A manufacturer must consider several factors when setting a particular pump's recommended operating range. Limits may be based purely on the wear life limitations of the pump thrust washer or on a predetermined minimum acceptable efficiency or head. Other factors must be considered in setting operating limits, including the need for sufficient fluid flow to allow for motor cooling and avoiding vibration induced by operation at very high or low flow rates. Operation at near shut-off conditions will cause localized overheating, particularly of the thrust washers resulting in excessive wear and premature failure.
This paper discusses pump axial thrust and pump thrust washer limitations. Tests were performed to determine actual values of pump thrust and washer wear. A series of curves showing a pump "operating range" based purely on axial thrust considerations are included.