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Modernisation of drinking water treatment plants with ductile cast iron valves

Even before this project, Stadtwerke Sindelfingen GmbH already had good experiences with the ductile cast iron valves of ERHARD GmbH & Co. KG as regards service, reliability, maintenance and, not least, cost. According to its company philosophy “think global – act local”, ecological considerations are an essential part of the strategy concept of the Sindelfingen municipal utilities. One of these ecological considerations concerns the Sindelfingen waterworks: since its construction in 1977 it had started to age, three different items of drinking water treatment equipment were renovated and/or optimised. For example, air admission and release valves, butterfly valves, dismantling joints as well as soft-seated gate valves had to be replaced in a wide variety of processing units. So it was obvious to fall back on ductile cast iron valves during the modernisation of the water treatment.

Valves made of ductile cast iron

PAS10 dismantling joints, ERHARD ROCO wave butterfly valves with integral electric drive

ERHARD TWIN-AIR admission and release valves for pipe networks

So now, for example, filtration no longer happens in multi-layer filters but in single-layer filters. The corrosion protection of the vessels was renewed and the new valves installed: On the modern single-layer filters, which are stocked with quartz sand and with activated carbon, ERHARD TWIN-AIR air admission and release valves are now operating, for example to discharge just about 100 m3/h of air safely and securely during air purging. The compact and space-saving TWIN-AIR air admission and release valve is perfectly suited for use in larger pipe networks and at all times guarantees safe and automatic air admission and release for the pipeline during filling, during operational air release and during the drainage process.


Double-eccentric butterfly valves, dismantling joints made of ductile cast iron

A large number of ERHARD ROCO wave double-eccentric valves of nominal sizes DN 100 to DN 300, pressure stage PN 16, with slider crank mechanism and with integral electric drive and/or with handwheel, for the most part with corresponding dismantling joints (ERHARD PAS10), have also been installed. The ductile cast iron butterfly valves with the patented wave design offer optimum energy efficiency and hence significant energy savings. High-quality EKB epoxy and enamel coatings plus a broad range of special coatings ensure lasting protection. The ERHARD PAS10 is equipped with two flanges and one pressure ring. This construction makes it possible to reduce the number of threaded rods as these only have a bracing function. The ERHARD PAS10 is equipped with 25 % threaded rods for pressure stages PN 10 and PN 16 and with 50 % threaded rods for pressure stages PN 25 and PN 40. 


Soft seated Multamed gate valve

In the widest variety of inlet and outlet pipelines, new soft seated ERHARD Multamed ductile cast iron gate valves have been. The construction of this generation currently offers many advantages over the previous ones, one of which is decisive: after it opens, the wedge is entirely outside the passage, meaning that medium flow is not constricted.

Authors: Matthias Müller und Boris Vaihinger, ERHARD GmbH & Co. KG

The article was slightly shortened by the editors. You can find the complete article with various illustrations as a PDF in the download area under Downloads Annual Issues EADIPS FGR.