Statutory Instruments
2001 No. 55
WEIGHTS AND MEASURES
The Units of Measurement Regulations 2001
Made
10th January 2001
Laid before Parliament
15th January 2001
Coming into force
8th February 2001
The Secretary of State, being a Minister designated( 1 ) for the purposes of section 2(2) of the European Communities Act 1972( 2 ) in relation to units of measurement to be used for economic, health, safety or administrative purposes, in exercise of the powers conferred by that sub-section, hereby makes the following Regulations:—
Citation and commencement
1. These Regulations may be cited as the Units of Measurement Regulations 2001 and shall come into force on 8th February 2001.
Interpretation
2. In these Regulations—
“the Act” means the Weights and Measures Act 1985( 3 ), and
“the Regulations” means the Units of Measurement Regulations 1986( 4 ).
Amendment of the Act
3. —(1) The Act shall be amended as follows.
(2) In section 8(5A)( 5 ), after the words “the use for trade” there shall be inserted “up to and including 31 December 2009,”.
Amendment of the Regulations
4. —(1) The Regulations shall be amended as follows.
(2) In regulation 7, after the words “specified circumstances”, there shall be inserted “up to and including 31 December 2009”.
(3) In paragraph 1 of Schedule 1, the text under the table which appears beneath the heading “Special name and symbol of the SI unit of temperature for expressing Celsius temperature.” shall be replaced as follows:
“ Celsius temperature t is defined as the difference t = T − T o between the two thermodynamic temperatures T and T o where T o = 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”. ” .
(4) In paragraph 2 of Schedule 1, the definitions of the SI supplementary units shall be replaced as follows:
“ Unit of plane angle
The radian is the angle between two radii of a circle which cut off on the circumference an arc equal in length to the radius.
(International standard ISO 31-1: 1992. British Standard BS 5775-1:1993)
Unit of solid angle
The steradian is the solid angle of a cone which, having its vertex in the centre of a sphere, cuts off on the surface of the sphere an area equal to that of a square with sides of length equal to the radius of the sphere.
(International standard ISO 31-1: 1992. British Standard BS 5775-1:1993). ”
(5) Paragraph 4 of Schedule 1 shall be replaced by the following:
“ Units used with the SI, whose values in SI are obtained experimentally
4.
| Quantity | |||
|---|---|---|---|
| Note: The prefixes and their symbols listed in Schedule 2 may be used in conjunction with these two units and with their symbols. ” . | |||
| Energy | Electronvolt | eV | The electron volt is the kinetic energy acquired by an electron in passing through a potential difference of 1 volt in vacuum. |
| Mass | Unified atomic mass unit | u | The unified atomic mass unit is equal to 1/12 of the mass of an atom of the nuclide 12 C |
(6) In Schedule 2, the table below the heading shall be replaced by the following:
| “ Factor | Prefix | Symbol | Factor | Prefix | Symbol |
|---|---|---|---|---|---|
| 10 24 | yotta | Y | 10 −1 | deci | d |
| 10 21 | zetta | Z | 10 − 2 | centi | c |
| 10 18 | exa | E | 10 −3 | milli | m |
| 10 15 | peta | P | 10 − 6 | micro | μ |
| 10 12 | tera | T | 10 −9 | nano | n |
| 10 9 | giga | G | 10 −12 | pico | p |
| 10 6 | mega | M | 10 −15 | femto | f |
| 10 3 | kilo | k | 10 − 18 | atto | a |
| 10 2 | hecto | h | 10 − 21 | zepto | z |
| 10 1 | deca | da | 10 −24 | yocto | y ” |
.
Kim Howells
Parliamentary Under-Secretary of State for Consumers and Corporate Affairs,
Department of Trade and Industry
10th January 2001
S.I. 1976/897 .
section 8(5a) of the Weights and Measures Act 1985 was inserted by the Units of Measurement Regulations 1994.