3S-COLORIMETER – TP / Orthophosphate

Illustration of the Colorimeter TP in a sample picture

Compact on-line colorimetric analyser for TP / orthophosphate measurement in water.

Phosphorus occurs in several forms: ortho, poly and
organically bound. Further classification can be made on wheter the phosphorus is dissolved (passing through a 0.45 micron filter). In TP oxidation / digestion, polyphosphates and organic phosphorus are converted into orthophosphate.

Organic phosphorus is converted to orthophosphate by UV catalyzed persulfate digestion; polyphosphates are converted to orthophosphate by sulphuric acid digestion.
All forms of phosphorus are converted to its ortho form in the TP procedure, in the presence of persulfate and an acid background.

Method description:
The Total Phosphorus concentration can be measured using two
different methods depending on the range requested:

  • Photochemical oxidation and blue colorimetric method;
  • Photochemical oxidation and yellow colorimetric method.

Both methods use advanced photochemical oxidation, sulphuric acid,
heat, UV irradiation and a chemical oxidizer (sodium persulfate).
After the complete oxidation of the phosphorus in the sample to PO4,
then a colorimetric reaction is performed and the intensity of the colour
developed is proportional to the phosphate concentration present in the sample.


This image illustrates an example of how the photochemical oxidation method works to the measurement of the Total Phosphorus
  • Waste water treatment plants;
  • Industrial applications;
  • Surface water monitoring;
  • Process control.

  • Dual compartment enclosure;
  • Color touchscreen interface, simple and user friendly menus and functions;
  • Batch analysis: programmable frequency;
  • Temperature heated reaction cell;
  • Small dimensions;
  • Automatic calibration / validation / cleaning;
  • Built in peristaltic pump for sampling;
  • Low reagent level alarm;
  • Loss of sample input;
  • Separate waste line for sample containing reagents;
  • Long autonomy; low maintenance, low operating cost.

Robust and reliable
Designed for industrial and environmental on-line applications ensures
the highest level of robustness in the electronics, mechanics and
hydraulics components.

Easy installation
To start measurement is enough to power the analyzer and connect reagents,
sample and waste line.


  • Dual stream;
  • Multistream;
  • Dilution module;
  • Datalogger;
  • Filtration unit.

Hydraulic compartment

In this image is shown how the hydraulic compartment is set

Technical specifications

from 0 to 15 ppm TP (others upon request)
Method: Oxidation and colorimetric reaction
Measuring time: Starting from 7 minutes (plus programmable oxidation time)
Frequency: Programmable
Maximum measured error: 5% of measuring range end
Heated reaction cell: Yes
Reagents: Nº 2 (yellow method)- 3 (blue method) solutions consumption is less than 1 liter / month for continuous operation
Outputs: 2 analogic outputs 4-20 mA, RS232
Alarms: Up to 4 relays (configurable setting: system alarm, high value, low value, command for an external device ...)
Autocleaning: Integrated
Filtration: Option, depending on the sample characteristics
Protection: IP54
Ambient temperature: >0 - 45°C
Sample temperature: >0 - 45°C
Datalogger: Integrated (option)
Power supply: 110-240 Vac / 80 VA / 50-60 Hz
Operating cost: Very low
Dimensions: 600mm x 370mm x 210mm
Weight: Around 20 kg
Installation time: Few minutes

For all enquiries

+39 (0)185 799024

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