The 4RV-AF foam pump seat is provided with flange holes for fixing to the baseplate or foundation. There are screw holes on the top of the pump casing for water filling and air release, which are used to fill water and remove air from the pump casing before starting the pump. On the flange of the pump suction and pressure cone, there are pressure measuring screw holes for installing vacuum and pressure gauges. There is a drainage screw hole at the bottom of the pump casing for emptying accumulated water during pump shutdown and maintenance. In addition, a drainage screw hole is set at the bottom of the transverse groove of the pump seat to drain any leaking water droplets that flow out of the packing box at any time. All these screw holes, if temporarily useless during pump operation, can be tightened with threaded plugs (also known as "plugs").

Among the above parts, the impeller and pump shaft are the rotating components in the centrifugal pump, while the pump casing and pump seat are the fixed components in the centrifugal pump. There are three intersecting parts between these two parts: the shaft sealing device between the pump shaft and pump casing is a packing box, as shown in Figure 2-4, Figure 11; The leakage reducing device at the joint between the impeller and the inner wall of the pump casing is a leakage reducing ring, as shown in Figure 2-4, Figure 12; The rotating connection device between the pump shaft and the pump seat is the bearing seat, as shown in Figure 2-4, Figure 13.