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Physical & Chemical properties

Vapour pressure

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vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2013 May
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
according to guideline
OECD Guideline 104 (Vapour Pressure Curve)
GLP compliance:
Type of method:
other: Photocell BP detection method, Vapor Pressure Curve
Key result
20 °C
Vapour pressure:
3 206 Pa

*INFORMATION REQUIRMENTS-The study does not need to be conducted if the melting point is above 300C. If the melting point is between 200C and 300C, a limit value based on measurement or a recognized calculation method is sufficient. Vapor pressure testing is also not required for chemicals with a standard boiling point of <30C, as these substances will have vapor pressures above the limit of measurement. (105Pa)





The vapor pressure measurements were conducted using a photocell detection method which employs a Mettler FP90 temperature control module and a Mettler FP81HT measurement cell. The tests were conducted according to Method A2 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC). 




A reference material, m-xylene, was first run to confirm the accuracy of the method. In Table VII-1, the measured vapor pressure data of m-xylene are compared to recommended literature vapor pressure data from Reference VII-1.


The sample was placed in a glass boiling point tube to height of 15 mm. A boiling point capillary was then inserted to act as a boiling chip. The sample temperature was controlled by the FP90/FP81HT system as was the detection of the boiling point of the sample. Pressure was regulated by a manifold consisting of stainless steel tubing, two manometers, vacuum pump, a surge tank, and a bleed valve. The vacuum apparatus was connected to the glass sample tube via a short section of silicone tubing. The pressure was then set to the desired value and allowed to stabilize. The sample temperature was then raised slowly to a value approximately 30 ⁰C below the expected boiling point. The sample was then allowed to degas at constant temperature for 5 minutes . The measurement of the boiling point at stated pressure was then determined by increasing the sample temperature at a rate of 1 ⁰C/minute until the instrument detected boiling of the sample. Boiling was optically detected by a photocell in the FP81HT. The boiling point is defined as the point when the bubble rate in the sample tube reaches 0.6 Hz.



The measured data were regressed to an Antoine equation and the vapor pressure at 20 ⁰C calculated from the resulting equation (Figure VII-1). 




The MPK raw measured data are reported in Table VII-2. The Method A4 estimated value of vapor pressure at 20 °C is 3280 Pa versus the extrapolated value of 3206 Pa. The greatest value of vapor pressure, 3206 Pa, between these two values is reported as the vapor pressure of MPK at 20 °C since it is the most conservative.



Table VII-1. m-Xylene reference vapor pressure measurements


                                Measured                             Reference               Deviation from

Temp, °C             Pressure, mm Hg               Pressure, mm Hg       Reference, mm Hg

44.5                                  20                                      23.9                               -3.9

57.0                                    40                                        43.3                               -3.3

72.6                                    80                                        84.5                               -4.5

89.8                                    162                                     163.5                            -1.5

109.7                                  333                                     321.6                             11.4

139.4                                 760                                    766.2                            -6.2



Table VII-2. MPK vapor pressure measurements


Temp, ⁰C           Pressure, mm Hg             Pressure, Pa

29.2                                    40                         5333

42.5                                    80                         10666

58.3                                    159                      21198

77.1                                    329                      43863

102.7                                  760                      101325

Figure VII-1. Regression of measured vapor pressure data

FigureVII-2. Plot of measured vapor pressure and estimated vapor pressure at 20°C



Figure VII-3. Estimation of Vapor Pressure at 20 ⁰C from Normal Boiling Point





Figure VII-3. Estimation of Vapor Pressure at 20 ⁰C from Normal Boiling Point (continued)



VII-1. Design Institute for Physical Properties (DIPPR) 801 Thermophysical Property Database, Sponsors’ Version, January 2011.


VII-2. W. J. Lyman, W. F. Reehl, and D. H. Rosenblatt,Handbook of Chemical Property Estimation Methods, McGraw-Hill, 1982.

The vapor pressure of the test substance was determined to be 3206 Pa at 20 C.
Executive summary:

The vapor pressure of the test substance was determined to be 3206 Pa at 20 C.

Description of key information

The vapor pressure of the test substance was determined to be 3206 Pa at 20 C.

Key value for chemical safety assessment

Vapour pressure:
3 206 Pa
at the temperature of:
20 °C

Additional information