2009 No. 3046
The Units of Measurement Regulations 2009
Made
Laid before Parliament
Coming into force
The Secretary of State, being a Minister designated1 for the purposes of section 2(2) of the European Communities Act 19722 in relation to units of measurement to be used for economic, health, safety, or administrative purposes, in exercise of the powers conferred by that subsection, makes the following Regulations:
Citation and commencement1
These Regulations may be cited as the Units of Measurement Regulations 2009 and come into force on 1st January 2010.
Interpretation2
In these Regulations, “the 1986 Regulations” means the Units of Measurement Regulations 19863.
Removal of time limit on use of supplementary indications3
1
In section 8(5A) of the Weights and Measures Act 19854 (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 Regulations4
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 17O per mole of 16O and 0.0020052 mole of 18O per mole of 16O.”; 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.
iv
for sub-paragraph (3) substitute the table and the notes set out in the Schedule.
Consequential amendments of the Units of Measurement Regulations 20015
1
The Units of Measurement Regulations 20015 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).
SCHEDULESubstituted 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
m2.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
m2.kg.s-2
Power*, radiant flux
Watt
W
J.s-1
m2.kg.s-3
Electric charge, quantity of electricity
coulomb
C
s.A
Electric potential, potential difference, electromotive force
Volt
V
W.A-1
m2.kg.s-3.A-1
Electric resistance
Ohm
V.A-1
m2.kg.s-3.A-2
Conductance
siemens
S
A.V-1
m-2.kg-1.s3.A2
Capacitance
Farad
F
C.V-1
m-2.kg-1.s4.A2
Magnetic flux
weber
Wb
V.s
m2.kg.s-2.A-1
Magnetic flux density
Tesla
T
Wb.m-2
kg.s-2.A-1
Inductance
Henry
H
Wb.A-1
m2.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
m2.s-2
Dose equivalent, dose equivalent index
sievert
Sv
J.kg-1
m2.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.
(This note is not part of the Regulations)