MetrologyActivities of Metrology
Metrology, a science of measurements, encompasses three main fields: Scientific Metrology, Industrial Metrology and Legal Metrology.

The first metrological field, Scientific Metrology, is that part of metrology which deals with problems common to all metrological questions irrespective of the quantity measured. It covers general theoretical and practical problems concerning units of measurements, including their realization and dissemination through scientific methods, the problems of errors and uncertainties in measurement and the problems of metrological properties of measuring instruments.

Secondly, Industrial Metrology deals with measurements in production and quality control. It covers calibration procedures, calibration intervals, control of measurement processes, and management of measuring instruments in industry to ensure that they are in a state of compliance with requirements for their intended use.

The third metrological field, the subject of our aim in SLSB, concerns Legal Metrology. It is that part of Metrology which is subject to legal/regulatory control. It is defined in the International Vocabulary of Legal Metrology as that part of Metrology relating to activities which result from statutory requirements and concern measurement, units of measure measurement, measuring instruments and methods of measurement which are performed by competent bodies.

The present trend of globalization of trade is the strongest thrust boosting the current importance of Metrology and its rapid development. However it is also the most important challenge to Legal Metrology as far as trade agreements based on elimination of Technical Barriers to Trade (TBT’s) and mutual recognition agreements of conformity assessment is concerned.

Legal Metrology is by its regulatory nature, is particularly sensitive to the elimination of Technical Barriers to Trade (TBT’s). Government regulations are without exception real and potential technical barriers to trade, unless regionally and ultimately internationally harmonized. The harmonization of metrological requirements as well as of conformity assessment and verification procedures is therefore becoming most urgent and an important challenge to legal metrology.

Application of Legal Metrology

The scope of Legal Metrology depends on national regulations and may differ from our country to country. In general, most countries have legislation to control trade measurements. In Sierra Leone, the Weights and Measures Act No. 5 of 2010 satisfies this requirement.

A few countries also regulate measurements in the following areas: public health and human safety (e.g. in the medical field and road safety) and environmental protection and pollution monitoring. Measurements are practically involved into all commercial transactions.

In ordinary commercial transactions, Legal Metrology ensures that during the sale of any commodity in loose form, the actual delivery to the purchaser is not less than the quantity contracted and paid for. In the case of pre-packaged goods, the primary requirement is that the packages intended for retail sale should be marked with the correct statement of net quantity and the name of the packer in such style and form as to be readily seen by the purchaser. In addition, the packing of certain commodities may be in rationalized standard quantities to facilitate quantity and price comparison. E.g. net content inspection of pre-packages carried out by the Sierra Leone Standards Bureau (SLSB) Legal Metrology Officers protects consumers who cannot verify the net quantity of contents.

Legal Metrology therefore ensures fair trade practices and maintains a competitive marketplace. It also encourages manufactures, distributors and retailers to follow good manufacturing and distribution practices. Legal control on the measurements involving public health and human safety is equally important from the consumer protection view point. E.g. a clinical thermometer or blood pressure instrument which is not properly verified may lead to wrong diagnosis and incorrect medication. In addition, the field of environmental protection and pollution monitoring is heavily regulated and is one of the most important measurement activities of modern Legal Metrology.

Relevance of Legal Metrology in Export Promotion

The importance of Legal Metrology in export promotion is reached by controlling pre-packaged commodities and measuring instruments:

Control of pre-packaged commodities:

In recent decades, the take-off of pre-packaged commodities has received considerable impetus because of the ease and convenience with which they can be transported and marketed. Weighing and measuring in the presence of the purchaser is now tending to be gradually reduced and is expected to be limited to a few select items in the near future. Requirements for the sale of pre-packaged goods are part of national legislation in many countries and they usually provide the following:

1 Labelling Requirements

Every package intended for retail sale has to bear the following main information:

  1. The identity of the product (common or generic name of the commodity contained in the package)
  2. The name and place of business of the manufacturer, packer, distributor, importer or retailer and;
  3. The net quantity of the product.

The information has to be conspicuously, legibly and unambiguously displayed on the “principal display panel”, that is part of the package or of its label which is likely to be shown or examined by the customer under normal conditions of sale. There is a minimum size of letters normally prescribed for the declaration of the net quantity established in relationship to either the area of the principal display panel. The way of declaring the net quantity, including the symbols for units and the number of decimal places to be used, is usually also regulated.

2  Standardisation of Pack Sizes

To facilitate price comparison and to prevent unfair competition, many countries have provided for prescribed standard pack sizes for certain essential commodities.  For example, rice is packaged in 50kg and 25kg bags respectively here in Sierra Leone.  The Metrology Department ensures that the scales are calibrated within acceptable limits.

    Control for pre-packaged products

In order to ensure the accuracy of the net content of packages, i.e. the quantity of the commodity without the package material the law may provide for the checking at any level of distribution including the point of pack, import, distribution and wholesale transactions, and sale (e.g. where pre-packages are offered or exposed for sale or where they are sole).

Metrological Control of Measuring Instruments

In a type or pattern approval scheme, one or more instruments of the same pattern are subjected to rigorous tests prescribed under the law.  The objective of all such tests is to ensure that the instruments of the pattern concerned comply with the relevant statutory requirements and are suitable for use in the regulated area in such a way that they are expected to provide reliable measurement results over a defined period of time and under varied conditions of use.

Initial Verification:

Initial verification means the verification of a measuring instrument which has not been verified previously.  Under the law, every such item to be used in regulated areas has to be verified and stamped before being released for use or even sold to the user.  Generally, the accuracy requirements for initial verification are more stringent than those for subsequent verification or inspection.

Subsequent Verification:

Subsequent verification means any verification of a measuring instrument after an initial verification.

Inspection or Supervision:

Inspection or supervision is the control exercised in respect of the manufacture, import, installation, use, maintenance and repair of measuring instruments, performed in order to check whether the metrology law and regulations are properly complied with.

Legal Metrology Services offered by Sierra Leone Standards Bureau (SLSB)

SLSB while emphasizing conformity assessment and fair trade offers the following services:

1  Pre-packaged Commodities Control:

Since the adoption of the Weights and Measures Act of 2010, SLSB offers services of controlling pre-packaged commodities where industries are visited and their products are tested to meet international requirements.  This service will help to promote the export of Sierra Leonean products and increase of consumer confidence.

2 Verification of measuring Instruments (balances, fuel dispensers etc) to ensure that all equipment used meet international requirements for ensuring exact measurements.

3 Carry out Inspections:  this is done either while measuring instruments or pre-packaged commodities are verified or at an arranged time when appropriate to do so.

4  Sensitisation: awareness sessions for Sierra Leonean industrialist are conducted especially during World Metrology day on May 20th each year to help them understand the importance of measurements in domestic, regional and global trade.

Measurements are essential to nearly all aspects of the human activity ranging from production control, measurement of environmental quality, health and safety assessment, conformity assessment of products to consumer protection and fair trade assurance.