What is LPG

As LPG (Liquefied Petroleum Gas) we commonly designate propane, butane or their mixtures, being gained in petroleum refineries from processing of crude oil or as fallout at natural gas extraction. The key property of LPG is the fact that it is highly calorific gas, which easily condenses even at relatively low pressures and current temperatures. Thank to these properties it can be stored also in small tanks or cylinders.

propan-butan

Another key property of LPG is its easy vaporization and possibility of combustion in gaseous state, when it has even 3x greater calorific value than natural gas and at the same time belongs among most ecological fuels. Pure propane vaporizes at temperatures higher than -43°C, which in our conditions guarantee sufficient quantity of vapor for all appliances. In comparison, butane has essentially worse evaporative ability, and therefore is supplied mixed with propane.

Liquefied hydrocarbon gas is a colorless, easily evasive liquid with specific odor. It is inflammable and explosive, nontoxic; its vapors are even double as heavier as air. By liquefying it decreases its volume by ca. 260 times. It has different physic-chemical properties in gaseous and liquid phases.

 PropaneButane
Chemical notation C3H8 C4H10
Density in liquid phase at 20°C 0,498 kg.l-1 0,578 kg.l-1
Density in gaseous phase at 15°C 2,019 kg.m-3 2,590 kg.m-3
Density in gaseous phase (air = 1) 1,562 2,091
Boiling point - 42,6 °C - 0,5 °C
Melting point - 190,16 °C - 134,96 °C
Gas volume, achieved by evaporation of
1 kg liquid phase 0°C, 101,325 kPa
1 kg liquid phase 20°C, 101,325 kP		  
0,496 m3
0,553 m3		  
0,368 m3
0,395 m3
Combustion heat (liquid phase)
Combustion heat (gaseous phase)		 50,43 MJ.kg-1
101,82 MJ.m3		 51,75 MJ.kg-1
134,02 MJ.m3
Calorific value (liquid phase)
Calorific value (gaseous phase)		 46,34 MJ.kg-1
93,57 MJ.m3		 47,70 MJ.kg-1
123,55 MJ.m3
Octane index 100 89

 

 methanepropanei-butanen-butane
Calorific value MJ/m3 35,90 93,15 123,36 123,91
Combustion heat MJ/m3 39,94 101,36 133,85 134,41
Calorific value MJ/kg 50,04 46,35 45,57 45,74
Combustion heat MJ/kg 55,66 50,43 49,45 49,62