Notes on balance correction of screw pump  


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05/20/2020 3:31 am  

Notes on balance correction of screw pump

Use these expansion coefficients and the difference between the temperature when the pump is calibrated and the temperature when the pump is running to calibrate the centerline height of the shaft. The distance that the machine should be padded up when cooling is the calculated distance shown in the table.

The purpose of any shaft alignment is to adjust the centerline of the mechanical shaft to each other, not to adjust the center of the flexible connection. At operating temperature, the correction number (TIR) is within 0 003in of the total indicated reading, including angle and parallelism. Refer to a good calibration process to obtain or guarantee accuracy. Flexible connections can have a large amount of misalignment, which is independent of the alignment between the shafts of the equipment. The purpose of shaft positioning is to extend the service life and service life of the mechanical device, rather than the service life of the joint. If the hot water circulating pump and / or driver are used, the pump will generate enough thermal expansion (possibly LH or more) after operating at rated temperature for a period of time. At this time, the equipment shall be shut down to ensure that the calibration is within the effective limit.

Calibration with the pump and drive chain assembled cannot be relied on. Transportation, hoisting, handling and irregular base will make the positioning worse. The final calibration should be done almost at the last step before the pump actually starts. If the pump is installed on site, the positioning inspection shall be carried out after the pump runs stably for several hours or days.

Sometimes it is necessary to use elastic frame to reduce the vibration and transfer the vibration to the following foundation. Such an elastic frame cannot be installed next to the pump or driver, but it can be installed between the pump or driver base or bracket and the foundation. The pump and driver must be rigidly positioned, not elastically positioned, because under the action of transmitting torque, the elastically mounted cannot maintain enough accurate positioning.

For most equipment, the direction of rotation is very important. Usually indicated by an arrow plate. Remember that there are some drives that rotate in the opposite direction from the input shaft to the output shaft. Most engines and turbines must be purchased in a specific direction of rotation, as do pumps. Standard AC motors are usually bi-directional; their direction of rotation depends on the connection of the power cable. If it is impossible to foresee their rotation direction in advance, it is recommended to make the motor instantly energized (lightly touched and then quickly disconnected) when the flexible connection of the motor shaft is not connected, so as to check whether its rotation direction is correct for other parts of the driving equipment. If not, two of the cables need to be reversed. If necessary, after the reverse connection and before reconnecting the flexible connection, verify that the direction of rotation is correct.




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