# 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 Réaumur 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   