Chemical, thermal and mechanical processes are applied with the help of pumps, agitators, refiners and sorters in the individual steps of paper production – raw material preparation, stock preparation and paper finishing.
The raw material cellulose as well as the chemical additives place high demands on the mechanical seal used – the media are abrasive, viscous, high-temperature and sometimes toxic.
CHETRA mechanical seals meet the relevant requirements of TA-air and ATEX and the demands of increased environmental awareness and at the same time economic efficiency.
Extreme operating conditions and highest requirements
Innovative, often customized solutions based on decades of experience in the industry with well-founded application technology expertise.
Thorough and "leak-free" sealing of latex mixtures
One of Finland’s largest paper manufacturers experienced difficulties in sealing latex mixtures in the coating kitchens. This special application in paper production is one of the most difficult sealing tasks in the industry.
Due to excessive leakages with the seals used so far, the most important latex pumps were successfully converted to CHETRA double mechanical seal type 821 with barrier pressure system.
Service life of seals in handmade propellers at a new standard
Due to service life problems with gaskets in handmade propellers some domestic and foreign paper mills asked CHETRA for a solution.
Due to strong shaft deflections special requirements arise. Often the propeller runs above the level of the stock and hits it. Stock densities of 5% ATRO and above are also difficult to handle.
A stationary CHETRA GLRD of the 201 series designed for these requirements mastered all sealing requirements and solved the problems. Service lives of 10 years are achieved.
Standardization and continuous improvement
In Austria’s largest corrugated cardboard factory, the sealing technology was put on a new, standardised basis. Three CHETRA GLRD types are sufficient at all relevant points throughout the plant:
Type 700 – single metal bellows GLRD up to 2 (2.5) % ATRO.
Type 208 N – Single metal bellows mechanical seal in stationary design up to 3.5 % ATRO without flushing.
Type 807 – Double mechanical seal with double relief for higher sealing pressure or pressureless supply as operating mode; ATRO > 3.5 %.
The plant of the Austrian manufacturer is also accompanied by CHETRA with a Continuous Improvement Process (CIP).
In this process, the mechanical seal that is to be overhauled or repaired is continuously examined and assessed in order to ensure permanent improvements and optimisations in product, operation and general conditions.