Specifications Relating to Non-automatic Weighing Devices (1998) (SI/98-81)

7 The verification scale interval for Class  and weighing devices that are equipped with auxiliary indicating elements corresponds to the value of the scale interval preceding the actual scale interval of the auxiliary indicating element, and is larger than the actual scale interval.

Performance - General

In-service Limits of Error

• 8 (1) The in-service limits of error set out in column I of the table to this section apply, in respect of each class of non-automatic weighing devices set out in column II of that table, according to the specified load.

• (2) In the table to this section, m means the weight of the load placed on the weighing device, and is expressed in the number of verification scale intervals.

• (3) The in-service limits of error that apply to a Class weighing device are ±1 e where the load is not less than zero and not more than 500 verification scale intervals, and where the load exceeds 500 verification scale intervals, calculated by adding ±1 e for each additional 800 verification scale intervals or less, to a maximum of ±22 e.

  Column I	Column II
  Limits of error	Class	Class	Class	Class
  ± 1 e	0 ≤m≤ 50 000	0 ≤m≤ 5 000	0 ≤m≤ 500	0 ≤m≤ 50
  ± 2 e	50 000 <m≤ 200 000	5 000 <m≤ 20 000	500 <m≤ 2 000	50 <m≤ 200
  ± 3 e	m> 200 000	20 000 <m≤ 100 000	2 000 <m≤ 4 000	200 <m≤ 400
  ± 5 e	– – –	– – –	4 000 <m≤ 10 000	400 <m≤ 1 200

Acceptance Limits of Error

9 The acceptance limits of error applicable for each class of non-automatic weighing device are one-half the in-service limits of error set out in section 8 for that device for a specified load.

Modules

10 Where a module, such as an indicating element, or a weighing and load-receiving element, is tested separately for approval pursuant to section 3 of the Weights and Measures Act,

• (a) in the case of a module that is the only part of a weighing device that is subject to measurement errors due to disturbances or influence factors, the acceptance limits of error are the limits of error set out in these Specifications for that device for a specified load; and

• (b) in the case of all other modules, the acceptance limits of error are 0.7 times the limits of error set out in these Specifications for the weighing device for a specified load.

Differences Between Results

11 Regardless of the difference between the results permitted by these Specifications, no weighing result shall have an error that exceeds the applicable limits of error for the given load, with the exception of results obtained during disturbance tests.

Repeatability

12 The difference between the results of several weighings of the same load placed in approximately the same location on a weighing and load-receiving element shall not exceed the absolute value of the applicable in-service limits of error for that load.

Eccentric Loading

13 The difference between the results for different positions of a load placed on a weighing and load-receiving element shall not exceed the absolute value of the applicable in-service limits of error for that load.

Load Discrimination and Sensitivity

14 With respect to non-automatic indicating devices, the addition or removal of a load equal to the applicable in-service limits of error for the load placed on the weighing and load-receiving element, but not exceeding two verification scale intervals, shall cause

• (a) in the case of a weigh-beam or beam-over-pan scale that is without a supplementary indicating element and

  • (i) is equipped with a trig loop, a movement in the position of the weigh-beam from the centre position to either limit of the trig loop, and

  • (ii) is not equipped with a trig loop, the position of rest of the weigh-beam or lever system to change from the horizontal position or midway between limiting stops to either limit of motion; and

• (b) in the case of a weigh-beam or beam-over-pan scale that has a supplementary indicating element that has graduations without specific values, the position of the indicator to change

  • (i) in the case of a Class or device, by at least 1 mm (0.04 in.),

  • (ii) in the case of a Class or device with a maximum capacity not exceeding 30 kg (70 lb.), by at least 2 mm (0.08 in.), and

  • (iii) in the case of a Class or device with a maximum capacity greater than 30 kg (70 lb.), or a Class device, by at least 5 mm (0.2 in.).

15 With respect to automatic indicating devices, the addition or removal of a load equivalent to 1.4 times the actual scale interval to or from the weighing and load-receiving element shall cause a change of

• (a) in the case of an analogue indicating element, at least one actual scale interval; and

• (b) in the case of a digital indicating element, two actual scale intervals.

Return-to-Zero

• 16 (1) Under stable environmental conditions, the deviation from zero as soon as the weight indication has stabilized following the removal of a load that has remained on a weighing and load-receiving element for up to 30 minutes shall not exceed

  • (a) in the case of a single range weighing device, one-half of the verification scale interval;

  • (b) in the case of a multiple range device, one-half of the verification scale interval for the range being tested; and

  • (c) in the case of a multi-interval device, one-half of the smallest verification scale interval.

• (2) In the case of a multiple range device, following the removal of a load greater than the maximum capacity of the first range, which load has remained on the weighing and load-receiving element for up to 30 minutes, and immediately after switching the device to its lowest weighing range, the indication near zero shall not vary by more than one verification scale interval of the lowest weighing range over a period of five minutes after switching the device to its lowest weighing range.

Creep

17 If a load is kept on a weighing and load-receiving element under stable environmental conditions, the difference between the weight indication obtained immediately after placing the load on the element and the weight indication observed during the following 30 minutes shall not exceed the absolute value of the applicable limits of error for that load.

Agreement of Indications and Recordings

18 The weight values that are indicated or recorded by the indicating and recording elements of a weighing device and any equipment and accessories attached to the weighing device or used in conjunction with it shall agree

• (a) exactly, in the case of digital values produced by electronic elements, equipment and accessories that have the same verification scale intervals;

• (b) within 0.25 times the verification scale interval, in the case of analogue values produced by elements, equipment and accessories that have the same verification scale intervals; and

• (c) within 0.6 times the largest verification scale interval or the verification scale interval common to the elements, equipment and accessories, in all other cases.

Computation

• 19 (1) The calculated value of the net weight shall equal the value of the gross weight minus the value of the tare weight.

• (2) Indicated or recorded monetary value shall equal the product, rounded to the nearest cent, obtained by multiplying the weight indication or registration by the price per unit.

Durability

20 A weighing device shall maintain its metrological characteristics and perform within the applicable limits of error for at least 100 000 weighings for a weighing device with a maximum capacity of not more than 1 000 kg (2 000 pounds), and for at least 300 weighings in all other cases.

Performance – Influence Factors

Off-level Effect

• 21 (1) A portable or movable weighing device, other than a device of the freely suspended type or an on-board weighing system, shall be equipped with a permanent means of indicating when it is level, unless it is capable of performing within the applicable limits of error when tilted up to three degrees or five per cent in any direction from a level position.

• (2) An on-board weighing system shall be

  • (a) capable of performing within the applicable limits of error when tilted up to three degrees or five per cent in any direction from a level position; and

  • (b) equipped with a means to blank the weight indications and prevent the transmission, printing and storage of the weight results when the registrations are no longer within the applicable limits of error.

Declared Conditions of Use

22 A weighing device shall perform within the applicable limits of error when exposed to the range of conditions specified by the manufacturer, as well as at any temperature, humidity, pressure, voltage, frequency or other influencing factors that may be encountered under normal conditions of use.

Temperature Effect on No Load Indication

23 The weight indication at or near zero shall not vary by more than

• (a) in the case of Class weighing devices, one verification scale interval for each change in temperature of 1°C;

• (b) in the case of Class weighing devices, three verification scale intervals for each change in temperature of 5°C; and

• (c) in the case of all other classes of weighing device, one verification scale interval for each change in temperature of 5°C.

Temperature

• 24 (1) A weighing device shall perform within the applicable limits of error when exposed

  • (a) where a temperature range is marked on the device, within that temperature range; and

  • (b) where no temperature range is marked on the device, at any temperature of at least -10°C and no more than 40°C.

• (2) The minimum marked temperature range on a weighing device shall be

  • (a) in the case of Class devices, 5°C;

  • (b) in the case of Class devices, 15°C; and

  • (c) in the case of Class , and devices, 30°C.

Barometric Pressure

25 The weight indication at or near zero on a weighing device shall not vary by more than one verification scale interval for a change in barometric pressure of 1 kPa in the barometric pressure range of 95 to 105 kPa.

Voltage and Frequency Variations

26 A weighing device that operates using alternating current shall, when exposed to voltage variations from -15 per cent to +10 per cent and to frequency variations of ± 2 per cent of its marked nominal values,

• (a) perform within the applicable limits of error; or

• (b) blank the weight indication and prevent the transmission, printing and storage of weight results.