Tungsten

Additional physico-chemical information

Administrative data

Endpoint:

other: dust cloud explosion

Type of information:

experimental study

Adequacy of study:

key study

Study period:

N/A to 2004-05-01

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:

Well documented, scientifically sound study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Explosion indices were measured using a standard method in a 20-I-spherical combustion chamber

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

tungsten metal

IUPAC Name:

tungsten metal

Constituent 2

Reference substance name:

Tungsten

EC Number:

231-143-9

EC Name:

Tungsten

Cas Number:

7440-33-7

Molecular formula:

W

IUPAC Name:

tungsten

Details on test material:

- Name of test material (as cited in study report): tungsten
- Analytical purity: 99.9%

Results and discussion

Results:

Explosive (not specified): yes, only for tungsten particles of 0.6-0.9 um and conetrations of 450 g/m3 or larger. Increasing concentrations at this size required increasing pressures for ignition from 0.2 bars at 450 g/m3 to 3.9 Bars at 2000 g/m3.

Any other information on results incl. tables

The coarser dusts (12 µm and 5 µm) did not appear to explode under the standard method conditions in the concentration range of 250 to 6000 g/m3 (12-µm dust) and 300 to 7000 g/m3 (5-µm dust), respectively. For the smallest particle size tested (0.6 -0.9 µm), the lower explosion limit was measured to be 450 g/m3. Starting from this limit, the maximum overpressure increased first with concentration, reached its maximum of at least 4.7 bar at 5000 g/m3 and then slowly decreased. The pressure rise rate showed the same behavior, its maximum was reached at the same concentration to be at least 260 bar/s. These values were measured at initial pressure lower 1 bar due to rather high explosive concentrations; the correction to the 1 bar initial pressure gives the calculated values of 5.7 bar and 310 bar/s, respectively.

Applicant's summary and conclusion

Conclusions:

The 12 µm and 5 µm tungsten dusts were not explosive under standard conditions, as tested using a 20-I-spherical combustion chamber. However, the finest particle size tested (0.6-0.9 µm) was determined to be explosive in this test under a wide range of concentrations (450 g/m3- 7500 g/m3).