M-26—Class approval policy

Category: Mass
Issue date: 2026-03-03
Effective date: 2026-04-01
Revision number: 1
Supersedes: M-26

Table of contents

1.0 Purpose

The purpose of this bulletin is to describe Measurement Canada's (MC) policy and process for granting class approvals.

2.0 Scope

This bulletin applies to MC and authorized service provider (ASP) personnel, traders, manufacturers and individuals who hold or are authorized to use a notice of class approval. It also applies to all devices covered under a notice of class approval. It does not apply to large-capacity weighing devices covered by a type approval. Class approvals apply only to specific non-automatic weighing and load-receiving elements. They do not apply to self-contained weighing devices with integrated indicators, nor to indicating elements.

3.0 Background

The Weights and Measures Act allows MC to approve measuring devices, or classes, types or designs of devices for use in trade.

Most approvals granted by MC are approvals of specific types of devices defined by a consistent set of designs and model numbers. Type approvals include restrictions on the design, dimensions and capacity of approved devices. The device type identified on a notice of type approval cannot be changed unless the approval holder advises MC's mass laboratory of the proposed changes, and the laboratory revises the notice of type approval to allow these changes.

Measurement Canada also grants class approvals, which are broader than type approvals. A class approval covers more than a range of device models. It covers an entire class of devices, such as all hopper scales (within set parameters) manufactured by the manufacturer named on the notice of class approval. It also allows for a significant variation of the design of these devices.

Class approvals apply only to specific non-automatic weighing and load-receiving elements. They do not apply to self-contained weighing devices with integrated indicators, nor to indicating elements. A primary weight indicator used with a class-approved weighing device must be approved separately by MC's mass laboratory before the associated weighing system is initially examined and certified by an MC inspector or ASP.

The requirement is that all devices used in trade must be approved pursuant to the Weights and Measures Act. It is up to manufacturers and traders to determine whether they wish to obtain a type approval or class approval, subject to eligibility.

Once a class approval is granted, all devices of the class described in the notice of class approval, whether manufactured by or for the approval holder, are considered to be approved. If a device is manufactured for the class approval holder, the class approval holder continues to assume all responsibility for the design, composition and construction of the device.

Non-automatic weighing devices with a configured capacity of more than 10,000 kg can be covered by a class approval of the appropriate class, as defined below.

Non-automatic weighing devices with a configured capacity of 10,000 kg or less may be covered by a class approval if it is of such size or configuration that it cannot be readily tested in MC's mass laboratory. See subsection 4.4 below for additional details.

There are currently four distinct classes of devices for which MC may grant an approval:

  • Platform load-receiving element: A platform load-receiving element used for static weighing, and may include additional supporting structures such as those found on paper roll scales, steel coil scales or ingot scales. It does not include any on-board weighing devices.
  • Tank or hopper load-receiving element: A tank or hopper load-receiving element used for static weighing. May include devices used in a discontinuous totalizing weighing system (bulk weighers). It does not include any on board weighing devices.
  • Vehicle weighbridge: A vehicle load-receiving element used for static weighing. It does not include portable wheel weighers.
  • Railway weighbridge: A railway load-receiving element used for static weighing. It includes a railway/vehicle combination scale.

4.0 Policy

4.1 Authorities granted to the class approval holder

A notice of class approval identifies the approval holder and grants them the authority to:

  • build, or have built, an unlimited number of devices of the class and within the parameters specified in the notice of class approval; such devices are considered as approved devices,
  • install, or have installed, devices covered by the class approval, each of which requires an initial examination by an MC inspector or ASP before being used in trade.

4.2 Delegation of authorities

A class approval holder may authorize another person or establishment to build or modify an existing device and have it examined using the approval holder's notice of class approval. The class approval holder assumes all responsibility for the design, composition and construction of the device regardless of who performed the work. The device must be marked in accordance with the notice of class approval, including the class approval number, and be identified as having been built or modified by the holder of the class approval.

This delegation of authority must be made in writing in the form of an authorization letter signed by a senior official of the establishment granted the class approval. The letter must indicate that the approval holder assumes full responsibility for the device. A copy of the letter must be provided to the MC inspector or ASP prior to the initial examination of the device in question.

4.3 Ownership of the notice of class approval

The person or establishment (approval holder) named in the notice of class approval is considered its sole owner. The notice of class approval cannot be used by or transferred to another person or establishment and will be deemed invalid unless that person or establishment has been delegated the authority to use it by the approval holder in accordance with subsection 4.2.

However, if the establishment that owns a notice of class approval is sold, the purchaser becomes the new holder and owner of that notice. If the business name of the establishment is changed during the sale process, the new owner must contact MC's mass laboratory to request that the establishment name indicated on the notice of class approval be modified accordingly.

If the establishment closes or otherwise ceases to operate, the notice of class approval is considered to have expired. Any delegation of authority made in accordance with subsection 4.2 will also be considered expired at that time. Devices already installed under the authority of the original class approval may remain in service but no new devices will be permitted to be installed.

4.4 Class approval of additional authorized devices

Although class approvals typically only apply to non-automatic weighing devices with a capacity of more than 10,000 kg, devices with a configured capacity of 10,000 kg or less may be eligible to be covered by a class approval if they are of such a size or configuration that they cannot be easily tested in MC's mass laboratory. The largest devices that can be tested in MC's mass laboratory are typically those with a maximum capacity of 10,000 kg or less and with dimensions that fit in a space of 3.5 m x 2.5 m by 2 m high. The laboratory will evaluate the size of each device to determine whether the device can be tested in its facility.

If a class approval holder wants to build a device with a capacity of 10,000 kg or less to be covered by the approval, they must send a request for a revision of the notice of class approval to MC's mass laboratory. The class approval holder must do this every time they want an additional authorized device to be covered by the class approval. Devices with a capacity of 10,000 kg or less must be explicitly listed on the notice of class approval to be considered approved. The notice of class approval will include basic information about the additional authorized devices such as their capacity, serial number and location.

When MC's mass laboratory receives a request for revision of a notice of class approval to include an additional authorized device with a capacity of 10,000 kg or less, it will determine whether testing in the laboratory is feasible and whether the device can be covered by the class approval. The laboratory will only consider including another additional authorized device to the notice of class approval if it is unable to test the device due to its dimensions, design or application. The decision to include an additional authorized device rests solely with MC's mass laboratory.

If the device is deemed to be covered by the class approval as an additional authorized device, MC's mass laboratory will revise the existing notice of class approval to explicitly authorize its use. If the device is not deemed to be covered by a class approval, the device will need to be evaluated by MC's mass laboratory for type approval. In this case, the class approval holder will need to apply for and receive a new notice of type approval before the device can be used in trade.

Note: Before April 1, 2026, MC's mass laboratory issued a class approval authorization letter (CAAL) upon acceptance of a device with a capacity of less than 10,000 kg. This practice has been replaced with the revision of the notice of class approval. Over time, all existing CAALs will be retired and the information will be incorporated explicitly into the notice of class approval. This will have no impact on devices previously authorized under a CAAL.

4.5 Marking of class-approved devices

Devices authorized by a class approval must be marked pursuant to the Specifications Relating to Non-automatic Weighing Devices (1998) and the Weights and Measures Regulations.

Even in cases where the authority to use a notice of class approval has been delegated to another person or establishment (see subsection 4.2), the markings must be consistent with those required by the notice of class approval.

4.6 Load cells for class-approved devices

Class-approved devices are not subject to many of the normal tests performed on non-automatic weighing devices (including temperature susceptibility). As such, to ensure that the load cells used on class-approved devices are less susceptible to influence factors and disturbances, MC requires that all class-approved devices initially examined on or after January 1, 2012, must be equipped with approved and compatible load cells. Refer to bulletin M-25—Load Cells and Force Transducers Used in Trade Devices for details.

MC does not approve load cells separately, but accepts as approved any load cell identified on a certificate issued from one of the following organizations:

MC has developed the following tools that aid in determining whether a load cell is compatible for a particular device:

5.0 Obtaining a class approval

5.1 Eligibility

To be eligible for a class approval, potential applicants must already hold a non-conditional type approval for at least one non-automatic weighing device with a capacity of more than 10,000 kg in the class for which they are seeking approval. If they do not meet this requirement, they must first apply for a type approval of such a device. Once they have been granted a non-conditional type approval for the device, they can apply for a class approval.

Devices with a capacity of more than 10,000 kg are generally too large to be tested in MC's mass laboratory. However, they may be eligible for a type D conditional approval as described in bulletin GEN-04—Policy on the conditional approval of devices.

5.2 Applying for and obtaining a class approval

An applicant seeking a class approval must complete and submit a type approval request form. Once MC has verified the applicant's eligibility, it will issue a notice of class approval to the applicant within MC's service standard for approvals.

After the applicant has received the notice of class approval, it's their responsibility to ensure each weighing device being installed under the authority of the class approval is marked with the approval number indicated on the notice of class approval. Markings must be compliant with the Weights and Measures Regulations and the Specifications Relating to Non-automatic Weighing Devices (1998) where applicable.

A notice of class approval may include specific requirements applicable to the device class. Each class-approved device must undergo an initial examination to ensure it meets all of these specific requirements.

6.0 Requesting an examination of a class-approved device

The initial examination of a device with a maximum capacity of more than 10,000 kg that is covered under a valid notice of class approval requires the authorization of the class approval holder. If the device bears all the required markings, including the class approval number, MC will consider this sufficient authorization to perform the initial examination. Subsequent examinations do not require authorization from the class approval holder. The initial examination performed after the replacement of an indicating element does not require authorization from the class approval holder of the load receiving element.

To request an initial examination of a device with a maximum capacity of 10,000 kg or less, the device owner will need to provide proof that it is covered under a notice of class approval. This proof may also be required for subsequent examinations. The following is acceptable proof:

  • The device is explicitly listed on a notice of class approval as an additional authorized device (see subsection 4.4), or
  • The device is listed in a CAAL issued before April 1, 2026, and the CAAL is available to the inspector.

The certified maximum capacity is the value of the maximum load applied (combination of local standards and strain load) to the device during the initial examination. The certified maximum capacity may be increased at any subsequent examination where the device is tested and certified with a greater load. A class-approved device designed with a maximum capacity of more than 10,000 kg must be initially examined with local standards of at least 10,000 kg. If the device cannot be tested with local standards of at least 10,000 kg, then one of the following must happen:

  • The class approval holder must request a revision of the notice of class approval to include the device as an additional authorized device.
  • The class approval holder must apply to have the individual device tested and type approved.

7.0 Modifying a class-approved device

If a class-approved device with a maximum capacity of 10,000 kg or less is modified, the class approval holder must notify MC's mass laboratory. The laboratory will evaluate whether the device may continue to be covered by the existing class approval.

If a class-approved device with a maximum capacity of more than 10,000 kg is modified, the class approval holder must notify MC's mass laboratory, unless the device's capacity changes to 10,000 kg or less. If that is the case, the class approval holder must contact MC's mass laboratory to request that the device be included on the notice of class approval as an additional authorized device.

Modifications are considered either as minor or metrologically significant. To determine if modifications are minor or metrologically significant, the person or establishment performing the modifications must refer to bulletin M-08—Alterations to previously certified weighing devices or systems requiring recertification. In the case of metrologically significant modifications, a new initial examination of the device will be required.

The reporting of modifications is required pursuant to section 41 of the Weights and Measures Regulations.

7.1 Minor modifications

If minor modifications are made to a class-approved device, the original approval number is retained and a device examination is not required.

7.2 Metrologically significant modifications

If metrologically significant modifications are made to a class-approved device by the holder of the original class approval, the device will require a new initial examination. Typically, the original approval number is retained, but a different class approval number can be assigned when the device is initially examined again following the metrologically significant modifications.

If metrologically significant modifications are made to the device by a person or establishment other than the holder of the original class approval, that person or establishment may:

  • retain the original class approval number marked on the device only if they have written authorization by the class approval holder, who assumes all responsibility for the modified device,
  • change the approval number marked on the device to the number of their own valid and applicable class approval, and assumes all responsibility for the modified device,
  • change the approval number marked on the device to the number of a valid and applicable class approval, only if they have written authorization by the class approval holder, who assumes all responsibility for the modified device design.

If the approval number marked on the device is changed as described above, all markings on the device must be updated accordingly.

In all cases, the class approval holder assumes all responsibility for the design, composition and construction of the device, including any intellectual property concerns that may arise. The class approval holder is also responsible for ensuring that the modified device meets all applicable requirements in the Weights and Measures Regulations, the Specifications Relating to Non-automatic Weighing Devices (1998) and the notice of class approval.

8.0 Revisions

The purpose of revision 1 was to:

  • incorporate the content of the Guide for the approval of large capacity weighing devices and Load cells for all CLASS approved devices,
  • remove the "scale systems assembly" type of class approval,
  • lowercase the word "CLASS," which is not an acronym, as per subsection 3(1) Weights and Measures Act,
  • update the bulletin to accurately reflect changes to the policy and process since its original publication, and
  • make editorial changes throughout the document.
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