Measurement of active oxygen during the steel making process is of critical importance to ensure a problem free process, ensure that the grade specifications are met and to optimize materials and energy consumption. Actose® sensors allow the measurement of active oxygen in the molten steel which in turn enables the parametric evaluation of carbon/aluminium in the melt. The estimate of the carbon level in the BOF process allows steel makers to determine the end of blow and the knowledge of active oxygen allows steel makers to estimate the quantity of aluminium de-oxidant to be added. The accurate determination of oxygen content with Actose® sensor in killed steel, enables quick heat turnaround during secondary steelmaking.

The Actose® oxygen sensor is based on a magnesia stabilized zirconia solid electrolyte which transports oxygen ions at the molten steel temperature. The oxygen ions travel between a reference electrode of known oxygen activity and the steel melt. By measuring the millivolts generated due to this movement of the oxygen ions, the oxygen activity in the steel melt is calculated by the Nernst equation given below:

emf= \frac{RT}{nF}ln\frac{a_{O_{2},steel}}{a_{O_{2},ref}}


emf is the measured electromotive force between the 2 terminals

R is universal gas constant

T is the measured metal temperature

n is number of electrons transported

F is Farraday’s constant

a_{{O_{2},steel}} is the oxygen activity of steel

a_{{O_{2},ref}} is the oxygen activity of the reference material

Actose® sensors are designed to robustly, reliably and accurately measure the temperature and active oxygen content in the molten steel. Since the oxygen level in the molten steel is closely linked to carbon/aluminium levels as the case may be, the active oxygen measurements are used in empirical relations to reliably predict the dissolved carbon and aluminium levels in the molten steel.

Actose® Catalog  – Sensor for active oxygen measurement in molten steel



Acutap (TO) is a drop sensor specifically designed for temperature, oxygen and carbon measurement in the BOF. Typically, in order to measure these parameters, the converter must be tilted and a sensor then dipped manually into the molten metal in order to measure the parameters. By using Acutap, these steps can be avoided and at the push of a button, a probe is “dropped” into the converter while the converter is still vertical. The probe consists of a active oxygen sensor fixed onto a metal weight and connected to a measuring instrument by a long length of coiled cable. When the probe head is dropped into the metal, the weight carries it downward and into the metal and long cable uncoils while transmitting the sensor signal to the measuring instrument. Acutap is an alternative to sublance measurements for existing converter shops where logistical reasons prevent the use of sublance sensors.

By avoiding the need to tilt the converter for taking a measurement, significant savings in time can be realized in the BOF process. These savings in time translate to higher productivity. Additionally, lower metal losses are also realized as the need for de-slagging (and the consequent loss of some metal along with the slag) are avoided for taking a measurement. Acutap probes are available for both temperature and oxygen measurement. For more information about Acutap probes, please contact us.

Actose® Instrument


The Actose® instrument is a rugged PC based measuring instrument designed to measure the temperature of molten steel as well as the emf corresponding to the active oxygen content in the molten steel. Based on the measured temperature and emf, the instrument calculates the active oxygen level of the molten steel and the carbon/aluminium  (as the case may be) level of the molten steel. Several options for Level 2 communication with plant PLC systems are available.

The instrument is based on a fanless industrial PC and designed to operate in challenging systems. All changes in parametric settings can be performed using the 7″ resistive touchscreen available on the instrument. Real-time trace of the measurement is available on the screen in order to diagnose the measurement and traces as well as final measured values are stored on board for post measurement analysis.