Propane Butane Mixture - Evaporation Pressure
It is common to distribute a mixture of propane (C3H8) and butane (C4H10) (LPG) for combustion purposes.
Propane is more suited to colder environments since it evaporates at -44oF (-42oC) at atmospheric pressure. Butane evaporates at 33oF (0.6 oC) at atmospheric pressure.
Vapor pressures for mixtures of the two products relative to atmospheric pressure (gauge pressure) are indicated below.
| Liquid Mixture | Vapor Pressure (psig) | |||||
|---|---|---|---|---|---|---|
| Propane (C3H8) (%) | 100 | 70 | 50 | 30 | 0 | |
| Butane (C4H10) (%) | 0 | 30 | 50 | 70 | 100 | |
| Temperature (oF) | -44 | 0 | 0 | 0 | 0 | 0 |
| -30 | 6.8 | 0 | 0 | 0 | 0 | |
| -20 | 11.5 | 4.7 | 0 | 0 | 0 | |
| -10 | 17.5 | 9 | 3.5 | 0 | 0 | |
| 0 | 24.5 | 15 | 7.6 | 2.3 | 0 | |
| 10 | 34 | 20.5 | 12.3 | 5.9 | 0 | |
| 20 | 42 | 28 | 17.8 | 10.2 | 0 | |
| 30 | 53 | 36.5 | 24.5 | 15.4 | 0 | |
| 40 | 65 | 46 | 32.4 | 21.5 | 3.1 | |
| 50 | 78 | 56 | 41 | 28.5 | 6.9 | |
| 60 | 93 | 68 | 50 | 36.5 | 11.5 | |
| 70 | 110 | 82 | 61 | 45 | 17 | |
| 80 | 128 | 96 | 74 | 54 | 23 | |
| 90 | 150 | 114 | 88 | 66 | 30 | |
| 100 | 177 | 134 | 104 | 79 | 38 | |
| 110 | 204 | 158 | 122 | 93 | 47 | |
- 1 psi (lb/in2) = 144 psf (lbf/ft2) = 6894.8 Pa (N/m2) = 6.895x10-3 N/mm2 = 6.895x10-2 bar
Note that the evaporation temperature is not the only parameter that influences on evaporation of the propane butane mixture. Evaporation requires heat and if the heat transferred to the liquid gas is limited - the liquid cools down and the evaporation is reduced.
- Larger consumers requires heat exchangers fueled with hot water, electric heater or combustion of the propane butane mix itself to supply the evaporation heat.
- Smaller consumers requires propane butane mix containers with efficient heat transfer from the surroundings. By example - composite containers provides less heat transfer compared to steel containers and may cause problems at lower surroundings temperatures.
Propane Butane Mix Vapor Diagram - psig
Propane Butane Mix Vapor Diagram - bar
Butane Vapor Pressure (abs)
| Temperature (oC) | Vapor Pressure (bar abs) |
|---|---|
| -101.5 | 0.0013 |
| -77.8 | 0.013 |
| -59.1 | 0.053 |
| -44.2 | 0.13 |
| -16.3 | 0.53 |
| -0.5 | 1.01 |
| 18.8 | 2.03 |
| 50.0 | 5.07 |
| 79.5 | 10.1 |
| 116 | 20.3 |
Related Topics
• Combustion
Boiler house topics, fuels like oil, gas, coal, wood - chimneys, safety valves, tanks - combustion efficiency.
• Gases and Compressed Air
Air, LNG, LPG and other common gas properties, pipeline capacities, sizing of relief valves.
• Material Properties
Material properties of gases, fluids and solids - densities, specific heats, viscosities and more.
Related Documents
Butane - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculators, figures and tables with dynamic and kinematic viscosity of liquid and gaseous butane, C4H10, at varying temperarure and pressure, SI and Imperial units.
Butane - Thermal Conductivity vs. Temperature and Pressure
Online calculators, figures and tables showing thermal conductivity of liquid and gaseous butane, C4H10, at varying temperature and pressure, SI and Imperial units.
Butane - Thermophysical Properties
Chemical, physical and thermal properties of n-Butane.
Density of Aqueous Solutions of Organic Substances as Sugars and Alcohols
Changes in density of aqueous solutions with changes in concentration at 20°C. Density of some sugars, alcohols and other organic substances in water is plotted as function of wt%, mol/kg water and mol/l solution.
Freezing Mixtures and Cooling Agents
Freezing mixtures, cooling agents and freezing points.
Gases - Explosion and Flammability Concentration Limits
Flame and explosion limits for gases like propane, methane, butane, acetylene and more.
Liquids - Vapor Pressures
Vapor and saturation pressure for some common liquids.
LPG - Gas Properties
Liquefied Petroleum - LP - gas properties.
LPG - Liquefied Petroleum Gas
LPG or Liquefied Petroleum Gas.
LPG Pipes - Pressure Loss vs. Gas Flow
Resistance and pressure loss in liquid LPG pipes.
LPG Tanks - Relief Valves Capacities
Required capacities of relief valves on LPG vaporizers and tanks.
Propane - Density and Specific Weight vs. Temperature and Pressure
Online calculator, figures and tables showing density and specific weight of propane, C3H8, at temperatures ranging from -187 to 725 °C (-305 to 1300 °F) at atmospheric and higher pressure - Imperial and SI Units.
Propane - Dynamic and Kinematic Viscosity vs. Temperature and Pressure
Online calculators, figures and tables showing dynamic and kinematic viscosity of liquid and gaseous propane at varying temperarure and pressure, SI and Imperial units.
Propane - Latent Heat of Vaporization vs. Temperature
Latent heat with vaporized propane.
Propane - Prandtl Number vs. Temperature and Pressure
Figures and tables with Prandtl Number of liquid and gaseous propane at varying temperarure and pressure, SI and Imperial units.
Propane - Thermal Conductivity vs. Temperature and Pressure
Online calculator, figures and tables showing thermal conductivity of liquid and gaseous propane at varying temperarure and pressure, SI and Imperial units.
Propane - Thermal Diffusivity vs. Temperature and Pressure
Figures and tables showing thermal diffusivity of liquid and gaseous propane at varying temperarure and pressure, SI and Imperial units.
Propane - Thermophysical properties
Chemical, physical and thermal properties of propane gas - C3H8.
Propane - Vapor Pressure vs. Temperature
Vapor pressure vs. temperature.
Propane Air Mixture
Energy content and specific gravity of propane air mixtures.
Propane Gas - Sizing of Pipe Lines
Sizing low pressure propane gas pipe lines - Metric units.