BigPatents India

Controlled , energy-saving minimum quantity device of a multistage centrifugal pump having a maximum pressure special stage. Centrifugal pump of multistage design, a flow guide duct being disposed in the pump casing (1), behind the last pump stage (4), for the extraction of a part- quantity of the total pump delivery, which flow guide duct feeds the extracted part-quantity to an additional impeller and the impeller applies a further pressure increase to the part-quantity. A pressure-boosting special impeller (5), which is known per se and which is disposed within the centrifugal pump behind its last pump stage (4), generates a pressure-enhanced part- quantity. This part—quantity flows to a line system (6) provided with a flow divider (7), at least two branch lines (8, 9) branching off from the flow divider (7) and at least one branch line (8) being provided with a shut-off member (12) . A reversion of the throttled-off part—quantity of the special impeller to the final pressure of the centrifugal pump is therefore realized during continuous operation of the centrifugal pump. (FIG.1)