Cap. 214 《十進制條例》Metrication Ordinance

生效中

版本日期: 2021-10-21

Cap. 213C

Cap. 214A

附屬法例 (9)

To provide for the replacement in enactments of non-metric units by metric units and for matters connected therewith.

(Format changes—E.R. 5 of 2021)

[9 July 1976]

1. Short title

This Ordinance may be cited as the Metrication Ordinance.

(Format changes—E.R. 5 of 2021)

2. Interpretation

(1)

In this Ordinance, unless the context otherwise requires—

International System of Units (國際單位制) means the system of units of measurement from time to time recommended for international use by the General Conference of Weights and Measures; metric units (十進制單位) means— (a)the base units, supplementary units, derived units and symbols of the International System of Units specified in the second and third columns of Parts I, II and III of the First Schedule and defined, in the case of the base units and supplementary units, in the fourth column of the said Part I or II, as the case may be, opposite each such unit; (b)any other units of measurement belonging to the International System of Units; (c)such decimal multiples and sub-multiples of the metric units referred to in paragraphs (a) and (b) as may be formed by the use of the prefixes of the International System of Units specified in the second and third columns of Part IV of the First Schedule and determined, in respect of any particular decimal multiple or sub-multiple of a metric unit by reference to the factor, specified in the first column of that Part, by which such metric unit is multiplied; (d)the units of measurement in general international use, but not belonging to the International System of Units, which are specified in the second column of the Second Schedule, the respective equivalent values whereof, expressed in SI units, being specified or referred to in the fourth column of that Schedule; non-metric units (非十進制單位) means all units of measurement other than metric units.

(2)

In this and in any other Ordinance, unless the context otherwise requires—

(a)

the abbreviation “SI” stands for the International System of Units; and (E.R. 5 of 2021)

(b)

each of the symbols in the third column of the First and Second Schedules stands for the unit or prefix opposite thereto in the second column.

(Format changes—E.R. 5 of 2021)

3. Chief Executive may amend Ordinance by order

(1)

The Chief Executive may, by order published in the Gazette, amend any Ordinance for the purpose of replacing references therein to non-metric units by references to metric units which are either equivalent or approximate thereto or which enable the references to non-metric units to be expressed in convenient metric terms.

(2)

In any order made under subsection (1) the Chief Executive may, for the purposes of the Ordinance amended thereby—

(a)

prohibit the use of non-metric units after a date specified in the order;

(b)

declare the extent to which, and the period during which, non-metric units may continue to be used;

(c)

provide for exemptions from the use of metric units for such periods and on such conditions as he may specify;

(d)

generally make such incidental provisions as he thinks expedient to achieve the purposes of this Ordinance.

(3)

For the purposes of subsection (1), the non-metric base units set out in the second column of the Third Schedule shall be equivalent to the values expressed in SI base units set out in the third column thereof.

(Amended 65 of 2000 s. 3)

(Format changes—E.R. 5 of 2021)

4. Amendment of Schedules

The Chief Executive may, by order published in the Gazette, amend the First, Second or Third Schedule.

(Amended 65 of 2000 s. 3)

(Format changes—E.R. 5 of 2021)

First Schedule — International System of Units

[ss. 2 & 4]

Part I — SI Base Units

First Column		Second Column	Third Column	Fourth Column
Quantity		Name	Symbol	Definition
1.	time	second	s	It is defined by taking the fixed numerical value of the caesium frequency Δν_Cs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s^-1.
2.	length	metre	m	It is defined by taking the fixed numerical value of the speed of light in vacuum c to be 299 792 458 when expressed in the unit m s^-1, where the second is defined in terms of the caesium frequency Δν_Cs.
3.	mass	kilogram	kg	It is defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10^-34 when expressed in the unit J s, which is equal to kg m² s^-1, where the metre and the second are defined in terms of c and Δν_Cs.
4.	electric current	ampere	A	It is defined by taking the fixed numerical value of the elementary charge e to be 1.602 176 634 × 10^-19 when expressed in the unit C, which is equal to A s, where the second is defined in terms of Δν_Cs.
5.	thermodynamic temperature	kelvin	K	It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1.380 649 × 10^-23 when expressed in the unit J K^-1, which is equal to kg m² s^-² K^-1, where the kilogram, metre and second are defined in terms of h, c and Δν_Cs.
6.	amount of substance	mole	mol	One mole contains exactly 6.022 140 76 × 10²³ elementary entities. This number is the fixed numerical value of the Avogadro constant N_A, when expressed in the unit mol^-1 and is called the Avogadro number. The amount of substance, symbol n, of a system is a measure of the number of specified elementary entities. An elementary entity may be an atom, a molecule, an ion, an electron, any other particle or specified group of particles.
7.	luminous intensity	candela	cd	It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 10¹² Hz, K_cd, to be 683 when expressed in the unit lm W^-1, which is equal to cd sr W^-1, or cd sr kg^-1 m^-2 s³, where the kilogram, metre and second are defined in terms of h, c and Δν_Cs.

Notes—1.The SI derived units are defined as products of powers of the SI base units.2.The 7 SI base units in this Part and the 22 SI derived units with special names and symbols in Part III may be used in combination to express the units of other derived quantities. All other SI units are combinations of some of these 29 units.

Part II — SI Supplementary Units

Part III — SI Derived Units Having Special Names and Symbols

	First Column	Second Column	Third Column
	Quantity	Special Name	Symbol (unit expressed in terms of base units)
1.	plane angle	radian	rad(= m/m)
2.	solid angle	steradian	sr(= m²/m²)
3.	frequency	hertz	Hz(= s^-1)
4.	force	newton	N(= kg m s^-2)
5.	pressure, stress	pascal	Pa(= kg m^-1 s^-2)
6.	energy, work, amount of heat	joule	J(= kg m² s^-2)
7.	power, radiant flux	watt	W(= kg m² s^-3)
8.	electric charge	coulomb	C(= A s)
9.	electric potential difference	volt	V(= kg m² s^-3 A^-1)
10.	capacitance	farad	F(= kg^-1 m^-2 s⁴ A²)
11.	electric resistance	ohm	Ω(= kg m² s^-3 A^-2)
12.	electric conductance	siemens	S(= kg^-1 m^-2 s³ A²)
13.	magnetic flux	weber	Wb(= kg m² s^-2 A^-1)
14.	magnetic flux density	tesla	T(= kg s^-2 A^-1)
15.	inductance	henry	H(= kg m² s^-2 A^-2)
16.	Celsius temperature	degree Celsius	°C(= K)
17.	luminous flux	lumen	lm(= cd sr)
18.	illuminance	lux	lx(= cd sr m^-2)
19.	activity referred to a radionuclide	becquerel	Bq(= s^-1)
20.	absorbed dose, kerma	gray	Gy(= m² s^-2)
21.	dose equivalent	sievert	Sv(= m² s^-2)
22.	catalytic activity	katal	kat(= mol s^-1)

Notes—1.The SI derived units are defined as products of powers of the SI base units.2.The 7 SI base units in Part I and the 22 SI derived units with special names and symbols in this Part may be used in combination to express the units of other derived quantities. All other SI units are combinations of some of these 29 units.

Part IV — SI Prefixes

First Column	Second Column	Third Column
Factor by which the unit is multiplied	Name	Symbol
10²⁴	yotta	Y
10²¹	zetta	Z
10¹⁸	exa	E
10¹⁵	peta	P
10¹²	tera	T
10⁹	giga	G
10⁶	mega	M
10³	kilo	k
10²	hecto	h
10¹	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

Note—The SI prefixes are used to form names and symbols of decimal multiples and sub-multiples of the SI units.

(First Schedule replaced L.N. 167 of 2019)

Second Schedule — Non-SI Units in General International Use

[ss. 2 & 4]

	First Column	Second Column	Third Column	Fourth Column
	Quantity	Name	Symbol	Value in SI units
1.	time	minute	min	60 s
2.	time	hour	h	3 600 s
3.	time	day	d	86 400 s
4.	plane and phase angle	degree	°	(π /180) rad
5.	plane and phase angle	minute	’	(π /10 800) rad
6.	plane and phase angle	second	”	(π /648 000) rad
7.	area	hectare	ha	10⁴ m²
8.	volume	litre	l, L	10^-3 m³
9.	mass	tonne	t	10³ kg
10.	mass per unit length (Note 1)	tex	tex	10^-6 kg/m
11.	length (Note 2)	nautical mile (international)		1 852 m
12.	speed velocity (Note 2)	knot (international)		(1 852/3 600) m/s

Notes—1.This unit is used in the textile industry for the measurement of the linear density of yarn.2.Related to nautical and aeronautical navigation and meteorology. One knot is equal to one nautical mile per hour.

(Second Schedule replaced L.N. 167 of 2019)

Third Schedule — Values of Non-metric Basic Units Expressed in terms of SI Base Units

[ss. 3 & 4]

	First Column	Second Column	Third Column
	Quantity	Non-metric basic unit	Value in SI base unit
1.	length	yard	0.914 4 m
2.	mass	pound	0.453 592 37 kg
3.	capacity	gallon	4.546 09 × 10^-3 m³(Note 1)
4.	temperature interval	degree Fahrenheit	5/9 K (Note 2)

Notes—1.Correct to 6 significant figures.2.A formal definition of the Fahrenheit scale of temperature is not thought to exist, but for most practical purposes Fahrenheit temperature may be defined by the equation f = 1.8T – 459.67 where f is the Fahrenheit temperature expressed in degrees Fahrenheit (symbol °F) and T is the thermodynamic temperature expressed in kelvins (symbol K).

(Third Schedule replaced L.N. 167 of 2019)