When it comes to the conveyance of material flows, centrifugal pumps are the preferred choice in all branches of industry. As centrifugal pumps are turbo-machines and therefore possess characteristic performance data, the desired delivery flow (working point) will only be attained in conjunction with the overall system. This is of decisive importance to the economical use of centrifugal pumps. A grounding in fluid mechanics and thermodynamics is vital when it comes to their operation in plant. This grounding is provided here by an examination of examples from various important manufacturers.