The Measuring Instruments Regulations 2016 SCHEDULE 1G — AUTOMATIC WEIGHING INSTRUMENTS (MI-006) (Annex VIII to the Directive)

Rated Operating Conditions

1

The manufacturer shall specify the rated operating conditions for the instrument as follows:

Rated Operating Conditions

1

For the measurand: The measuring range in terms of its maximum and minimum capacity.

1

For the electrical supply influence quantities:

1

For the mechanical and climatic influence quantities: The minimum temperature range is 30 °C unless specified otherwise in the following chapters of this Schedule. The mechanical environment classes according to Schedule 1A, paragraph 1.3.2 are not applicable. For instruments which are used under special mechanical strain, e.g. instruments incorporated into vehicles, the manufacturer shall define the mechanical conditions of use.

1

For other influence quantities (if applicable): The rate(s) of operation. The characteristics of the product(s) to be weighed.

1

These categories are divided into four accuracy classes: Y(I), Y(II), Y(a) & Y(b) which shall be specified by the manufacturer.

Accuracy classes

1

The manufacturer shall specify both the reference accuracy class Ref(x) and the operational accuracy class(es) X(x).

1

An instrument type is designated a reference accuracy class, Ref(x), corresponding to the best possible accuracy for instruments of the type. After installation, individual instruments are designated for one or more operational accuracy classes, X(x), having taken account of the specific products to be weighed. The class designation factor (x) shall be ≤ 2, and in the form 1 × 10 k , 2 × 10 k or 5 × 10 k where k is a negative whole number or zero.

1

The reference accuracy class, Ref(x) is applicable for static loads.

1

For the operational accuracy class X(x), X is a regime relating accuracy to load weight and (x) is a multiplier for the limits of error specified for class X(1) in paragraph 2.2.

1

Accuracy Classes Instruments are divided into four accuracy classes as follows: 0.2; 0.5; 1; 2.

Accuracy classes

1

Instruments are divided into three accuracy classes as follows: 0.5; 1; 2.

Accuracy classes

1

Instruments are divided into four accuracy classes as follows: 0.2; 0.5; 1; 2.

2

Permissible effect of disturbances — Electromagnetic environment The required performance and the critical change value are given in the relevant Chapter of this Schedule for each type of instrument.

MPE

2

MPE Category Y instruments

Verification scale interval — multi-interval instruments

2

1 For i = r the corresponding column of Table 2 applies with e replaced by e r . Minimum value 1 n = Max i /e (i+1) For i = r the corresponding column of Table 2 applies with e replaced by e r . Maximum value n = Max i /e i Where: i = 1, 2, … r i = partial weighing range r = total number of partial ranges

Static weighing error

2

For static loads under rated operating conditions, the MPE for reference accuracy class Ref(x), shall be 0.312 of the maximum permissible deviation of each fill from the average; as specified in Table 5; multiplied by the class designation factor (x).

2

For instruments where the fill may be made up from more than one load (e.g. cumulative or selective combination weighers) the MPE for static loads shall be the accuracy required for the fill as specified in paragraph 2.2 (i.e. not the sum of the maximum permissible deviation for the individual loads).

Deviation from average fill

2

Note: The calculated deviation of each fill from the average may be adjusted to take account for the effect of material particle size.

Error relative to pre-set value (setting error)

2

For instruments where it is possible to pre-set a fill weight; the maximum difference between the pre-set value and the average mass of the fills shall not exceed 0.312 of the maximum permissible deviation of each fill from the average, as specified in Table 4.

2

MPEs

Measurement Range

2

The manufacturer shall specify the measurement range, the ratio between the minimum net load on the weighing unit and the maximum capacity, and the minimum totalised load.

2

The minimum totalised load Σ min shall not be less than 800 d for class 0.5, 400 d for class 1, 200 d for class 2. Where d is the totalisation scale interval of the general totalisation device.

MPE

2

The MPEs for weighing-in-motion of a single wagon or a total train are shown in Table 8.

2

The MPEs for the weight of coupled or uncoupled wagons weighing-in-motion shall be one of the following values, whichever is the greatest: — the value calculated according to Table 8, rounded to the nearest scale interval; — the value calculated according to Table 8, rounded to the nearest scale interval for a weight equal to 35 % of the maximum wagon weight (as inscribed on the descriptive markings); — one scale interval (d).

2

The MPEs for the weight of train weighing-in-motion shall be one of the following values, whichever is the greatest: — the value calculated according to Table 9, rounded to the nearest scale interval; — the value calculated according to Table 9, for the weight of a single wagon equal to 35 % of the maximum wagon weight (as inscribed on the descriptive markings) multiplied by the number of reference wagons (not exceeding 10) in the train, and rounded to the nearest scale interval; — one scale interval (d) for each wagon in the train, but not exceeding 10 d.

2

When weighing coupled wagons; the errors of not more than 10 % of the weighing results taken from one or more passes of the train may exceed the appropriate MPE given in paragraph 2.2, but shall not exceed twice the MPE.

Suitability

3

Means shall be provided to limit the effects of tilt, loading and rate of operation such that maximum permissible errors (MPEs) are not exceeded in normal operation.

3

Adequate material handling facilities shall be provided to enable the instrument to respect the MPEs during normal operation.

3

Any operator control interface shall be clear and effective.

3

The integrity of the display (where present) shall be verifiable by the operator.

3

Adequate zero setting capability shall be provided to enable the instrument to respect the MPEs during normal operation.

3

Any result outside the measurement range shall be identified as such, where a printout is possible.

Measurement Range

3

In specifying the measurement range for class Y instruments the manufacturer shall take account that the minimum capacity shall not be less than:

Performance Under Influence Factor And Electromagnetic Disturbance

3

The MPE due to influence factors shall be as specified in paragraph 2.1.

3

The critical change value due to a disturbance is a change of the static weight indication equal to the MPE as specified in paragraph 2.1 calculated for the rated minimum fill, or a change that would give equivalent effect on the fill in the case of instruments where the fill consists of multiple loads. The calculated critical change value shall be rounded to the next higher scale interval (d).

3

The manufacturer shall specify the value of the rated minimum fill.

Totalisation scale interval

3

The totalisation scale interval (dt) shall be in the range: 0.01 % Max ≤ d t ≤ 0.2 % Max

Scale interval (d)

3

The relationship between the accuracy class and the scale interval shall be as specified in Table 9.

Conformity assessment

4

The conformity assessment procedures specified in the modules in Schedule 1B applicable to automatic weighing instruments that the manufacturer can choose between are: (a) For mechanical systems: (i) B and D; (ii) B and E; (iii) B and F; (iv) D1; (v) F1; (vi) G; or (vii) H1. (b) For electromechanical instruments: (i) B and D; (ii) B and E; (iii) B and F; (iv) G; or (v) H1. (c) For electronic systems or systems containing software: (i) B and D; (ii) B and F; (iii) G; or (iv) H1.

Dynamic Setting

4

The dynamic setting facility shall operate within a load range specified by the manufacturer.

4

When fitted, a dynamic setting facility that compensates for the dynamic effects of the load in motion shall be inhibited from operating outside the load range, and shall be capable of being secured.

Minimum Totalised Load ( Σ min )

4

The minimum totalised load ( Σ min ) shall be not less than the load at which the MPE is equal to the totalisation scale interval (dt) and not less than the minimum load as specified by the manufacturer.

Speed of the belt

4

The speed of the belt shall be specified by the manufacturer. For single-speed beltweighers, and variable-speed beltweighers having a manual speed setting control, the speed shall not vary by more than 5 % of the nominal value. The product shall not have a different speed than the speed of the belt.

Measurement range

4

The minimum capacity shall not be less than 1 t, and not greater than the value of the result of the minimum wagon weight divided by the number of partial weighings.

4

The minimum wagon weight shall not be less than 50 d.

Performance Under Influence Factors And Electromagnetic Disturbances

5

The MPEs due to influence factors are:

5

For category Y instruments — For each load in automatic operation; as specified in Table 1, — For static weighing in non-automatic operation; as specified in Table 1.

5

The critical change value due to a disturbance is one verification scale interval.

5

Temperature range: — For class Y(I) the minimum range is 5 °C, — For class Y(II) the minimum range is 15 °C.

Zero Setting

5

Instruments that do not tare weigh after each discharge shall have a zero setting device. Automatic operation shall be inhibited if zero indication varies by: — 1 d t on instruments with automatic zero setting device; — 0.5 d t on instruments with a semi-automatic, or non-automatic, zero setting device

General Totalisation Device

5

It shall not be possible to reset the general totalisation device to zero.

Performance under influence factor and electromagnetic disturbance

5

The MPE due to an influence factor shall be as specified in Table 10.

5

The critical change value due to a disturbance is one scale interval.

Operator Interface

6

Operator adjustments and reset function shall be inhibited during automatic operation.

Performance under influence factors and electromagnetic disturbances

6

The MPE due to influence factor, for a load not less than the Σ min , shall be 0.7 times the appropriate value specified in Table 7, rounded to the nearest totalisation scale interval (d).

6

The critical change value due to a disturbance shall be 0.7 times the appropriate value specified in Table 7, for a load equal to Σ min , for the designated class of the beltweigher; rounded up to the next higher totalisation scale interval (d).

Printout

7

On instruments equipped with a printing device, the reset of the total shall be inhibited until the total is printed. The printout of the total shall occur if automatic operation is interrupted.

Performance under influence factors and electromagnetic disturbances

8

The MPEs due to influence factors shall be as specified in Table 6.

8

The critical change value due to a disturbance is one totalisation scale interval for any weight indication and any stored total.