Division 2 The MPE, positive or negative in mm, between two non-consecutive scale marks is (a + bL), where:
United Kingdom
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L is the value of the length rounded up to the next whole metre; and
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a and b are given in Table 1 below.
When a terminal interval is bounded by a surface, the MPE for any distance beginning at this point is increased by the value c given in Table 1.
| Table 1 | |||
| Applies to the tape/dip weight combinations. | |||
| If the nominal tape length exceeds 30 m, an additional mpe of 0,75 mm shall be permitted for each 30 m of tape length. | |||
| Accuracy Class | a (mm) | b | c (mm) |
|---|---|---|---|
| I | 0,1 | 0,1 | 0,1 |
| II | 0,3 | 0,2 | 0,2 |
| III | 0,6 | 0,4 | 0,3 |
| D — special class for dipping tapesf1 Up to and including 30 mf2 | 1,5 | zero | zero |
| S — special class for tank strapping tapes For each 30 m length when the tape is supported on a flat surface | 1,5 | zero | zero |
Dip tapes may also be of Classes I or II in which case for any length between two scale marks, one of which is on the sinker and the other on the tape, the MPE is ± 0,6 mm when application of the formula gives a value of less than 0,6 mm.
The MPE for the length between consecutive scale marks, and the maximum permissible difference between two consecutive intervals, are given in Table 2 below.
| Table 2 | |||
| Length i of the interval | MPE or difference in millimetres according to accuracy class | ||
|---|---|---|---|
| I | II | III | |
| i ≤ 1 mm | 0,1 | 0,2 | 0,3 |
| 1 mm < i ≤ 1 cm | 0,2 | 0,4 | 0,6 |
Where a rule is of the folding type, the jointing shall be such as not to cause any errors, supplementary to those above, exceeding: 0,3 mm for Class II, and 0,5 mm for Class III.
Annotations
Footnotes
- f1
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Applies to the tape/dip weight combinations.
- f2
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If the nominal tape length exceeds 30 m, an additional mpe of 0,75 mm shall be permitted for each 30 m of tape length.