Coker A.K. Fortran Programs for Chemical Process Design, Analysis, and Simulation

CHAPTER 10

The International

System of Units (SI) and

Conversion Tables

The International System of Units, or the SI units, are derived from

Systeme International d'Unites and are evolved from the mass-length-

time-temperature system. This is derived from the seven base units of

length, mass, time, temperature, amount of substance, electric current,

and luminous intensity. Also, two supplementary units of plane angle

and solid angle are required to describe the physical and chemical prop-

erties. Table 10-1 lists the supplementary units and their symbols.

All other units in SI are derived from the nine base and supplemen-

tary units. Table 10-2 gives approved derived units with names, formu-

las, and their symbols. Lists of derived SI units that do not have approved

names but are widely used in chemical engineering are given in Table

10-3.

The wide range in magnitude of the units used in normal practice

requires the use of different sized units, rather than a powers-of-ten nu-

merical multiplier. SI provides prefixes for decimal multiples and sub-

multiples of the base supplementary and approved derived units. Table

10-4 shows these prefixes by name, symbol, and magnitude. In addition

to learning the new units and symbols, conversion is required when

numerical values are reported in imperial or the c.g.s units. The conver-

sion of units is mainly handled through the use of conversion tables as

listed in Table 10-5.

777

Table 10-1

SI and Supplementary Units

Type

base

Supplementary

Quantity and Symbol

Length, L

mass, m

time, t

temperature, T

amount of substance, n

electric current, I

luminous intensity, I

plane angle, 0

solid angle, co

Unit

meter

kilogram

second

Kelvin

mole

ampere

candela

radian

steradian

Unit

Symbol

m

kg

K

tool

A

cd

rad

sr

Reproduced by permission of the American Institute of Chemical Engineers 9 1979, A.I. Ch.E.

778

Table 10-2

SI Derived Units with Special Names

Quantity and symbol

frequency, f

force, F

pressure, stress

p,'c

energy, work,

quantity of heat,

E,W,Q

power, radiant

flux, P

quantity of electricity,

electric charge, Q

electric potential,

potential difference,

electromotive force, E

capacitance, C

electric resistance, R

conductance, G

magnetic flux, ~)

magnetic flux density, B

inductance, L

luminous flux, F

illuminance, B

radioactivity, )v

absorbed dose, D

Unit

hertz

newton

pascal

joule

watt

coulomb

volt

farad

ohm

siemens

weber

tesla

henry

lumen

lux

becquerel

gray

Unit

symbol

Hz

N

Pa

W

V

Wb

H

lm

lx

Bq

Formula

s-i

kg.m]s 2

N/m 2, kg/m.s 2

N/m, kg.m2/s 2

J/s, kg.m2/s 3

A.s

W/A, kg/A.s 3

C/V, A2.sa]kg.m 2

V/A, m2.kg/A2.s 3

A/V, A2.s3/kg.m 2

V.s, m2.kg/A.s 2

Wb/m 2, kg/A.s 2

Wb/A, m2.kg/A.s

cd.sr

cd.sr]m 2

S-l

Gy

J/kg

Reproduced by permission of the American Institute of Chemical Engineers 9 1979, A.I. Ch.E.

779

Table 10-3

Some Derived SI Units

Property

Common Symbol

thermal conductivity k

heat transfer rate q

heat transfer coefficient h

specific enthalpy H

heat capacity Cp

Newtonian viscosity g

kinematic viscosity v

thermal diffusivity c~

volumetric flow rate q

power P

enthropy S

density 9

mass velocity

SI units formula

W/m.K

W

W/m2.K

J/kg

J/kg.K

Pa.s, kg/m.s

m2/s

m2s

m3/s

W

J/K

kg/m 3

G kg/s.m 2

concentration c kg/m 3

concentration c mol/m 3

velocity u m/s

acceleration a,g m/s 2

mass transfer coefficient k c m/s

mass diffusivity D m2/s

moment I N.m

thermal flux q/A W/m 2

mass flux (molar) Na/A mol/m2.s

momentum flux

mass transfer rate

mass flow rate

~y/A

Na

w

R

surface tension

gas constant

Pa

mol/s

kg/s

N/m

Pa.m3/mol.K, J/mol.K

Reproduced by permission of the American Institute of Chemical Engineers 9 1979, A.I. Ch.E.

780

Table 10-4

Magnitude Prefixes for SI Units

Name

atto

femto

pico

nano

micro

milli

centi

deci

deka

hecto

kilo

mega

giga

tera

peta

exa

Symbol

m

da

M

G

Magnitude

10-18

10-15

10-12

10 -9

10

-6

10 .3

10 -2

lO-I

101

102

103

106

109

1012

10 Is

1018

Reproduced by permission of the American Institute of Chemical Engineers 9 1979, A.I. Ch.E.

781

e

T-- C

I11 0

l"

0

E

T "T

X X rq

oo ~ d

E

"T

eq

X ~

0 i 0

rq

E ~ ~ x

eq ~

?

o ~ o rn ~

.__ ~ r-e3 ~

782

c~J

E

".~

. ~ c~ o

E ~ w

.~. X ,~ X X

'2

0

"d" X ~ ~.~

783

? ? T

u", x ° x

x g ~ _

x x

("3 (3O

--

r~h (N 0

0

0", 0 0

eq

X ~ ~ ~ oO

E ,,.d x __., x r-.

[.~

E "~ o4

0

X ,,i, t,q

0"') ~ O0

O0

~

("-

e4 04

D---

co

X ~

X

X ~ ~ ~

r,h

"" (N ~

784

e~

"-- X t',l =

c~

~ X 2 '--~

c'q

~ - ~ ~

0"~ oo

0",

--- ~ ~ ~

~ o

cq

785

03

o-, -

oo

co r'4

0 ~- 0

,-- C'q

03

c- X ,~ X

o,

r--- ~ ,,,o

786

Coker A.K. Fortran Programs for Chemical Process Design, Analysis, and Simulation

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