Valves for pig cleaning
The campus of the Swiss Federal Institute of Technology in Lausanne is a pioneer in the use of lake water for heating and cooling. Since 1978, the university buildings have been cooled with lake water. Today, heating energy is also sustainably obtained from the lake. In recent years, the energy center on Lake Geneva has faced a new adversary: the quagga mussel.
Danger from the depths
The invasive quagga mussel has been spreading rapidly in European waters for several years. Unlike other mussel species such as the zebra mussel, the quagga mussel survives in deeper and colder locations, colonizing systems that have largely been spared from mussel infestation until now. Pipes that lead into affected surface waters such as Lake Geneva must be regularly cleaned of deposits inside using pigs.
Free passage for the pig
A full bore knife gate valve was manufactured at Sistag's Swiss production plant for the main inlet of the lake water system. This allows the pipe to be shut off for inspection work at the power plant. Unlike conventional valves, the Wey knife gate valve has a fully unobstructed passage that corresponds exactly to the pipe diameter and allows pigs to pass through. Special bronze scrapers remove deposits from the gate every time it is opened. A unique sealing system ensures 100% tightness in both flow directions.
From prototype to success story
After extensive testing and a first successful cleaning cycle, a second valve was replaced by an identical Wey knife gate valve. The special valve design has proven itself so well that Sistag has quickly developed the custom-made product into a new product series: the Wey knife gate valve FB. The full bore valve has since been used in various Swiss lake water systems, such as Lake Biel and Lake Zug, in the fight against quagga mussels.
