International System of Units (SI) [Part 1] (According to JIS Z 8203 “SI units and recommendations for the Data Sheet use of their multiples and of certain other units” and Z 8202 “Quantities and units”) ■ Origin of the term SI (International System of Units) SI stands for Système International d'Unités in French (International System of Units in English), an internationally accepted official abbreviation. ■ Purpose and historical background of the SI The Metre Convention was signed in 1875 to oversee the keeping of metric system as a unified international system of units. Then, the metric system had more than ten variations, losing its consistency. At the 9th General Conference on Weights and Measures (Conférence Générale des Poids et Mesures: CGPM) in 1948, a resolution was adopted “to use a unified system of units in all fields”. The International Committee for Weights and Measures (Comité International des Poids et Mesures: CIPM) of the treaty organization started a process to establish a unified system and determined the framework of the SI in 1960. In 1973, the International Organization for Standardization (ISO) developed the standard ISO 1000, which describes SI units and recommendations for the use of them, leading to global adoption of the system. In Japan, a policy to introduce SI units into JIS through the following three phases was determined in 1972; the introduction of SI units into JIS progressed rapidly. First phase: Use of conventional units followed by SI units e.g. 1 kgf [9.8 N] Second phase: Use of SI units followed by conventional units e.g. 10 N {1.02 kgf} Third phase: Use of SI units only e.g. 10 N The Measurement Act in Japan was fully revised in 1992 and enacted in 1993 to unify statutory measurement units into SI units. Under the new Measurement Act, a transition period of up to seven years was granted before the exclusive use of SI units for “pressure” and “moment of force” in the field of hydraulics, and the period expired on September 30, 1999. Since October 1, 1999, it has been mandatory to use SI units as statutory measurement units for transactions and certifications. Commercially available pressure gauges are in SI units. The units used in this catalogue are SI units.

All units used in this catalogue are SI units as applicable in the third phase of the SI implementation process.

■ Structure of SI units and JIS Z 8203

Base Units (7)

Supplementary Units (2) SI Units Derived Units with Special Names (19)

Derived Units

Other Derived Units

Prefixes (20) and Decimal Multiples of SI units

Important Non-SI Units Accepted for Use with SI Units

Base Units Supplementary Units

Base Unit Supplementary Unit Quantity Quantity Name Symbol Name Symbol

Length meter Plane Angle radian

Mass kilogram Solid Angle steradian

Time second Data Sheet Electric Current ampere

Thermodynamic kelvin Temperature Amount of mole

Substance ) Luminous

candela SI Intensity (

International System of Units

Data Sheet 865 International System of Units (SI) Data Sheet [Part 2]

Prefixes Derived units Derived units are expressed algebraically in terms of base units and Prefixes are used to form decimal multiples of SI units. supplementary units (by means of the mathematical symbols of Prefix multiplication and division) in the International System of Units. Unit Multiplier Name Symbol Derived units expressed in terms of SI base units yotta Derived Unit zetta Quantity Name Symbol exa 2 peta Area square meter m tera Volume cubic meter m3 giga Speed, Velocity meter per second m/s mega Acceleration meter per second squared m/s2 kilo -1 hecto Wavenumber reciprocal meter m 3 deka Density kilogram per cubic meter kg/m deci Current Density ampere per square meter A/m2 centi Magnetic Field ampere per meter A/m milli Strength (Amount-of-substance) 3 micro Concentration mole per cubic meter mol/m nano Specific Volume cubic meter per kilogram m3/kg pico Luminance candela per square meter cd/m2 femto atto zepto Derived units with special names yocto Derived Unit Quantity Name Symbol Definition

Non-SI units accepted for use with SI units -1 Frequency hertz Hz s Quantity Unit Name Unit Symbol Force newton N kg･m/s2

2 minute Pressure, Stress pascal Pa N/m Time hour Energy, Work, Amount of Heat joule J N･m day Amount of Work Done Per Time, Motive Power, Electrical watt W J/s degree Power Plane minute Electric Charge, Amount of coulomb C A･s Angle second Electricity Electric Potential, Potential Difference, Voltage, volt V W/A Volume liter Electromotive Force Mass metric ton Capacitance farad F C/V Electric Resistance ohm Ω V/A The letter “L” may be used as the symbol for liter, when the symbol “l” for liter might be confused with any other (Electric) Conductance siemens S A/V character (as a general rule, Yuken uses “L”). Magnetic Flux weber Wb V･s ● Units accepted for use with SI units for Magnetic Flux Density, tesla T Wb/m2 usefulness in special fields Magnetic Induction Inductance henry H Wb/A Quantity Unit Name Unit Symbol Celsius Temperature degree celsius/degree ºC Energy electronvolt Luminous Flux lumen lm cd･sy

atomic mass unit 2 Atomic Mass Illuminance lux lx lm/m astronomical unit Activity Referred to a becquerel Bq S-1 Distance Radionuclide parsec Absorbed Dose gray Gy J/kg Fluid Pressure bar Dose Equivalent sievert Sv Gy

866 Data Sheet International System of Units (SI) Data Sheet [Part 3]

■ Use of SI units

Space and Time Dynamics Heat

Decimal Decimal Decimal Quantity SI Unit Multiple Quantity SI Unit Multiple Quantity SI Unit Multiple Unit Unit Unit

3 Thermodynamic Plane Angle mg/m or K (kelvin) rad Density, Temperature (radian) Concentration kg/dm3 or 3 Celsius ºC (degree 3 g/cm kg/m Temperature Celsius or (kilogram degree) per cubic Temperature Interval, Solid Angle sr K or ºC (steradian) meter) Temperature Difference

Amount of Length, Width, 2 Moment of kg·m Heat Height, m Inertia (kilogram Thickness, (meter) meter Radius, squared) J (joule) Diameter, Length of Path Force Heat Flow Traveled, Rate W (watt) Distance N (newton) Thermal Conductivity 2 Area m Coefficient of Heat (square Transfer meter) Specific Heat Capacity Moment of

Force 3 Volume m Electricity and Magnetism N·m (cubic meter) (newton Electric meter) Current A (ampere) Time Pressure s (second) Pa (pascal)

Electric Potential, Angular rad/s Electric Potential (radian per Difference, V (volt) Velocity second) Voltage, Electromotive Speed, Velocity m/s Force (meter per Stress (pascal or GPa, second) newton per MPa or (Electric) 2 Acceleration m/s square N/mm2, Resistance (meter per meter) kPa (Direct (Remarks) MΩ second 2 is also referred Pa or N/m Current) squared) to as megohm.

Periodic and Related Phenomena Ω (ohm) Viscosity Pa·s (pascal Frequency second) Kinematic m2/s (Active) Viscosity (square meter Electric per second) Power

Hz (hertz) Work, Energy, W (watt) Amount of Data Heat Sheet Rotational s-1 Speed, (per second) (joule) Revolutions J Power, Amount Dynamics of Work Done Sound Per Unit of Frequency Mass Time W (watt)

kg )

(kilogram) Hz (hertz) SI ( Flow Rate m3/s Sound Pressure Level* (cubic meter * This SI unit is not provided by ISO per second) 1000-1973 and ISO 31 Part 7-1978, but JIS adopts and specifies dB (decibel) as International System a unit accepted for use with SI units. of Units

Data Sheet 867 International System of Units (SI) Data Sheet [Part 4]

■ SI unit conversion factors table (Shaded columns represent SI units.)

Force Moment of inertia N N·m Newton Newton meter

2 2 Note) 1 N·m = 1 kg•m /s

Pressure Pa pascal mmHg or Torr

Note) 1 Pa = 1 N/m2

Stress Viscosity 2 Pa MPa or N/mm Pa•s pascal Megapascal or pascal second newton per square milimeter

Note) 1 P = 1 dyn•s/cm2 = 1 g/cm•s Note) 1 Pa•s = 1 N•s/m2, 1 cP = 1 mPa•s

Work, energy, amount of heat Kinematic viscosity 2 J m /s joule square meter per second

Note) 1 cSt = 1 mm2/s, 1 St = 1 cm2/s

Note) 1 J = 1 W•s, 1 W•h = 3,600 W•s Note) 1 cal = 4.186 05 J (according to the Measurement Act)

Power (amount of work done per unit of time or motive power) Thermal conductivity kW kilowatt W/(m•K) watt per meter kelvin

Note) 1 cal = 4.186 05 J (according to the Measurement Act)

Note) 1 W = 1 J/s, PS: French Note) 1 PS = 0.735 5 kW (according to the Act for Enforcement of the Measurement Act)

Note) 1 cal = 4.186 05 J (according to the Measurement Act)

Specific heat capacity Coefficient of heat transfer Temperature J/(kg•K) W/(m2•K) joule per kilogram watt per meter kelvin squared kelvin

T1: Thermodynamic K (kelvin) temperature ºC (degree) T2: Celsius temperature Note) 1 cal = 4.186 05 J (according to the Measurement Act) Note) 1 cal = 4.186 05 J (according to the Measurement Act) T3: °F

868 Data Sheet