ISO 21940-23:2012

Overview

ISO 21940-23:2012 - Mechanical vibration - Rotor balancing - Part 23 - specifies safety requirements for enclosures and other protective measures at the measuring station of centrifugal (rotational) balancing machines. The standard is focused on minimizing mechanical hazards generated by rotors during balancing operations. It defines protection classes, limits of applicability, and procedures for verification, while excluding devices for adjusting mass distribution, rotor transfer systems and special enclosure features (noise reduction, windage reduction, vacuum).

Key facts:

• Applies to the measuring station of balancing machines (centrifugal/rotational).
• Requires a documented risk assessment covering intended use and foreseeable misuse.
• Replaces ISO 7475:2002 (main change: deletion of protection class 0).

Key Topics and Requirements

• Risk assessment: Users/manufacturers must assess hazards from all access directions, intended use, maintenance and foreseeable misuse, and verify applicability of listed hazards.
• List of significant hazards: Includes crushing, shearing, impact/stabbing, entanglement, ejection of masses, excessive vibration/noise, electrical hazards, ergonomic risks and human error.
• Protection classes: The standard defines different classes of protection for enclosures and describes limits of applicability for each class (selection guidance provided, e.g., Annex A).
• Safety requirements: Structural attachment to foundation, protection against contact with rotating parts, and containment of flying parts/correction masses.
• Verification and testing: Procedures to verify enclosure performance and protective measures (see Clause 6 and informative annexes for impact-test equipment and examples).
• Information for use: Instruction handbook, marking and user information requirements are specified to support safe operation and maintenance.

Practical Applications and Users

Who uses ISO 21940-23:2012:

• Balancing machine manufacturers - to design compliant enclosures and supply safety information.
• Machine users and workshop managers - to select, install and operate balancing machines safely.
• Safety engineers and risk assessors - to perform hazard analyses and choose appropriate protection classes.
• Service/repair facilities and test labs - for safe balancing of unknown or variable rotors.

Typical uses:

• Specifying enclosure requirements for new balancing machines.
• Selecting protection class for specific rotor types and operating speeds.
• Verifying containment capability against detached parts or rotor disintegration.
• Preparing instruction manuals, markings and safety documentation.

Related Standards

• ISO 21940 series (other parts on vocabulary, procedures, tolerances, machine description): ISO 21940-1, -2, -11, -12, -13, -14, -21, -31, -32.
• Normative references in this part: ISO 1925 (Balancing - Vocabulary) and ISO 4849 (Personal eye-protectors).

Keywords: ISO 21940-23:2012, rotor balancing, enclosures, protective measures, balancing machines, mechanical vibration, measuring station, safety requirements, risk assessment.