DYNAMIC ROTOR BALANCING
Dynamic balancing corrects the mass distribution of rotors and rotating assemblies, eliminating the vibration that destroys bearings, seals and journals. Hydro Pumps balances components up to 5 tonnes on an instrumented bench, to quality grade G2.5 of ISO 21940-11.
What we balance
A bench with digital precision instrumentation for pump and rotating machinery components.
Rotors and impellers
Open, semi-open and closed impellers for centrifugal and vertical pumps — including rotors recovered by welding or thermal spray.
Complete rotating assemblies
Shaft + impeller + sleeves balanced as an assembly, eliminating tolerance stack-up.
Shafts and couplings
Lineshafts, cardan shafts and power transmission couplings.
Fans and blowers
Industrial fan, exhauster and blower rotors — same physics, same bench.
Single or two-plane correction
Static (single-plane) balancing for discs and dynamic (two-plane) for long rotors, according to component geometry.
Balancing report
Document with initial and residual unbalance, grade achieved and traceability of the applied correction.
Why G2.5 and what it means
The ISO 21940-11 quality grade
ISO 21940-11 (which replaced the classic ISO 1940-1, keeping the same values) defines balance quality grades — G2.5 is the grade specified for pump rotors, turbines and precision machinery. The number expresses the product of permissible residual eccentricity and maximum service angular velocity.
In practice: the lower the G number, the less residual vibration allowed. Balancing a pump rotor to G2.5 means that, at operating speed, the remaining unbalance is low enough not to excite perceptible vibration at the bearings.
The invisible cost of unbalance
Unbalance is the most common cause of vibration in rotating machinery — and the 1× RPM vibration it generates is a cyclic load that drastically shortens bearing life, loosens fasteners, degrades mechanical seals and can crack baseplates.
Every rotor that undergoes repair, welding, coating or component replacement must be rebalanced before returning to operation. That is why balancing is a mandatory step in every Hydro Pumps overhaul — and is also offered as a standalone service for third-party components.
Rotor balancing questions
What maintenance engineers ask about the service.
Whenever it undergoes repair (welding, coating, machining), when vibration analysis shows a dominant 1× RPM component, after impeller or sleeve replacement, and in every overhaul. Newly manufactured rotors should also be verified before assembly.
Static balancing corrects unbalance in a single plane — adequate for thin discs. Dynamic balancing corrects in two planes and is mandatory for long rotors, where unbalance creates a moment as well as a force. Our bench performs both, according to part geometry.
We balance any rotating component within the 5-tonne capacity: pump rotors, fans, exhausters, blowers, shafts and couplings — including as a standalone service for parts recovered by third parties.
Initial and residual unbalance per plane, quality grade achieved per ISO 21940-11, mass and position of applied corrections, and traceable component identification. It is the document that proves rotor condition before assembly.
Related services and resources
Repaired rotor or 1× RPM vibration?
Send the component for balancing on an instrumented bench — with a documented G2.5 report.