Kolmer motors go to England: Increasing demand for fish-friendly pumps
The Water Board and other government departments are increasingly requiring that suppliers of pumps deliver what they call “fish-friendly” equipment as the result of a European regulation from 2000. Under this law, each member state is obliged to work against any operations or products that could impede fish migration. Under normal conditions, due to pumping activities, the death rate of any fish bigger than 6 inches (15 cm) is nearly 12%, which in the Netherlands alone signifies the premature death of millions of fish. This fact has led the Water Board to explore the usage of fish-friendly pumps. Kolmer Special Motors is taking part in this new demand by supplying the motors necessary for the production of such pumps.

An example of Kolmer’s involvement is a pump provided for the Royal Society for Protection of Birds (RSPB) in the U.K. The product was a fish-friendly, submerged pump with an integrated permanent magnet motor placed together in a fixed outdoor situation. The choice of the pump was based on its compact construction and its high efficiency. Thoroughly ecological, it was produced by the Pentair Nijhuis Company who specializes in patented fish-friendly pumps. The pump and its motor were placed in a nature reserve that gets flooded from time to time to remove any excess water, ensuring a dry area in time for the breeding season.

In Holland, there are more that 5000 pumping stations, most of which are not yet fish-friendly. The death rate among fish is not easily established because so many different types of pumps and locations are involved. However, why the fish die was clearly established in the research of Dr. Bart van Esch of the University of Eindhoven (NL). He writes: “A lot of research results from the U.S.A. are available, where since 1994, research has been on-going as to the damage to the fish population due to water power plants. As a result, they developed fish-friendly water turbines. The results of those studies were also useful in designing fish-friendly pumps.” Van Esch has also investigated the causes of fish mortality in Holland, performing experiments with the carp and eel species.

Causes
One of the causes is mechanical damage, which occurs when the fish hits the impeller of the pump. The forces inflicted on the fish are varying, due to too high a shearing rate. As a result, the fish are actually pulled apart. Also, the rapid variation in pressure plays a role in the damage caused, as it can lead to internal bleeding or the rupture of the swim bladder. In the latter case, the harm is indirect as the fish becomes disoriented and presents itself as an easy prey to predators.

Solutions
The solution that Nijhuis and Kolmer offer is a pump that is 100% safe for eels and 97% for scaly fish, thanks to a new type of impeller with an adapted form that allows maximum passage. The impeller works at a low rotation rate, but thanks to Kolmer’s motor, its energy consumption remains low. In most cases, the existing electric system does not need to be replaced. The motor possesses the following specifications – SQCw/160p/25kW/450rpm – built into the pump by Kolmer Special Motors.