In the multi-stage feed water pump, the water flows in the same water pump casing. At this time the pump pressure is equal to the sum of the impeller pressure. The pumps generally have two kinds of structure: A is of the impeller and vaned diffuser shell made as an independent unit and lid with a few long screw pierces through the unit and before and after the pump, the pump a whole composition; another is made from cast iron segment common shell, sections of the guide wheel, impeller by load segment. The partition and guide adjacent screws are fixed. The impeller is fixed on the pump shaft. The most common is the first.
Water pump shaft is supported at both ends in the bearing seat, bearing in the bearing seat generally use sliding bearing, with lubricating oil, the packing seal.
The pump suction side cover behind the first stage impeller, first stage impeller is with "anti teeth" nut on the shaft. The so-called "anti teeth", refers to the direction and the direction of the rotation of the impeller rotation direction of the same rotation. This is not because the rotating impeller and the nut is loosened.
Each segment of the impeller outlet are respectively and an access guide wheel alignment, otherwise the efficiency of the pump, the flow will reduce, and even cause increasing of the axial thrust, the thrust bearing load increase and fever, so the maintenance after installation, each equipped with a section of the impeller and vaned diffuser, the relative position was measured at the impeller outlet and guide entrance. If there is no alignment can change between the pump body clip pad thickness changes, or between the impeller sleeve length alignment.
