 mm (HxWxD)
Weight4.5 kg
Enclosure RatingIP68
Material of ConstructionBlack Acetal Co-Polymer, Polypropylene
Seal MaterialNitrile
Cable EntriesIntegral Cable Gland
Cable Type4 core, 2 Twisted Pair, 5mm O/D Polyurethane Coated
Cable Length5 metres standard, 100 metres maximum
Process ConnectionsInlet and Bypass: 1/2" BSP with 12 mm hosetail
Outlet: 1/4" BSP with 8 mm hosetail
Service RequirementAutomatic Self Cleaning
Wiper and Dessicant Replacement yearly (application dependent)

Environmental Data

Operating Temperature 0 - 50ºC
Storage Temperature -20 to 60ºC
Location Indoor

Interface to Monitor

Sensor OutputRS485
Power12 VDC from Monitor

Measurement Principal

Principal of OperationLight Attnuation
Blue LED Lght Source
Turbidity Limit100 NTU
Optical Path Length40 mm

Measurement Characteristics

AccuracyBetter than +/- 2% FSD on real sample
ResolutionDependent on range setting, typcially +/- 2%
RepeatabilityBetter than +/- 1% FSD on real sample
Response Time90% of step change in 2 minutes at 1 l/min
Flowrate0.5 to 5 l/minute
Low Range0 - 200 ºHazen
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