National Physical Laboratory

InstMC Weighing and Force Measurement Panel: Documents and Standards - Automatic Weighing Instruments

Directive 2004/22/EC of the European Parliament and of the Council of 31 March 2004 on measuring instruments

OIML G 11, 1992, Mobile equipment for the verification of road weighbridges

OIML R 50-1, 1997, Continuous totalizing automatic weighing instruments (belt weighers) Part 1: Metrological and technical requirements - Tests

OIML R 50-2, 1997, Continuous totalizing automatic weighing instruments (belt weighers) Part 2: Test report format

OIML R 51-1, 2006, Automatic catchweighing instruments Part 1: Metrological and technical requirements - Tests

OIML R 51-2, 2006, Automatic catchweighing instruments Part 2: Test report format

OIML R 61-1, 2004, Automatic gravimetric filling instruments Part 1: Metrological and technical requirements - Tests

OIML R 61-2, 2004, Automatic gravimetric filling instruments Part 2: Test report format

Supplement to OIML R 61, 2004, Certificate transformation requirements

OIML R 106-1, 2011, Automatic rail-weighbridges Part 1: Metrological and technical requirements - Tests

OIML R 106-2, 1997, Automatic rail-weighbridges Part 2: Test report format

OIML R 107-1, 2007, Discontinuous totalizing automatic weighing instruments (totalizing hopper weighers) Part 1: Metrological and technical requirements - Tests

OIML R 107-2, 2007, Discontinuous totalizing automatic weighing instruments (totalizing hopper weighers) Part 2: Test report format

OIML R 134-1, 2006, Automatic instruments for weighing road vehicles in motion. Total vehicle weighing

OIML R 134-2, 2009, Automatic instruments for weighing road vehicles in motion. Total vehicle weighing Part 2: Test report format

Statutory Instrument No. 1259, 2006, Measuring Instruments (Beltweighers) Regulations

Statutory Instrument No. 1258, 2006, Measuring Instruments (Automatic Gravimetric Filling Instruments) Regulations

Statutory Instrument No. 1257, 2006, Measuring Instruments (Automatic Catchweighers) Regulations

Statutory Instrument No. 1256, 2006, Measuring Instruments (Automatic Rail-weighbridges) Regulations

Statutory Instrument No. 1255, 2006, Measuring Instruments (Automatic Discontinuous Totalisers) Regulations

Statutory Instrument No. 2761, 2003, Weighing Equipment (Automatic Catchweighing Instruments) Regulations

Statutory Instrument No. 2454, 2003, Weighing Equipment (Automatic Rail-weighbridges) Regulations

Statutory Instrument No. 1208, 2001, Weighing Equipment (Beltweighers) Regulations

Statutory Instrument No. 388, 2000, Weighing Equipment (Automatic Gravimetric Filling Instruments) Regulations

Statutory Instrument No. 387, 2000, Weighing Equipment (Filling and Discontinuous Totalising Automatic Weighing Machines) (Amendment) Regulations

Statutory Instrument No. 797, 1996, Weighing Equipment (Filling and Discontinuous Totalising Automatic Weighing Machines) (Amendment) Regulations

Statutory Instrument No. 1320, 1986, Weighing Equipment (Filling and Discontinuous Totalising Automatic Weighing Machines) Regulations

Statutory Instrument No. 914, 1983, Weighing Equipment (Beltweighers) Regulations

WELMEC 2.6, 2008, Guide for the Testing of Automatic Catchweighing Instruments


Directive 2004/22/EC of the European Parliament and of the Council of 31 March 2004 on measuring instruments (PDF File PDF 446 KB)

This document is known as the Measuring Instruments Directive (MID) and applies to, among other measuring devices, automatic weighing instruments, specific details of which are given in Annex MI-006. This Directive establishes the requirements the devices have to satisfy in order to be sold or used for "measuring tasks for reasons of public interest, public health, public safety, public order, protection of the environment, protection of consumers, levying of taxes and duties and fair trading".


OIML G 11 (ex P 5), 1992, Mobile equipment for the verification of road weighbridges
(PDF File PDF 10.8 MB)

This brochure constitutes a synthesis of information available on the subject of road weighbridge verification equipment. It is intended mainly for guidance and has no official status.


OIML R 50-1, 1997, Continuous totalizing automatic weighing instruments (belt weighers) Part 1: Metrological and technical requirements - Tests
(PDF File PDF 274 KB)

This Recommendation specifies the metrological and technical requirements for continuous totalizing automatic weighing instruments of the belt conveyor type (belt weighers), and provides procedures for evaluating an instrument's characteristics in a uniform and traceable way. It applies to:

  • belt weighers that determine the mass of a product in bulk by using the action of gravity on that product
  • belt weighers that are intended for use with either single or variable speed belt conveyors

The metrological requirements cover accuracy classes, maximum permissible errors, minimum load values, minimum flowrate, simulation tests, and in-situ tests. The technical requirements cover suitability for use, security of operation, indicating devices, out-of-range indication, zero-setting device, displacement transducer, belt weighers inclusive of conveyor, installation conditions, ancillary devices, sealing, descriptive markings, and verification marks. Electronic belt weighers also need to comply with other requirements classed as general, application, fault action, switch-on procedure, functional, and examination and tests.

Metrological controls of belt weighers consist of pattern evaluation, initial verification, and in-service inspection - details of these stages are given, together with general test method principles and, in Annex A, detailed test procedures. The results of the tests should be presented in accordance with OIML R 50-2.


OIML R 50-2, 1997, Continuous totalizing automatic weighing instruments (belt weighers) Part 2: Test report format
(PDF File PDF 208 KB)

The test report format given in this Recommendation allows the results of the tests and examinations performed on a belt weigher to be presented in a standard manner. The format consists of a checklist and a test report.

The checklist is a summary of the examinations carried out on the instrument, including the conclusions of the results of the tests and checks performed in accordance with OIML R 50-1.

The test report is a record of the results of the tests carried out, based on the tests detailed in Annex A of OIML R 50-1.

The use of this format for the evaluation of belt weighers to OIML R 50-1 is strongly recommended or, for application within the OIML Certificate System, mandatory.


OIML R 51-1, 2006, Automatic catchweighing instruments Part 1: Metrological and technical requirements - Tests (PDF File PDF 349 KB)

This Recommendation specifies the metrological and technical requirements and test procedures for automatic catchweighing instruments (catchweighers), and applies to instruments that weigh pre-assembled discrete loads automatically.

The metrological requirements covers accuracy classes (of which there are two - X(x) for instruments producing packages to OIML R 87 requirements and Y(y) for all other instruments), maximum permissible errors for each class, maximum and minimum capacities, test weight indications, measurement units, effects of eccentric loading, influence factors, and maximum permissible errors for influence factor tests.

The technical requirements cover suitability for use, security of operation, zeroing and tare devices, indication of weighing results, printing devices, price computing instruments, weigh or weigh-price labelling instruments, descriptive markings, and verification marks.

Electronic catchweighers also need to comply with other general requirements, functional requirements, and examination and tests.

Metrological controls of catchweighers consist of pattern approval, initial verification, and in-service inspection - details of these stages are given, together with test methods and, in Annex A, detailed testing procedures. The results of the tests should be presented in accordance with OIML R 51-2.


OIML R 51-2, 2006, Automatic catchweighing instruments Part 2: Test report format (PDF File PDF 446 KB)

The test report format given in this Recommendation allows the results of the tests and examinations performed on a catchweigher to be presented in a standard manner. The format consists of a checklist and a test report.

The checklist is a summary of the examinations carried out on the instrument, including the conclusions of the results of the tests and checks performed in accordance with OIML R 51-1.

The test report is a record of the results of the tests carried out, based on the tests detailed in Annex A of OIML R 51-1.

The use of this format for the evaluation of catchweighers to OIML R 51-1 is strongly recommended or, for application within the OIML Certificate System, mandatory.


OIML R 61-1, 2004, Automatic gravimetric filling instruments Part 1: Metrological and technical requirements - Tests
(PDF File PDF 254 KB)

This Recommendation specifies the metrological and technical requirements for automatic gravimetric filling instruments which sub-divide a bulk product into fills of predetermined and virtually constant mass by automatic weighing, the fills being kept separate.

The metrological requirements cover accuracy classes, limits of error, maximum permissible setting errors, influence factors and their maximum permissible errors, and units of measurement.

The technical requirements cover suitability for use, security of operation, fill setting devices, final feed cut-off devices, feeding devices, load receptors, zero-setting and tare devices, equilibrium mechanisms, security, descriptive markings, verification marks, and control instruments.

Electronic instruments also need to comply with additional requirements, classed as general, functional, and examination and tests.

Metrological controls of filling instruments consist of pattern approval, initial verification, and in-service inspection - details of these stages are given, together with test methods and, in Annex A, detailed testing procedures. The results of the tests should be presented in accordance with OIML R 61-2.


OIML R 61-2, 2004, Automatic gravimetric filling instruments Part 2: Test report format
(PDF File PDF 315 KB)

The test report format given in this Recommendation allows the results of the tests and examinations performed on a filling instrument to be presented in a standard manner. The format consists of a checklist and a test report.

The checklist is a summary of the examinations carried out on the instrument, including the conclusions of the results of the tests and checks performed in accordance with OIML R 61-1.

The test report is a record of the results of the tests carried out, based on the tests detailed in Annex A of OIML R 61-1.

The use of this format for the evaluation of filling instruments to OIML R 61-1 is strongly recommended or, for application within the OIML Certificate System, mandatory.


OIML Supplement to OIML R 61, 2004, Certificate transformation requirements
(PDF File PDF 101 KB)

It identifies those requirements in OIML R 61 (2004) that have changed compared with OIML R 61 (1996), as well as new requirements.


OIML R 106-1, 2011, Automatic rail-weighbridges Part 1: Metrological and technical requirements - Tests
(PDF File PDF 472 KB)

This Recommendation specifies the requirements and test methods for automatic rail-weighbridges used to determine the mass of railway wagons when they are weighed in motion. It is intended to provide standard requirements and test procedures to evaluate the metrological and technical characteristics of such instruments in a uniform and traceable way.

The metrological requirements cover accuracy classes, maximum permissible errors, scale intervals, minimum capacities, minimum wagon weights, single axle or bogie weights, agreement between indicating and printing devices, weighing test methods, influence quantities, and conditions of use.

The technical requirements cover composition, suitability for use, security of operation, indicating and printing devices, installation, descriptive markings, and verification marks.

Electronic instruments also need to comply with additional requirements, classed as general, application, functional, and examination and tests.

Metrological controls of such instruments consist of pattern approval, initial verification, and in-service inspection - details of these stages are given, together with test methods and, in Annex A, detailed testing procedures. Annex B covers alignment calibration of single-axle weighing instruments. The results of the tests should be presented in accordance with OIML R 106-2.


OIML R 106-2, 1997, Automatic rail-weighbridges Part 2: Test report format
(PDF File PDF 216 KB)

The test report format given in this Recommendation allows the results of the tests and examinations performed on an automatic rail-weighbridge to be presented in a standard manner. The format consists of a checklist and a test report.

The checklist is a summary of the examinations carried out on the instrument, including the conclusions of the results of the tests and checks performed in accordance with OIML R 106-1.

The test report is a record of the results of the tests carried out, based on the tests detailed in OIML R 106-1.

The use of this format for the evaluation of filling instruments to OIML R 106-1 is strongly recommended or, for application within the OIML Certificate System, mandatory.


OIML R 107-1, 2007, Discontinuous totalizing automatic weighing instruments (totalizing hopper weighers) Part 1: Metrological and technical requirements – Tests
(PDF File PDF 978 KB)

This Recommendation specifies the requirements and test methods for discontinuous totalizing automatic weighing instruments (totalizing hopper weighers), and provides standard requirements and procedures for evaluating an instrument's metrological and technical characteristics in a uniform and traceable way. It applies to instruments having a load receptor in the form of a hopper, but does not apply to:

  • 'weighing-in-motion' instruments
  • instruments that totalize the bulk load by multiplying the weight of a preset constant load by the number of weighing cycles

The metrological requirements cover accuracy classes, maximum permissible errors, scale interval form, totalization scale interval, minimum load values, agreement between indicated and printed values, and influence quantities. The technical requirements cover suitability for use, security of operation, instruments with control indicating devices, totalization indication and printing devices, ancillary devices, sealing, descriptive markings, and verification marks. Electronic instruments also need to comply with other requirements classed as general, application of requirements for disturbances, functional, and examination and tests.

Metrological controls of such instruments consist of pattern evaluation, initial verification, and in-service inspection - details of these stages are given, together with general test method principles and, in Annex A, detailed test procedures. The results of the tests should be presented in accordance with OIML R 107-2.


OIML R 107-2, 2007, Discontinuous totalizing automatic weighing instruments (totalizing hopper weighers) Part 2: Test report format
(PDF File PDF 456 KB)

The test report format given in this Recommendation allows the results of the tests and examinations performed on a totalizing hopper weigher to be presented in a standard manner. The format consists of a checklist and a test report.

The checklist is a summary of the examinations carried out on the instrument, including the conclusions of the results of the tests and checks performed in accordance with OIML R 107-1.

The test report is a record of the results of the tests carried out, based on the tests detailed in Annex A of OIML R 107-1.

The use of this format for the evaluation of totalizing hopper weighers to OIML R 107-1 is strongly recommended or, for application within the OIML Certificate System, mandatory.


OIML R 134-1, 2006, Automatic instruments for weighing road vehicles in motion. Total vehicle weighing
(PDF File PDF 285 KB)

This Recommendation specifies the requirements and test methods for automatic instruments for weighing road vehicles in motion, and provides standard requirements and procedures for evaluating an instrument's metrological and technical characteristics in a uniform and traceable way. It only applies to instruments which are installed in a controlled weighing area and where the vehicle speed is controlled - it does not apply to instruments that are installed directly into or onto a normal road surface.

The metrological requirements cover accuracy classes, maximum permissible errors, scale interval , minimum capacity, individual axle or axle group loads, agreement between indicated and printed values, influence quantities, units of measurement, and conditions of use. The technical requirements cover suitability for use, security of operation, zeroing devices, use as a control instrument, indicating and printing devices, installation, sealing devices, descriptive markings, and verification marks. Electronic instruments also need to comply with other requirements classed as general, application of requirements for disturbances, functional, and examination and tests.

Metrological controls of such instruments consist of type evaluation, initial verification, subsequent verification, and in-service inspection - details of these stages are given together with test methods and, in Annex A, detailed test procedures. Annex B gives some practical instructions for the installation and operation of such instruments. The results of the tests should be presented in accordance with OIML R 134-2.


OIML R 134-2, 2009, Automatic instruments for weighing road vehicles in motion. Total vehicle weighing Part 2: Test report format
(PDF File PDF 422 KB)

The test report format given in this Recommendation allows the results of the tests and examinations performed on an automatic instrument for weighing road vehicles in motion to be presented in a standard manner. The format consists of a checklist and a test report.

The checklist is a summary of the examinations carried out on the instrument, including the conclusions of the results of the tests and checks performed in accordance with OIML R 134-1.

The test report is a record of the results of the tests carried out, based on the tests detailed in Annex A of OIML R 134-1.

The use of this format for the evaluation of automatic instruments for weighing road vehicles in motion to OIML R 134-1 is strongly recommended or, for application within the OIML Certificate System, mandatory.


Statutory Instrument No. 1259, 2006, Measuring Instruments (Beltweighers) Regulations

These Regulations implement Directive 2004/22/EC into British legislation. An explanatory memorandum (PDF File PDF 53 KB) to Statutory Instruments 1255 to 1259 inclusive (2006) has been prepared by NWML.


Statutory Instrument No. 1258, 2006, Measuring Instruments (Automatic Gravimetric Filling Instruments) Regulations

These Regulations implement Directive 2004/22/EC into British legislation. An explanatory memorandum (PDF File PDF 53 KB) to Statutory Instruments 1255 to 1259 inclusive (2006) has been prepared by NWML.


Statutory Instrument No. 1257, 2006, Measuring Instruments (Automatic Catchweighers) Regulations

These Regulations implement Directive 2004/22/EC into British legislation. An explanatory memorandum (PDF File PDF 53 KB) to Statutory Instruments 1255 to 1259 inclusive (2006) has been prepared by NWML.


Statutory Instrument No. 1256, 2006, Measuring Instruments (Automatic Rail-weighbridges) Regulations

These Regulations implement Directive 2004/22/EC into British legislation. An explanatory memorandum (PDF File PDF 53 KB) to Statutory Instruments 1255 to 1259 inclusive (2006) has been prepared by NWML.


Statutory Instrument No. 1255, 2006, Measuring Instruments (Automatic Discontinuous Totalisers) Regulations

These Regulations implement Directive 2004/22/EC into British legislation. An explanatory memorandum (PDF File PDF 53 KB) to Statutory Instruments 1255 to 1259 inclusive (2006) has been prepared by NWML.


Statutory Instrument No. 2761, 2003, Weighing Equipment (Automatic Catchweighing Instruments) Regulations

These Regulations implement OIML R 51 into British legislation.

Regulation 1 specifies the name and date of the Regulations coming into force, regulation 2 contains a definition of, among other terms, "automatic catchweighing instrument", and regulation 3 applies the Regulations to automatic catchweighing instruments. Regulation 4 sets out a transitional exclusion, regulation 5 sets out general duties relating to the use for trade of an instrument, and regulation 6 specifies certain requirements which must be met for an instrument to be passed as fit for use for trade, including successful testing in accordance with OIML R 51-1. Regulation 7 allows supplementary indications in imperial units up to 31 December 2009, regulation 8 incorporates some supplementary requirements, and regulation 9 deals with the import of instruments from other EEA States. Regulation 10 specifies circumstances in which an instrument should not be passed as fit for use for trade, regulations 11 to 16 relate to the stamping and obliteration of stamps, and regulation 17 makes consequential amendments to other Regulations.


Statutory Instrument No. 2454, 2003, Weighing Equipment (Automatic Rail-weighbridges) Regulations

These Regulations implement OIML R 106 into British legislation.

Regulation 1 specifies the name and date of the Regulations coming into force, regulation 2 contains a definition of, among other terms, "automatic rail-weighbridge", and regulation 3 applies the Regulations to automatic rail-weighbridges. Regulation 4 sets out a transitional exclusion, regulation 5 sets out general duties relating to the use for trade of an automatic rail-weighbridge, and regulation 6 specifies certain requirements which must be met for an automatic rail-weighbridge to be passed as fit for use for trade, including successful testing in accordance with OIML R 106-1. Regulation 7 incorporates some supplementary requirements, regulation 8 deals with the import of instruments from other EEA States, and regulation 9 specifies circumstances in which an automatic rail-weighbridge should not be passed as fit for use for trade. Regulations 10 to 15 relate to the stamping and obliteration of stamps.


Statutory Instrument No. 1208, 2001, Weighing Equipment (Beltweighers) Regulations

These Regulations replace S.I. 1983/914 in the light of OIML R 50. The 1983 Regulations continue to apply to beltweighers passed as fit for use for trade before 28 September 2001. The Regulations apply to beltweighers for use for trade and continue to prescribe such beltweighers for the purposes of the Weights and Measures Act 1985. The effect of prescription is to make it unlawful to use these beltweighers for trade unless they have been tested, passed as fit for such use, and stamped by an inspector of weights and measures.
The Regulations make the following changes of substance:
  • a new accuracy class of beltweigher - Class 0.5 - may be used for trade; Classes are to be determined in accordance with OIML recommendations
  • the 1983 Regulations restricted their application to beltweighers which are designed to operate at only one speed - these Regulations are of wider application as they are not restricted to single-speed beltweighers
  • the testing of beltweighers may now be carried out elsewhere than at their place of use
  • an inspector may now require a person in possession of a beltweigher to be tested to provide handling equipment and assistance
  • tests are now to be carried out in accordance with the provisions of OIML R 50-1
  • provision is now made for dispensing with testing of beltweighers imported from other States of the EEA


Statutory Instrument No. 388, 2000, Weighing Equipment (Automatic Gravimetric Filling Instruments) Regulations

These Regulations implement OIML R 61 into national legislation. OIML R 61 makes requirements for type approval, installation, markings, use, testing, and verification of Automatic Gravimetric Filling Instruments. These Regulations also contain a provision allowing instruments from another country of the E.E.A. to be passed as fit for use in trade without the need for further testing in Great Britain, provided that they have already been tested on the same basis as required by these Regulations.


Statutory Instrument No. 387, 2000, Weighing Equipment (Filling and Discontinuous Totalising Automatic Weighing Machines) (Amendment) Regulations

These Regulations amend S.I. 1986/1320 to provide an exception enabling an inspector to test a filling machine, when the conditions for testing are not met, if dismantling and reassembly or transportation could not, in the inspector's opinion, affect accuracy or functioning. They allow weighing machines imported from the E.U. and the E.E.A. not to be tested by an inspector when he is presented with the requisite documentation, unless he is not satisfied with the information in the documentation.


Statutory Instrument No. 797, 1996, Weighing Equipment (Filling and Discontinuous Totalising Automatic Weighing Machines) (Amendment) Regulations

These Regulations are known in the weighing industry as the Automatic Weighing Machine (AWM) Regulations and amend S.I. 1986/1320 as amended by S.I. 1994/1851.

The major amendments are the provision relating to the sealing, after testing, of AWMs to take account of the recommendations of OIML R 107, a new provision concerning the erection of discontinuous totalisers before testing, and requirements relating to methods of testing.


Statutory Instrument No. 1320, 1986, Weighing Equipment (Filling and Discontinuous Totalising Automatic Weighing Machines) Regulations

These Regulations prescribe Filling and Discontinuous Totalising Automatic Weighing Machines for the purposes of the Weights and Measures Act 1985 and exclude them from application of the Weights and Measures Act 1963, excluding counter machines, platform scales, and weighbridges.

They deal with materials, principles of construction, manner of erection, inspection, testing, passing as fit for use in trade, stamping and the obliteration of stamps, and the prescribed limits of error for all automatic weighing machines manufactured for use in trade.


Statutory Instrument No. 914, 1983, Weighing Equipment (Beltweighers) Regulations

These Regulations exclude beltweighers from application of the Weights and Measures Act 1963, where they were formally prescribed within the class of Automatic Weighing Machines. The regulations define the purposes for which beltweighers may be used in trade, their materials and principles of construction, marking, manner of erection and use for trade, testing as fit for use in trade, stamping, and the obliteration of their stamps.


WELMEC 2.6, 2008, Guide for the Testing of Automatic Catchweighing Instruments
(Adobe Acrobat PDF file PDF 103 KB)

The guide describes the procedures suitable to be used when testing automatic catchweighing instruments. The document is based on the OIML recommendation R51 on automatic catchweighing instruments. This guide gives additions to, or interpretations of, OIML R51 accepted by WELMEC members. This guide refers also to other WELMEC guides and especially those developed for non-automatic weighing instruments (NAWIs) and the WELMEC Type Approval Agreement. This document also describes the national regulations of some European Countries as far as the requirements influence the acceptance of test results. This guide mainly describes instruments with a transport system and front end loaders. Other (Class Y(y)) instruments will be added in a later stage.