Textual Amendments
F1Schs. 6-9 inserted (E.W.S.) (31.12.2020) by The Product Safety and Metrology etc. (Amendment etc.) (EU Exit) Regulations 2019 (S.I. 2019/696), reg. 1, Sch. 26 para. 45 (with Sch. 26 para. 5) (as amended by S.I. 2020/676, regs. 1(1), 2); 2020 c. 1, Sch. 5 para. 1(1)
1. Units of massE+W+S
The units of mass used shall be the legal units within the meaning of the Weights and Measures Act 1985 relating to units of measurement F2.
Subject to compliance with this condition, the following units are permitted—
(a)SI units: kilogram, microgram, milligram, gram, tonne;
(b)imperial unit: troy ounce, if weighing precious metals;
(c)other non-SI unit: metric carat, if weighing precious stones.
For instruments that make use of the imperial unit of mass referred to above, the relevant essential requirements specified below shall be converted to that unit, using simple interpolation.
2. Accuracy classesE+W+S
2.1. The following accuracy classes have been defined—E+W+S
(a)I special
(b)II high
(c)III medium
(d)IIII ordinary
The specifications of these classes are given in Table 1.
| Accuracy classes | ||||
|---|---|---|---|---|
| Class | Verification scale interval (e) | Minimum capacity (Min) | Number of verification scale intervals n = ((Max)/(e)) | |
| minimum value | minimum value | maximum value | ||
| I | 0,001 g ≤ e | 100 e | 50 000 | |
| II | 0,001 g ≤ e ≤ 0,05 g | 20 e | 100 | 100 000 |
| 0,1 g ≤ e | 50 e | 5 000 | 100 000 | |
| III | 0,1 g ≤ e ≤ 2 g | 20 e | 100 | 10 000 |
| 5 g ≤ e | 20 e | 500 | 10 000 | |
| IIII | 5 g ≤ e | 10 e | 100 | 1 000 |
The minimum capacity is reduced to 5 e for instruments in classes II and III for determining a conveying tariff.
2.2. Scale intervalsE+W+S
2.2.1. The actual scale interval (d) and the verification scale interval (e) shall be in the form—E+W+S
1 x 10k, 2 x 10k, or 5 x 10k mass units,
k being any integer or zero.
2.2.2. For all instruments other than those with auxiliary indicating devices—E+W+S
d = e.
2.2.3. For instruments with auxiliary indicating devices the following conditions apply—E+W+S
e = 1 x 10kg;
d < e ≤ 10 d.
Those conditions do not apply for instruments of class I with d < 10–4 g, for which e = 10–3 g.
3. ClassificationE+W+S
3.1. Instruments with one weighing rangeE+W+S
Instruments equipped with an auxiliary indicating device shall belong to class I or class II. For these instruments the minimum capacity lower limits for these two classes are obtained from Table 1 by replacement in column 3 of the verification scale interval (e) by the actual scale interval (d).
If d < 10–4 g, the maximum capacity of class I may be less than 50 000 e.
3.2. Instruments with multiple weighing rangesE+W+S
Multiple weighing ranges are permitted, provided they are clearly indicated on the instrument. Each individual weighing range is classified according to point 3.1. If the weighing ranges fall into different accuracy classes the instrument shall comply with the severest of the requirements that apply for the accuracy classes in which the weighing ranges fall.
3.3. Multi-interval instrumentsE+W+S
3.3.1. Instruments with one weighing range may have several partial weighing ranges (multi-interval instruments).E+W+S
Multi-interval instruments shall not be equipped with an auxiliary indicating device.
3.3.2. Each partial weighing range i of multi-interval instruments is defined by—E+W+S
| — its verification scale interval ei | with e(i + 1) > ei |
| — its maximum capacity Maxi | with Maxr = Max |
| — its minimum capacity Mini | with Mini = Max (i – 1) |
| and Min1 = Min |
Where:
i = 1, 2, …r,
i = partial weighing range number,
r = the total number of partial weighing ranges
All capacities are capacities of net load, irrespective of the value of any tare used.
3.3.3. The partial weighing ranges are classified according to Table 2. All partial weighing ranges shall fall into the same accuracy class, that class being the instrument's accuracy class.E+W+S
| Multi-level instruments | ||||
|---|---|---|---|---|
i = 1, 2, …r, i = partial weighing range number, r = the total number of partial weighing ranges | ||||
| Class | Verification scale interval (e) | Minimum capacity (Min) | Number of verification scale intervals | |
| Minimum value | Minimum value F3 n = ((Maxi) / (e(i+1))) | Maximum value n = ((Maxi) / (ei)) | ||
| I | 0,001 g ≤ ei | 100 e1 | 50 000 | |
| II | 0,001 g ≤ ei ≤ 0,05 g | 20 e1 | 5 000 | 100 000 |
| 0,1 g ≤ ei | 50 e1 | 5 000 | 100 000 | |
| III | 0,1 g ≤ ei | 20 e1 | 500 | 10 000 |
| IIII | 5g ≤ ei | 10 e1 | 50 | 1 000 |
Textual Amendments
F3For I = r, the corresponding column of Table 1 applies, with e replaced by er.
4. AccuracyE+W+S
4.1. On implementation of the procedures laid down in regulation 36, the error of indication shall not exceed the maximum permissible error of indication as shown in Table 3. In the case of digital indication the error of indication shall be corrected for the rounding error.E+W+S
The maximum permissible errors apply to the net value and tare value for all possible loads, excluding preset tare values.
| Maximum permissible errors | ||||
|---|---|---|---|---|
| Load | Maximum permissible error | |||
| Class I | Class II | Class III | Class IIII | |
| 0 ≤ m ≤ 50 000 e | 0 ≤ m ≤ 5 000 e | 0 ≤ m ≤ 500 e | 0 ≤ m ≤ 50 e | ± 0,5 e |
| 50 000 e < m ≤ 200 000 e | 5 000 e < m ≤ 20 000 e | 500 e < m ≤ 2 000 e | 50 e < m ≤ 200 e | ± 1,0 e |
| 200 000 e < m | 20 000 e < m ≤ 100 000 e | 2 000 e < m ≤ 10 000 e | 200 e < m ≤ 1 000 e | ± 1,5 e |
4.2. The maximum permissible errors in service are twice the maximum permissible errors fixed in Section 4.1.E+W+S
5. Weighing results of an instrument shall be repeatable, and shall be reproducible by the other indicating devices used and in accordance with other methods of balancing used.E+W+S
The weighing results shall be sufficiently insensitive to changes in the position of the load on the load receptor.
6. The instrument shall react to small variations in the load.E+W+S
7. Influence quantities and timeE+W+S
7.1. Instruments of classes II, III and IIII, liable to be used in a tilted position, shall be sufficiently insensitive to the degree of tilting that can occur in normal use.E+W+S
7.2. The instruments shall meet the metrological requirements within the temperature range specified by the manufacturer. The value of this range shall be at least equal to—E+W+S
(a)5 °C for an instrument in class I;
(b)15 °C for an instrument in class II;
(c)30 °C for an instrument in class III or IIII.
In the absence of a manufacturer's specification, the temperature range of – 10 °C to + 40 °C applies.
7.3. Instruments operated from a mains power supply shall meet the metrological requirements under conditions of power supply within the limits of normal fluctuation.E+W+S
Instruments operated from battery power shall indicate whenever the voltage drops below the minimum required value and shall under those circumstances either continue to function correctly or be automatically put out of service.
7.4. Electronic instruments, except those in class I and in class II if e is less than 1 g, shall meet the metrological requirements under conditions of high relative humidity at the upper limit of their temperature range.E+W+S
7.5. Loading an instrument in class II, III or IIII for a prolonged period of time shall have a negligible influence on the indication at load or on the zero indication immediately after removal of the load.E+W+S
7.6. Under other conditions the instruments shall either continue to function correctly or be automatically put out of service.]E+W+S