Tables and general data
SI units and their relation to other units
The International
System of Units (SI System) is based on six primary units:
Quantity Unit
Symbol
length metre m
mass kilogram kg
time second s
electric current ampere
A
temperature degree Kelvin
K
luminous intensity candela
cd
Multiples
SI prefixes are
used to indicate multiples and submultiples such as 106 or 10–3
Prefix Symbol
Prefix Symbol
10 deca
da 10–1 deci d
102 hecto h 10–2 centi c
103 kilo k 10–3 milli
m
106 mega M 10–6 micro
ì
109 giga G 10–9 nano n
1012 tera T 10–12 pico p
Example: One millionth
of a metre is expressed as one micrometre, 1 ìm.
Derived units
The most
important derived units for the foundryman are:
Quantity Unit Symbol
Force newton N (kg m/s2)
Pressure, stress newton
per square metre or pascal N/m2 (Pa)
Work, energy joule J
(Nm)
Power, heat flow rate watt, joule per second W
(J/s)
Temperature degree
Celsius °C
Heat flow rate watt
per square metre W/m2
Thermal conductivity watt
per metre degree W/m
K
Specific heat capacity joule per kilogram degree J/kg K
Specific latent heat joule
per kilogram J/kg
SI, metric, non-SI and non-metric conversions
Length:
1 in =
25.4 mm
1 ft =
0.3048 m
1 m =
1.09361 yd
1 km =
1093.61 yd = 0.621371 miles
1 mile =
1.60934 km = 1760 yd
1 yd =
0.9144 m
Area:
1 in2 =
654.16 mm2
1 ft2 =
0.092903 m2
1 m2 = 1.19599 yd2 = 10.76391 ft2
1 mm2 =
0.00155 in2
1 yd2 =
0.836127 m2
1 acre =
4840 yd2 = 4046.86 m2 = 0.404686 m2 hectare
1 hectare =
2.47105 acre = 10 000 m2
Volume:
1 cm3 =
0.061024 in3
1 dm3 = 11
(litre) = 0.035315 ft3
1 ft3 =
0.028317 m3 = 6.22883 gal (imp)
1 gal (imp) = 4.54609
l (litre)
1 in3 =
16.3871 cm3
1 l (litre) = 1
dm3 = 0.001 m3 = 0.21997 gal (imp)
1 m3 =
1.30795 yd3 = 35.31467 ft3
1 pt (pint) =
0.568261 l
1 US gal =
3.78541 l = 0.832674 gal (imp)
1 ft3/min (cfm) =
1.699 m3/h
1 ft3/sec =
28.31681/s
Mass:
1 lb (pound) =
0.453592 kg
1 cwt =
50.802 kg
1 kg =
2.20462 lb
1 oz =
28.349 gm
1 ton =
2240 lb = 1.01605 t (tonne) = 1016.05 kg
1 ton (US) = 2000 lb
= 907.185 kg
Force:
1 kgf =
9.80665 N = 2.20462 lbf = 1 kp (kilopond)
1 lbf =
4.44822 N
1 pdl (poundal) =
0.138255 N
Density:
1 kgf/m3
= 0.062428 lb/ft3
1 lb/ft3
= 16.0185 kg/m3
1 g/cm3 =
1000 kg/m3
Pressure,
stress:
1 kgf/cm2 =
98.0665 kPa (kN/m2)
1 kgf/mm2 =
9.80665 N/mm2 = 1422.33 lbf/in2 = 0.63497 tonf/in2
1 lbf/in2 (psi) =
6.89476 kPa (kN/m2)
1 Pa (N/m2) =
0.000145038 lbf/in2
1 in w.g. (in H2O) =
249.089 Pa
1 N/mm2 = 1 MPa =
145.038 lbf/in2 = 0.06475 tonf/in2 =
0.10197 kgf/cm2
Power:
1 kW =
3412 Btu/hr
1 hp (horsepower) =
0.745700 kW
Energy,
heat, work:
1 Btu = 1.05506 kJ
1 cal =
4.1868 J
1 kWh = 3.6 MJ
= 3412 Btu
1 therm = 100 000 Btu =
105.506 MJ
1 kJ =
0.277778 W.h
Specific
heat capacity, heat transfer:
1 cal/g°C = 1 kcal/kg°C = 4186.8 J/kg.K
1 Btu/lb°F = 4186.8 J/kg.K
1 Btu/h =
0.293071 W
1 cal/cm.s°C = 418.68 W/m.K (thermal
conductivity)
1 Btu.in/ft2h°F = 0.144228 W/m.K (thermal
conductivity)
1 Btu/ft2h°F = 5.67826 W/m2.K (heat transfer
coeff.)
Miscellaneous:
1 std.atmos. =
101.325 kPa = 760 mm Hg = 1.01325 bar
1 bar = 100 kPa =
14.5038 lbf/in2
1 cP (centipoise) =
1 mPa.s
1 cSt (centistoke) =
1 mm2/s
1 cycle/s =
1 Hz (Hertz)
1 hp =
745.7 W
Useful
approximations:
1 Btu =
1 kJ 1 kg = 21/4
lb
1 ft =
30 cm 1 kgf = 10 N
1 gal =
41/2 l 1 std atmos.
= 1 bar
1 ha =
21/2 acre 1 km = 5/8 mile
1 hp =
3/4 kW 1 litre = 13/4
pint
1 in =
25 mm 1 lbf = 41/2 N
1 therm =
100 MJ 1 yd = 0.9 m
1 tonf/in2 =
15 N/mm2
1 psi (lbf/in2) =
7 kPa
1 N (newton) =
the weight of a small apple!
Temperature:
°F = 1.8 × °C +
32
°C = (°F – 32)/1.8
0°C (Celsius) =
273.15 K (Kelvin)
Sumber : Foundryman's Hand Book
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