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Continuous totalizing automatic weighing instruments

COMMITTEE DRAFT OIML/3 CD

Date: March 2010

Reference number:

OIML TC 9/SC 2/R50-1 3 CD

Supersedes document:

Second Committee Draft - Continuous totalizing automatic weighing instruments (belt weighers)

OIML TC 9/TC 2 Automatic weighing instruments

Secretariat: Morayo Awosola

National Measurement Office, Teddington, London, United Kingdom

Email: Morayo.awosola@nmo.gov.uk

Circulated to P- and O-members and liaison internal bodies and external organizations

for:

TC 9/SC 2 Members

comments to Secretariat by 30 June 2010.....

TITLE OF THE CD (English):

OIML R 50-1

Continuous totalizing automatic weighing instruments (belt weighers).

Part 1: Metrological and technical requirements

TITLE OF THE CD (French):

OIML R 51-1

Instruments de pesage totalisateurs continus fonctionnement automatique (peseuses sur bande).

Partie 1: Exigences mtrologiques et techniques

Original version in: English:

OIML R 50-1 Edition 1997 (E)

CONTENTS

Foreword.........................................................................................................................

Terminology (terms and definitions)................................................................................. ....

Part 1: Metrological and technical requirements

1General.....................................................................................................

1.1 Scope

1.2 Application

1.3 Terminology

2 Metrological requirements ..........................................................................

2.1 Accuracy classes

2.2 Maximum permissible errors

2.3 Agreement between multiple indicating devices

2.4 Minimum value of minimum totalized load (min)

2.5 Minimum flowrate (Qmin)

2.6 Units of measurement

2.7 Simulation tests

2.8 In-situ tests

3 Technical requirements.......................................................................

3.1 Suitability for use

3.2 Security of operation

3.2 Securing of components, interfaces and pre-set controls

3.3 Totalization indicating and printing devices

3.4 Zero-setting device

3.5Belt profile correction device

3.6 Displacement transducer

3.7 Belt weighers inclusive of conveyor

3.8Descriptive markings

3.9 Verification marks

4 Requirements for electronic belt weighers .........................................

4.1 General requirements

4.2 Application

4.3 Acting upon a significant fault

4.4 Indicator test display

4.5 Functional requirements

4.6 Interfaces

4.7 Data storage devices

4.8 Software

Part 2 Metrological controls and performance tests

5 Metrological controls......................................................................

5.1 Type evaluation

5.2 Initial verification

5.3 Subsequent metrological control

6 Test methods.........................................................................

6.1 General test procedure

6.2 Verification standards

6.3 Test of belt displacement without conveyor

6.4 True quantity value of the mass of the test load

6.5 Indicated mass

6.6Calculation of error

6.7 Examination and tests

Annex A Test procedures for continuous totalizing automatic weighing instruments ..

A.1 Documentation

A.2 Examination for initial verification

A.3 General requirements for electronic instruments under test (EUT)

A.4 Test program

A.5 Metrological performance tests during type evaluation

A.6 Additional functionality

A.7 Influence factors and disturbance tests during type evaluation

A.8 Metrological characteristics

A.8 In-situ product tests

Bibliography ........................................................................................

FOREWORD

The International Organization of Legal Metrology (OIML) is a worldwide, intergovernmental organization whose primary aim is to harmonize the regulations and metrological controls applied by the national metrological services, or related organizations, of its Member States.

The two main categories of OIML publications are:

a) International Recommendations (OIML R), which are model regulations that establish the metrological characteristics required of certain measuring instruments and which specify methods and equipment for checking their conformity; the OIML Member States shall implement these Recommendations to the greatest possible extent;

b) International Documents (OIML D), which are informative in nature and intended to improve the work of the metrological services.

OIML Draft Recommendations and Documents are developed by technical committees or subcommittees which are formed by the Member States. Certain international and regional institutions also participate on a consultation basis.

Cooperative agreements are established between OIML and certain institutions, such as ISO and IEC, with the objective of avoiding contradictory requirements; consequently, manufacturers and users of measuring instruments, test laboratories, etc. may apply simultaneously OIML publications and those of other institutions.

International Recommendations and International Documents are published in French (F) and English (E) and are subject to periodic revision.

OIML publications may be obtained from the Organizations headquarters:

Bureau International de Mtrologie Lgale

11, rue Turgot - 75009 Paris - France

Telephone: 33 (0)1 48 78 12 82 and 42 85 27 11

Fax: 33 (0)1 42 82 17 27

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CONTINUOUS TOTALIZING AUTOMATIC WEIGHING INSTRUMENTS

(BELT WEIGHERS)

TERMINOLOGY (terms and definitions)

The terminology used in this Recommendation conforms to the International Vocabulary of Basic and General Terms in Metrology (VIM:2007) [1], the International Vocabulary of Legal Metrology VIML:2000 [2], the OIML Certificate System for Measuring Instruments B3:2003 [3], and to the OIML D 11- International Document for General requirements for Electronic Measuring Instruments OIML D 11, 3.4 [4]. In addition, for the purposes of this Recommendation, the following definitions apply.

T.1 General definitions

T.1.1Weighing instrument

Measuring instrument used to determine the mass of a body by using the action of gravity on this body.

Note: In this Recommendation mass (or weight value) is preferably used in the sense of conventional mass or conventional value of the result of weighing in air according to OIML R 111 [5] and OIML R 28 [6], whereas weight is preferably used for an embodiment (or material measure) of mass that is regulated in regard to its physical and metrological characteristics.

The instrument may also be used to determine other quantities, magnitudes, parameters or characteristics related to the determined mass.

According to its method of operation, a weighing instrument is classified as automatic or nonautomatic.

T.1.2 Automatic weighing instrument

An instrument that weighs without the intervention of an operator and follows a predetermined program of automatic processes characteristic of the instrument.

T.1.3 Continuous totalizing automatic weighing instrument (belt weigher)

An automatic weighing instrument for continuously weighing a bulk product on a conveyor belt, without systematic subdivision of the mass and without interrupting the movement of the conveyor belt.

Note:In this Recommendation a continuous totalizing automatic weighing instrument (belt weigher) is called an instrument.

T.1.4True quantity value

Quantity value consistent with the definition of a quantity. VIM, 2.11 [1].

T.1.5Belt speed control

T.1.5.1Single speed belt weigher

A belt weigher that is installed with a conveyor belt designed to operate at a single speed.

T.1.6 Variable speed or multiple speed belt weigher

A belt weigher that is installed with a conveyor belt designed to operate at a variable speed (within a range) or at more than one set speed.

T.1.7 Control method

The method used to determine the mass of the product used as the test load during product tests. This will generally involve the use of a weighing instrument, referred to as the control instrument (see T.1.11).

T.1.8Metrologically relevant

Any device, module, part, component or function of a weighing instrument that may influence the weighing result or any other primary indication is considered as metrologically relevant.

T.1.9Legally relevant

The part of a measuring instrument, device or software subject to legal control.

T.1.10Audit trail

Historical record (or continuous data file) of the instrument data, adjustments and weighing operations.

T.1.11Control instrument

Separate weighing instrument used to determine the true quantity value of the mass of the test loads during product tests.

T.2 Construction

Note: In this Recommendation the term device is used for any means by which a specific function is performed irrespective of the physical realization e.g. by a mechanism or a key initiating an operation; the device may be a small part or a major portion of an instrument.

T.2.1 Load receptor

The part of the belt weigher intended to sense the load on the belt.

T.2.1.1Types of load