In September 2016, AVK Armaturen delivered six double eccentric butterfly valves series 756 in dimensions DN1000 and DN800 for the supply line from the water reservoirs to the clean water pump stations of the Walddörfer Waterworks in Hamburg.
The AVK butterfly valves with stainless steel seat ring replace the originally installed butterfly valves from the 1980s. The replacement was necessary due to leakage of the old valves. The refurbishment took place during ongoing daily operation of the plant. Next to the butterfly valves four single-shut-off AVK hydrants series 35/31 were installed for the purpose of air release and intake during filling respectively drainage of the pipe system. The access to the valves and hydrants is granted by AVK plastic surface boxes series 80/30 and 80/31. Thanks to the mix of materials of the plastic body and cast iron lid, the risk of freezing and therefore blocking the lid is eliminated.
At the end of last year, AVK delivered five more double eccentric butterfly valves in DN800. The new butterfly valves replaced gate valves in short length from 1965 placed in the basement of the valve chamber, that is located between two reservoirs. The originally installed gate valves needed to be replaced due to wear. Two of the AVK butterfly valves are actuated by an electric actuator and three of them are manually operated.
About the waterworks
Hamburg, situated in the north of Germany, with its 1.734 million inhabitants, has a total of 16 waterworks. Already in the year 1848, a modern water supply system went online in Hamburg. In these times, the main water source used to be the rivers Elbe and Alster. From the beginning of the 20th century, more and more groundwater was sourced from deep rock layers with the help of well-systems, as the raw water was of a very high quality. Drinking water was for the last time ever sourced from the Elbe River in 1964.
Due to an increasing urbanization in the north of Hamburg and an even faster increasing demand for drinking water supply after World War II, two more waterworks were founded next to the existing one from 1892. One of them was the waterworks Walddörfer, that went online in 1965. The waterworks consists today of 21 wells in an underground depth of 200-380 metres and 11,500 metres of raw water pipelines. The raw water, which is already free of pollution, is treated step-by-step, first by aeration, followed by filtration in 12 closed rapid gravity filters, and is finally led via cascades, where excess carbon dioxide is discharged and another aeration takes place. Finally the drinking water is stored in one of three reservoirs with a total volume of 30,000 m³ storage space. Depending on the individual demand, the water is distributed into the supply pipe system via four pump stations. The waterworks has a daily performance of 38,000 m³ constant load and a peak load of 60,000 m³ drinking water.
