Coupling alignment

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Before the water pump is installed, the plane and elevation of the installation foundation should be rechecked. These include centerline alignment, horizontal alignment, and marking alignment – key aspects of the installation process that must be thoroughly understood. The installation procedure for horizontal units is shown in Figure 12—1—12. The thick-lined box in the diagram represents the overall installation program, while the thin-lined boxes represent the installation contents of each step within the overall installation program; arrows indicate the processes. ⑴. Centerline alignment: Centerline alignment involves aligning the longitudinal and transverse centerlines of the water pump. First, determine the longitudinal and transverse center lines on the base surface; then, draw plumb lines from the inlet and outlet flange surfaces of the water pump (for centrifugal pumps with double suction) as well as from the axis center. Adjust the position of the water pump so that these plumb lines align with the longitudinal and transverse center lines on the base, as shown in Figure 12–1–13. file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-227.png file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-229.png file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-246.png file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-250.png ⑵. Horizontal alignment: Horizontal alignment involves adjusting the pump so that it is level both vertically and horizontally. Generally, a level or plumb line is used; for single-suction centrifugal pumps, measurements are taken on the pump shaft and the outlet flange surface, as shown in Figures 12–1–14 and 12–1–15. The double-suction centrifugal pump is measured on the side of the inlet and outlet flange surfaces, as shown in Figure 12—1—16. Use adjusting shims to center the bubble on the level, or to make the distance from the flange surface to the vertical line equal or coincide with the vertical line. For horizontal double-suction centrifugal pumps, four points that can be connected to form a cross are selected on the split surface of the pump casing. A level is placed at these four points, and the readings from the level at each point are measured. If the readings are equal, then the pump is aligned both vertically and horizontally, as shown in Figure 12–1–17. file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-516.png (12—1—1). In this equation: file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image8.wmf represents the distance from the reference point; file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image9.wmf represents the distance in the same direction; file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image10.wmf ； file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image11.wmf——file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image9.wmf Reading of the level staff, file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image10.wmf ； file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image12.wmf – The reading of the level gauge on the pump shaft, file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image10.wmf ； file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image13.wmf – the diameter of the pump shaft, file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image10.wmf. 2. Installation of the motor: file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-809.png Horizontal water pumps and motors are mostly driven by couplings. The installation of horizontal motors generally uses the water pump as the reference axis; the motor shaft is adjusted so that its coupling is parallel and concentric with the coupling of the already installed water pump, while maintaining a certain gap, thereby meeting the requirement for the two axes to be coaxial. ⑴. Measurement of the relative position of the two axes. To adjust the positions of the two axes to meet the coaxial requirement, it is first necessary to determine their relative position in space. The tools used to measure the relative position of two axes mainly include rulers, feeler gauges, and dial indicators. Use a ruler and feeler gauge to measure the relative position of the two axes, as shown in Figure 12—1—18, at file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image14.wmf. file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-1017.png When measuring, determine the radial and axial clearances by pressing the up, down, left, and right buttons respectively, and enter the readings in the four positions outside and inside the circle in Figure 12—1—19. When using this method for measurement, the accuracy is low due to limitations of the measuring tools. For couplings that require high alignment precision, a dial indicator can be used to measure the relative displacement of the two shafts. Figure 12—1—20 shows a schematic diagram of measurement using two dial indicators simultaneously. The dial of the dial indicator is mounted on the half coupling of the motor shaft, while the contacts of the dial indicator make contact with the end face and the outer circular surface of the other half coupling. Take the position at the top of the vertical plane as the starting point (represented by file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image15.wmf and file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image16.wmf), adjust the readings of the two dial indicators to zero, and then rotate the motor shaft. This allows for the measurement of the readings when the dial indicators reach 90°, 180°, and 270°: file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image17.wmf, file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image18.wmf, file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image19.wmf, and file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image20.wmf, file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image21.wmf, file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image22.wmf. When recording the readings of the dial indicators, a reading of “+” is indicated when the contacts of the indicator move towards the dial face, while a reading of “-” is indicated in the opposite direction. file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-1486.png⑵. Adjustment direction of the half coupling, and calculation of adjustment dimensions. The dimensions of the two-axis radial displacement are equal to (file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image15.wmf-file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image24.wmf) / 2 in the vertical plane, and equal to (file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image25.wmf-file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image26.wmf) / 2 in the horizontal plane. The two axes have an axial tilt that is equal to (file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image27.wmf-file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image21.wmf) / 2 in the vertical plane, and equal to (file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image20.wmf-file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image22.wmf) / 2 in the horizontal plane. The calculation of these values depends not only on the absolute value of the readings, but also on the plus or minus signs of the readings, as well as on the measuring device. But this relative displacement represents a value at the half coupling. The common adjustment method is to change the relative position of the motor and the foundation so that the radial and axial clearances meet the standards. To this end, it is also necessary to convert the relative displacement at the half coupling in order to adjust the adjustment amount at the location shown in Figure 12—1—21, and to determine its adjustment direction. Let the relative positions of the two axes in one plane be as shown in Figure 12–1–21. To align the two axes coaxially, the vertical adjustment amounts at the motor’s front and rear foot screw holes, at file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image28.wmf and file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image9.wmf, are respectively file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image29.wmf and file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image30.wmf. Since file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image31.wmf is similar to file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image32.wmf, it follows that: file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image33.wmf. In equation (12–1–2): file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image34.wmf represents the difference between the two measurement readings taken by the axial dial indicator in the vertical plane, at positions of 0° and 180°; file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image35.wmf, file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image36.wmf ； file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image37.wmf – the distance from the center of the motor’s half-coupling to the foot bolt holes; file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image28.wmf. Also, refer to file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image38.wmf and file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image36.wmf ； file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image39.wmf – the distance between the contacts of the dual-axis dial indicator and the centerline of the motor shaft; file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image40.wmf, file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image36.wmf. file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-2461.png By substituting the above values, we get: file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image42.wmf (12—1—3) file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image43.wmf (12—1—4) Where: file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image44.wmf – half the difference between the two measurement readings of the radial dial gauge in the vertical plane. It can be concluded that the vertical adjustment amount for the motor foot screw hole at file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image28.wmf is: file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image45.wmf (12—1—5). Similarly, the vertical adjustment amount for the motor foot screw hole at file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image9.wmf is: file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image46.wmf (12—1—6). Likewise, the horizontal adjustment amounts for the motor foot screw holes at file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image28.wmf and file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image9.wmf are: file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image47.wmf (12—1—7) and file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image48.wmf (12—1—8). In the formulas above, if values such as file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image50.wmf and file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image51.wmf are positive, it indicates that the motor shaft should move vertically upward, in the direction of file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image15.wmf (file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image52.wmf), and shims should be placed at the motor foot screw holes at file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image28.wmf and file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image9.wmf. Conversely, the shims should be reduced to move the motor shaft downward. If values such as file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image53.wmf and file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image54.wmf are positive, it indicates that the motor shaft should move in the direction of file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image26.wmf (file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image55.wmf); otherwise, it should move in the direction of file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image25.wmf (file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/ksohtml/wps_clip_image56.wmf). After adjusting the misalignment between the two axes, it is necessary to measure the values again for calculation, and compare them with the allowable error limits specified in the standards; if these requirements are not met, further adjustment is required. Until the specification requirements are met. III. Installation of vertical units: Small vertical axial flow pumps are installed on the pump beams in the pump floor, as well as on the motor beams in the motor floor, as shown in Figure 12–1–22. The installation of small axial flow pump units is generally carried out from bottom to top ； Pump first, then motor ； Follow the principle of fixing the components first and then rotating them. The elevation, levelness, concentricity, play, and clearance of vertical units are crucial during installation and must be carefully controlled. The installation procedure for small vertical axial flow pumps is shown in Figure 12—1—23. 1. Installation of the elbow and guide vane assembly: After positioning the pump beam, lift the elbow and guide vane assembly onto the pump beam. Place a water-stop rubber at the end of the elbow and connect it to the outlet pipe. Using the upper bearing surface of the elbow as a reference plane, place a level on this surface, adjust the shims, and tighten the screws that connect the elbow to the outlet pipe in order to align the elbow horizontally. 2. Installation of the motor base: Due to machining errors in the various components of the unit, cumulative errors occur after these components are assembled together. Therefore, the motor base installation elevation specified in the drawings differs from the actual condition of the component, and the actual installation elevation of the motor base is often determined through a pre-installation method. During pre-installation, the pump shaft is lifted into the upper and lower guide bearing holes; the impeller and the impeller housing are tentatively assembled so that the center of the blades aligns with the center of the impeller housing. The distance between the coupling plane at the upper end of the pump shaft is measured, and based on these measurements, the actual installation height of the motor base is calculated. Then remove the impeller and lift it off the pump shaft, and lift the motor base to the predetermined installation height. Using the bearing surface of the motor base as the calibration surface, place the square level on this surface and adjust the levelness of the motor base by using shims.