How to choose dynamic and static balance

Based on the conditions for single-sided (static) balancing of the rotor mentioned above, and in conjunction with the technical standards related to pumps (such as GB3215 and API610, version 8), the requirements for rotors that are to be balanced only statically are as follows: For single-stage and two-stage pumps, when the operating speed is less than 1800 revolutions per minute, it is sufficient to perform only static balancing, regardless of whether D/b < 6 or D/b ≥ 6. However, if dynamic balancing is required, it is necessary to ensure that D/b < 6; otherwise, only static balancing can be performed. 2 = For the rotors of single-stage and two-stage pumps, when the operating speed is ≥ 1800 revolutions per minute, static balancing is sufficient if D/b ≥ 6. However, the remaining unbalance after balancing must be equal to or less than 1/2 of the allowable unbalance. If dynamic balancing is required, it is necessary to check whether the balance of the two correction surfaces can be achieved separately on a balancing machine; if not, only static balancing can be performed. 3= For some rotors such as open impellers, if end support cannot be provided, only static balancing is sufficient. Since the ends cannot provide support, a cantilever structure is necessary; as a result, performing dynamic balancing on a balancing machine is very dangerous, and single-sided (static) balancing can only be carried out on a balancing stand.

In the GB9239-88 balancing standard, the conditions for achieving static balance of a rigid rotor are defined as follows: \"If the spacing between the supports of the disc-shaped rotor is large enough and the axial runout of the disc portion during rotation is very small, so that couple imbalance (dynamic balance) can be ignored, then the imbalance can be corrected using a single correction surface, thereby achieving single-sided (static) balance. It is necessary to verify whether these conditions are met for a given rotor.\" After balancing a large number of rotors of a certain type on a plane, the maximum residual couple imbalance can be determined and then divided by the support distance. If, under the most unfavorable conditions, this value is not greater than half of the allowable remaining unbalance, then single-sided (static) balancing is sufficient. It is clear from this definition that there are mainly three conditions under which a rotor only requires single-sided (static) balancing: one of them is that the rotor has a disc-shaped geometry ； One is that the support spacing when the rotor is balanced on a balancing machine should be large ； Another requirement is that the end-face runout of the correction surface must be very small when the rotor is rotating.

Static balance is performed on all centrifugal pumps, while dynamic balance is applied only to multi-stage pumps and high-speed pumps