M-06—Metric conversion of weighing devices

Date: 1998-03-02
Bulletin: M-06-E (rev. 1)
Category: Mass
Supersedes: M-06-E
Document(s): W&M Regulations, section 9, 41, 66, 121, 126, 127, 131, 172; SGM 3-15.3, 15.4; SRNAWD, sections 30, 34


1. This bulletin addresses the metric conversion of weighing devices and applies to all devices that are approved to register only in Canadian units of measurement. It sets out acceptable methods of conversion based on the requirements of sections 66, 121 and 126 of the Weights and Measures Regulations as well as sections 30 and 34 of the Specifications Relating to Non-Automatic Weighing Devices.

2. Section 9 of the Weights and Measures Regulations provides for the modification of approved devices, to enable them to measure in metric units, if such modifications conform to the applicable requirements established by the Regulations and the Specifications.

3. A scale that is modified to measure in terms of metric units shall not have a metric capacity greater than 111% of the approved capacity in Canadian units. For example, a scale with an approved capacity of 100 000 pounds would normally be converted to 50 000 kilograms.

4. When a scale is converted to measure in metric units by replacing an indicating mechanism that includes a non-computing dial, a cylindrical or fan chart, all or part of a beam, or a tip weight, the replacement indicating mechanism and any other component parts required to make the replacement indicator compatible to the scale:

4.1 need not be submitted to Measurement Canada for approval,

4.2 shall be of comparable design, composition and construction to the original, unless approved by Measurement Canada,

4.3 shall be adequately secured in the same manner as the original, and

4.4 must have graduations or markings of the same size and character as before conversion, and the graduations and markings shall conform, as applicable, to sections 127 and 131 of the Regulations, in the case of automatic weighing devices, and section 34 of the Specifications Relating to Non-Automatic Weighing Devices, for non-automatic weighing devices.

5. It is recommended that replacement indicating mechanisms that compute monetary values be submitted to Measurement Canada for examination in order to ensure that they conform to applicable requirements.

6. When an insert is installed to convert a beam to measure in metric units where there was not an insert before, the beam shall be suitably altered to install the insert, and the insert shall be of good and permanent quality with a minimum thickness of 1.5 millimetres.

7. Subject to section 172 of the Regulations, Ministerial Specification SGM 3, subsections 15.3 and 15.4, and except as may otherwise be allowed by a Notice of Approval, the maximum value of the finest graduation or increment that is permissible when a scale is modified to measure in terms of metric units is set out in the following table (applies to previously inspected or newly manufactured scales):

Table 1
Present or approved value of finest graduation Converted value of finest graduation
50 pounds 20 kilograms
20 pounds 10 kilograms
10 pounds 5 kilograms
5 pounds 2 kilograms
2 pounds 1 kilogram
1 pound 0.5 kilogram
0.5 pound or 8 ounces 0.2 kilogram
0.2 pound or 4 ounces 0.1 kilogram
0.1 pound or 2 ounces 0.05 kilogram
0.05 pound or 1 ounce 0.02 kilogram
0.02 pound or 1/2 ounce 0.01 kilogramFootnote 1
0.01 pound or 1/8 ounce 0.005 kilogramFootnote 2

8. A scale with a full capacity dial may be converted to measure in terms of both metric and Canadian units of measure (dual indication).

8.1 When a scale is modified in this manner, the dial chart shall be marked with metric units of measure on the outer arc or indicating line.

9. A scale with a dial and tare bar(s) may be modified to measure in terms of both metric and Canadian units of measure when:

9.1 the dial chart has dual indication as described above;

9.2 the tare bar is only marked with a zero indication;

9.3 the scale capacity is derated to the value of the metric indication on the chart.

10. All dial scales that are not modified in this manner shall be converted such that all means of indication are in terms of metric units only; this includes charts, tare bars and drop weights.

11. Within 5 days of conversion, the person who alters a scale to indicate in terms of metric units shall report the conversion to the nearest Measurement Canada office as required by section 41 of the Regulations.

12. The nameplate of a scale that has been converted to metric must be modified to indicate the conversion.

13. The identification markings may be made on a subsidiary to the original nameplate or on a replacement nameplate.

14. In the case of a scale that is modified by replacing the indicating mechanism, the scale shall be marked with all the information on the original nameplate, as well as:

14.1 the new capacity of the scale expressed in terms of metric units of measure; and

14.2 the new approval number, if applicable.

15. The pinning of beams at half their capacity for the purposes of converting weighing devices to the metric system is prohibited.

16. Revision: The purpose of this revision is to:

  1. correct the legislative references by removing quoted sections that were repealed with the coming into force of the Specifications Relating to Non-Automatic Weighing Devices as well as adding the applicable sections from these specifications; and
  2. to make minor changes to the text.
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