In the pumping business, product innovations usually percolate up in small increments. With the creation of Flygt's N-impeller, Ulf Arbeus has pushed the industry -- and his company -- forward with the force of a tidal wave. The N-impeller is one of the major inventions in pumping technology during the last century. The impeller combines a very high hydraulic efficiency with outstanding clogging resistance. "At first, the idea of the N-impeller was unthinkable. There was convention to overcome," says Ulf. Prior to the N-impeller, it was widely believed that pumps with a single-vane impeller -- the rotating element that forces water through a pump -- were less likely to clog than multi-vaned impellers. But, except for their tendency to clog, multi-vaned impellers were more efficient. Breaking with popular wisdom, Ulf combined a back-swept leading edge with a relief groove. With this design, he theorized, any contamination that initially fastened on the leading edge would be transported out toward the relief groove and expelled. Test after test proved Ulf's theory right and revealed that the pump was even more powerful than originally believed. During one grueling test, rags were fed into the pump every 15 seconds, yet the N-impeller sustained its pumping power. For the first time ever, a Flygt pump achieved 80 percent efficiency, exceeding even H.H. Andersson's widely used definition of the highest possible efficiency. The field tests with wastewater plants were even more encouraging. In most instances, the customers wanted to keep the test pump and buy additional ones. Today, a full 50 percent of all Flygt replacement pumps are equipped with N-impellers. Sales have exceeded $60 million and are expected to grow by 16 percent annually. In addition, with promising results in sludge handling, the N-impeller is opening new, very interesting market potential for Flygt within wastewater treatment plants. Once unthinkable, Ulf Arbeus' N-impeller now has unlimited potential.			Ulf Arbeus Manager, Hydraulic End and Application Department Flygt Solna, Sweden