In the previous section, we know that the dry-run and dry-run-like failure of the pump is due to insufficient cooling of the pump. In a centrifugal pump, the cooling of the pump is either done by the pumped liquid itself, or in the case of some mechanically sealed pumps, by applying external cooling to the mechanical seal. If the cooling is done completely by the pumped liquid, such as in sealless pumps such as magnetic drive pumps and canned motor pumps, then a minimum flow must be maintained to prevent overheating. The recommended minimum flow value is usually shown when making the pump selection. Please note that this minimum flow value is usually derived based on tests conducted using water at ambient temperature. If your liquid medium has poor thermal conductivity, or you are pumping the liquid at elevated temperatures, or you are running the pump at higher speeds using a VFD, then the required minimum flow will likely be higher. Please consult with the pump manufacturer or their authorized representatives for such applications.