20100426 Moving Equipment Technology Exchange Area – Weekly Question Activity

This post was last edited by upc-ljb on 2010-4-27 08:35. Below is part of the training material I prepared for the maintenance staff after repairing the high-temperature, high-pressure radial feed pump in our company. The key to installing the balance disc is adjusting the total stroke and the half stroke. During maintenance, methods such as adding shims and applying coatings are used to ensure or restore the dimensional chain and total play of the pump in the axial direction. To ensure no friction between the impeller and the stator and to keep the impeller outlet aligned with the guide vane inlet, thermal expansion of the rotor must also be taken into account in hot oil pumps; multi-stage pumps are equipped with an appropriate amount of axial play. When the total axial shift of each stage of impeller is too small, it is generally necessary to shorten the length of the impeller sealing ring ； When the total axial movement of each stage of impeller is too large, the impeller seal ring is generally rewelded or replaced ； The axial displacement of impellers at all levels can be adjusted by adding or removing shims on the contact surface of the rear hub of the impeller ； The axial displacement of the final impeller can be adjusted by machining a shorter balance disc hub or by adding or removing shims in front of the balance disc hub. The half-penetration amount can be adjusted by changing the thickness of the adjustment shim behind the balance disc. After the maintenance of this pump, the total stroke volume was 6.80 mm, and the half-stroke volume was 3.4 mm.

Answer: The axial movement of multi-stage centrifugal pumps equipped with balance discs can be adjusted by adding or removing shims at the balance hub and balance seat. Measurement and adjustment of the axial clearance in multi-stage pumps: Definition: The axial clearance in a centrifugal pump refers to the axial gap between the rotor and the stator. Forward clearance: The distance between the front cover of the impeller and the stator… Backward clearance: The distance between the rear cover of the impeller and the stator… Total clearance: Forward clearance + Backward clearance. Purpose: 1) To ensure that there is no friction between the impeller and the stator, and to keep the rotor in its central position. 2) The impeller outlet is aligned with the guide vane inlet (Q, H). 3) For hot oil pumps, the thermal expansion of the rotor must be taken into account. Measurement: For used multi-stage centrifugal pumps, only the rear end play (the play without removing the balance disk) and the total end play of the final impeller (the play after removing the balance disk) are measured. Standard: The total stroke of small centrifugal pumps is 3~4 mm. The total axial movement of large centrifugal pumps is 6~7 mm. The total stroke of the hot oil pump is 6~7 mm. Without thrust bearings: the rear play is 0.5~1.0 mm less than the front play. With thrust bearings: the end dimension is 0.5~1.0 mm smaller than that without them. Adjustments: 1) If the total axial shift of the impellers in each stage of the centrifugal pump is too small → shorten the length of the collar. 2) If the total axial shift of the impellers in each stage is too large → weld on additional material to the collar or replace it. 3) The axial shift of the impellers in each stage can be adjusted by adding or removing shims on the contact surface between the rear hub and the impeller. 4) The axial displacement of the final impeller can be adjusted by turning the hub of the balance disc shorter or by adding or removing shims in front of the balance disc hub. 7. Bearing positioning 1) Without thrust bearings: Ensure that the clearance of the bearing in the bearing hole in both the forward and backward directions is greater than half of the allowable displacement. The radial clearance between the balance disc sleeve and the hub is 0.2–0.4 mm; for media with high temperatures, high viscosity, or containing sediment, this value should be increased appropriately. The clearance between the wheels must be maintained at (half the thrust amount + 2 mm). 2) With thrust bearings: It ensures that the axial clearance between the balance disc and the balance ring is 0.1–0.2 mm, the axial displacement of the rotor is 0.1–0.15 mm, and the radial clearance between the balance disc sleeve and the hub is 0.2–0.4 mm. If this value is too large, the automatic adjustment function of the balance disc will be lost. 3) Push the rotor forward so that the balance disc makes contact with the balance ring; measure the positioning of the rear bearing to ensure the range of movement of the balance disc.

Adjust using the shims on the flat side of the hide/hide

Adjust by adding shims on the side of the balance disc. 1. Measure the total axial play of the shaft. 2. Install shims to measure the lateral play from the working side to the non-working side.

It should be adjusted by increasing or decreasing the thickness of the bearing gland shims; when the axial play is large, reduce the thickness of the shims

This post was last edited by xj1983220 on 2010-4-27 at 14:11. Answer: The axial displacement of multi-stage centrifugal pumps equipped with balance discs can be adjusted by adding or removing shims at the balance hub and balance seat. Measurement and adjustment of the axial clearance in multi-stage pumps: Definition: The axial clearance in a centrifugal pump refers to the axial gap between the rotor and the stator. Forward clearance: The distance between the front cover of the impeller and the stator… Backward clearance: The distance between the rear cover of the impeller and the stator… Total clearance: Forward clearance + Backward clearance. Purpose: 1) To ensure that there is no friction between the impeller and the stator, and to keep the rotor in its central position. 2) The impeller outlet is aligned with the guide vane inlet (Q, H). 3) For hot oil pumps, the thermal expansion of the rotor must be taken into account. Measurement: For used multi-stage centrifugal pumps, only the rear end play (the play without removing the balance disk) and the total end play of the final impeller (the play after removing the balance disk) are measured. Standard: The total stroke of small centrifugal pumps is 3~4 mm. The total axial movement of large centrifugal pumps is 6~7 mm. The total stroke of the hot oil pump is 6~7 mm. Without thrust bearings: the rear play is 0.5~1.0 mm less than the front play. With thrust bearings: the end dimension is 0.5~1.0 mm smaller than that without them. Adjustments: 1) If the total axial shift of the impellers in each stage of the centrifugal pump is too small → shorten the length of the collar. 2) If the total axial shift of the impellers in each stage is too large → weld on additional material to the collar or replace it. 3) The axial shift of the impellers in each stage can be adjusted by adding or removing shims on the contact surface between the rear hub and the impeller. 4) The axial displacement of the final impeller can be adjusted by turning the hub of the balance disc shorter or by adding or removing shims in front of the balance disc hub. 7. Bearing positioning 1) Without thrust bearings: Ensure that the clearance of the bearing in the bearing hole in both the forward and backward directions is greater than half of the allowable displacement. The radial clearance between the balance disc sleeve and the hub is 0.2–0.4 mm; for media with high temperatures, high viscosity, or containing sediment, this value should be increased appropriately. The clearance between the wheels must be maintained at (half the thrust amount + 2 mm). 2) With thrust bearings: It ensures that the axial clearance between the balance disc and the balance ring is 0.1–0.2 mm, the axial displacement of the rotor is 0.1–0.15 mm, and the radial clearance between the balance disc sleeve and the hub is 0.2–0.4 mm. If this value is too large, the automatic adjustment function of the balance disc will be lost. 3) Push the rotor forward so that the balance disc makes contact with the balance ring; measure the positioning of the rear bearing to ensure the range of movement of the balance disc.

Answer: The axial movement of multi-stage centrifugal pumps equipped with balance discs can be adjusted by adding or removing shims at the balance hub and balance seat. Measurement and adjustment of the axial clearance in multi-stage pumps: Definition: The axial clearance in a centrifugal pump refers to the axial gap between the rotor and the stator. Forward clearance: The distance between the front cover of the impeller and the stator… Backward clearance: The distance between the rear cover of the impeller and the stator… Total clearance: Forward clearance + Backward clearance. Purpose: 1) To ensure that there is no friction between the impeller and the stator, and to keep the rotor in its central position. 2) The impeller outlet is aligned with the guide vane inlet (Q, H). 3) For hot oil pumps, the thermal expansion of the rotor must be taken into account. Measurement: For used multi-stage centrifugal pumps, only the rear end play (the play without removing the balance disk) and the total end play of the final impeller (the play after removing the balance disk) are measured. Standard: The total stroke of small centrifugal pumps is 3~4 mm. The total axial movement of large centrifugal pumps is 6~7 mm. The total stroke of the hot oil pump is 6~7 mm. Without thrust bearings: the rear play is 0.5~1.0 mm less than the front play. With thrust bearings: the end dimension is 0.5~1.0 mm smaller than that without them. Adjustments: 1) If the total axial shift of the impellers in each stage of the centrifugal pump is too small → shorten the length of the collar. 2) If the total axial shift of the impellers in each stage is too large → weld on additional material to the collar or replace it. 3) The axial shift of the impellers in each stage can be adjusted by adding or removing shims on the contact surface between the rear hub and the impeller. 4) The axial displacement of the final impeller can be adjusted by turning the hub of the balance disc shorter or by adding or removing shims in front of the balance disc hub. 7. Bearing positioning 1) Without thrust bearings: Ensure that the clearance of the bearing in the bearing hole in both the forward and backward directions is greater than half of the allowable displacement. The radial clearance between the balance disc sleeve and the hub is 0.2–0.4 mm; for media with high temperatures, high viscosity, or containing sediment, this value should be increased appropriately. The clearance between the wheels must be maintained at (half the thrust amount + 2 mm). 2) With thrust bearings: It ensures that the axial clearance between the balance disc and the balance ring is 0.1–0.2 mm, the axial displacement of the rotor is 0.1–0.15 mm, and the radial clearance between the balance disc sleeve and the hub is 0.2–0.4 mm. If this value is too large, the automatic adjustment function of the balance disc will be lost. 3) Push the rotor forward so that the balance disc makes contact with the balance ring; measure the positioning of the rear bearing to ensure the range of movement of the balance disc.

Answer: The axial movement of multi-stage centrifugal pumps equipped with balance discs can be adjusted by adding or removing shims at the balance hub and balance seat. Measurement and adjustment of the axial clearance in multi-stage pumps: Definition: The axial clearance in a centrifugal pump refers to the axial gap between the rotor and the stator. Forward clearance: The distance between the front cover of the impeller and the stator… Backward clearance: The distance between the rear cover of the impeller and the stator… Total clearance: Forward clearance + Backward clearance. Purpose: 1) To ensure that there is no friction between the impeller and the stator, and to keep the rotor in its central position. 2) The impeller outlet is aligned with the guide vane inlet (Q, H). 3) For hot oil pumps, the thermal expansion of the rotor must be taken into account. Measurement: For used multi-stage centrifugal pumps, only the rear end play (the play without removing the balance disk) and the total end play of the final impeller (the play after removing the balance disk) are measured. Standard: The total stroke of small centrifugal pumps is 3~4 mm. The total axial movement of large centrifugal pumps is 6~7 mm. The total stroke of the hot oil pump is 6~7 mm. Without thrust bearings: the rear play is 0.5~1.0 mm less than the front play. With thrust bearings: the end dimension is 0.5~1.0 mm smaller than that without them. Adjustments: 1) If the total axial shift of the impellers in each stage of the centrifugal pump is too small → shorten the length of the collar. 2) If the total axial shift of the impellers in each stage is too large → weld on additional material to the collar or replace it. 3) The axial shift of the impellers in each stage can be adjusted by adding or removing shims on the contact surface between the rear hub and the impeller. 4) The axial displacement of the final impeller can be adjusted by turning the hub of the balance disc shorter or by adding or removing shims in front of the balance disc hub. 7. Bearing positioning 1) Without thrust bearings: Ensure that the clearance of the bearing in the bearing hole in both the forward and backward directions is greater than half of the allowable displacement. The radial clearance between the balance disc sleeve and the hub is 0.2–0.4 mm; for media with high temperatures, high viscosity, or containing sediment, this value should be increased appropriately. The clearance between the wheels must be maintained at (half the thrust amount + 2 mm). 2) With thrust bearings: It ensures that the axial clearance between the balance disc and the balance ring is 0.1–0.2 mm, the axial displacement of the rotor is 0.1–0.15 mm, and the radial clearance between the balance disc sleeve and the hub is 0.2–0.4 mm. If this value is too large, the automatic adjustment function of the balance disc will be lost. 3) Push the rotor forward so that the balance disc makes contact with the balance ring; measure the positioning of the rear bearing to ensure the range of movement of the balance disc.

Change the position of the balance disc on the pump shaft. If the gap is large, try to move the balance disc towards the inlet; otherwise, move it in the direction of the outlet. The specific values will be determined after measurement. This is how I adjust the pumps in my unit. I see my favorite again :) :handshake