When we talk about water, we usually associate it with our most important foodstuff. This medium is also exploited in many fields of industry and production. There are numerous applications and uses. Water as an artwork, in contrast, is less frequently encountered, assuming we ignore ice sculptures and fountains. A group of English artists created something completely new for the Ruhrtriennale at Zeche Zollverein.
Today the coal mine, in operation until 1986, is an industrial monument. It has been part of UNESCO's cultural heritage programme since 2001. Here, at the Schacht XII (Shaft XII) coking coal bunker, the Raintower installation was created. The 'walls' of the monolithic structure are formed by innumerable water droplets, falling to the ground from a height of approximately 20 m. The optical simulation of a tower results. The artwork was created by a group of London artists, calling themselves rAndom International. They are known for their art installations, predominantly based on light and movement. As a counterpoint to the solid, static architecture of the former mine, stands the transient tower of water.
An optical illusion with lots of background engineering
Some refined engineering is required to create the optical illusion of a tower of water. The entire installation primarily comprises three components:
A steel structure at a height of approximately 20 m, attached to the coking coal bunker tower, a water containment with dimensions 12 x 12 x 1.40 m high, and a pump installation with piping, which ensures that the water in the containment is pumped up to the steel structure.
This structure protrudes approximately 10 metres in the free space in front of the coal bunker. This provides the necessary distance between the water and the building wall. Connected to the 'distance piece' is another steel structure with dimensions 6 x 8 m. Water is uniformly sprayed from approximately 600 nozzles at a pressure of around 1.0 bar. The ensuing waterfall thus gives the impression of a three-dimensional object. A particular challenge here was to find the right balance between the clear structure of the water walls and the water pressure necessary to achieve them. Due to the approximately 20 m drop height, the water may drift. The water tower appears to be displaced and does not form vertical, but inclined side walls. This is an undesired side effect. The required water volume, the water pressure at the nozzles and the nozzle design itself therefore required precise coordination. Around 26,000 litres of water each minute are required to maintain the illusion. The drop speed and height mean that every water droplet requires around 2 to 3 seconds from the nozzle to the ground. If the flow of water is interrupted, the tower disintegrates from the top downwards. The falling water is caught in a 12 x 12 x 1.40 m containment. The basin comprises a steel substructure for support. The side walls consist of formwork panels, cladded on the inside with a PE-HD mat.
Because this component is accessible, the upper covering is formed by fine meshed steel segments. On the one hand they are capable of allowing the falling water to pass through, and on the other to allow visitor groups in, who then find themselves inside the tower. It was originally planned to use mine water as the medium. Because this could not be implemented for hygienic reasons, they resorted to traditional tap water. Entrainment and evaporation losses are approximately 20 to 25% per day and are compensated by input from the public water network. However, the ultimate aim is to form a closed water loop. To achieve this, a third component is required:
The pump technology with piping from the containment to the steel structure with the spray nozzles. The pumps used are four Söndgerath SPT submersible drainage pumps. They are capable of delivering the necessary 440 litres of water per second to an elevation of 20 m and maintaining the required water pressure. The connecting PVC pipes transfer the pumped water up the coking coal bunker into the steel structure. Visitors now have the opportunity of observing the spectacle from afar or entering the interior of the water tower. It is particularly spectacular in the dark, when a very special optical effect is achieved by the use of light. The falling water produces noises similar to heavy rainfall. Water, light and sound backdrop create an impressive atmosphere and mesmerise the visitors.
Söndgerath submersible pumps: safe and reliable
SPT submersible pumps are designed for immediate use. The low weight and enclosed motor guarantee simple installation and safe, faultless operation. The pumps can transport dirt particles within the water with no problems and remain reliable in slurping mode and dry running. They are therefore particularly suited to the Raintower remit.
The installation does not need to be adapted to the respective heads if water levels vary.
The integrated motor protection circuit breaker not only protects the motor, but also facilitates an automatic restart function.
The stainless steel cooling jacket and effective heat dissipation guarantee absolute dry running reliability and surfacing operation at full load.
Even under exceptional operating conditions effective sealing and a high degree of reliability is guaranteed thanks to the double mechanical face seal.
The submersible drainage pumps can be flexibly used for different applications. They can be operated in any position, either vertically, horizontally or upside down.
Servicing is totally problem-free: thanks to the modular design components are interchangeable between different types.
The pumps are capable of reaching the required delivery heights and flow rates without problems.
Whenever fluids need to be transported or pumped, pump engineering is in the background. Without them life – as we know it – would be unthinkable. However, because pumps are often hidden from view, their work is not always immediately obvious. This means there is always a risk of misjudging the technology. The fact is that solutions need to be found for the respective tasks, in which the pumps are employed in the right place. This also applies to the art installation at Zeche Zollverein. The Raintower could not have happened without the use of the four special submersible pumps. The rAndom International group performed a wide range of tests using different techniques and also a variety of pumps in order to create this perfect illusion.
So a pump in the right place is not what's needed, but the right pump in the right place.
Designation: Submersible drainage pump
Motor output: 39.5 kW
Weight: 270 kg
Model: electric, double-jacket, submersible pump
Submersion depth: max. 20 m
Shaft seal: double mechanical face seal
Maximum capacity: for 20 m delivery height, 120 l/sec
Project: Raintower at Zeche Zollverein for Ruhrtriennale
Project planning: Studio rAndom International
When: August 2013
Key data: delivery height 20 m, storage container 12 x 12 x 1.40 m, pumping capacityPumps: approx. 26.000 litres/minute
Pump technology: Söndgerath Pumpen GmbH, Zur Schmiede 7, 45141 Essen, Germany