Tungsten

Flammability

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

flammable solids

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:

UN Manual of Tests and Criteria: Test N.1 (Test method for readily combustible solids)

Version / remarks:

The tests were performed per UN Manual of Tests and Criteria for Transportation of Dangerous Goods, Section 33, Classification Procedures, Test Methods and Criteria Relating to Class 4, Test N.1: Test Method for Readily Combustible Solids.

Principles of method if other than guideline:

The sixth revised edition of the UN Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria clarifies that the “whole length of the sample” is to be taken as 100 mm: “Powders of metals or metal alloys should be classified when they can be ignited and the reaction spreads over the whole length (100 mm) of the sample in 10 minutes or less.”

GLP compliance:

not specified

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Several manufacturers submitted samples for testing with Fisher particulate size between 0.76 and 9.8 µm

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 67 sec; FSSS: 0.8 microns

Burning time:

>= 61 - <= 75 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 80 sec; FSSS=2.45 microns

Burning time:

>= 71 - <= 92 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 100 sec; FSSS=0.8 microns

Burning time:

>= 86 - <= 115 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 143 sec; FSSS=2.54 microns

Burning time:

>= 132 - <= 153 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 194 sec; FSSS= 0.76 microns

Burning time:

>= 171 - <= 221 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 200 sec; FSSS=2.87 microns

Burning time:

>= 178 - <= 217 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 209 sec; FSSS=3.24 microns

Burning time:

>= 197 - <= 224 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 273 sec; FSSS=4.35 microns

Burning time:

>= 255 - <= 291 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 277 sec; FSSS= 3.76 microns

Burning time:

>= 261 - <= 292 s

Interpretation of results:

Category 1 (flammable solids) based on GHS criteria

Conclusions:

Those tungsten powders with particle size less or equal than a Fisher Size of 4.35 microns in general had a burning time less than 300 seconds (5 minutes) and are considered flammable powders Category 1 (Packing Group II).

Reference 2

Endpoint:

flammable solids

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:

UN Manual of Tests and Criteria: Test N.1 (Test method for readily combustible solids)

Version / remarks:

The tests were performed per UN Manual of Tests and Criteria for Transportation of Dangerous Goods, Section 33, Classification Procedures, Test Methods and Criteria Relating to Class 4, Test N.1: Test Method for Readily Combustible Solids.

Principles of method if other than guideline:

The sixth revised edition of the UN Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria clarifies that the “whole length of the sample” is to be taken as 100 mm: “Powders of metals or metal alloys should be classified when they can be ignited and the reaction spreads over the whole length (100 mm) of the sample in 10 minutes or less.”

GLP compliance:

not specified

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Several manufacturers submitted samples for testing with Fisher particulate size between 0.76 and 9.8 µm

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 305 sec; FSSS= 5.25 microns

Burning time:

>= 268 - <= 348 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 310 sec; FSSS: 4.01 microns

Burning time:

>= 296 - <= 345 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 317 sec; FSSS= 4.75 microns

Burning time:

>= 301 - <= 345 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 338 sec; FSSS= 5.1 microns

Burning time:

>= 295 - <= 380 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 364 sec; FSSS= 5.3 microns

Burning time:

>= 334 - <= 412 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 417 sec; FSSS= 7 microns

Burning time:

>= 363 - <= 470 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 463 sec; FSSS= 6.4 microns

Burning time:

>= 424 - <= 493 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 511 sec; FSSS= 6.78 microns

Burning time:

>= 432 - <= 615 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 530 sec; FSSS= 7.85 microns

Burning time:

>= 503 - <= 577 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 559 sec; FSSS= 7.45 microns

Burning time:

>= 500 - <= 634 s

Interpretation of results:

Category 2 (flammable solids) based on GHS criteria

Conclusions:

Those tungsten powders with particle size between greater than a Fisher Size of 4.35 microns and less than 9 microns in general had a burning time greater than 300 seconds (5 minutes) and less than 600 seconds (10 minutes) are considered flammable powders Category 2 (Packing Group III).

Reference 3

Endpoint:

flammable solids

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:

UN Manual of Tests and Criteria: Test N.1 (Test method for readily combustible solids)

Version / remarks:

The tests were performed per UN Manual of Tests and Criteria for Transportation of Dangerous Goods, Section 33, Classification Procedures, Test Methods and Criteria Relating to Class 4, Test N.1: Test Method for Readily Combustible Solids.

Principles of method if other than guideline:

The sixth revised edition of the UN Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria clarifies that the “whole length of the sample” is to be taken as 100 mm: “Powders of metals or metal alloys should be classified when they can be ignited and the reaction spreads over the whole length (100 mm) of the sample in 10 minutes or less.”

GLP compliance:

not specified

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Several manufacturers submitted samples for testing with Fisher particulate size between 0.76 and 9.8 µm

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 648 sec; FSSS= 5.95 microns

Burning time:

>= 580 - <= 733 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 694 sec; FSSS: 9.4 microns

Burning time:

>= 659 - <= 732 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 704 sec; FSSS= 9.6 microns

Burning time:

>= 635 - <= 788 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 726 sec; FSSS= 9.8 microns

Burning time:

>= 690 - <= 777 s

Key result

Test procedure:

burning rate test over 100 mm length

Remarks:

Avg= 728 sec; FSSS= 9 microns

Burning time:

>= 644 - <= 866 s

Interpretation of results:

not classified based on GHS criteria

Conclusions:

Those tungsten powders with particle size greater or equal than a Fisher Size of 9 microns in general had a burning time greater than 600 seconds are considered non-flammable powders.

Description of key information

Several tungsten metal powder were tested using the new recommended 100 mm testing train. A total of 32 tungsten powder samples with a Fisher Sub Sieve Size (FSSS) ranging from 0.76 µm to 9.8 µm. The flammability tests were performed per UN Manual of Tests and Criteria for Transportation of Dangerous Goods, Section 33, Classification Procedures, Test Methods and Criteria Relating to Class 4, Test N.1: Test Method for Readily Combustible Solids.The scope of the laboratory’s accreditation (ISO/IEC 17025:2017) includes DOT 4.1 Ignitability and Burn Rate. Those with particle size less than 4.35 µm fell into CLP Cat 1 (Packing Group II) with a burning time of less than 300 seconds. Those with particle size between 4.35 µm and 9.0 µm fell into CLP Cat 2 (Packing Group III), with burning times between above of 300 to 600 seconds. Tungsten samples with particles sizes of equal to or greater than 9 µm with a burning time above 600 seconds did not meet the Class 4.1 or CLP flammable solid criteria.

Key value for chemical safety assessment

Flammability:

flammable

Justification for classification or non-classification

1. Those tungsten powders with particle size less or equal than a Fisher Size of ≤4.35 microns in general had a burning time less than 300 seconds (5 minutes) and are considered flammable powders Category 1 (Packing Group II).  
2. Those tungsten powders with particle size between greater than a Fisher Size of 4.35 microns and less than 9 microns in general had a burning time greater than 300 seconds (5 minutes) and less than 600 seconds (10 minutes) are considered flammable powders Category 2 (Packing Group III).
3. Those tungsten powders with particle size greater or equal than a Fisher Size of 9 microns in general had a burning time greater than 600 seconds are considered non-flammable powders.