The SPI water quality system measures the concentration of peroxide or chlorine residual in water distribution on the basis of colorimetric analysis.

Colorimetric analysis is the method of determining the concentration of a chemical in a solution with the aid of a specially formulated reagent.

The intensity of the discolouration after the introduction of the reagent forms the basis for calculating the quantity of peroxide or chlorine in the water.

This process provides extremely accurate analysis.

The SPI method starts with colorimetric principles, and is fully automated and integrated to deliver a more precise and more accurate measurement than other forms of measurement, and is not affected by pH, flow or water matrix effects which frequently distort the results found in conventional measurement technologies.

SPI II series - 170

The SPI-170 is a fixed-panel water quality measurement system based on the colorimetric measuring method that utilizes peroxide reagent discoloration.

The intensity of the coloration after measurement with the reagent is proportional to the quantity of Hydrogen Peroxide (P170) or Chlorine (C170) in the water.

The greatest advantage of colorimetric measurement is that it is not affected by external factors like pH and flow.

The SPI-170 is preassembled on a single panel (L x W x H = 485 x 485 x 100 mm) with a control unit and intake/analysis unit.

The SPI II series technology is patent pending.

Functions of the SPI-170 are:

  • Measuring the hydrogen peroxide or chlorine level
  • Measuring the pH level
  • Measuring the flow
  • Controlling the dosing pumps for hydrogen peroxide, chlorine or acid
  • Flow protection (no flow/no dose)
  • Circulation contact protection
  • A supply voltage of 12VDC

Specifications of the measurable parameters:

  • Hydrogen Peroxide or Chlorine
    • Method: peroxide colour reagent
  • pH
    • Method: pH gel-electrode
  • Flow
    • Method: via pulse or current sending flow meters like VDO, Burkert, INEL (if your type isn’t mentioned, please contact us)
Measurement Method Range Accuracy
Hydrogen peroxide Peroxide colour 0 - 200 ppm ± 0.1 ppm
Chlorine DPD 0-5 ppm ± 0.1 ppm
pH Electrode 2 - 12 pH ± 0.05 pH
Flow Pulse or Current 0 – 100 % ± 1%



The SPI-170 makes use of simple operating software. The complete operation is executed using the buttons on the panel. The display shows measured values and settings. The hardware features an internal memory where data, reports and calibration settings are stored. These data are available on demand and are provided with a date and time of occurrence.

With the optional SPI-REMOTE software, it is possible to control and access the data on the SPI using a network connection or the Internet.

With the optional SPI-GRAPHS software, data can be downloaded using the remote connections.


Click Here

Technical Data:

Technical data
Reading variables Chlorine, pH, Flow, Circulation
  Chlorine Colorimetric (525 nm)
  pH Electrode
  Flow Pulse input / 0-20mA
Reading resolution Hydrogen Peroxide, pH, Flow
  Hydrogen Peroxide 0.1ppm
  pH 0,01 pH
  Flow 1%
Control characteristic PI based
Hydrogen Peroxide output pulses Pulses from 0-1/600
Hydrogen Peroxide output Optorelay 24V, 200mA
Acid output pulses Pulses from 0-1/600
Acid output Optorelay 24V, 200mA
Supply 24VDC, 8W / 12VDC, 6W
Communication (optional) LAN/Ethernet
Protection class IP65
Dimensions 485mm x 485mm x 100mm
Alarm outputs 2x relay 24V, 1A
Cycle time 5sec. – 7200sec.
Use of reagent < 0,04ml / cycle
Use of water 30mL / cycle
Display 4x20 digits
Menus Reading overviews, pump outputs, alarms, reports, calibration, settings
Interface panel 6 user keys
Data logger 250 records once every 10sec / 7200sec
Battery Data backup is protected by a battery during data loss
Reagent 100mL Peroxide Colour (+/- 2500 readings )
Flow through water pot 5l/h<flow<50l/h
Solenoids 3x electromagnetic solenoid 4 Watt
Date / time Also accurate after power loss.


The SPI-D141 is a hand-held, portable version of the SPI-170. It is also used to calibrate the 170.

  • 1. Display
  • 2. Buttons:
    • On/Off: This button is used to activate the hand meter.
    • Calib: This button is used to zero the blank measurement.
    • Enter: This button is used to confirm your choice.
    • Menu: This button is used to switch to the different parameters of your hand meter.
  • 3. Channel 1: Supplied with a blue LED. This channel can be used for measurement of peroxide and is used as reference (control) for chlorine and pH.
  • 4. Channel 2: Supplied with a green LED. This channel can be used for measurement of chlorine and pH and is used as reference (control) for peroxide.

The D141 is suitable for measuring the following:

  • Hydrogen Peroxide
  • Free Available Chlorine
  • Total Available Chlorine
  • pH
Measurement Method/Procedure Range Accuracy
Hydrogen Peroxide PerO reagentia 0-100 ppm 0-15 ppm +/- 0.1 and 15-100 +/- 2 ppm
Free Available Chlorine DPD 0-2 mg/L ± 0.03 mg/L
Total Available Chlorine DPD 0-2 mg/L ± 0.03 mg/L
pH phenol rood pH 6,4 - 8,5 ± 0.03 pH