Ursa Technologies Ltd


High Concentration Chlorine Dioxide (ClO2) Process Streams

These streams have special requirements due to their highly corrosive and toxic nature. Control of ClO2 gas phase concentrations is essential due to risk of explosion at higher concentrations.

Uses: Process Analyzer and Control

  • ClO2 Generator Product Gas, 0 to 20% ClO2
  • ClO2 Bleaching Solutions (to storage tank and to bleachery), 0 to 15 g/l ClO2
  • ClO2 0 to 3 g/l ClO2
  • ClO2 Other, as needed (call)

C2L15_176px.jpg - 31kb
Model C2L15 for 0-15 g.p.l.
Chlorine Dioxide (aqueous)

Benefits: Automatic Control of ClO2 Gaseous and Aqueous Concentration Levels

  • You know when the ClO2 plant has started up without resorting to iodometric / thiosulphate titrations from a gas stream sample.
  • You know when the ClO2 plant is shut down in a safe condition with the diluent air flow interlocked with the analyzer to below 1% ClO2 v/v.
  • You know that dilution air flow is controlled from the analyzer so that safe and efficient operating conditions are maintained within the generator.
  • You know that safety and efficiency prevail with a hot generator and a cool gas product, as made possible by controlling the recycled flow of cold absorption column off-gas.

C2L15_176px.jpg - 31kb
Model C2G20 for 0-20% v/v
Chlorine Dioxide (gas)

Features and Principles of Operation:

Analytical Method:

The ClO2 concentration is directly proportional to spectral absorbance at appropriate wavelengths. Our analyzers utilize this principle to continuously monitor the concentration of ClO2 in various liquid and gaseous process streams within the chemical preparation and bleaching system. The sample flows through the spectrophotometer block to provide a continuous readout and electrical signal proportional to ClO2 concentration.

Continuous Readout

Sample Flow and Optical Design:

For gaseous ClO2 applications, the sample flows through a sample cell from the upper CPVC bulkhead fitting on the side and exits through the lower CPVC bulkhead fitting on the side. For solution ClO2 applications, entrance into the sample cell is through the lower bulkhead fitting, and exiting at the upper bulkhead fitting.

All the wetted surfaces in the analyzer are of CPVC or Teflon, materials which are chemically inert to ClO2 and halogen solutions. The optical path consists of light passing through an inert sample cell.

After passing through the sample, the light enters a diode array spectrophotometer. This uses certain wavelengths of light for reference and other wavelengths of light for analytical measurement. The quantities of light detected at measurement and reference wavelengths are rapidly determined (milli-seconds timescale). The log ratio of these values is proportional to the concentration of the component being measured. Use of reference wavelengths makes it possible to compensate for some non-analyte sample variability, variation in light source and/or the condition of the sample cell.


The analyzer is controlled by a small but powerful computer. Electronics are protected by a high quality power conditioning system. Interfacing within the analyzer is via USB standard interfaces. The unit includes analog and digital I/O capabilities, along with a robust set of solid state relays. Electrical power and signal cables enter and exit the analyzer via standard PVC bulkhead connectors on the side of the case.


Equipment and Electrical Specifications:

  • 15" colour touch screen display with armoured glass.
  • System Accuracy: ± 3% of range with constant sample.
  • Power Required: 100-130 volts AC, 60 Hz. / Convertible to 196 - 260 volts AC, 50-60 Hz.
  • Battery back-up: The unit will continue to function for at least 40 minutes (and up to one hour) if external power is removed
  • Recorder Output: 4-20mA and various (optional) 0-1V, 0-10V, wireless, ethernet.
  • Relay Control: NO or NC, 5A 110V AC rated, solid state relays open or close at preset high and low concentrations
  • Data back-up to memory stick and DVD (both included)
  • Mounting Configuration: Wall mounting using 4 fastening bolts, or stand mounting.
  • Shipping Weight: Approximately 50 kgs.

Operating Software:

Control software for these analyzers is proprietary and has been developed in house. It uses data from multiple wavelengths to provide concentration estimates and identify process error states. As such, it provides greater information than is available from single-beam single-wavelength types of analyzer, which is useful in process control and diagnostics. We are able to modify the software to meet specific needs of customers, subject to the cost of these modifications being born by the customers.


Each installation includes three (3) physical copies of the manual, plua a digital version.

Installation and Sampling:

  • Locate the NEMA IV cabinet enclosure as near as practical to the gas or liquid take-off point.
  • Ensure handy access to the analyzer with space for maintenance and re-calibration.
  • It is important to instrument air purge the NEMA IV enclosure in order to maintain the integrity of the computer and related circuitry.
  • In cases where the vertical gas feed and discharge piping is connected to the analyzer make sure the lines are trapped to prevent condensed gas entering the sample cylinder.
  • Isolate the analyzer for on-line removal by installing block valves on sample entry and exit piping.

On-site Training and Installation:

On-site training and installation may be available at separate cost, worldwide. Please ask.


Support is available by e-mail, telephone, fax or video conferencing (by appointment).


Ursa Technologies Ltd., #110, 12815 Clarke Place, Richmond, BC, V6V 2H9, Canada
phone604-241-0190 emailinfo@ursatech.com location-map