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 t 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 restored 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.
01When does a rotor need balancing?
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.
02What is the difference between static and dynamic balancing?
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.
03Do you balance components beyond pumps?
We balance any rotating component within the 5 t capacity: pump rotors, fans, exhausters, blowers, shafts and couplings, including as a standalone service for parts restored by third parties.
04What does the balancing report include?
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
Vibration Analysis
The diagnosis that identifies unbalance, misalignment and bearing defects.
Pump Overhaul
Complete reconditioning — balancing is a mandatory step of every repair.
Impellers & Rotating Assemblies
Supply of balanced impellers and rotating assemblies.
Guide: Grade G2.5
Static vs dynamic and what ISO 21940-11 grade G2.5 means.
Repaired rotor or 1× RPM vibration?
Send the component for balancing on an instrumented bench — with a documented G2.5 report.