Do centrifugal pumps require more Net Positive Suction Head (NPSH) margin at higher elevations than at sea level?

What are the various methods for controlling the rate of flow in centrifugal pumping systems? Is there an impact on efficiency?

Are there any special operational considerations for magnetically driven pumps and what are their implications?

How does viscosity affect the hydraulic performance of air operated diaphragm pumps?

What should I know about axial thrust for single suction impellers?