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Metrology, the science of measurement, is addressed in Mexico by various public institutions, the middle and higher education sector and private organizations.

The importance of metrology lies in the frame of reference that this field of knowledge provides, without which no standardization initiative would be feasible.

Legal, scientific or industrial metrology is a basic quality tool insofar as it ensures the accuracy of measurements and therefore is one of the cornerstones of industrial development and the certainty of trade transactions.

The forerunner of modern metrology in Mexico dates back to 1857, when the country adopted the Decimal Metric System.

The General Directorate of Standards (DGN) performs activities specifically focused on scientific, industrial and legal metrology and also coordinates efforts to support the federal public sector in the field.

It is also responsible for:

1.- Authorizing the use of units provided for in other measurement systems (procedure SE-04-001).

2.- Approving the model or prototype of measuring instruments and templates subject to an Official Mexican Standard (procedure SE-04-002).

3.- Authorizing national measurement standards (procedure SE-04-003).

4.- Certifying Official Mexican Standards (of measuring instruments) upon request when no accredited and approved certification body exists (procedure SE-04-005).

5.- Approving Calibration Laboratories and Verification Units of measuring instruments (procedure SE-04-007).

6.- Preserving national meter and kilogram prototypes or assigning custody to other entities for better preservation.

7.- Issuing the list of measuring instruments with mandatory initial, periodic and extraordinary verification and modifications to the list of measuring instruments

8.- Diffusing the use and application of the General System of Units of Measurement (NOM-008-SCFI-2002).

9.- Issuing Official Mexican Standards on metrology.

10.- Authorizing the Traceability of National and Foreign Standards.

Only available in Spanish

List of measuring instruments with Model or Prototype Approval in their respective standards
List of measuring instruments with Model or Prototype Approval in their respective standards
Approval NOM-005
Approval NOM-007
Approval NOM-009
Approval NOM-010
Approval NOM-011
Approval NOM-012
Approval NOM-014
Approval NOM-042
Approval NOM-044
Approval NOM-045
Approval NOM-046
Approval NOM-048

Measurement Traceability

All equipment used for tests and/or calibrations, including equipment for auxiliary measurements (for example, environmental conditions), which has a significant effect on the accuracy or validity of the outcome of the test, calibration or sampling, must be calibrated before being put into service.

The laboratory must have an established procedure and calibration program for its equipment.

Note: such a program should include a system of selection, use, calibration, verification, control and maintenance of the measurement standard, reference materials used as measurement standards and measuring and testing equipment used to carry out the tests and calibrations.

Authorization for the  traceability of measuring instruments applies when:

  1. There is no authorized national standard
  2. The authorized national standard is unavailable
  3. The accuracy offered does not meet the applicant's needs
  4. The calibration time is unjustifiably long
  5. There are no accredited and approved calibration laboratories for the said service

Authorization for reference materials applies when:

  1. The National Metrology Center or the National Nuclear Research  Institute does not have the materials in stock or available for sale.
  2. Accredited and approved laboratories who need to assess compliance to Official Mexican Standards where technical measurement and calibration services are required must be traceable to national or, where applicable, foreign standards.

Cases which do not require  authorization for traceability:

By agreement in official letter DGN-312-07-2004-950, the General Directorate of Standards issues a list of substances and materials which do not require a traceability ruling by the National Metrology Center, and consequently authorization for traceability to national or foreign standards need not be requested from the General Directorate.