Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Average boiling point

Definition, explanation and examples of calculation of various types of average boiling point of petroleum products and other mixtures of hydrocarbons: VABP, MABP, WABP, CABP and MeABP

Sponsored Links

Boiling point: The temperature at which a liquid turns into a gas

A mixture of different compounds boils over a certain range of temperature, reflecting the boiling point of each specific compound present in the mixture. For many purposes, it is suitably to calculate an average boiling point (ABP) of mixtures.

Then, the boiling point of each compound is weighted with regard to the fraction of the compound compared to the whole blend. There are several types of fractions that can be calculated: The mole fraction, the weight fraction and the volume fraction, and the type of fraction must be specified when the term average boiling point is used.  There is also a cubic average boiling temperature and a mean average boiling temperature. The definitions of each type of average boiling point are given by the formulas:

ABP_average_boiling_point

See also Average boiling point from gravity and molecular weight

Example: "Gasoline" mixture

Gasoline consists of branched paraffins, cycloparaffins and aromatics with carbon numbers typically from C4 to C12.

A "simple" gasoline could then contain a mixture of iso-pentane, 3-methylpentane, iso-octane, meta-xylene and hexylcyclohexane. The table below shows calculations of the different kinds of average boiling points of a mixture containing the given volume fractions of the five compounds

For full table - rotate the screen!

Compound Molweight Density@15°C Boiling point Xvol #mol Xmol Weight Xw
g/mol g/cm3 °C cm3/cm3 mol mol/mol g g/g
Iso-pentane 72.2 0.620 28 0.1 0.00086 0.13 0.062 0.084
3-methylpentane 86.2 0.660 63 0.2 0.00153 0.23 0.132 0.180
Iso-octane 114.2 0.690 99 0.3 0.00181 0.27 0.207 0.282
Meta-xylene 106.2 0.860 139 0.2 0.00162 0.24 0.172 0.234
Hexylcyclohexane 168.3 0.808 225 0.2 0.00096 0.14 0.162 0.220
MABP,  °C WABP,  °C VABP,  °C CABP,  °C MeABP,  °C
109.3 123.6 117.9 106.5 107.9

It can be seen that the WABP is biased against the densest components, while the MABP is biast against the lightest components.

However, a real gasoline contains hundreds of different compounds with individual properties, and a similar calculation is not possible to performe due to the complexity and lack of precise analytical tools.

The way to get past this restriction is to use a distillation curve obtained using a real distillation, as ASTM D86, or a gas chromatographic analysis, as ASTM D2887, to calculate VABP or WABP and then, use agreed correction factors to find the other kinds of ABPs.

Distillation curve naphtha

The table below shows results from a D86 and a D2887 analysis of a naphtha sample, and the calculated VABP and WABP and the slopes for the distillation curves, using the formulas:

VABP = 0.2*(T10% + T30% + T50% + T70% + T90%)   from D86

WABP = 0.2*(T10% + T30% + T50% + T70% + T90%)   from D2887

Slope = (T90% - T10%)/80

Fraction of sample recovered D86 D2887
Vol% (D86) or Wt% (D2887) °C °F °C °F
IBP 121 85
5 129 104
10 132 115
20 134 123
30 136 129
50 143 144
70 153 160
80 157 167
90 163 176
FBP 183 197
VABP 145 294
WABP 145 293
Slope, °C/% recovered 0.39 0.76
Slope, °F/% recovered 0.70 1.37


Correction factors are found by using the figures below. Note! The figures are using °C or °F, and results from D86.

The narrower the cut of the oil fraction (smaller slope), the smaller is the correction.


From_VABP_to_MABP

From_VABP_to_CABP


From_VABP_to_WABP


From_VABP_to_MeABP


The figures show that the correction from a VABP of 294°F to MABP is -6°F for a sample with a slope of 0.7°F/% recovered. That gives a MABP of 288°F.

The correction from a VABP of 294°F to CABP is only -1.5°F for a sample with a slope of 0.7°F/% recovered. (To see more detailes, right hand click on the figure and choose view image)

Sponsored Links

Related Topics

Related Documents

Tag Search

  • en: Average boiling point VABP MABP WABP CABP MeABP formula
Sponsored Links

Search the Engineering ToolBox

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

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

Translate this page to
About the Engineering ToolBox!

Privacy

We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.

Citation

This page can be cited as

  • Engineering ToolBox, (2017). Average boiling point. [online] Available at: https://www.engineeringtoolbox.com/Average-boiling-point-VABP-MABP-WABP-CABP-MeABP-formula-d_1994.html [Accessed Day Mo. Year].

Modify access date.

. .

close

3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Scientific Online Calculator

Scientific Calculator

12 7

Sponsored Links
.