unit of measure
conversions equivalences

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unit of measure of the temperature

The units of temperature used in Italy is the centigrade degree or Celsius degree proposed from the Swedish astronomer A. Celsius (1701 - 1744). The degree is the hundredth part of the thermometrical scale, gotten fixing 0 C the temperature of the melting ice and to 100 C that of the boiling water. They beyond the Celsius scale exist other two scale, the Raumur used in France, and the Fahrenheit scale used in the Anglo-Saxon countries.
  • CELSIUS     0 C 100 C
  • REAUMUR     0 R 80 R
  • FAHRENHEIT     32 F 212 F
They to each centigrade degree correspond 0.8 R e 1.8 F
1 C = 1 K

1 F = 5/9 K
1 Rankine (R Rank) = 5/9 k

For convert from C to F multiply for 9, divide the result for 5 and add 32.
For convert from F to C subtract 32, multiply the result for 5 and divide for 9.

Kelvin scale

The zero absolute has used for determine the scale of temperature definite Kelvin scale. The zero absolute -273.15 is the inferior limit, while an other fixed point is the triple point of the water. This point has constituted from the coexistence of the three states of the water, what: ice, liquid and vapor; is situated to 0.01 C, and corresponds to 273.16 Kelvin. The scale had created from William Thomson Kelvin (1824-1907) a mathematician and Irish physicist. The discovery of the zero absolute is of the 1702 for work of a French physicist, Guillaume Amontons. The reasoning that induced the physicist to this intuition was purely theoretical, for the scarce available technology to the epoch. In nature the least existing temperature is -273 C, measurable in the galaxies spaces, definite temperature of bottom of the Universe. From consider that to this temperature lack the "comma 15". In fact if we consider the heat like molecular movement, we can therefore subtract a quantity for slow down much this molecular agitation, but is absolutely impossible stop it. This is contrary to the Third Principle of the Thermodynamics that affirms that a system could not lose the possessed energy completely. 

unit of measure of the heat

The heat in the International System of units, is measured in joule (J). Is very often use, like units of measure, the calorie (cal), definite quantity of necessary heat to raise the temperature of 1 g of water distilled from 14.5 C to 15.5 C, to pressure standard. With the measurement effected from the physicist English J.Joule (1818-89), 1 cal is equivalent to 4.1855 J. The calorie and the kilocalorie (kcal) are very considered for express the energetic content of the foods.

international temperature scale ITS 90

substance
fixed point
temperature (K)
helium
boiling
3 - 5
hydrogen
triple point
13.8033
hydrogen
boiling
17
neon
triple point
24.5561
oxygen
triple point
54.3584
argon
triple point
83.3058
mercury
triple point
234.3156
water
triple point
273.16
gallium
melting
302.9146
indium
melting
492.7485
tin
melting
505.078
zinc
melting
692.677
aluminium
melting
933.473
silver
melting
1234.93
gold
melting
1337.33
copper
melting
1357.77
quantity report to 1 Joule
international BTU 1956 = 1055.056   eletronvolt (eV) = 1.6021892*10-19
medium BTU = 1055.87   erg = 1*10-7
BTU a 39 F = 1059.67   frigoria (fr fg) = 4.1855*103
BTU a 60 F = 1054.68   great calorie (Cal, kcal) = 4.1868*103
BTU thermochemistry = 1054.35   joule international 1948 = 1.000165
international calorie (cal) = 4.1868   termia (th) = 4.1855*106
medium calorie =  4.19002   therm = 1.055056*108
calorie thermochemistry = 4.184   ton di TNT (T) = 4.2*109
calorie at 15 C = 4.1855   ton equiv. petroleum (tep) = 4.1868*1010
calorie at 20 C = 4.18190   wattora (Wh) = 3.6*103
horse-hour (CVh) = 2.64779*106      
centigrade heat unit (CHU) = 1.8991      

BTU: British Termal Unit, equivalent to the quantity of necessary heat for raise the temperature of a pound of pure water from 60 to 61 F, and it is 1054.5 Joule.
BTUIT: Btu international, has stayed introduced for make coincide the express values in kcal/kg and in Btu/lb F.

heat of combustion

The principal characteristic of a fuel is his power calorific. This represents the amount of heat developed in the reaction of combustion in conditions predefined standard. Generally is measured in kcal/kg for the solid and liquid, while for the gases is expressed with kcal/m3. In many fuels, that contain hydrogen, has distinguished a superior calorific power (that it includes the heat of condensation of the water vapor that shape in the combustion) and a inferior calorific power (than it does not consider such heat).

inferior calorific power of some fuel (p.c.i.)

fuel p.c.i. (kcal/kg - kcal/m3)
firewood to burn 2500 - 4500
peat 3000 - 4500
firewood coal 7500
lignite 4000 - 6200
lithantrax 6800 - 9000
anthracite 8000 - 8500
coke 7000
fuel oil 9800
fuel for airplane 10400
diesel oil 10200
benzine for car 10500
crude oil 10000
liquified petroleum gas 11000
natural gas 8300
technical gas of cokeria 4300
technical gas of blast furnace 900

 


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