ISO 21940-31:2013
(Main)Mechanical vibration — Rotor balancing — Part 31: Susceptibility and sensitivity of machines to unbalance
Mechanical vibration — Rotor balancing — Part 31: Susceptibility and sensitivity of machines to unbalance
ISO 21940-31:2013 specifies methods for determining machine vibration sensitivity to unbalance and provides evaluation guidelines as a function of the proximity of relevant resonance rotational speeds to the operating speed. ISO 21940-31:2013 is only concerned with once-per-revolution vibration caused by unbalance. It also makes recommendations on how to apply the numerical sensitivity values in some particular cases. It includes a classification system that can be applied to machines which is related to their susceptibility to a change in unbalance. Machines are classified into three types of susceptibility and five ranges of sensitivity. The sensitivity values are intended for use on simple machine systems, preferably with rotors having only one resonance speed over their entire operating speed range. The sensitivity values can also be used for machines that have more resonance speeds in their operating speed range if the resonance speeds are widely separated (e.g. by more than 20 %). The sensitivity values given are not intended to serve as acceptance specifications for any machine group, but rather to give indications regarding how to avoid gross deficiencies as well as specifying exaggerated or unattainable requirements. They can also serve as a basis for more involved investigations (e.g. when in special cases a more exact determination of the required sensitivity is necessary). If due regard is paid to the values given, satisfactory running conditions can be expected in most cases. The consideration of the sensitivity values alone does not guarantee that a given magnitude of vibration in operating is not exceeded. Many other sources of vibration can occur which lie outside the scope of ISO 21940-31:2013.
Vibrations mécaniques — Équilibrage des rotors — Partie 31: Susceptibilité et sensibilité des machines aux balourds
General Information
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 21940-31
First edition
2013-08-15
Mechanical vibration — Rotor
balancing —
Part 31:
Susceptibility and sensitivity of
machines to unbalance
Vibrations mécaniques — Équilibrage des rotors —
Partie 31: Susceptibilité et sensibilité des machines aux balourds
Reference number
ISO 21940-31:2013(E)
©
ISO 2013
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ISO 21940-31:2013(E)
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ISO 21940-31:2013(E)
Contents Page
Foreword .iv
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Machine susceptibility classification . 1
4.1 General . 1
4.2 Type I: Low susceptibility. 2
4.3 Type II: Moderate susceptibility . 2
4.4 Type III: High susceptibility . 2
4.5 Machine susceptibility correction factors . 2
5 Modal sensitivity . 2
5.1 General . 2
5.2 Modal sensitivity ranges . 3
5.3 Characteristics of modal sensitivity ranges . 3
5.4 Values of modal sensitivity . 3
5.5 Operating speed . 7
5.6 Transient speed . 9
6 Experimental determination of modal sensitivity near resonance speed under
operational conditions .
...
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