When pumping non-Newtonian fluids,knowing the relationship between the viscosity, temperature and shear rate is very important.At lower shear rate(fluid at rest)grease has higher viscosity,but it increases as motion commences.Higher viscosity may mean more friction losses and thus more power required by the pump.This issue becomes particularly problematic for the suction(inlet)side to the pump.Higher friction losses from the supply tank to a pump inlet may result in cavitation,incomplete filing of the inlet ports,and damage to the pumps.Friction also means more heat generated.If the heat is not removed from the seal area of the pump,it will run hot and fail prematurely as well.The paper reviews pump operation when pumping grease at various temperatures, speeds and flow rates,and the friction losses are evaluated.An optimum pumping regime is evaluated and recommended from a practical,application-related viewpoint.
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