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Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
static method
Temp.:
20 °C
Vapour pressure:
78 Pa
Remarks on result:
other: (mean of 2 runs)

Temp / °C  Temp / K  P / mbar  **P / Pa 
Run 1 
*20  293.15  0.75  75
31.0  304.15  2 200
33.3  306.45  2.3  230
38.8  311.95  3.7  370
41.2  314.35  4.7  470
44.5  317.65  5.7  570
Run 2 
*20  293.15  0.81  81
31.2  304.35  2.2  220
33.2  306.35  2.6  260
37.0  310.15  3.5  350
40.5  313.65  4.7  470
44.1  317.25  6.3  630
46.3  319.45  7.5  750

* - Determined by extrapolation

** - Calculated

Conclusions:
The vapour pressure is estimated to be 78 Pa at 20°C (mean of 2 runs).
Executive summary:

This report contains the results of physical chemical tests conducted on Coolact 10. The tests were conducted in accordance with the protocols in EU Regulation (EC) 440/2008, as well as the OECD guideline n°104 and Chilworth Technology Ltd standard operating procedures. The work was subjected to Good Laboratory Practice audit

The test is conducted to determine the vapour pressure of a test substance by the Static method – using a U-tube manometer.

The static method involves placing a sample in a bulb maintained at constant temperature and connected to a pressure monitor and a vacuum pump. The method is suitable for multi-component systems. Results are subject to only slight errors for sample containing non-volatile impurities. The recommended range is 10 to 10^5 Pa.

A sufficient quantity of sample is added to the static method glassware. The glassware is attached to the vacuum system and both the system and the filled glassware are evacuated to a pressure of 13.3 Pa (0.1 torr). The vacuum is broken with nitrogen and the system is evacuated again. This procedure is repeated a further two times to remove any residual oxygen.

After the sample has been degassed, the vacuum line valve is closed along with the relevant static method glassware valves. The filled static method glassware is positioned in the constant temperature bath at the desired starting temperature. As the static apparatus approaches temperature equilibrium in the bath, nitrogen is added to the gas-sampling system until its pressure equals that of the sample. Periodically the pressure of the nitrogen in the gas-handling system is adjusted to equal that of the sample.

When the static apparatus reaches temperature equilibrium, final adjustments of the nitrogen pressure are made to equal the vapour indicated by the manometer section of the apparatus. When the liquid levels in the manometer arms are equal in height, balance is indicated. The nitrogen pressure in the system is recorded at the balance point.

In the case of liquids, the substance itself serves as the fluid in the differential manometer and for solids, depending on the pressure and temperature ranges, manometer liquids such as silicon fluids or phthalates are used. The temperature of the constant-temperature bath is increased by an appropriate amount. As the temperature rises, the pressure balance in the system is maintained. When temperature equilibrium is reached, final adjustments of pressure are made to establish balance. The system pressure is then recorded. This process is repeated at regular intervals until an adequate range of pressures has been obtained.

The vapour pressure is estimated to be 78 Pa at 20°C (mean of 2 runs).

Description of key information

The vapour pressure is estimated t be 78 Pa at 20°C

Key value for chemical safety assessment

Vapour pressure:
78 Pa
at the temperature of:
20 °C

Additional information

The vapour pressure of the substance was determined in a study which was conducted under GLP conditions and in accordance with the standardised guideline EU Method A.4, following the standard method. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

Under the conditions of the study the vapour pressure of the substance was estimated to be 78 Pa at 20°C

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