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Physical & Chemical properties

Additional physico-chemical information

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Administrative data

Endpoint:
additional physico-chemical information
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
Endpoint investigated:
other: dust cloud explosion

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
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 um and 5 um) did not appear to explode under the standard method conditions in the concentration range of 250 to 6000 g/m3(12 -um dust) and 300 to 7000 g/m3 (5-um dust), respectively. For the smallest particle size tested (0.6 -0.9 um), 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 um and 5 um 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 um) was determined to be explosive in this test under a wide range of concentrations (450 g/m3- 7500 g/m3).