Chemiewerk Bad Köstritz (CWK) has reported significant improvements in safety, reliability and process control through the use of Schubert & Salzer sliding gate valves for the handling of liquid and gaseous sulphur dioxide (SO₂) in its sodium thiosulphate production.
With a history spanning more than 195 years, CWK specialises in sulphur-based compounds and is one of only a few suppliers worldwide capable of producing thiosulphates on a commercial scale. The company has relied on Schubert & Salzer sliding gate valves for many years across a range of production processes.
A key application is the manufacture of sodium thiosulphate, where precise control of liquid SO₂ is essential. In the second stage of the batch process, liquid sulphur dioxide is introduced into a reaction vessel using a Schubert & Salzer Type 8043 sliding gate valve. Accurate flow regulation ensures consistent production quality while supporting safe operation.
The handling of sulphur dioxide presents major safety challenges due to its highly toxic nature. As CWK stores and processes large quantities of the substance, its facilities are subject to stringent major accident prevention regulations.
“Because we store and process SO₂ in very large quantities, the tightness and reliability of the valves used are of central importance,” said Marcus Nöthlich, operations engineer in the sulphur compounds division at CWK.
To meet these demands, the installed valves feature tongue-and-groove sealing in accordance with DIN EN 1092-1, a metal bellows seal for enhanced external tightness and compliance with TA-Luft requirements under ISO 15848-1.
According to CWK, the sliding gate valves have delivered a substantial increase in service life compared with previously installed valve technologies, which required complete replacement twice a year. Today, only individual wear parts need replacing after several years of operation, reducing maintenance costs, plant downtime and technician exposure to residual SO₂.
CWK also reports improved control accuracy, particularly when regulating gaseous SO₂ for pH adjustment. The company says the valves’ high control range enables precise flow regulation, helping to maintain product quality while enhancing operational efficiency and safety across the plant.
Sliding gate valves excel in handling toxic chemicals
