The Tetens equation works well for 0-50 ☌ range, but Buck beats all of them, for every checked value. T (☌)Īs you can notice, the Antoine equation is reasonably accurate for higher temperatures, but the low ones are calculated with quite a big error. The reference values come from Lide table with vapor pressure of water (all pressures given in kPa). The table below shows the comparison of the accuracies between different formulas, for several temperatures from 0-100 ☌ range (32-212☏). You can also use another equation, called the Goff-Gratch formula, but as it's more complicated (and approximately as accurate as Buck formula), we didn't implement it in our vapor pressure of water calculator. Buck formula, also known as Arden Buck equationīuck_pressure = 0.61121 * e^.Magnus formula, also known as August-Roche-Magnus or Magnus-Tetens equation.
Jump to the next section to read more about the constants in the Antoine formula. The temperature T is expressed in degrees Celsius and the vapor pressure P is in mmHg. Simple_pressure = e^(20.386 - (5132 / (temperature + 273)), where vapor pressure is expressed in mmHg and temperature in kelvins.Īntoine_pressure = 10^ In our calculator you'll find implemented:
The most well known and established is the Antoine equation, but other methods also exist (and they perform better in typical conditions). There are many different formulas thanks to which you can calculate the vapor pressure of water.
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