March 2021, MARIETTA, GA ~ InPro 4850i is a combination pH electrode featuring a sodium membrane glass that uses the sodium concentration in the process (brine) as a reference.

The difference in electrical potential between the pH-glass and the sodium reference glass is converted into the pH value. The sodium reference system is highly resistant to chlorine and other oxidizing agents. This makes the sensor very well suited for the demanding process conditions in chlor-alkali production.

Solution ground and shielding eliminate interference, and enable redox measurement. Digital signal conversion ensures 100 % signal integrity and stability. Intelligent Sensor Management (ISM) technology simplifies sensor handling and reduces sensor lifecycle costs. 

Precise and Reliable pH Measurements in Chlor-Alkali Production
A combination of elevated temperatures, the presence of oxidants, and highly sensitive sensor output signal makes reliable pH measurement in the chlor-alkali process very challenging.

This application note reviews these problems in relation to membrane cell chlorine production and explains how the InPro 4850i pH sensor solves all the measurement issues.

Chlor-Alkali Process pH Measurement
80% Reduction in Sensor Maintenance
Elevated temperatures, the presence of chlorine and high salt concentration throughout the chlor-alkali process make stable and reliable pH measurement with conventional pH sensors a constant challenge. Further, the conditions mean sensor lifetime is usually short, so sensor maintenance and replacement costs are high. Evonik Industries Fine Chemicals Co., Ltd. is a Sino-German joint venture that produces cyanuric chloride as well as the main raw materials for its production: sodium cyanide and chlorine.