Legal metrologicy of automatic weighing equipment

by marketing on 24 de October de 2022

Regulation for fair trade

It is important, both for brand image and consumer law, to ensure that products marketed in different packaging do not differ from one another. This requires uniformity of the product not only in terms of format, but also in terms of quantity. For example, if a consumer buys a product whose packaging is marked 250 g, it is essential that the scale on which the product has been weighed works according to standards to ensure that the quantity the customer is paying for is actually the quantity he is getting.

In order to guarantee greater market transparency, a series of rules, directives and decrees are proposed to guarantee greater production rationality.

From here it is essential to talk about metrology, the science that studies measurements and guarantees their standardisation through traceability. It operates in scientific, industrial and legal fields and regulates means, methods and instruments, such as dynamic checkweighers.

Who regulates these requirements?

Firstly, the International Organisation of Legal Metrology is responsible for establishing standards that regulate metrology but are not mandatory.

On a second level, the European Union promotes directives based on these guidelines, which are mandatory for all member states.

Finally, the government of each country decrees laws that respect these European directives.

In our case, these are the Royal Decrees, which are compulsory for all packagers and manufacturers in Spain.

How is compliance with these requirements regulated?

The regulations differ according to their scope of application. Some regulations affect the packers themselves and others affect the manufacturers of automatic weighing instruments, commonly known as dynamic checkweighers.

For the packer, one of the most important rules is RD 1801/2008, with regulations concerning nominal quantities for packaged products and the control of their actual content. This decree specifies that the effective content must be measured or controlled using a measuring instrument subject to metrological control.
Packaging that complies with the inspection procedures set out in this Royal Decree may receive the CE mark, which certifies that the packaging complies with the provisions of this Royal Decree.

There are two types of instruments used for metrological control:

- Non-automatic weighing instruments (IPFNA), with which production is controlled by sampling, as in a static scale.

- Automatic weighing instruments (IPFA) or dynamic checkweighers are those that verify the weight of 100% of the products.

With regard to the manufacturers of these dynamic checkweighers, they must in turn comply with the implications in terms of metrological control that are defined in Royal Decree RD 244/2016, in Law 32/2014 and in Order ICT/155/2020, the contents of which are in line with Directive 2014/32/EU (MID). All these regulations subject these measuring instruments that control the actual content of the packaged products to administrative and technical controls.

Thus, RD 244/2016 describes in its article 6 that the instruments that serve to
guarantee legal trade shall be subject to metrological control. When the instrument used does not intervene in the inscription and marking of the weight on the packaging, the instrument will not be subject to metrological control.

Initial stage

In order for a checkweigher to be considered metrological, it must fulfil two phases: the type examination phase and the metrological conformity phase.
1. TYPE EXAMINATION PHASE
This refers to the time when the equipment is manufactured.
When this occurs, it is essential that it complies with the conformity assessment, where it can be demonstrated that the measuring instrument is manufactured in accordance with the relevant type approval.
2. METROLOGICAL CONFORMITY PHASE
Conformity markings affixed to measuring instruments certify compliance with the essential requirements for putting them into use. An example of such a marking is shown on the right.

The CE symbolism identifies the application of a harmonised European control. The letter M, which represents metrological compliance, is accompanied by the last digits of the year in which it was put into service. Finally, the digits corresponding to the identification of the Notified Body that carried out the conformity assessment are added.

The following combinations can be used to make an equipment metrological:

Verification stage

In order to guarantee the maintenance of the metrological characteristics of an instrument throughout its useful life, the ICT/155/2020 order provides for the control stage for the metrological verification of instruments in use. It establishes two modalities: periodic verification and verification after repair or modification.

These verifications must be passed by the measuring instrument, paying particular attention to the maximum permissible errors of the instrument in service and its inviolability, in order to avoid possible fraudulent actions.

PERIODIC VERIFICATION

This verification consists of submitting the instrument to administrative, visual and technical examinations to check and confirm that the instrument maintains since its last verification the applicable metrological characteristics specifically with regard to the maximum permissible errors, as well as that it operates in accordance with its approved design or model.

The owner of the instrument is obliged to apply to the competent public administration or authorised metrological verification body for periodic verification before two years have elapsed since the previous verification, or before this period of time has elapsed since the instrument was put into service.

Before requesting periodic verification from the laboratory it is important to confirm that the equipment is
is still functioning according to the metrological regulations.
VERIFICATION AFTER REPAIR OR MODIFICATION

The repair or modification of an instrument under metrological control may only be carried out by an authorised repairer.

After the repair, it is not obligatory to carry out another verification, but can wait for the next periodic verification. However, if the owner of the instrument wants to be sure that the equipment complies after the repair or modification, he may request the competent public administration or authorised metrological verification body to verify the repair or modification. In such a case the verification shall have the effect of a periodic verification and the next verification shall not be carried out for two years.

Any measuring instrument that has passed a verification, in any of its modalities, shall have a label attached to it (verification label after repair or modification and periodic verification). Otherwise, if a verification has not been passed, the measuring instrument shall be fitted with a decommissioning label.

Converting equipment to metrological

Occasionally, a packaged goods manufacturer needs to convert a non-metrological dynamic checkweigher to a metrological measuring instrument, either due to a plant expansion or to comply with new regulations.

In such cases, a thorough evaluation of the instrument in question will be required to determine whether it is eligible for type examination. The certificate of conformity with the commissioning of the instrument must then be carried out.

Once the equipment has the conformity assessment modules, the owner of the instrument must request periodic verification after two years from a Notified Body, as it would enter the in-service instrument verification stage.

Varpe offers the service of exhaustive analysis of the instrument and carrying out the relevant modifications for possible metrological compliance and obtaining the B module. In addition, as a manufacturer, Varpe is authorised to carry out module D.
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