Legal for Trade Scales / Legal for Trade Balances

In principle, any verified scales and any scales that are appropriately conformity-assessed can be called legal-for-trade scales. Such a verifiable weighing instrument is either already marked with one or more verification seals or with the CE mark and the green metrology sticker. The green metrology sticker and the CE marking are inseparable to indicate conformity with the essential requirements of the Directive 90/384/EEC at the time the weighing instrument was placed on the market.

New weighing instruments placed on the market by the manufacturer in accordance with the regulations of the European Directives RL 2014/32/EU (Measuring Instruments Directive) or RL 2014/31/EU (Directive on Non-automatic Weighing Instruments) or in accordance with the national regulations based thereon with the declaration of conformity are considered to be verified. The verification period of the weighing instrument begins when it is placed on the market. No verification is necessary until the expiry of this period. Thereafter, or if the period ends prematurely, the weighing instrument must be calibrated. Verification continues to be carried out by the bodies authorised for this purpose, i.e. in Germany by the weights and measures offices. The scales that were calibrated before 01.01.2015 according to the provisions of the previous verification regulations can continue to be operated and recalibrated according to the deadlines.

The conformity assessment of the weighing instrument replaces the former initial verification. A conformity assessment body selected by the manufacturer confirms the conformity of the weighing instrument or type of weighing instrument with the applicable legal provisions by issuing a certificate of conformity. The manufacturer of the measuring instrument finally issues a written declaration of conformity for the assessed scale or the individual scales of the assessed scales type. The detailed information on European regulations in legal metrology can be found on the WELMEC website. When this organisation for cooperation in legal metrology was founded, the acronym WELMEC was formed from "Western European Legal Metrology Cooperation". However, WELMEC has an impact beyond this and today many states from Central and Eastern Europe are also represented in it.

Of course, the legal-for-trade scales – whether these are crane scales, truck scales, platform scales or analytical scale – must be able to accommodate the material to be weighed, depending on its size and condition, and must be suitable for the respective weighing range and conditions of use. However, if there is an obligation to use the verified scales, the following criteria, among others, must be added to the usual selection criteria:

- the accuracy class M I, M II, M III or M IV,
- the calibration value "e" in grams
- the minimum load.

The four accuracy classes for verified scales are defined in EU Directive 2014/31. The accuracy classes are distinguished by the verification scales interval "e", which in the case of the verified scales indicates the display steps of the scales instead of the division "d", by the number of possible display values as a multiple of the verification value and by the minimum load from which the scales may be used as the verified scales.

Here is a table based on Table 1 from Annex 1 of the Directive 2014/31/EU to distinguish between accuracy classes:

As can be seen in the table, the verified balances of accuracy class M III can have the same verification value of 0.1 grams as the verified balances with accuracy class M II. However, the precision scales then usually have a higher minimum weight and a higher number of possible measured values due to a larger weighing range. The smallest possible verification value is 0.001 gram. More detailed weight gradations may be displayed via so-called auxiliary display devices, for example as a clearly delimited additional decimal place.

The verified scales may not be used in legal metrology for weighing quantities below the minimum weight. This also applies to differential and net weighing. The verified scales of class M III have a minimum load of twenty times the verification value. With a calibration value of 0.1 grams, this means a minimum load of 2 grams, but with the verification value of 5 grams it already means a minimum load of 100 grams. If the weighing results below the minimum load are used in the legal-for-trade range, this is a violation of the Measurement and Calibration Law. In order for the users to be able to ascertain at any time whether the intended quantity is permissible for the legal-for-trade scales they are using, the minimum and maximum loads are mandatory data on the rating plate.

In addition to the weighing range, the accuracy class of the scales plays a decisive role for the testing effort and thus for the costs of reverification after the verification period has expired. According to the Fee Regulations for Measurement and Verification (Gebührenordnung zum Mess- und Eichwesen), issued on 24 March 2015, the verification of the scales with the display device for a maximum weight of up to 5 kilograms is

- for accuracy class I   190,60 euros,
- for accuracy class II  151,00 euros and
- for accuracy class III   78,40 euros.

Within the European Union, there are areas of application in which the use of the scales with CE marking or verification is mandatory. According to Article 1.2 (a) of Directive 90/384/EEC, these include:

Determination of the mass in trade for the goods, the cost of which is directly proportional to the weight or mass of the goods.

Determination of the mass for the calculation of levies, tariffs, duties, allowances, penalties, charges, compensation or similar. The payment does not have to be directly proportional to the mass, but the value of the mass must be decisive in determining the costs, e.g. in post offices, laundries, for the determination of transport charges or for the determination of waste charges.

Determination of the mass for the application of legal provisions and the preparation of expert opinions for judicial purposes. This includes the use of the scales by the persons who are not experts in metrology but whose expert opinions are based on the weighing results. The scales used for the same purpose by the experts from laboratories are not covered by this Article, provided that these laboratories adequately maintain, calibrate and adjust their scales.

Determination of the mass in the practice of medicine when weighing patients for the reasons of medical supervision, examination and treatment. Examples are the use of personal scales in hospitals and health centres for medical purposes including diets.

Determination of the mass for the preparation of medicinal products in pharmacies on the basis of a doctor's prescription and determination of mass in analyses in medical and pharmaceutical laboratories. Medical laboratories carry out analyses at the request of the doctor. Pharmaceutical laboratories are testing laboratories of drug manufacturers (control of the final weight, control of the composition, gravimetric and quantitative analysis of the drugs).

Determination of the price according to the mass for the direct sale in open outlets and in the manufacturing of the pre-packaged products. The first case refers to the use of the price calculating scales, in particular the use of the price calculating counter scales, and the latter to the use of the scales for the production of pre-weighed, not pre-determined quantities.

Directive 76/211/EEC on the filling the certain pre-packaged products by weight or by volume also specifies in Annex I, point 4, that a verified weighing instrument or a verified volumetric instrument must be used:

"The quantity (or contents) contained in a pre-pack, known as the actual quantity, must be measured or checked by weight or volume under the responsibility of the packer and/or importer. The measurement or check should be made with an officially verified measuring instrument suitable for the intended use."

If it is established that the verified scales are mandatory for your application, it is not sufficient just to purchase the verified or legal-for-trade scales. You may only use the verified scales as it was tested during the conformity assessment. The use of the additional devices such as PCs and printers is possible if these have either also been calibrated (mandatory for open points of sale) or the weighing values are stored in the scales unchanged and indelibly for a specified time. This is to ensure that the trading partner can check the weighing result within the specified time period. Within 6 weeks after commissioning, the newly acquired legal-for-trade scales must be registered with the local verification authority. By means of these registrations, the weights and measures authorities keep the lists of legal-for-trade scales operated in their area of jurisdiction. If the verification expires at the end of the year, the users in Germany are obliged to submit an application for verification at least 10 weeks in advance. For this purpose, the verification authorities provide forms and additional information via the internet. The verification authorities are entitled to check that the verified scales are being used properly. They have to ensure effective monitoring on the basis of the application concept and, if possible, combine this with the performance of verification.

Here is a brief overview of the user's obligations:

- Use the verified scales only with the valid verification (§31 MessEG - Use of Measuring Instruments),
- Keep work reports and invoices of repairers (§31 MessEG - Use of measuring instruments),
- Report the newly acquired verified scales to the competent weights and measures office within 6 weeks (§ 32 MessEG
- obligation to report),
- Apply for calibration in due time (§ 37 MessEG
- Verification and verification period)
- Keep operating instructions ready and always use the verified scales properly (§ 54 MessEG - Monitoring of use).

The verification of the measuring instruments serves to protect the consumers. Thus, for example, it is provided that in trading goods where the same weights are used as a basis for all the buyers and sellers, the verified scales are to be used for the weighings that are price-relevant for the total price. The requirement to use the same weights and measures is already laid down in the Bible, the Koran and in medieval local law. In the Bible, the 3rd Book of Genesis verse 19 states:

35 Ye shall not deal unjustly in judgment with the cubit, with weight, with measure.
36 Right scales, right pounds, right bushels, right pitchers shall be with you;

This regulation is again concretised to the effect that one should not use two different weights and measures, the greater in buying and the lesser in selling. In Deuteronomy 5 verse 25 it says:

13 Thou shalt not have two weights in thy sack, great and small;
14 And in thy house thou shalt not have two bushels, great and small.
15 Thou shalt have a full and right weight, and a full and right bushel.

Thus, for centuries, doubts about weights and measures have been removed or confirmed by legislation and official testing. All the scales whose weighing results are significant for the price determination or other important purposes are to be monitored and marked by an independent body. Occasions, intervals and approved bodies for testing may differ from country to country. In Germany, every calibrated scales must be rechecked by the locally competent weights and measures office after the calibration period has expired. To ensure accuracy, the weights used by the verification authorities for verification are also checked annually and compared with more accurate test weights. This procedure with several stages guarantees high accuracy by comparing the test weights to the kilogram prototype, which is stored in Braunschweig at the Physikalisch-Technische Bundesanstalt.

If you have bought the verified scales from PCE Instruments, you will also receive the information about the verification period or the necessary recalibration. As a manufacturer, PCE Instruments has carried out the necessary EC initial calibration and verified it with a conformation certificate.

After the verification period has expired, the previously verified scales must be presented to the verification office for reverification.

This is where the "load reversal" takes place. In the past, the calibration officials presented themselves to you for the checks, now you have to take action and apply for a recalibration in good time. As a customer, you must ensure that your previously verified scales can be verified again by the verification office in good time, before the verification period expires.

The Calibration Law provides for a ten-week period for this. Should you miss the deadline for the recalibration of your scales, you risk a fine.

In the event of an unannounced inspection by the calibration office, you must have all the papers and the operating instructions for the verified scale ready (quote from the Verification Law: "Evidence of maintenance, repairs or other interventions on the measuring device, including such by means of electronic measures, for a period of up to three months after the end of the specified verification period pursuant to § 41 paragraph 1 number 6, must be kept for a maximum of five years.")

Please also make sure that there are no additional electronic devices at the installation site of the verified scales set up in order to avoid external influences on the scales.