Trihexyl phosphate

Auto flammability

Link to relevant study record(s)

Reference

Endpoint:

auto-flammability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13-20 Oct 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.15 (Auto-Ignition Temperature (Liquids and Gases))

GLP compliance:

yes (incl. QA statement)

Remarks:

Rheinland-Pfalz Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht, Kaiser-Friedrich-Strasse 7, D-55116 Mainz

Auto-ignition temperature:

280 °C

Atm. press.:

ca. 1 000 hPa

Pre-determination:

The ignition attempts of the pre-determination program are presented in the following table:

T vessel (°C)	No. of drops used	Ignition y/n	Observation
200.7	5	n	fume
222.5	5	n	fume
246.2	5	n	fume
269.4	5	n	lots of fume
291.8	5	n	lots of fume
315.1	5	y	flame and plop ignition after 13 s

Selected T: 300 °C. The temperature was selected at the ZPA3 corresponding to an initial oven temperature of 200 °C. Using a constant heating rate, the subsequent ignition trials were conducted every 20 ± 5 K.

Atmospheric pressure during the pre-test was 99468 Pa.

First test series:

The ignition attempts of the first test series of the main determination (using programs HAl and H-A2) are presented in the following table:

Used program	Selected T*	T vessel (°C)	No. of drops used	Ignition y/n	Observations
H-A1	333	333.4	5	y	flame and plop ignition after 11 s
H-A1	328	328.1	5	y	flame and plop ignition after 9 s
H-A1	323	323.3	5	y	flame and plop ignition after 9 s
H-A1	318	318.3	5	y	flame and plop ignition after 9 s
H-A1	313	313.3	5	y	flame and plop ignition after 9 s
H-A1	308	308.4	5	y	flame and plop ignition after 10 s
H-A1	303	303.4	5	n	fume
H-A1	303	302.5	9	n	lots of fume
H-A1	303	303.4	13	n	lots of fume
H-A1	303	303.4	17	n	lots of fume
H-A2	306	305.0	5	y	flame and plop ignition after 18 s
H-A2	304	303.5	5	y	flame and plop ignition after 12 s
H-A2	302	301.5	5	y	flame and plop ignition after 15 s
H-A2	300	300.5	5	y	flame and plop ignition after 25 s
H-A2	298	298.0	5	y	flame and plop ignition after 19 s
H-A2	296	296.1	5	y	flame and plop ignition after 22 s
H-A2	294	293.6	5	n	fume
H-A2	294	294.0	9	n	fume
H-A2	294	293.8	13	n	fume
H-A2	294	294.0	17	n	fume

* The selected temperature was suggested automatically by the ZPA3.

The first 10 ignition trials were conducted on 13. Oct. 2015 (atmospheric pressure during the trials 99468 Pa) and the other ones on 14. Oct. 2015 (atmospheric pressure during the trials 99706 Pa). Lowest value of the first test series is 296 °C.

Second test series:

The ignition attempts of the second test series of the main determination are presented in the following table:

Used program	Selected T*	T vessel (°C)	No. of drops used	Ignition y/n	Observations
H-A1	313	312.8	5	y	flame and plop ignition after 12 s
H-A1	308	308.2	5	y	flame and plop ignition after 12 s
H-A1	303	303.4	5	y	flame and plop ignition after 16 s
H-A1	298	298.2	5	n	lots of fume
H-A1	298	298.3	9	y	flame and plop ignition after 20 s
H-A1	293	293.1	9	y	flame and plop ignition after 21 s
H-A1	288	288.1	9	n	lots of fume
H-A1	288	288.4	5	y	flame and plop ignition after 25 s
H-A1	283	283.4	5	n	lots of fume
H-A1	283	283.4	9	n	lots of fume
H-A1	283	283.4	13	n	lots of fume
H-A1	283	283.4	17	n	lots of fume
H-A2	286	286.4	5	n	lots of fume
H-A2	286	286.4	9	y	flame and plop ignition after 29 s
H-A2	284	283.4	9	y	flame and plop ignition after 41 s
H-A2	282	282.2	9	n	lots of fume
H-A2	282	281.9	5	n	lots of fume
H-A2	282	282.4	13	y	lots of fume
H-A2	282	282.2	17	y	lots of fume

* The selected temperature was suggested automatically by the ZPA3.

The first 14 ignition trials were conducted on 15. Oct. 2015 (atmospheric pressure during the trials 99500 Pa) and the other ones on 16. Oct. 2015 (atmospheric pressure during the trials 99744 Pa). Lowest value of the second test series is 283 ° C.

Third test series:

The ignition attempts of the third test series of the main determination are presented in the following table:

Used program	Selected T*	T vessel (°C)	No. of drops used	Ignition y/n	Observations
H-A1	293	293.1	12	y	flame and plop ignition after 22 s
H-A1	288	288.2	12	n	lots of fume
H-A1	288	288.2	8	y	flame and plop ignition after 39 s
H-A1	283	282.5	8	n	lots of fume
H-A1	283	283.0	4	n	lots of fume
H-A1	283	283.0	12	n	lots of fume
H-A1	283	283.2	16	n	lots of fume
H-A1	283	283.2	20	n	lots of fume
H-A2	286	285.6	8	y	flame and plop ignition after 29 s
H-A2	284	284.0	8	y	flame and plop ignition after 34 s
H-A2	282	281.5	8	n	lots of fume
H-A2	282	281.7	4	n	lots of fume
H-A2	282	281.5	12	n	lots of fume
H-A2	282	281.9	16	n	lots of fume
H-A2	282	282.0	20	n	lots of fume

* The selected temperature was suggested automatically by the ZPA3.

The ignition trials were conducted on 19. Oct. 2015 (atmospheric pressure during the trials 100133 Pa). Lowest value of the third test series is 284 °C. As the difference of the three test series was more than 10 K, a fourth test series was also performed and the results of the last three test series were used for evaluation.

Fourth test series:

The ignition attempts of the fourth test series of the main determination are presented in the following table:

Used program	Selected T*	T vessel (°C)	No. of drops used	Ignition y/n	Observations
H-A1	293	292.8	8	y	flame and plop ignition after 29 s
H-A1	288	288.3	8	y	flame and plop ignition after 73 s
H-A1	283	288.2	8	y	flame and plop ignition after 60 s
H-A1	278	278.3	8	n	lots of fume
H-A1	278	278.2	4	n	lots of fume
H-A1	278	278.3	12	n	lots of fume
H-A1	278	278.2	16	n	lots of fume
H-A1	278	278.3	20	n	lots of fume
H-A2	281	281.2	8	y	flame and plop ignition after 50 s
H-A2	279	279.2	8	n	lots of fume
H-A2	279	279.2	4	n	lots of fume
H-A2	279	279.2	12	n	lots of fume
H-A2	279	279.4	16	n	lots of fume
H-A2	279	279.0	20	n	lots of fume

*The selected temperature was suggested automatically by the ZPA3. The ignition trials were conducted on 20. Oct. 2015 (atmospheric pressure during the trials 100219 Pa). Lowest value of the fourth test series is 281 °C.

Result:

The requirements for repeatability of the DIN standard are stated as follows: Three lowest values of the main test have to lie within a range of 10 K (if auto ignition temperature is below 300 °C) respectively 20 K (if auto ignition temperature is above 300 °C). The following lowest values were recorded:

Experiment	Value	Ignition delay	Drops used
First test series*	296°C	22 s	5
Second test series	283 °C	41 s	9
Third test series	284 °C	34 s	8
Fourth test series	281 °C	50 s	8

*The first test series was not used for evaluation because the deviation was too high in comparison to other test series.

The lowest value of the auto ignition temperature is 281 °C. This value was determined using 8 drops test item. The test item showed auto ignition after 50 seconds. The auto ignition temperature (result of determination) is the lowest value from the lowest values of the three experiments, rounded down to a whole multiple of 5 °C. Therefore, the auto ignition temperature is stated as 280 °C.

As three lowest values of the main test have to lie within a range of 10 K (if auto ignition temperature is below 300 °C) respectively 20 K (if auto ignition temperature is above 300 °C), and the largest difference between measured ignition temperatures was 3 K, the result is considered valid.

Description of key information

280 °C (EU A.15)

Key value for chemical safety assessment

Autoflammability / Self-ignition temperature at 101 325 Pa:

280 °C

Additional information

The self-ignition temperature of the substance trihexyl phosphate (CAS No. 2528-39-4) was determined according to procedure and demands of EU-Method A.15 and DIN 51 794. The acceptable range which is demanded in the DIN standard was fulfilled.