ตำรายาของประเทศไทย
Thai Pharmacopoeia

สำนักยาและวัตถุเสพติด กรมวิทยาศาสตร์การแพทย์ กระทรวงสาธารณสุข

Bureau of Drug and Narcotic, Department of Medical Sciences, Ministry of Public Health

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1.14 WEIGHTS AND MEASURES: SI UNITS

1.14 WEIGHTS AND MEASURES: SI UNITS

          The International System of Units (SI) is used in this Pharmacopoeia and comprises three categories of units, namely basic units, derived units and supplementary units.

          The basic units are set out in Table 1. The derived units may be formed by combining the basic units according to certain algebraic relationships between the corresponding quantities. Some of these derived units have special names and symbols. The SI units used in this Pharmacopoeia are shown in Table 2.

         Certain units of the SI have not yet been classified as basic or derived; they are known as supplementary units and are shown in Table 3.

         Some important and widely used units outside the international system are shown in Table 4.

         The prefixes shown in Table 5 are used to form the names and symbols of the decimal multiples and submultiples of SI units.

Table 1 Basic Units

Quantity Name of Basic SI Unit Symbol
Length metre m
Mass kilogram kg
Time second s
Electric current ampere A
Thermodynamic temperature kelvin K
Amount of substance mole mol
Luminous intensity candela cd

Table 2 Derived SI Units Used in the Thai Pharmacopoeia and Their Equivalence with Other Units​

Quantity Name of
Derived
SI Unit		 Symbol Expression
in Basic
SI Units		 Equivalence with
Other Units
Absorbed dose of
     ionizing radiation		 gray Gy m2s-2 1 Gy   = 1 joule per kg
           = 100 rad
Energy, work,
     quantity of heat		 joule J kgm2s-2 1 J      = 107 ergs
Electrical potential,
     potential difference,
     electromotive force		 volt V kgm2A-1s-3  
Electric resistance ohm Ω kgm2A-2s-3  
Quantity of electricity Coulomb C As  
Force newton N kgms-2 1 N    = 105 dynes    
Frequency hertz Hz s-1 1 Hz  = 1 cycle per second 
Power watt W kgm2s-3  
Pressure pascal Pa kgm-1s-2 1 kPa = 7.5 mm Hg
          = 7.5 Torr
          = 1.45 Ib/in2
Radioactivity becquerel Bq s-1 1 Bq   = 2.703 × 10-11 curies

Table 3 Supplementary Units​

Quantity Name of
Supplementary
SI Unit		 Symbol
Plane angle radian rad
Solid angle steradian sr

Table 4 Units Used with the International System​

Quantity Unit Value in SI Units
Name Symbol
Time minute
hour
day		 min
h
d		 1 min = 60 s
1 h = 60 min = 3,600 s
1 d = 24 h = 86,400 s
Plane angle degree
minute
second		 º
´
”		 1º =(¶/180) rad
1´ = (1/60)º = (¶/10,800) rad
1” = (1/60)´ = (¶/648,000) rad
Volume litre l 1 l = 1 dm3 = 10-3m3
Light lux
lumen		 lx
lm		 1 lx = 1 lumen m2
1 lm = luminous flux emitted per
unit solid angle from a uniform
source of  1 candela
Mass tonne
gram		 t
g		 1 t = 103 kg
1 g = 10-3 kg

Note In the Pharmacopoeia, conditions of centrifugation are defined by reference to the acceleration due to gravity (g): g = 9.80665 ms-2

Table 5 Decimal Multiples and Sub-multiples​

Factor Prefix Symbol
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

 

APPENDICES • 1.14 WEIGHTS AND MEASURES: SI UNITS
view 1,182 ผู้เข้าชม / View
หมายเหตุ / Note : TP II 2011 PAGE 342-343
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