Revoked — SGM-3 — Specifications Relating to the Design, Composition, Construction and Performance of Electronic Automatic Weighing Devices

These specifications were revoked and their requirements integrated in the Weights and Measures Regulations with the regulatory amendments SOR/2012-28, which came into force on May 1st, 2012.

Amendments to the Weights and Measures Regulations (Integration of SGM-1 and SGM-3 Specifications) (SOR/2012-28)

Category: Mass
Specification: Revoked—SGM-3—Specifications Relating to the Design, Composition, Construction and Performance of Electronic Automatic Weighing Devices
Date: 1999-08-17

Table of Contents

Short Title

1. These specifications may be cited as the Weights and Measures Specifications SGM-3. (SI/98-27)

Authority

2. These specifications are established pursuant to section 13 of the Weights and Measures Regulations, C.R.C., c. 1605. (SI/98-27)

Interpretation

2.1 In these specifications, "scale" means any automatic weighing machine to which these specifications apply. (SI/98-27)

Application

3. Except as may be otherwise allowed by a Notice of Approval these specifications apply to any electronic digital indicating scale capable of use in trade with electronic components, other than a conveyor scale or one to which Weights and Measures Specifications SGM-1 apply. (SI/98-27)

Motion Detector

4. Except as may otherwise be allowed by a Notice of Approval, a scale shall incorporate a non-operator controlled motion detector to prevent the recording of a weight signal until the load receiving element is stable within

  1. plus or minus one (1) minimum increment of registration, if it has a capacity of 2000 kilograms or less, or
  2. plus or minus three (3) minimum increments of registration, if it has a capacity of more than 2000 kilograms.

4.1 The values recorded shall be within the applicable limits of error prescribed by the Weights and Measures Regulations.

4.2 The load receiving element shall be stable, as required by 4, at least 0.4 second before a weight signal is recorded.

4.3 The motion detector and automatic zero control circuits shall be interlocked so that use of the latter is inhibited during operation of the former.

Electronic Indicators

5. The contrast between any digital display and the background shall have a ratio equal to or greater than 4 to 1.

5.1 A scale shall incorporate a test system for verifying that all display segments are neither continuously on nor off; such test system shall permit verification of display segments without the need for any tools or by a self-verifying automatic system that indicates the occurrence of any failure.

Weight Units

6. Associated with any digital weight registration there shall be suitably located an appropriate name, symbol or abbreviation for the unit of measurement registered.

Capacity Indication

7. No digital indicating element or recording element shall display or print any value when the load exceeds 105 per cent of the rated capacity of the scale.

Zero

8. The maximum zero range of the type which may be adjusted from the scale exterior shall not exceed four per cent of rated scale capacity; unless operable only a detachable tool, when activated, such adjustment mechanism shall only return the scale to a zero balance condition.

8.1 Automatic means to maintain a digital zero balance condition shall be non-operator controlled, and the maximum load that may be placed on the load receiving element, with the scale indicating zero and "rezero" without indicating a weight value, shall be a mass equal to 0.6 of a minimum increment of registration.

8.2 The maximum zero range of an automatic means of maintaining zero shall not exceed 4 per cent of rated scale capacity.

Tare

9. The tare mechanism shall operate only in the direction of under-registration with respect to the zero load balance condition of the scale.

9.1 A scale may be equipped with full scale tare; however, the gross weight shall not exceed the rated capacity within limits given in paragraph 7.

9.2 An automatic tare mechanism control shall be identified within the word "TARE", the letters "TR", or words or letters that convey the same meaning.

9.3 Except as many otherwise be allowed by Notice of Approval the minimum increment of tare shall be the same as the minimum increment of registration.

9.4 The use of any mechanism to convert units of measurement (for example, lb/kg switch) shall be inhibited when tare is entered in a scale unless this mechanism converts all values of weight registration when activated.

9.5 When a device is capable of registering gross, net or tare weight, all such displays shall be appropriately marked.

9.6 When a device is equipped to display only one weight value at a time, there shall be visual confirmation on or adjacent to the weight display that the tare mode is operating.

Construction and Design to Facilitate Inspection

10. Except as may otherwise be allowed by a Notice of Approval, means shall be provided to seal only the coarse zero and span adjustment controls so that all other components and adjustments are readily accessible without breaking the seal; such means shall be readily observable upon inspection without the necessity of disassembling any part requiring the use of mechanical means separate from the scale.

Withstanding Variations

11. A scale shall withstand vertical forces to 150 per cent of rated capacity without affecting calibrations, and to 300 per cent of rated capacity without permanent degradation.

11.1 Except as may otherwise be allowed by a Notice of Approval, a scale shall meet or exceed the performance criteria of the Weights and Measures Regulations, when tested after being calibrated and zeroed under any possible combinations of the following operating conditions:

  • ambient temperature -10° C to +40° C
  • relative humidity 10% to 95%

11.2 A scale shall be capable of operating within ± 10% of rated voltage and ± 2% frequency variation of nominal frequency rating.

Load Indication

12. For the same load kept on a scale, the difference between the indication obtained at the moment of placing the load and the indication obtained eight hours later shall not exceed the permissible acceptance limit of error for loads applied set out in Division 6 of the Weights and Measures Regulations.

12.1 The variation on returning to zero after the removal of a load which has remained on the scale for half an hour may not exceed one-half the finest digital increment of registration.

12.2 The no load indication shall not vary any more than one minimum increment of registration for a difference in ambient temperature of 5° C.

Junction Boxes

13. Junction boxes shall have a provision for sealing when they contain calibration adjustments.

Multiplexed Scales

14. When a single electronic indicator is coupled to two or more load-receiving elements with independent weighing systems:

  1. the indicator shall be equipped with separate calibrating circuits for each load-receiving element, so that the adjustment of one circuit shall not affect the calibration of any other;
  2. each calibrating circuit shall be appropriately marked to identify which load-receiving element it controls and that indication shall be clearly visible to both the operator and customer standing in their normal positions;
  3. the indicator shall be provided with means to prohibit the activation of any load-receiving element not in use and with automatic means to indicate clearly and definitely which load-receiving element or elements is in use; and
  4. any interconnecting cable which affects or can affect calibration shall be suitably identified to indicate with which load-receiving element it is associated

Miscellaneous

15. A scale shall meet or exceed the performance criteria prescribed by the Weights and Measures Regulations and by these specifications when tested at a constant ambient temperature, that is, a temperature that does not vary more than 5° C.

15.1 A scale shall meet or exceed the performance criteria of the Weights and Measures Regulations when scanned at a distance of 2 metres with

  1. a 460 MHz (commercial) 4 watt, hand-held communicator, and
  2. a 27MHz (citizen's band) 4 watt, hand-held communicator

15.2 The value of the minimum increment of registration shall be equal to the number of kilograms or pounds expressed by one of the following formulae:

1 × 10n, 2 × 10n or 5 × 10n,

where n represents a whole number, positive, negative or equal to zero.

15.3 Subject to subsection 172(2) to the Weights and Measures Regulations and except as may be specified in the Notice of Approval for special cases or for special conditions of use, the maximum value of the finest digital increment that is permissible for electronic scales is as set out in the following tables:

Capacity of Scale (in kilograms) Maximum Value of Finest Digital Increment (in kilograms)
over 100,000 20
over 20,000 to 100,000 10
over 10,000 to 20,000 5
over 5,000 to 10,000 2
over 2,000 to 5,000 1
over 1,000 to 2,000 0.5
over 500 to 1,000 0.2
over 200 to 500 0.1
over 100 to 200 0.05
over 50 to 100 0.02
over 20 to 50 0.01
20 and under 0.005

Capacity of Scale (in pounds) Maximum Value of Finest Digital Increment (in pounds)
over 200,000 50
over 40,000 to 200,000 20
over 20,000 to 40,000 10
over 10,000 to 20,000 5
over 5,000 to 10,000 2
over 2,000 to 5,000 1
over 1,000 to 2,000 0.5
over 500 to 1,000 0.2
over 200 to 500 0.1
over 100 to 200 0.05
over 50 to 100 0.02
50 and under 0.01

15.4 The finest digital increment of a scale that is converted from the Canadian system of units to the International system of units shall not be greater than but can be finer than the converted value set out in the following table:

Present Value (Finest Digital Increment) lbs or oz Converted Value (Finest Digital Increment) (in kilograms)
50 lbs 20
20 lbs 10
10 lbs 5
5 lbs 2
2 lbs 1
1 lb 0.5
0.5 lb or 8 oz 0.2
0.2 lb or 4 oz 0.1
0.1 lb or 2 oz 0.05
0.05 lb or 1 oz 0.02
0.02 lb or ¼ oz 0.01
0.01 lb or 1/8 oz 0.005

15.5 When a scale has analogue and digital means of indication these shall be interlocked so that the use of the latter is inhibited during operation of the former.