Customer: Zweckverband Wasserversorgung Kleine Kinzig
Products: VAG EKN® Butterfly Valves, VAG CEREX® Butterfly Valves, VAG RIKO® Plunger Valves, VAG DUOJET® Automatic Air Valves
The Kleine Kinzig water supply is the only drinking water reservoir in the state of Baden-Württemberg, and is one of the state's central water supplies. The reservoir is located in the vast forest between Freudenstadt and Alpirsbach and is fed by creeks and sources in the Black Forest. With a maximum holding capacity of 13 million m3, it supplies 250,000 inhabitants. VAG valves were used to build a preliminary purification stage.
In addition to supplying drinking water, the Kinzig reservoir serves as flood protection, compensates low water and supplies sustainable energy. The water is processed into drinking water in the waterworks below the reservoir from where it flows through pipes and pumps to the members of the cooperative. The control centre for the whole station is in the waterworks.
At the end of 2004, a new preliminary purification stage equipped with VAG valves was put into operation. The purpose of the new stage was to improve the quality of the water especially when it is very cloudy. FeCI3 flocculation only has to be carried out for strong cloudiness, mainly of mineral origin.
The raw water flows out of the reservoir at the inlet pressure through the new preliminary purification stage. From there, about 90 per cent of the treated water is guided through a turbine into the basin and flows through the previous treatment stages into the finished-water reservoir. The hardness of the remaining 10 per cent of the water is increased, and the water guided past the turbine back into the main water flow for the first hardening.
The planning for the new preliminary purification stage started in 2002. While the required building was being constructed, the invitation to tender for the process engineering was issued. All of the products and work had to meet the high requirements of drinking water. The planning was awarded to the experienced civil engineering company Alwin Eppler GmbH & Co., KG in Dornstetten, which specializes in drinking water, wastewater and hydraulic engineering. A total of eight plant engineering companies submitted bids. The order for the delivery and installation of the process engineering components – and hence the valves – was awarded to Kopf AG Umwelt- und Energietechnik in Sulz-Bergfelden.
From day one, Kopf AG managed the engineering and construction of the reservoir, where valves made by VAG and other manufacturers had been operating for almost 30 years. Kopf AG has years of experience and – like the awarding authority – believes that high quality products are more economically viable than 'cheap' valves. This was clearly stated in the tender. The price also influenced the decision for VAG valves. ‘Once we had determined that the quality was right, we looked at the economic viability,' explained Siegfried Hezel, Project Manager at Kopf AG: 'We’ve been using VAG valves for years and know from experience that their quality and service life are excellent.'
The type of actuator – electric or pneumatic – had not been decided upon yet in the planning phase. Although the water works' technical department had good experiences with electric actuators, they set aside their scepticism and took a closer look at pneumatic actuators and what other operators had to say. Everyone they spoke to was very positive. The pneumatically actuated valves also proved themselves in the continuous load test.
On the manufacturer's side, VAG’s extensive experience with pneumatically actuated valves proved to be a tremendous asset. Following the evaluation of the financial and technical criteria, the choice fell on pneumatic actuators by FESTO. The team’s initial scepticism quickly disappeared. Today, having gained their own positive experiences, the cooperative is keen on using the technology in future projects.
Even when the water level and hence the pressure is low, the required flow rates still have to be maintained to guarantee the supply of drinking water. This means a flow rate of 770 litre/ second when the waterworks are running at full capacity. VAG met this requirement with compelling hydraulic solutions. Trapped air (cavitation) damages material over a longer period of time. VAG's product engineers spent time in the planning phase working on a favourable flow plan that prevented cavitation and optimised the safety and service life of the valves and the pipes.
More than 100 of VAG's valves are operating in the preliminary purification stage, a showcase project that is a popular destination for field trips and excursions. The high requirements of today’s drinking water technology have been cleverly solved.
Additional valves were delivered and installed until April 2004. The new preliminary purification stage was put into operation in November 2004. All of the remaining works were completed in 2005.
A total of 58 valves (CEREX 200L in the nominal dimensions DN 100 and DN 250) are pneumatically actuated. In addition to the CEREX Wafer-type Butterfly Valves, EKN Double Flange Butterfly Valves, Plunger Valves and DUOJET Air Valves were installed. All of the tasks could be handled by valves in the standard product range; customisations were not necessary.
All of the valves were delivered on time and functioned as expected. Like the awarding authority, VAG believes in environmentally friendly installations and waste disposal. And last, but certainly not least, the cooperation between the parties was excellent: 'Drinking water is not like any other product. We have to deliver consistently high quality. We can't simply throw away a batch that doesn’t turn out,' explains Joachim Rapp, managing director of the Kleine Kinzig cooperative. 'That's why it was important that we could rely on a timely delivery and high quality.'
Rapp speaks from experience: the drinking water reservoir has been in operation for some 30 years. 'We've been working with VAG for years, for one, because they have good cost-effective products, but especially because they understand the high demands we have on products and services. And their know-how and reliability are first-rate.’
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