Laboratory Redox Measurement by GS Rapidox II


  • Reduces waste
  • Increases the use of recycled cullet
  • Filters dust
  • Lowers environmental contamination
  • Optimizes fining processes
  • Minimizes changeover times
  • Decreases energy consumption                                                   

    By means of

    Rapid measurement of oxygen activity (Redox)


    Fast response times (less than 10 minutes)
    Wide dynamic range (1-10-9 bar)
    High reproducibility (typical standard deviation 5mV at 1300C)

Optimizing the production process

Glass melting in industrial furnaces is a complex process involving fusion of raw materials, degassing of primary melts, homogenization, and conditioning.

Controlling combustion processes, optimizing energy consumption, and minimizing harmful emissions are essential, as today's glass makers face ever-increasing pressure from commercial and environmental standpoints.

Measuring oxygen activity, or redox state of batch raw materials and melts, provides valuable information regarding foaming and fining characteristics as well as final product properties, particularly color.

Flexibility and reliability in operation

Using experience gained in over 30 years of design and supply of temperature and gas sensors for the control of metal melts, Heraeus Electro-Nite has developed the Rapidox - a fast, accurate system for determining oxygen activity in glass melts. The traditional Rapidox furnace has been recently upgraded to the GS Rapidox II. The integrated design of this newer system  is well adapted to the glass making research environment, as well as in the factory where it provides information for optimum control of production processes.

A disposable oxygen sensor, combined with a Ni/NiO reference and an iridium wire sealed in vitreous silica, results in a fast response and an interference-free operation up to 1400C.

A sensor combined with a Mo/MoO2 reference and an iridium wire sealed in alumina ceramics can be used in temperatures up to 1650C.

Samples are introduced in thermally shock resistant ceramic crucibles which are rotated during the measuring procedure.

This, together with rapid heating to a homogenization temperature (normally 1300C) provides a close simulation of real furnace conditions.

Typical measuring cycles including heating, homogenization and oxygen activity are performed in less than two hours. 

Your problem - our solution 

 GS Rapidox II can be used for a variety of applications in the glass industry including:

  • Batch redox control for the characterization of "unknown" components, such as recycled cullet and filter dust, an aspect of importance to container glass producers
  • Monitoring of the melting process by analysis of scoop samples taken from the melting tank, e.g. during a color change of a container or float glass furnace
  • Evaluation of the samples taken from the feeder and the final glass products, is important to obtaining a stable forming process and for ensuring consistent color quality

Measurements for:

Container glass

GS Rapidox II has been successfully applied on a routine basis for measuring the reducing of organics and other pollutants which may be present in the cullet. Values measured can be used to correct the batch "recipe" in order to stabilize the color and fining of the melt.

Float glass

GS Rapidox II measurements can aid in control of the fining and foaming processes which take place during float glass melting. The oxygen partial pressures in glasses, as a function of temperature, relate to the addition of extra required amounts of fining agents such as sulfates and minor amounts of coke or blast furnace slag.

Fiber glass

GS Rapidox II measurements can aid in controlling foaming processes. Additionally, GS Rapidox II measurement can show the effects of different raw materials and scrap recycling upon the radiative properties of the fibers during the forming process, including the fiber breakage.

TV glass

Fining efficiency of antimony and nitrates often used for TV glass production can be monitored by measuring the change in oxygen activity in the melt with using varying temperatures.

Speciality glasses

GS Rapidox II can be a valuable tool in optimizing the production of a variety of speciality glasses ranging from fiber glass to domestic high quality tableware.

All other kinds of glasses

Other uses include:

  • Control of reducing agents before addition to the batch, e.g. blast furnace slags
  • Monitoring the redox state of coloring agents before mixing them with glass


Electrical connections

      Supply voltage: 220/230 V     
      Supply phase: single,  with earth
      Supply frequency: 50/60 Hz
      Maximum power consumption: 5 kVA                            
      Circuit breaker rating: 25 amps
      Computer interface: RS232C

Operational parameters

      Ambient to 1650C
      Temperature stability: 1C

Sample crucible

      Thermally shock resistant
      Accommodates sample weights up to 360 grams


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