Anyone who charges by weight does not weigh only for themselves. The customer must be able to trust that 500 g on the display is also 500 g in the bag. That is why the law imposes requirements on scales used for such applications. In the Netherlands, those requirements are laid down in the Dutch Metrology Act (Metrologiewet) and the Measuring Instruments Decree (Meetinstrumentenbesluit).
In this article you will read what the law regulates for non-automatic weighing instruments, in which situations legal verification is mandatory and what that means for maintenance and repair. It is a practical explanation and not legal advice; the legal texts themselves can be found at wetten.overheid.nl. If your scale needs to be verified again, read more about scale verification and re-verification.
What does the law regulate for scales?
The Dutch Metrology Act and the Measuring Instruments Decree transpose European Directive 2014/31/EU into Dutch rules. That directive concerns non-automatic weighing instruments: scales that require an operator during weighing, for example to place the load or read the result. Retail scales, bench and floor scales, laboratory balances and many weighbridges fall into this group.
Broadly speaking, the law regulates three things:
- Which applications require a legally verified instrument.
- Which requirements an instrument must meet before it is put into use for those applications. This is shown by the metrology marking: the M mark next to the CE marking.
- What the user must do afterwards to keep the instrument reliable.
The CE mark alone is not a legal verification. Only with the M mark, the year and the number of the notified body is the scale suitable for legally regulated applications. How to read that type plate is explained in M mark, seals and accuracy classes.
When is legal verification mandatory?
A scale must be legally verified if it is used for:
- selling by weight, where the price depends on the weighed weight;
- calculating charges or levies on the basis of weight;
- determining the quantity in prepackages;
- medical weighing, such as weighing patients;
- preparing medicines in a pharmacy;
- medical and pharmaceutical analyses.
If you weigh only for internal use, such as production control, stock control or recipes, legal verification is not mandatory. Your quality system will then usually require a calibration with certificate. The difference between these terms is explained in calibrating, adjusting and verifying scales.
Market stall, shop and web shop
The obligation depends on the application, not on the location or the size of the business. A market stall selling cheese by the kilo has the same obligation as a supermarket. The same applies to door-to-door sales or sales at an event: if the customer pays on the basis of the weighed weight, the scale must be legally verified.
With a web shop, the customer does not see the scale, but the principle is the same. If an order is weighed out and that weight determines the price, for example for coffee, nuts or meat per 100 g, that weighing falls under the law. If you are unsure whether your situation is covered, for example because you pass on costs based on weight, seek advice before buying a scale.
The role of the RDI
Supervision lies with the Dutch Authority for Digital Infrastructure (Rijksinspectie Digitale Infrastructuur, RDI). During an inspection, an inspector can check whether a scale used for a legally regulated application carries the M mark, whether the seals are intact and whether the instrument weighs within the permitted error.
If the scale does not comply, it may no longer be used for that application until it has been verified again, and the supervisory authority can take enforcement action. General information on legal metrology can be found at rdi.nl.
No fixed re-verification period, but a duty of care
For most scales, the Netherlands has no fixed periodic re-verification period. A verified scale therefore does not have to be verified again every year. That does not mean you no longer need to pay attention to it. As the user, you must ensure that the instrument remains within tolerance for as long as you use it for legally regulated applications.
In practice, companies fulfil that duty of care as follows:
- a periodic calibration or check by a laboratory, recorded in a certificate;
- simple interim checks with a calibrated check weight, as described in checking your scale between calibrations;
- immediate action in case of doubt: a scale that has been dropped, overloaded or gives strange readings is taken out of use until it has been checked.
A calibration certificate is not a legal verification. It does, however, show that you actively monitor the reliability of your scale. For a class III scale, you will often use M1 weights for such checks.
Re-verification after repair or a broken seal
A legal verification remains valid only as long as nobody interferes with the weighing mechanism. Re-verification is mandatory if:
- a repair has been carried out on the weighing mechanism, such as replacing a load cell or weighing indicator;
- a seal has been broken, for example to adjust the scale.
Until the re-verification, the scale may not be used for legally regulated applications. In practice we see that the re-verification is forgotten particularly after urgent repairs. Therefore include the re-verification in your repair procedure. A step-by-step plan can be found in re-verification after repair.
What about Belgium?
Belgium applies the same European directive. There too, the M mark and intact seals are the starting point for legally regulated applications. The main difference: in Belgium, periodic re-verification of verified scales is mandatory. Supervision lies with the FPS Economy (FOD Economie).
If you have sites in both countries, plan separately for each country. For Belgian periods and procedures, rely on the information from the FPS Economy, and do not automatically adopt the Dutch approach.
How MASSLAB helps you
MASSLAB is a Recognised Verifier (Erkend Keurder) under the Dutch Metrology Act and carries out re-verifications of verified scales, for example after adjustment or repair. Beforehand, we check on the basis of make, type and serial number whether we are permitted to perform the verification for your specific instrument. If you also need a calibration certificate for your quality system, we combine both in a single visit, for customers throughout the Netherlands and Belgium. Read more about re-verification of scales or about scale calibration.