ensure fair trade and to protect consumers from being deceived by
inaccurate measurements the mandatory control of measuring instruments
through verification has been impose by the governs across the centuries.
It is considered the vulnerability of the consumer in the market
in many consumers defense codes, which prescribe the govern action
aiming effectively to protect the consumer assuring products and
services with adequate standards of quality, security, durability
The legal metrology service, in Brasil a competence of Inmetro,
takes this vulnerability into account but also has the commitment
of being independent and impartial in the execution of its public
duties not having economic self-interest so that parties concerned
the measurement result are satisfied.
The International Vocabulary of Terms in Legal Metrology
(VIML) defines the legal metrology as being:
"part of metrology
relating to activities which results from statutory requirements
and concern measurement, units measurement, measuring instruments
and methods of measurement and which are performed by competent
To ensure the credibility of measurement result in legal metrology
are necessary the regulations, the technical means and the operational
Purposes for Legal Metrology:
- to protect the consumer when he or she
purchases measurable goods and services and to provide the prerequisites
for reliable measurements in commercial transactions in the interest
of fair trade,
- to ensure reliability of measurement in health,
labors and environmental protection and in similar areas of public
- to strengthen confidence in official measurements.
Impacts of the Legal
Metrology on society and economy benefits:
of a measuring instrument category:
- consumer protection,
- level playing field for commercial transaction,
- effective store control,
- reduction of complains and cost of the
- frauds control,
- full benefits to national product exportation,
- full collection of government's taxes.
- objective and field of application
- units of measurement
- metrological and technical requirements
- marking of an instrument
- metrological control
- testing procedures
The metrological requirements specify some performance
tests and the maximum permissible errors to a given instrument's
accuracy class, under nominal operational conditions, influence
factors (influence of quantities and time) and disturbances (ex.
electromagnetic compatibility). The accuracy of the used verification
standards should be also specified, commonly it is applied the 1/3
proportion in the accuracy levels of legal metrology reference standards.
The technical requirements are aiming at preventing
functional and operational fails and not facilitating manipulations
or frauds. The indication and/or printing of a measuring result
shall be clear and unambiguous.
The Legal Metrological
Control [VIML 2.1] has the following operational processes or activities:
- legal control of measuring
- metrological supervision, and
- metrological expertise.
The Legal Control of Measuring
Instrument may subject the instruments to the following operations
of preventive nature:
- type approval,
- initial verification of new measuring
- periodical verification of instruments
- after repair verification of instruments
- maintenance of measuring instruments,
- participation in comparison measurements.
The Metrological Supervision
[VIML 2.3] The Metrological Supervision [VIML 2.3]
"Control exercised in
respect of the manufacture, import, installation, use, maintenance
and repair of measuring instruments, performed in order to check
that they are used correctly as regards the observance of metrological
laws and regulations". It includes checking the correctness
of the quantities indicated on and contained in prepackages.
The Metrological Supervision may need investigation
with inspection carried out on-spot in conditions in situ that is
normally performed at manufacturers and repairs of measuring instruments,
at users of measuring instruments and at manufacturers or importers
of prepackages products or, carried out ex-situ in the laboratory
of a competent body. Legal actions are to be taking in case of any
violation found in the supervision. In many cases the supervision
is made joint the normal operations of the legal control of a measuring
instrument for economical efficiency.
The Metrological Expertise
"All the operations for the purpose of examining
and demonstrating, e.g. to testify in a court, the condition of
a measuring instrument and to determine its metrological properties,
among others by reference to the relevant statutory requirements".
Inmetro also collaborates for the uniformity of
Legal Metrology activities application in the world, for its active
participation in the Mercosul and the OIML - International Organization
of Legal Metrology.