PRODUCT AND QUALITY

Metrology and measurement of product attributes Lecture 4

“the science that deals with measurement”

NCSL INTERNATIONALSERVING THE WORLD OF MEASUREMENT

“to determine the dimension, quantity or capacity of something”

Measure

Metrology

METROLOGY

Metrology covers three main tasks:1. The definition of internationally accepted units of

measurement, e.g. the metre.2. The realisation of units of measurement by scientific methods,

e.g. the realisation of a metre through the use of laser beams.3. The establishment of traceability chains in documenting the

accuracy of a measurement, e.g. the documented relationship between the micrometer screw in a precision engineering workshop and a primary laboratory for optical length metrology.

CATEGORIES OF METROLOGY

Metrology is separated into three categories with different levels of complexity and accuracy:

1. Scientific metrology deals with the organisation and development of measurement standards and with their maintenance (highest level).

2. Industrial metrology has to ensure the adequate functioning of measurement instruments used in industry as well as in production and testing processes.

3. Legal metrology is concerned with the accuracy of measurements where these have influence on the transparency of economical transactions, health and safety. Fundamental metrology has no international definition, but it signifies the highest level of accuracy within a given field. Fundamental metrology may therefore be described as scientific metrology, supplemented by those parts of legal and industrial metrology that require scientific competence.

METRIC SYSTEM (SI)

Simple to use Bases of ten

All other units derived from primary seven For example: V = cm3 = 1 mL

SI BASE UNIT DEFINITIONS The metre is the length of the path travelled by light in a vacuum during a time

interval of 1/299 792 458 of a second. The kilogram is equal to the mass of the international prototype of the kilogram. The second is the duration of 9 192 631 770 periods of the radiation corresponding

to the transition between the two hyperfine levels of the ground state of the cesium-133 atom.

The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 metre apart in vacuum, would produce between these conductors a force equal to 2 x 10 -7 newton per metre of length.

The kelvin is the fraction 1/273,16 of the thermodynamic temperature of the triple point of water.

The mole is the amount of substance of a system that contains as many elementary entities as there are atoms in 0,012 kg of carbon-12. When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.

The candela is the luminous intensity in a given direction of a source that emits monochromatic radiation of frequency 540 x 10 12 hertz and has a radian intensity in that direction of 1/683 watts per steradian

THE UNITS OUTSIDE THE SI WHICH ARE ACCEPTED FOR USE TOGETHER WITH SI UNITS BECAUSE THEY ARE WIDELY USED OR BECAUSE THEY ARE USED WITHIN SPECIFIC SUBJECT AREAS

CLOCKS: ATOMIC TIMEOne part per quadrillion accuracy!!!

Accurate frequency gives accurate distance and time.

THE MODERN KILOGRAM

http://www.bipm.fr

The SIkilogram drifts!

TEMPERATURE: KELVIN, CELSIUS, AND FAHRENHEIT

294 K70 F21 C

273.15 K32 F0 C

77 K-321 F-196 C

4.2 K-452 F-269 C

0 K-459.67 F-273.15 C

Water freezes

Air liquefies

Helium liquefies

Room temperature

Absolute zero

THE KELVIN: THE SI UNITThe kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.

(0.006 atm)

TRADE METROLOGY

Trade Metrology (Weights and Measures) is the entirety of thelegislative, administrative and technical procedures established bythe Trade Metrology Act and Regulations, and implemented in orderto specify and to ensure, in a regulatory or contractual manner, theappropriate quality and credibility of measurements related to tradetransactions where a measuring instrument is the basis for saidtransactions

A few examples are Sale of prepacked goods – scales, volume measuring instruments

Maize meal Beer milk

Sale of Petrol – Liquid fuel dispensers Sale in front of customer – scales

Fresh fruit Biltong

WHAT IS LEGAL METROLOGY?

Legal Metrology is the entirety of the legislative,administrative and technical proceduresestablished by, or by reference to publicauthorities, and implemented on their behalf inorder to specify and to ensure, in a regulatory orcontractual manner, the appropriate quality andcredibility of measurements related to officialcontrols, trade, health, safety and the environment

LEGAL METROLOGY IMPACT

Legal Metrology extends scope of Trade Metrologythrough regulations coupled with impact assessments

Expands enforcement through increased marketsurveillance – coupled to scope and new fee structure

Provision is made for effective and relevant penalties Provision is made for regulating verification and repair

activities to counter conflict of interest In legal metrology the government is one of the parties

WHY MOVE INTO LEGAL METROLOGY?

Technological developments developments in

Agriculture Use of water – needs to be measured – SA water scarce country

industry transportation

Speed trapping equipment Breath analysers Overloading – destroyed road network

Movement of direct sales of products to multiplicity of transactions through production, wholesaling, processing and retail trade

DRIVER FOR CHANGE IN METROLOGY DOMAIN

Expanding scope of legal metrology Quality measurements to be introduced e.g. grain Trade measurements expanded to include

water, gas, electricity, telephone meters

Regulatory/Legal measurements Environment, health and safety (water pollution, blood pressure)

TELEPHONE METER

Utility meters Electricity meters Smart meters/ Pre-paid meters Gas meters: Domestic and Bulk/ Smart meters Water meters

Emissions: Vehicles, Manufacturing plants Telephone meter: Land line, Cellphone

Bytes• Medical devices: Syringes, Blood pressure instruments

SCALES

Baby scales Incorrect diagnosis Death

LEGAL METROLOGY INTERNATIONALLY The International Organisation of Legal Metrology (OIML)

was established in 1955 with the signing of the OIMLConvention by 24 countries. Currently there are 59member states and some 67 corresponding members

South Africa acceded to the OIML in 1998 The OIML was established to disseminate information

on legal metrology laws and regulations, thedevelopment and promotion of international bestpractice, elimination of barriers to trade caused by legalmetrology and to develop and promote MutualRecognition Acceptance Agreements in legal metrology

REGIONAL AND INTERNATIONAL PARTICIPATION

WTO

OIML

AFRIMETS

SADCMEL

NRCS

SADC/COMESA/ EAC

INTERESTED IN METROLOGY?Academic Subjects

Physical Science PhysicsMaterial Properties

Math FormulaStatistical Analysis

Computer ScienceAutomation Programming Database Building

Writing SkillsTechnical WritingManagement Systems

NCSL INTERNATIONALSERVING THE WORLD OF MEASUREMENT