One of the most important issues in multi-stage pump assembly is to check that the center of the impeller exit is the same as the center of the guide (deflector) inlet. That is, each impeller exit center must be aligned with the center of the guide wing inlet. Adjusting the "center of consistency" not only ensures the normal efficiency of the pump, but also to prevent the rotation, or impeller and other hazards before and after touch. The center of the "center" is mainly determined by the position of the balance disc. The pump moves in front of and behind the balance disc during operation, which directly influences the center of the impeller outlet and the guide wing inlet. Since the balance disc is working, Maintains a small clearance (usually 0.1-0.25 mm) range of play, automatically balance the axial force. Therefore, check the adjustment "center of the agreement" can balance plate close to the gimbal in the case. The "center of the agreement" is: lock the rotor lock nut, tighten the body of the tightening bolt is the balance plate close to the balance ring, the impeller outlet center and guide vane inlet center. Operation, due to the balance of the balance ring and the balance ring is only about 0.1 mm, it can also be considered in the. There are several ways to align: The first method: 1, will be fitted suction shaft sleeve and key shaft into the suction shell. 2, into the first stage impeller and impeller block, and the impeller close to the front sleeve. Then move the pump shaft so that the center of the first stage impeller outlet coincides with the center of the first stage guide vane. At this point in the front end of the pump shaft relative to the end face of the packing gland make a mark, easy to check the final alignment of the impeller and the guide wing. It should be noted that when adjusting the center of the first-stage impeller outlet centering with the guide vanes, the impeller should abut against the front bushing. At this point the impeller can not be pressed tightly into the shell. 3, in the middle of laying a layer of green shell paper pad, fitted with the second stage of the impeller. Then, install the impeller sleeve, the middle stage, the third stage impeller, ... and even the pump housing, install the pump body bolts and nuts, and tighten the nuts. 4, mounted on the balance plate, with the sleeve and sleeve lock nut lock the balance plate. The balance disc close to the balance ring, check the shaft end of the mark, if the marker position has not changed, indicating the first stage impeller exit center and first stage guide vane center. Since the impeller pitch and guide vane spacing are measured and adjusted to be equal before assembly, the impellers at all levels are aligned with the corresponding guide vanes, respectively. If the mark position is changed, the thickness of the spacer between the balance disc hub and the final-stage impeller hub is not suitable as long as the thickness of the spacer is adjusted to solve the problem. The second method: check and adjust the method of checking the amount of axial movement of the rotor. In the case where the impeller exit coincides with the guide wing inlet center, there is a proper clearance on both sides of the impeller. In the balance plate before the impeller can move on both sides of the range, known as the rotor axial movement. Equipped with a balance plate, the balance plate in close contact with the balance ring, the rotor can not move in the direction of inhalation, but only to the discharge direction of movement. Therefore, check the rotor after the installation of balancing disk axial movement, if equal to the specified value, indicating good in the middle; if less than the specified value, the impeller bias to the discharge end; if greater than the specified value, indicating impeller bias suction side. The third method: 1, will be fitted suction shaft sleeve and key shaft into the suction shell. 2, into the first stage impeller and impeller block, and the impeller close to the front sleeve. 3, in the middle of laying a layer of green shell paper pad, fitted with the second stage of the impeller. Then, install the impeller sleeve, the middle stage, the third stage impeller, ... and even the pump housing, install the pump body bolts and nuts, and tighten the nuts symmetrically. Install a special length greater than the balance disc hub length and total amount of slip and the sleeve, install the sleeve, and lock with a lock nut. 4, to promote the rotor to move to the front extreme, and then before the end of the gland packing as a reference, make a mark on the pump shaft, and then pull the rotor to move to the rear extreme, and then make a mark on the shaft at the reference Total channeling amount. 5, remove the stopper, fitted with balance plate, and locked. Place the balancer against the balance ring and make a mark on the shaft. Then pull the rotor back to the end and make a mark on the shaft. Measuring the distance between the two marks, if equal to half the total channeling, the impeller exit center and guide vane center of imports. Otherwise, the thickness of the shim between the balance disc hub and the final impeller hub needs to be adjusted. For multi-stage pumps with ball bearings on both ends, the inner ring of the bearing is fixed on the shaft while the outer ring is supported on the bearing frame. The axial run-out of the whole rotor slides on the outer ring of the bearing in the bearing seat. Therefore: 1, disassembly of the shaft shoulder multi-stage pump, the position of the front sleeve must be marked, easy to restore the original assembly. 2, bearing gland bosses and rolling bearing outer race along the axial to leave a play clearance.