Statutory Instrument 2001 No. 55

The Units of Measurement Regulations 2001

---

© Crown Copyright 2001

Statutory Instruments printed from this website are printed under the superintendence and authority of the Controller of HMSO being the Queen's Printer of Acts of Parliament.

The legislation contained on this web site is subject to Crown Copyright protection. It may be reproduced free of charge provided that it is reproduced accurately and that the source and copyright status of the material is made evident to users.

It should be noted that the right to reproduce the text of Statutory Instruments does not extend to the Queen's Printer imprints which should be removed from any copies of the Statutory Instrument which are issued or made available to the public. This includes reproduction of the Statutory Instrument on the Internet and on intranet sites. The Royal Arms may be reproduced only where they are an integral part of the original document.

The text of this Internet version of the Statutory Instrument which is published by the Queen's Printer of Acts of Parliament has been prepared to reflect the text as it was Made. A print version is also available and is published by The Stationery Office Limited as the The Units of Measurement Regulations 2001, ISBN 0 11 019070 X. The print version may be purchased by clicking here. Braille copies of this Statutory Instrument can also be purchased at the same price as the print edition by contacting TSO Customer Services on 0870 600 5522 or e-mail:customer.services@tso.co.uk.

Further information about the publication of legislation on this website can be found by referring to the Frequently Asked Questions.

To ensure fast access over slow connections, large documents have been segmented into "chunks". Where you see a "continue" button at the bottom of the page of text, this indicates that there is another chunk of text available.

"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][a], 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[b] = 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
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 12C


Note: The prefixes and their symbols listed in Schedule 2 may be used in conjunction with these two units and with their symbols.".

    (6) In Schedule 2, the table below the heading shall be replaced by the following:

"     



Factor	Prefix	Symbol	Factor	Prefix	Symbol
1024	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
109	giga	G	10-12	pico	p
106	mega	M	10-15	femto	f
103	kilo	k	10- 18	atto	a
102	hecto	h	10- 21	zepto	z
[d] 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

[2] 1972 c. 68.back

[3] 1985 c. 72.back

[4] S.I. 1986/1082, amended by S.I. 1994/2867 and S.I. 1995/1804.back

[c][5] section 8(5A) of the Weights and Measures Act 1985 was inserted by the Units of Measurement Regulations 1994.back

[b] Amended by Correction Slip. Page 1, regulation 4(3), second line of replacement text, after "temperatures T and T₀": delete T substitute "T₀";back

[c] Amended by Correction Slip. Page 1, bottom of page, after footnote [4], add footnote [5]:

"section 8(5A) of the Weights and Measures Act 1985 was inserted by the Units of Measurement Regulations 1994." back

[d] Amended by Correction Slip. page 2, regulation 4(6) replacement table, entry for 10¹ should read:

101

deca

da

10-24

yocto

y"

Instead of:

10 1

Deca

Da

10-24

yocto

y"

back