Propane Butane Mix - Evaporation Pressure

Evaporation pressure of Propane Butane mixtures

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.

The vapor pressure of a mixture of the two products are indicated in the table below:

Vapor Pressure (psig)
Mixture 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) = 6,894.8 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 - imperial units - psig

Propane Butane Mix Vapor Diagram - bar

propane butane mix vapor diagram - imperial units - bar

Related Topics

  • Combustion - Boiler house topics - fuels like oil, gas, coal, wood - chimneys, safety valves, tanks - combustion efficiency
  • Gas and Compressed Air - Gas properties, capacities of pipelines, sizing of relief valves - air, LNG, LPG and more
  • Material Properties - Material properties - density, heat capacity, viscosity and more - for gases, fluids and solids

Related Documents

Search the Engineering ToolBox

- "the most efficient way to navigate the Engineering ToolBox!"

Engineering ToolBox - SketchUp Edition - Online 3D modeling!

3D Engineering ToolBox - draw and model technical applications

Engineering ToolBox - SketchUp Edition - add standard and customized parametric components - like flange beams, lumbers, piping and more - to your SketchUp model - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro. Add from the Sketchup Extension Warehouse!

Translate the Engineering ToolBox!
About the Engineering ToolBox!