|In order to use scales and balances in an
"approved" manner, that is for trade purposes and certain
other commercial transactions where the approval of a
scale or balance is a legal requirement, it is necessary
to demonstrate the scales or balance meets certain standards.
In the USA this is done through the NTEP approval process. In Europe and many other countries it is done by showing compliance with OIML Recommendation 76 (R76).
is the National Type Evaluation Program. NTEP oversees
the testing of weighing equipment by government laboratories
within the USA. The NTEP approval is recognised with the
USA and some other countries. The basic requirements are
given in Handbook 44.
Through 12 participating laboratories, NTEP examines the design, features, operating characteristics and performance of weighing and measuring devices to ensure compliance with national requirements. Essentially, it provides a central evaluation process that satisfies the requirements for rollout of measuring devices in all fifty states. In addition, NTEP acts as a clearinghouse for enforcement practices, using the expertise and input from both regulatory and industry representatives to develop consensus on appropriate standards and procedures.
International Organisation of Legal Metrology was created
to promote the global harmonisation of legal metrology
procedures. The members of OIML are countries throughout
the world that use the OIML Recommendations for the creation
of National Standards for Metrology. Within the European
Union the European standard EN45501 is based upon the
OIML R76 for Non-Automatic Weighing Equipment.
When a scale or balance is approved it has been tested by an approved Standards Laboratory to meet the published standards. These standards cover the metrology of the weighing equipment, operation, standards of construction, security, labelling and testing of Electromagnetic characteristics. The scales will have labels identifying conformance, be fitted with methods to seal the calibration if required and be issued with a Certificate of Conformity.
EC Type Approval
|EC Type Approval can be granted to all electronic
and most mechanical non-automatic weighing instruments
(NAWI). The instrument has to meet the essential requirements
contained in the EC Directive 90/384/EEC as amended, and
implemented into UK Law under the 1995 Regulations (SI
1995 No. 1907). The most common route for ensuring the
essential requirements of the Directive are met is through
the European Standard for NAWIs, BS EN 45501.
EC Type Approval is demonstrated by meeting the requirements of BS EN 45501. As BS EN 45501 is equivalent to OIML R76, it is common that the test laboratory applies for the OIML certificate based upon the test results.