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Asked: 2022-12-05T09:09:19+05:30 In:

How to calculate the permissible residual unbalance?

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How to calculate the permissible residual unbalance?

rotor unbalance
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    1. Permissible residual unbalance of a rotor can be found by two ways. They are

      Way-1 Using Direct Relation

      Permissible residual unbalance can be found using following relation.

      U_{Per}= 1000 \times \, \frac{G \, m}{\omega}

      Where U_{Per} represents Maximum Permissible Residual Unbalance in a rotor.

      G represents the balancing quality grade. G is selected based on the application. For example, G 6.3 is used for the rotors of fans and pumps.

      m represents the rotor mass.

      \omegarepresents the angular velocity of the rotor.

      Way-2 Using Graph

      Permissible residual unbalance can be calculated using following graph as well.

      Let us consider, you have to determine the permissible residual unbalance for a centrifugal pump rotor (G 6.3) of mass (m) with a service speed of 2000 RPM, then Specific Permissible Residual Unbalance can be determined from the following graph.


      Figure 3: Graph represents the permissible residual unbalance.
      Select the speed in X-axis (2000 RPM) and draw a vertical line that intersects the balance quality grade line G 6.3. From here draw a horizontal line that intersects Y- axis. The corresponding value in Y axis represents the e_{Per}   i.e., Specific Residual Permissible Residual Unbalance. Total Permissible Residual Unbalance can be determined using following relation.

      U_{Per}= 1000 \times \, \frac{G \, m}{\omega}

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