At a big oil refinery in Vienna an 18 unit cooling tower has been retrofitted with fan and drive equipment in combination with a significant noise reduction. Public authorities only allowed the necessary retrofitting of the cooling tower after 18 years of operation, if the dominating noise generation of the towers would be effectively reduced. From an inventory study by acoustic specialists it hs turned out that the cooling tower fans were the dominating noise sources for the exposed urban area, in spite of the presence of splashing water in the tower. Two fans have been selected for qualification together with quiet drive equipment. Finally a super low noise fan with special shape could only be accepted. Beside the choice for the fan, the low noise demands had an impact on the selection on all other equipment like E-mothers and gearboxes. The correctness fo the noise analyses was confirmed by control readings after the retrofit job. The presentation will review problem inventory, equipment selection procedure, technical impact of noise requirements on all components and verification.