ISO 21940 Balance G Grades
ISO 21940 Balance Quality G Grades are used to calculate balance tolerances in conjunction with the rotor weight and service speed (RPM).
Guidance for balance quality grades for rotors with rigid behaviour.
BALANCE QUALITY GRADE G | MAGNITUDE e per Ω mm/s |
MACHINERY TYPES – GENERAL EXAMPLES |
---|---|---|
G 4000 | 4 000 |
|
G 1600 | 1 600 |
|
G 630 | 630 |
|
G 250 | 250 |
|
G 100 | 100 |
|
G 40 | 40 |
|
G 16 | 16 |
|
G 6,3 | 6,3 |
|
G 2,5 | 2,5 |
|
G 1 | 1 |
|
G 0,4 | 0,4 |
|
NOTE 1 Typically, completely assembled rotors are classified here. Depending on the particular application, the next higher or lower grade may be used instead. For components, see clause 9.
NOTE 2 All items are rotating if not otherwise mentioned (reciprocating) or self-evident (e.g. crankshaft drives). NOTE 3 For some additional information on the chosen balance quality grade, see Figure 2 which contains generally used areas (service speed and balance quality grade G) based on common experience. NOTE 4 For some machines, specific International Standards stating unbalance tolerances exist. NOTE 5 The selection of a balance quality grade G for a machine type requires due consideration of the expected duty of the rotor when installed in situ which typically reduces the grade to a lower level if lower vibration magnitudes are required in service. NOTE 6 The shaft height of a machine without feet, or a machine with raised feet, or any vertical machine, is to be taken as the shaft height of a machine in the same basic frame, but of the horizontal shaft foot-mounting type. When the frame is unknown, half of the machine diameter should be used. |
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