Cap. 214

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 [ss. 2 & 4]International System of Units 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 ΔνCs, 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 ΔνCs. 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 ΔνCs. 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 ΔνCs. 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 ΔνCs. 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 NA, 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, Kcd, 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 ΔνCs. 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 [ss. 2 & 4]Non-SI Units in General International Use 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 [ss. 3 & 4]Values of Non-metric Basic Units Expressed in terms of SI Base Units 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)