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Physical & Chemical properties

Flash point

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flash point of flammable liquids
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to guideline
EU Method A.9 (Flash-Point)
Principles of method if other than guideline:
The study was performed as described in the guideline DIN 51758 (Pensky-Martens closed cup method) in accordance with the Standard Operating Procedures.
GLP compliance:
Type of method:
closed cup
Key result
Flash point:
> 200 °C
Atm. press.:
101.325 kPa

No flash point could be determined up to 200 °C.

The flash point for methyl phosphonic acid was found to be >200 °C.
Executive summary:

The determination of the flash-point of the test item was performed in accordance with the EEC Directive Annex V of 67/548 Test A 9 Flash Point. In the Pensky-Martens closed cup flash point test, a brass test cup is filled with FAT 91186/A TE (dry residue, liquid) and fitted with a cover. The sample is heated up with the help of an electrically operated furnace and stirred at specified rates. An ignition source is directed into the cup at regular intervals (from 110 °C it is measured after every degree) with simultaneous interruption of stirring until a flash that spreads throughout the inside of the cup is seen. The corresponding temperature is the flash point. However, based on the findings of the study, no flash point for the test substance could be seen up to 200 °C.

Description of key information

Methylphosphonic acid is an organic phosphorous substance with a very low volatility. The purified chemical is solid at room temperature forming white crystals. The 70 % aqueous solution which is the preferred trade form has been shown to produce practically non-volatile fractions of MPA. Therefore, the purified crystalline form as well as the 70 % aqueous solution are considered to have a flash point far above 200 °C (if at all) before thermal combustion of the chemical occurs. These test results are in line with other test results listed in various databases.

Key value for chemical safety assessment

Flash point at 101 325 Pa:
200 °C

Additional information