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Physical & Chemical properties

Auto flammability

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Endpoint:
relative self-ignition temperature (solids)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
August 1993 - November 1994
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Qualifier:
no guideline followed
Principles of method if other than guideline:
Deposited dust:
This test determines the ignition temperature of a dry product on a hot surface.
The testing apparature, type MP-2 from Kühner company, consists of 5 separated and isolated blocks of aluminium. Round heating plates are connected on the surface with the aluminium block. The test material is put onto these heating plates. The temperature of those heating plates is 240,270,300, 330, 360°C respectively which can be controlled via an controlling device.
The test material is prepared by drying, grinding, sieving through a standardized sieve of 0.25mm (according to DIN 4188) and homogenous mixing.
Approx. 100 mg of test material is put onto the 360°C hot heating plate and is observed for 5 minutes. If a reaction occurs such as flame, glowing, sparkling or spontaneous deflagration, the test material is put onto the heating plate with the next lower temperature and is observed the same way.
All observations are recorded.
The reaction is evaluated, if the test substance ignites within 5 minutes (flame, glowing, sparkling) or decomposes without flames (decomposition time > 5 seconds).
The ignition properties are categorized in 6 classes (Bewertungszahlen – BWZ) in no reaction, and reaction at 360, 330, 300, 270, 240°C respectively.
GLP compliance:
not specified
Key result
Relative self-ignition temperature:
360 °C
Remarks on result:
other:
Remarks:
at atm. press.: no reaction observed

At the highest tested temperature (360°C) there was no reaction observed for deposited dusty dicyandiamide.

Conclusions:
No ignition on surfaces until 360°C for deposited dusty dicyandiamide.
Executive summary:

The test determines the ignition temperature of a deposited dusty test substance on hot surfaces. The test is conducted according to test protocol. The surface area of the substance is increased intentionally in this test by preparing the test substance accordingly to simulate the deposited dusty properties. The ignition temperature of deposited dusty test material is expected to be lower than the ignition temperature of the solid with larger particle diameters. At the hottest temperature in this test (360°C) there was no reaction observed for deposited dusty dicyandiamide.

Endpoint:
relative self-ignition temperature (solids)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
August 1993 - November 1994
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Qualifier:
no guideline followed
Principles of method if other than guideline:
Dispersed dust:
This test determines the ignition temperature of flammable dispersed dusty substances on hot surfaces.
A test apparature (graphic attached) according to the requirements of the German Federal Institution for Material Testing (BAM) is used.
The test material is prepared by drying, grinding, sieving through a standardized sieve of 0.25mm (according to DIN 4188) and homogenous mixing.
The oven is heated to 600°C; afterwards the heating is turned off. Approx. 0.1g of the test material is injected into the oven and the reaction is observed visually and acoustically. The reaction is evaluated, if the test material ignites or detonates.
If the test material shows such a reaction, the test is repeated with 50°C less until no more reaction is observed.
Then, the oven is heated to a temperature 50°C higher than the lowest temperature observed with a reaction. By reducing the temperature stepwise by 5°C the temperature is determined, at which the test material barely ignites / detonates. At 5°C lower no more reaction has to be observed.
At this temperature, the amount of test material is varied using 0.3 and 0.5 g.
The 5 lowest temperature values with reaction as well as the 5 highest temperatures without reaction are recorded for every amount tested in 5°C-intervals.
The ignition temperature is defined as the lowest temperature of the heated surface, at which the most explosive mixture of test material with air can be ignited.
GLP compliance:
not specified
Key result
Relative self-ignition temperature:
600 °C
Remarks on result:
other:
Remarks:
at atm. press.: no reaction observed

At the highest tested temperature (600°C) there was no reaction observed for dispersed dusty dicyandiamide.

Conclusions:
No ignition on surfaces until 600°C for dispersed dusty dicyandiamide.
Executive summary:

The test determines the ignition temperature of a dispersed dusty test substance on hot surfaces. The test is conducted according to the test protocol. The surface area of the substance is increased intentionally in this test by preparing the test substance accordingly to simulate the dispersed dusty properties. The ignition temperature of dispersed dusty test material is expected to be significantly lower than the ignition temperature of the solid with larger particle diameters. At the hottest temperature in this test (600°C) there was no reaction observed for dispersed dusty dicyandiamide.

Description of key information

Two tests for dusty dicyandiamide are available evaluating the auto flammability on hot surface

for deposited and dispersed dicyandiamide with particle diameter of 0.25mm. Both tests exhibited no reactions on hot surfaces.

Key value for chemical safety assessment

Additional information

The test for deposited dicyandiamide (100 mg) was conducted for 5 min on a hot surface up to 360°C. No reaction was observed.

The test for dispersed dicyandiamide was conducted on a surface up to 600°C. No reaction was observed.

As the tests were conducted with smaller particle diameters due to grinding and sieving the tested dusty dicyandiamide is expected to react even more sensible with regard to auto-flammability as original dicyandiamide produced directly from the operating facilities. Therefore it is concluded that the self-ignition temperature of dicyandiamide is higher than 360°C. This temperature is higher than the melting point (approx. 209 -212°C). Thus dicyandiamide melts before it is self-ignited.