Viking Pump's rotary positive displacement pumps, using gear and lobe principles, offer an alternative to centrifugal pumps in applications where system pressure or fluid viscosity fluctuates. The pumps provide a near-constant flow rate with minimal efficiency change, regardless of changes in system pressure or viscosity. Viking's high NPSHR capabilities keep fluid moving with less chance of cavitation in processes where a suction lift is required or where high vapor pressure fluid is being pumped. The pumps can handle fluids from 28 to 2,000,000 SSU viscosity. Viking Pump.