Packaged goods

It is a product placed in a single package, the nominal quantity of which (not more than 50 kg or 50 l) cannot be changed without breaking the package.

The rules of conduct for the packaging of goods are set out in the Act of 7 May 2009 on prepackaged goods.

The packer or the person ordering the packing is obliged to:

- notification to the director of the regional office of measures of the fact of packing within 7 days of its commencement,

- proper labeling of the product (name, nominal quantity, company),

- organize an internal check to ensure that the actual quantity of the goods corresponds to the nominal quantity.

Whether the actual quantity corresponds to the nominal quantity is finally determined by an external (official) control carried out using a reference method or another equally effective method. The reference method is a statistical method, described in detail in Annex 2 of the Act.

Therefore, the packer can use any method of measuring the net weight of his goods, but it must be a method that is so reliable that the reference method test will confirm a positive result.

If the packer or the party ordering the packing applies the e mark to his goods, he has more obligations.

In addition, it must prepare a description of its internal control system (for inspection by inspection authorities), conduct inspections and keep records of internal inspections performed. The storage period for the documentation should be 2 years (or as long as the shelf life of the goods, but not less than one year).

This applies to products with a nominal amount of 5g (5ml) to 10kg (10l).

The internal control checks the average value of the net weight of the goods in the batch. This value should correspond to the net value marked on the product packaging.

But that's not enough.

The batch cannot contain items whose net weight is clearly too small (underweight greater than twice the permissible error marked as T1). Slightly underweight pieces (underweight greater than T1 but less than twice T1) must also not be more than 2% in the lot.

In addition, internal inspections taking place directly on the production line must quickly catch failures in the production process, so they must take place at least once an hour.

The method strictly defines the requirements for the method of carrying out measurements of a batch of goods and their results. It determines the number of samples of goods taken from the batch, the formulas for calculating the average value and the permissible error of the net mass (T1) and the qualifying values ​​for the measurement results.

Two types of control are described:

- destructive control - measurement of the net weight of a sample consisting of 20 pieces (packages are destroyed when opened),

- non-destructive inspection - two-stage inspection, two samples are taken from a batch of goods, the amount taken for samples depends on the number of batches of goods, if the results of the first sample are unambiguous, the second sample is not needed.

The permissible number of defective items depends on the size of the batch and is given in the tables. The average value must correspond to the nominal value, taking into account a slight deviation resulting from the statistical method of calculating the average.

A detailed description of the reference method is contained in Annex 2 to the Act on Packaged Goods.

For internal control of packaged goods, scales with accuracy class III or better, which must be verified, should be used.

The condition that the scale accuracy cannot be worse than 20% of the admissible net mass error (T1) results in limitations as to the accuracy of the scales used, depending on the net mass of the packaged goods.

This is illustrated by the following table

Direct measurement of the net weight is only possible with the destructive method. There, the packaging is opened and emptied.

If we have a closed package that we do not want to open, we calculate the net weight by subtracting the tare weight from the gross weight. Two methods are possible here:

Method 1

Before filling each package, measure its individual tare, then measure the filled package and subtract its individual tare.

This method is used in particular for glass packaging with large differences in weight.

Method 2

The average tare is determined from a sample of 10 packs. The weight of the filled packages is then measured and the average tare is subtracted.

This method can be used provided that the tare determination error does not exceed 1/4 of the value of the allowable error in determining the net mass (0.25*T1). It is necessary to take into account the error of determining the tare caused by the dispersion of tares of individual packages and the accuracy of the scale used.

In practice, this method can be used for plastic and paper packaging, which usually have small differences in weight.

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