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Physical & Chemical properties

Flammability

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Description of key information

Key value for chemical safety assessment

Flammability:
non flammable

Additional information

Flammability:

The test item strontium sulfide is not a highly flammable solid in the sense of the European Commission Regulation (EC) No.440/2008, Method A.10/UN test N.1 and it is not a flammable solid in the sense of the classification criteria as laid down in Regulation (EC) No. 1272/2008 (CLP Regulation).

Pyrophoric properties:

In accordance with Regulation (EC) No 1907/2006 Annex XI, Section 1, testing for pyrophoric properties of solids is not considered to be required, since strontium sulfide is stable at ambient temperature. It also does not contain any chemical groups that might lead to spontaneous ignition a short time after coming in contact with air at room temperature (ca. 20 °C). Furthermore, long-term industrial experience in handling shows that strontium sulfide does not ignite (spontaneously) (i.e. the autoignition temperature is not below room temperature) in contact with air.

Flammability in contact with water:

The soluble compound strontium sulfide will initially dissociate upon dissolution in water and/or relevant physiological media into sulfide and strontium ions. Sulfide (S2-), hydrogen sulfide (sulfhydryl) anions (HS-) and hydrogen sulfide (H2S), respectively, coexist in aqueous solution in a dynamic pH-dependant equilibrium. Sulfide prevails only under very basic conditions (only at pH > 12.9), hydrogen sulfide anions are most abundant at pH 7.0 – 12.9, whereas at any pH < 7.0, hydrogen sulfide (aq) is predominant.

Hydrogen sulfide is known to a highly flammable (Index no.: 016-001-00-4) gas. However, the development of highly flammable gases of hydrogen sulfide (≥ 1L/kg per h) is impossible, since the pH value of a saturated solution is 13.5. According to the above; at pH 13.5, S2-(~90 %) and HS-(~10 %) are present in solution. Hence, strontium sulfide could be regarded as non-flammable in contact with water and must not be classified as such according to Regulation (EC) 1907/2006 Annex VII column 2) "flammability".

Justification for classification or non-classification

Strontium sulfide does not need to be classified for flammability according to Directive 67/548 EEC and CLP Regulation (EC) No 1272/2008based on testing results.