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Physical & Chemical properties

Flammability

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Endpoint:
flammable solids
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Na to: 2007-06-04
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Remarks:
Well documented study, conducted with methodology equivalent to EU methods A.10.
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
EU Method A.10 (Flammability (Solids))
Qualifier:
according to
Guideline:
other: U.N Classification of Redily Combustible Solids Division 4.1 and Packaging Group Assignment per UN Test N1(burning rate test)
GLP compliance:
not specified
Test procedure:
burning time (test type not further specified)
Remarks:
or specified in description of method (migrated information)
Burning time:
190 s

The sample ignited almost immediately and expanded while burning.

The sample (0.60-0.90 um in particle size) had a burning rate time of less than 10 minutes (190 seconds (3 minutes and 10 seconds)).

Conclusions:
Based on the results of the test, the substance was considered to be flammable.
Endpoint:
flammable solids
Type of information:
experimental study
Adequacy of study:
key study
Study period:
N/A to: 2004-06-01
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Remarks:
Conducted with methodology equivalent to EU methods A.10 and A.13.
Qualifier:
equivalent or similar to
Guideline:
EU Method A.10 (Flammability (Solids))
Qualifier:
equivalent or similar to
Guideline:
EU Method A.13 (Pyrophoric Properties of Solids and Liquids)
GLP compliance:
not specified
Test procedure:
burning time (test type not further specified)
Remarks:
or specified in description of method (migrated information)
Burning time:
417 s

As the test substance did not go into flame or carbonize filter paper within 5 minutes of contact with room air it was not considered pyrophoric.

The burning rates (mm/s) for the samples tested were as follows

1.1 µm = 0.55

1.0 µm = 0.56

1.5 µm = 0.60

2.5 µm = 0.38

3.5 µm = 0.24

size not reported = 0.25

4.5 µm = 0.2

5.0 µm = 0.19

6.0 µm = 0.18

8.0 µm = 0.078

12 µm = burned 8.7 cm in 40 minutes

The calculated times (total seconds) for burning the 250 mm sample lengths were as follows:

1.1 µm = 455, (< 10 minutes)

1.0 µm = 446, (< 10 minutes)

1.5 µm = 417, (< 10 minutes)

2.5 µm = 658

3.5 µm = 1042

size not reported = 1000

4.5 µm = 1250

5.0 µm = 1316

6.0 µm = 1389

8.0 µm = 3205

Powders are considered as very flammable when they can be inflamed and when the flame or reaction zone goes through the sample in <10 minutes.

Conclusions:
Only three samples (particle sizes 1.1, 1.0, and 1.5 um) had burning rate times of less than 10 minutes. Therefore, the test substance is considered to be flammable in this test at this particle size range. It is not considered to be a pyrophoric material.

Description of key information

Two studies were used to determine the flammability of a range of particle sizes of tungsten metal. The first study, examined particle sizes 0.6-0.9 um, which were found to have a burn time of 3 minutes, 10 seconds. The second study examined particle sizes 1.0-8.0 um (FSSS), and found that particle sizes 1.0, 1.1, and 1.5 um had a burn time of less than 10 minutes, while larger particle sizes burned slower and can be considered to be non-flammable.

Key value for chemical safety assessment

Flammability:
flammable

Additional information

Justification for classification or non-classification

Due to the burn times observed in the two studies, the following classification was assigned:

Particle sizes <1.0 um = Category 1 Flammability

Particle sizes 1.0 -1.5 um = Category 2 Flammability

Particle sizes >1.5 um = Not classified for flammability