Citation and commencement

1. These Regulations may be cited as the Units of Measurement Regulations 2009 and come into force on 1st January 2010.

Interpretation

2. In these Regulations, “the 1986 Regulations” means the Units of Measurement Regulations 1986( 3 ).

Removal of time limit on use of supplementary indications

3. —(1) In section 8(5A) of the Weights and Measures Act 1985( 4 ) (which allows the use for trade of supplementary indications up to and including 31 December 2009), omit “up to and including 31 December 2009,”.

(2) In regulation 7 of the 1986 Regulations (which relates to supplementary indications), omit “up to and including 31 December 2009”.

Further amendments of the 1986 Regulations

4. —(1) The 1986 Regulations are further amended as follows.

(2) In Schedule 1—

(a) in paragraph 1—

(i) at the end of the entry beginning “The kelvin” insert “This definition refers to water having the isotopic composition defined by the following amount-of-substance ratios: 0.00015576 mole of ²H per mole of ¹H, 0.0003799 mole of ¹⁷ O per mole of ¹⁶ O and 0.0020052 mole of ¹⁸ O per mole of ¹⁶ O.”; and

(ii) in the italic heading “Special name and symbol of the SI unit of temperature for expressing Celsius temperature”, for “SI unit” substitute “SI derived unit”;

(b) in paragraph 2—

(i) for the italic heading “Other SI units” substitute “SI derived units”;

(ii) omit sub-paragraph (1);

(iii) for sub-paragraph (2) substitute—

“ (2) General rule for SI derived units

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. ” ;and

(iv) for sub-paragraph (3) substitute the table and the notes set out in the Schedule.

Consequential amendments of the Units of Measurement Regulations 2001

5. —(1)The Units of Measurement Regulations 2001( 5 ) are amended as follows.

(2) In regulation 2 omit—

“ —

“ the Act ” means the Weights and Measures Act 1985, and ” .

(3) Omit regulations 3 and 4(2).

SCHEDULE Substituted paragraph 2(3) for Schedule 1 to the Units of Measurement Regulations 1986

“ (3) SI derived units with special names and symbols

Quantity	Unit Name	Unit Symbol	Expression in terms of other SI units	Expression 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*, radiant flux	Watt	W	J.s -1	m 2 .kg.s -3
Electric charge, quantity of electricity	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		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, dose equivalent index	sievert	Sv	J.kg -1	m 2. s -2
Catalytic activity	Katal	kat		mol.s -1

Notes

Units derived from SI base units may be expressed in terms of the units listed in this Schedule.

In particular, SI derived 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.

*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. ”