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U.K.+E.U.

Council Directive

of 20 December 1979

on the approximation of the laws of the Member States relating to units of measurement and on the repeal of Directive 71/354/EEC

(80/181/EEC)

THE COUNCIL OF THE EUROPEAN COMMUNITIES,

Having regard to the Treaty establishing the European Economic Community, and in particluar Article 100 thereof,

Having regard to Council Directive 71/354/EEC of 18 October 1971 on the approximation of the laws of the Member States relating to units of measurement(1), as last amended by Council Directive 76/770/EEC(2),

Having regard to the proposal from the Commission(3),

Having regard to the opinion of the European Parliament(4),

Having regard to the opinion of the Economic and Social Committee(5),

Whereas units of measurement are essential in the use of all measuring instruments, to express measurements or any indication of quantity; whereas units of measurement are used in most fields of human activity; whereas it is necessary to ensure the greatest possible clarity in their use; whereas it is therefore necessary to make rules for their use within the Community for economic, public health, public safety or administrative purposes;

Whereas, however, there exist international conventions or agreements in the field of international transport which bind the Community or the Member States; whereas these conventions or agreements have to be respected;

Whereas the laws which regulate the use of units of measurement in the Member States differ from one Member State to another and as a result hinder trade; whereas, in these circumstances, it is necessary to harmonize laws, regulations and administrative provisions in order to overcome such obstacles;

Whereas units of measurement are the subject of international resolutions adopted by the General Conference of Weights and Measures (CGPM) set up by the Metre Convention signed in Paris on 20 May 1875, to which all the Member States adhere; whereas the ‘International System of Units’(SI) was drawn up as a result of these resolutions;

Whereas the Council on 18 October 1971 adopted Directive 71/354/EEC on the approximation of the laws of the Member States in order to eliminate obstacles to trade by adopting the international system of units at Community level; whereas Directive 71/354/EEC was amended by the Act of Accession and by Directive 76/770/EEC;

Whereas these Community provisions have not overcome all the obstacles in this field; whereas Directive 76/770/EEC provides for the review before 31 December 1979 of the situation regarding units of measurement, names and symbols listed in Chapter D of the Annex thereto; whereas it has also proved necessary to review the situation regarding certain other units of measurement;

Whereas it is necessary, in order to avoid serious difficulties, to provide for a transitional period during which units of measurement which are not compatible with the international system can be phased out; whereas it is nevertheless essential to allow the Member States wishing to do so to bring into force as quickly as possible, on their territory, the provisions of Chapter I of the Annex; whereas it is therefore necessary to limit the duration of this transitional period at Community level while, at the same time, leaving the Member States free to curtail that period;

Whereas, during the transitional period, it is essential, particularly in order to protect the consumer, to maintain a clear position on the use of units of measurement in trade between the Member States; whereas the obligation on the Member States to allow use of supplementary indications on products and equipment imported from other Member States during this transitional period seems to serve this purpose well;

Whereas the systematic adoption of a solution of this kind for all measuring instruments, including medical instruments, is however not necessarily desirable; whereas the Member States should therefore be able to require that, on their territory, measuring instruments bear indications of quantity in a single legal unit of measurement;

Whereas this Directive does not affect the continued manufacture of products already on the market; whereas it does, however, affect the placing on the market and use of products and equipment bearing indications of quantity in units of measurement which are no longer legal units of measurement, when such products and equipment are necessary to supplement or replace components or parts of such products, equipment and instruments already on the market; whereas it is therefore necessary for Member States to authorize the placing on the market and the use of such products and equipment to complete and replace components, even when they bear indications of quantity in units of measurement which are no longer legal units of measurement, so that products, equipment or instruments already on the market may continue to be used;

Whereas the International Organization for Standardization (ISO) on 1 March 1974 adopted an international standard on the representation of SI and other units for use in systems with limited sets of characters; whereas it is advisable for the Community to adopt the solutions which have already been approved on a wider international level by ISO Standard 2955 of 1 March 1974;

Whereas Community provisions relating to units of measurement are to be found in several Community texts; whereas the question of units of measurement is so important that it is essential that reference may be made to a single Community text; whereas this Directive thereby consolidates all the Community provisions on the subject and repeals Directive 71/354/EEC,

HAS ADOPTED THIS DIRECTIVE:

Article 1U.K.+E.U.

The legal units of measurement within the meaning of this Directive which must be used for expressing quantities shall be:

(a)

those listed in Chapter I of the Annex;

(b)

[F1those listed in Chapter II of the Annex only in those Member States where they were authorised on 21 April 1973 ;]

(c)

[F2those listed in Chapter III of the Annex only in those Member States where they were authorized on 21 April 1973 and until a date to be fixed by those States. This date may not be later than 31 December 1994;

(d)

those listed in Chapter IV of the Annex only in those Member States where they were authorized on 21 April 1973 and until a date to be fixed by those States. This date may not be later than 31 December 1999.]

Article 2U.K.+E.U.

(a)

[F1The obligations arising under Article 1 relate to measuring instruments used, measurements made and indications of quantity expressed in units of measurement.]

(b)

This Directive shall not affect the use in the field of air and sea transport and rail traffic of units, other than those made compulsory by the Directive, which have been laid down in international conventions or agreements binding the Community or the Member States.

Article 3U.K.+E.U.

1.For the purposes of this Directive ‘supplementary indication’means one or more indications of quantity expressed in units of measurement not contained in Chapter I of the Annex accompanying an indication of quantity expressed in a unit contained in that Chapter.

[F12. The use of supplementary indications shall be authorised.]

3.However, Member States may require that measuring instruments bear indications of quantity in a single legal unit of measurement.

4.The indication expressed in a unit of measurement listed in Chapter I shall predominate. In particular, the indications expressed in units of measurement not listed in Chapter I shall be expressed in characters no larger than those of the corresponding indication in units listed in Chapter I.

F35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Article 4U.K.+E.U.

The use of units of measurement which are not or are no longer legal shall be authorized for:

However, the use of legal units of measurement may be required for the indicators of measuring instruments.

Article 5U.K.+E.U.

International standard ISO 2955 of [F215 May 1983], ‘Information processing — Representations of SI and other units for use in systems with limited character sets’ shall apply in the field covered by paragraph 1 thereof.

Article 6U.K.+E.U.

Directive 71/354/EEC shall be repealed on 1 October 1981.

[ F3. . . . .

F3 ]

[F4Article 6a U.K.+E.U.

Issues concerning the implementation of this Directive and, in particular, the matter of supplementary indications shall be further examined, and if necessary the appropriate measures adopted in accordance with the procedure referred to in Article 18 of Council Directive 71/316/EEC (6) .]

[F5Article 6b U.K.+E.U.

The Commission shall monitor market developments relating to this Directive and its implementation with regard to the smooth functioning of the internal market and international trade and shall submit a report on those developments, accompanied by proposals where appropriate, to the European Parliament and to the Council by 31 December 2019 .]

Article 7U.K.+E.U.

(a)

Member States shall adopt and publish before 1 July 1981 the laws, regulations and administrative provisions necessary to comply with this Directive and shall inform the Commission thereof.

They shall apply these provisions from 1 October 1981.

(b)

As from the date of notification of this Directive, Member States shall also ensure that the Commission is informed, in sufficient time to enable it to submit its comments, of any draft laws, regulations or administrative provisions which they intend to adopt in the field covered by this Directive.

Article 8U.K.+E.U.

This Directive is addressed to the Member States.

[X1ANNEX U.K.+E.U.

CHAPTER I U.K.+E.U. LEGAL UNITS OF MEASUREMENT REFERRED TO IN ARTICLE 1 (a)

1. SI UNITS AND THEIR DECIMAL MULTIPLES AND SUBMULTIPLES U.K.+E.U.

1.1. SI base units U.K.+E.U.
Quantity Unit
Name Symbol
Length metre m
Mass kilogram kg
Time second s
Electric current ampere A
Thermodynamic temperature kelvin K
Amount of substance mole mol
Luminous intensity candela cd
Definitions of SI base units: U.K.+E.U.
[F6Unit of length U.K.+E.U.

A metre is the length of the path travelled in a vacuum by light during 1/ 299 792 458 seconds.

(Seventeenth CGPM (1983), Resolution 1).]

Unit of mass U.K.+E.U.

The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram.

(Third CGPM (1901), page 70 of the conference report).

Unit of time U.K.+E.U.

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 caesium-133 atom.

(Thirteenth CGPM (1967), resolution 1).

Unit of electric current U.K.+E.U.

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

(CIPM (1946), resolution 2, approved by the ninth CGPM (1948)).

[F1Unit of thermodynamic temperature U.K.+E.U.

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

This definition refers to water having the isotopic composition defined by the following amount-of-substance ratios: 0,00015576 mole of  2 H per mole of  1 H, 0,0003799 mole of 17 O per mole of 16 O and 0,0020052 mole of 18 O per mole of  16 O.

(Thirteenth CGPM (1967), resolution 4 and Twenty-third CGPM (2007), resolution 10)]

Unit of amount of substance U.K.+E.U.
(1)

The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0·012 kilogram of carbon 12.

(2)

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.

(Fourteenth CGPM (1971), resolution 3).

Unit of luminous intensity U.K.+E.U.

The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency of 540 × 10 12 hertz and that has a radiant intensity in that direction of (1/683) watt per steradian.

(Sixteenth CGPM (1979), resolution 3).

1.1.1. [F1Special name and symbol of the SI derived unit of temperature for expressing Celsius temperature] U.K.+E.U.
Quantity Unit
Name Symbol
Celsius temperature degree Celsius °C

[F7Celsius temperature [X2t] is defined as the difference [X2t = T - T 0] between the two thermodynamic temperatures [X2T] and [X2T 0 where T 0]  = 273,15 K. An interval or difference of temperature may be expressed either in kelvins or in degrees Celsius. The unit degree Celsius is equal to the unit kelvin .]

[F11.2. SI derived units] U.K.+E.U.
F81.2.1.SI supplementary unitsU.K.+E.U.

[ F8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

F8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .]

Definitions of SI supplementary units:U.K.+E.U.
Unit of plane angleU.K.+E.U.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Unit of solid angleU.K.+E.U.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[F11.2.2. General rule for SI derived units U.K.+E.U.

Units derived coherently from SI base units are given as algebraic expressions in the form of products of powers of the SI base units with a numerical factor equal to 1.

1.2.3. SI derived units with special names and symbols U.K.+E.U.
a

Special names for the unit of power: the name volt–ampere (symbol VA ) when it is used to express the apparent power of alternating electric current, and var (symbol var ) when it is used to express reactive electric power. The var is not included in GCPM resolutions.

Quantity Unit Expression
Name Symbol In terms of other SI units In terms of SI base units
Plane angle radian rad m · m –1
Solid angle steradian sr m 2 · m –2
Frequency hertz Hz s –1
Force newton N m · kg · s –2
Pressure, stress pascal Pa N · m –2 m –1 · kg · s –2
Energy, work; quantity of heat joule J N · m m 2 · kg · s –2
Power a , radiant flux watt W J · s –1 m 2 · kg · s –3
Quantity of electricity, electric charge coulomb C s · A
Electric potential, potential difference, electromotive force volt V W · A –1 m 2 · kg · s –3 · A –1
Electric resistance ohm Ω V · A –1 m 2 · kg · s –3 · A –2
Conductance siemens S A · V –1 m –2 · kg –1 · s 3 · A 2
Capacitance farad F C · V –1 m –2 · kg –1 · s 4 · A 2
Magnetic flux weber Wb V · s m 2 · kg · s –2 · A –1
Magnetic flux density tesla T Wb · m –2 kg · s –2 · A –1
Inductance henry H Wb · A –1 m 2 · kg · s –2 · A –2
Luminous flux lumen lm cd · sr cd
Illuminance lux lx lm · m –2 m –2 · cd
Activity (of a radionuclide) becquerel Bq s –1
Absorbed dose, specific energy imparted, kerma, absorbed dose index gray Gy J · kg –1 m 2 · s –2
Dose equivalent sievert Sv J · kg –1 m 2 · s –2
Catalytic activity katal kat mol · s –1

Units derived from SI base units may be expressed in terms of the units listed in Chapter I.

In particular, derived SI units may be expressed by the special names and symbols given in the above table; for example, the SI unit of dynamic viscosity may be expressed as m –1 · kg · s –1 or N · s · m –2 or Pa · s.]

1.3. Prefixes and their symbols used to designate certain decimal multiples and submultiples U.K.+E.U.
[F7Factor Prefix Symbol
10 24 yotta Y
10 21 zetta Z
10 18 exa E
10 15 peta P
10 12 tera T
10 9 giga G
10 6 mega M
10 3 kilo [X3k]
10 2 hecto [X3h]
10 1 deca da
10 -1 deci d
10 -2 centi c
10 -3 milli m
10 -6 micro μ
10 -9 nano n
10 -12 pico p
10 -15 femto f
10 -18 atto a
10 -21 zepto z
10 -24 yocto y]

The names and symbols of the decimal multiples and submultiples of the unit of mass are formed by attaching prefixes to the word gram and their symbols to the symbol g .

Where a derived unit is expressed as a fraction, its decimal multiples and submultiples may be designated by attaching a prefix to units in the numerator or the denominator, or in both these parts.

Compound prefixes, that is to say prefixes formed by the juxtaposition of several of the above prefixes, may not be used.

1.4. Special authorized names and symbols of decimal multiples and submultiples of SI units U.K.+E.U.
a

The two symbols I and L may be used for the litre unit.

(Sixteenth CGPM (1979), resolution 6).

b

Unit listed in the International Bureau of Weights and Measures booklet as among the units to be permitted temporarily.

Quantity Unit
Name Symbol Value
Volume litre 1 or L a 1 l = 1 dm 3 = 10 -3 m 3
Mass tonne t 1 t = 1 Mg = 10 3 kg
Pressure, stress bar bar b 1 bar = 10 5 Pa
Note: U.K.+E.U.

The prefixes and their symbols listed in 1.3 may be used in conjunction with the units and symbols contained in Table 1.4. U.K.+E.U.

2. UNITS WHICH ARE DEFINED ON THE BASIS OF SI UNITS BUT ARE NOT DECIMAL MULTIPLES OR SUBMULTIPLES THEREOF U.K.+E.U.

a

The character (*) after a unit name or symbol indicates that it does not appear in the lists drawn up by the CGPM, CIPM o BIPM. This applies to the whole of this Annex.

b

No international symbol exists.

Quantity Unit
Name Symbol Value
Plane angle revolution* a b 1 revolution = 2 π rad
grade* or gon* gon*
degree °
minute of angle
second of angle
Time minute min 1 min = 60 s
hour h 1 h = 3 600 s
day d 1 d = 86 400 s
Note: U.K.+E.U.

The prefixes listed in 1.3 may only be used in conjunction with the names grade or gon and the symbol gon . U.K.+E.U.

[F73. UNITS USED WITH THE SI, WHOSE VALUES IN SI ARE OBTAINED EXPERIMENTALLY U.K.+E.U.

Note:

The prefixes and their symbols listed in 1.3 may be used in conjunction with these two units and with their symbols.]

Quantity Unit
Name Symbol Definition
Energy Electronvolt eV The electron volt is the kinetic energy acquired by an electron in passing through a potential difference of 1 volt in vaccum
Mass Unified atomic mass unit u The unified atomic mass units is equal to 1/12 of the mass of an atom of the nuclide 12 C.

4. UNITS AND NAMES OF UNITS PERMITTED IN SPECIALIZED FIELDS ONLY U.K.+E.U.

Quantity Unit
Name Symbol Value
Vergency of optical systems dioptre* 1 dioptre = 1 m -1
Mass of precious stones metric carat 1 metric carat = 2 × 10 -4 kg
Area of farmland and building land are a 1 a = 10 2 m 2
Mass per unit length of textile yarns and threads tex* tex* 1 tex = 10 -6 kg · m -1
Blood pressure and pressure of other body fluids Millimetre of mercury mm Hg(*) 1 mm Hg = 133,322 Pa
Effective cross-sectional area Barn b 1 b = 10 -28 m 2
Note: U.K.+E.U.

[F6The prefixes and their symbols listed in 1.3 may be used in conjunction with the above units and symbols, with the exception of the millimetre of mercury and its symbol. The multiple of 10 2 a is, however, called a hectare .] U.K.+E.U.

5. COMPOUND UNITS U.K.+E.U.

Combinations of the units listed in Chapter I form compound units.

[F2CHAPTER II U.K.+E.U. LEGAL UNITS OF MEASUREMENT REFERRED TO IN ARTICLE 1 (b), PERMITTED FOR SPECIFIC USES ONLY

Field of application Unit
Name Approximate value Symbol
Road traffic signs, distance and speed measurement mile 1 mile = 1 609  m mile
yard 1 yd = 0,9144 m yd
foot 1 ft = 0,3048 m ft
inch 1 in = 2,54 × 10 -2 m in
Dispense of draught beer and cider; milk in returnable containers pint 1 pt = 0,5683 × 10 -3 m 3 pt
[ F8 ]
Transaction in precious metals troy ounce 1 oz tr = 31,10 × 10 -3  kg oz tr

[F1The units listed in this Chapter may be combined with each other or with those in Chapter I to form compound units.] ]

CHAPTER III U.K.+E.U. LEGAL UNITS OF MEASUREMENT REFERRED TO IN ARTICLE 1 (c)

QUANTITIES, NAMES OF UNITS, SYMBOLS AND APPROXIMATE VALUES

a

[ F3 ]

Length
inch 1 in = 2·54 × 10 -2 m
foot 1 ft = 0·3048 m
[ F3 ]
mile 1 mile = 1 609 m
yard 1 yard = 0·9144 m
Area
square foot 1 sq ft = 0·929 × 10 -1 m 2
acre 1 ac = 4 047 m 2
square yard 1 sq yd = 0·8361 m 2
Volume
fluid ounce 1 fl oz = 28·41 × 10 -6 m 3
gill 1 gill = 0·1421 × 10 -3 m 3
pint 1 pt = 0·5683 × 10 -3 m 3
quart 1 qt = 1·137 × 10 -3 m 3
gallon 1 gal = 4·546 × 10 -3 m 3
Mass
ounce (avoirdupois) 1 oz = 28·35 × 10 -3 kg
troy ounce 1 oz tr = 31·10 × 10 -3 kg
pound 1 lb = 0·4536 kg
Energy
therm 1 therm = 105·506 × 10 6 J

Until the date to be fixed under Article 1 (c), the units listed in Chapter III may be combined with each other or with those in Chapter I to form compound units.]

[F9CHAPTER IV U.K.+E.U. LEGAL UNITS OF MEASUREMENT REFERRED TO IN ARTICLE I (d), PERMITTED IN SPECIALIZED FIELDS ONLY

Field of application Unit
Name Approximate value Symbol
Marine navigation fathom 1 fm = 1,829 m fm
Beer, cider, waters, lemonades and fruit juices in returnable containers pint 1 pt = 0,5683 × 10 -3 m 3 pt
fluid ounce 1 fl oz = 28,41 × 10 -6 m 3 fl. oz
Spirit drinks gill 1 gill = 0,142 × 10 -3 m 3 gill
Goods sold loose in bulk

ounce

(avoir dupois)

1 oz = 28,35 × 10 -3  kg oz
pound 1 lb = 0,4536 kg lb
Gas supply therm 1 therm = 105,506 × 10 6 J therm

Until the date to be fixed under Article 1 (d), the units listed in this Chapter may be combined with each other or with those in Chapter I to form compound units.]