Strontium

Flammability

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

flammable solids

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-05-19

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:

2015

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: VDI 2263, sheet 1

Version / remarks:

1990

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2013-03-22

Key result

Test procedure:

burning rate test: preliminary screening test

Burning time:

0 s

Remarks on result:

other: the test item could not be ignited by a flame, and thus did not propagate combustion by burning with flame or smouldering.

Preliminary Test

The test item did not ignite at room temperature using a flame as ignition source for 5 minutes. The test item glowed and melted.  

Main Test

In the preliminary test, the test item could not be ignited by a flame, and thus did not propagate combustion by burning with flame or smouldering. Therefore, the performance of the main test was not necessary.

Final Results

The test item Strontium could not be ignited applying a flame as ignition source for 5 minutes. Therefore, the test item is classified as follows:

UN Transport Regulation:

The test item in its commercial form (i.e. rods) does not meet classification criteria of a readily combustible solid in Class 4, Division 4.1 according to the UN Transport Regulation.

GHS (CLP Regulation EC 1272/2008: Annex 1: 2.7):

The test item in its commercial form (i.e. rods) does not meet classification criteria of a flammable solid according to GHS and EC 1272/2008 (CLP Regulation) Annex 1: 2.7.

Interpretation of results:

GHS criteria not met

Conclusions:

The test item Strontium could not be ignited applying a flame as ignition source for 5 minutes.Therefore, the test item is classified as follows:UN Transport Regulation: The test item in its commercial form (i.e. rods) does not meet classification criteria of a readily combustible solid in Class 4, Division 4.1 according to the UN Transport Regulation.GHS (CLP Regulation EC 1272/2008: Annex 1: 2.7): The test item in its commercial form (i.e. rods) does not meet classification criteria of a flammable solid according to GHS and EC 1272/2008 (CLP Regulation) Annex 1: 2.7.

Reference 2

Endpoint:

substances / mixtures which in contact with water emit flammable gases

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-05-19 to 2016-05-23

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.5 (Test method for substances which in contact with water emit flammable gases)

Version / remarks:

2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2013-03-22

Test procedure:

step 1

Identity of evolved gas:

other: hydrogen

Remarks:

assumption

Remarks on result:

other: The test item emitted gas when placed in a bowl containing distilled water, but a spontaneous ignition was not observed.

Test procedure:

step 2

Identity of evolved gas:

other: hydrogen

Remarks:

assumption

Remarks on result:

other: The test item emitted gas when placed onto a filter paper floating on the surface of a bowl containing distilled water, but a spontaneous ignition was not observed.

Test procedure:

step 3

Identity of evolved gas:

other: hydrogen

Remarks:

assumption

Remarks on result:

other: The test item emitted gas when a few drops of water were added to the test item, but a spontaneous ignition was not observed.

Key result

Test procedure:

step 4

Max. rate of gas release:

200 L/kg min

Identity of evolved gas:

other: hydrogen

Remarks:

assumption

Remarks on result:

other: form of the test item: swarf

The temperature during the tests was 21 °C

Step 1

The test item emitted gas when placed in a bowl containing distilled water, but a spontaneous ignition was not observed.

Step 2

The test item emitted gas when placed onto a filter paper floating on the surface of a bowl containing distilled water, but a spontaneous ignition was not observed.

Step 3

The test item emitted gas when a few drops of water were added to the test item, but a spontaneous ignition was not observed.

Step 4

Pieces and nuggets of the test item of different forms and sizes with a weight of approximately 10 or 5 g were used for the three tests. The following tables show the results of Step 4:

Table 1: Results of step 4 (Test 1)

Amount of test item [g]	Test 1
	10.00 (small pieces and swarf)
Amount of water [mL]	20
Temperature (H2O) [°C]	21.1
Time [s]	Amount of emitted gas [mL]	Time [s]	Amount of emitted gas [mL]
40	200	134	1300
75	300	144	1400
90	400	157	1500
95	500	169	1600
100	600	186	1700
103	700	200	1800
106	800	223	1900
110	900	248	2000
115	1000	390	>2000
120	1100	930	>2000
126	1200	--	--

As Table 1 indicates, the whole test item reacted with water within 930 s. The highest gas evolution rates were observed between 103 and 106 s of about 200 L/kg/min (12,000 L/kg/h).

Table 2:   Results of step 4 (Test 2)

Amount of test item [g]	Test 2
	5.10 (three nuggets)
Amount of water [mL]	20
Temperature (H2O) [°C]	21.1
Time [s]	Amount of emitted gas [mL]	Time [s]	Amount of emitted gas [mL]
690	200	2228	600
780	240	2430	640
830	260	2715	700
925	300	2940	740
1085	340	3300	800
1305	400	3600	840
1485	440	8100	1440
1740	500	10800	1440
1940	540	--	--

As Table 2 indicates, the whole test item reacted with water within 8100 s. The highest gas evolution rate was observed at 780 s of about 5.2 L/kg/min (314 L/kg/h).

Table 3:   Results of step 4 (Test 3)

Amount of test item [g]	Test 3
	5.59 (one nugget)
Amount of water [mL]	20
Temperature (H2O) [°C]	20.6
Time [s]	Amount of emitted gas [mL]	Time [s]	Amount of emitted gas [mL]
760	200	3580	780
1150	260	3680	800
1350	320	3933	840
1635	400	4180	880
2088	500	6110	1080
2200	520	7635	1200
2303	540	9630	1320
2500	580	15291	1420
2607	600	16320	1440
2812	640	18730	1460
3023	680	20760	1480
3121	700	22600	1480
3343	740	24420	1500

In test 3, most of the test item reacted with water within 24420 s. The residue of the test item was left in the apparatus over the weekend. After three days the total gas volume was determined to be 1540 mL. The highest gas evolution rate was observed at 1350 s of about 3.2 L/kg/min (193 L/kg/h).

Depending on the physical form of the test item, whether it exists in small pieces and sor in bigger nuggets, different results are obtained.

The following table summarizes the highest gas evolution rates.

Gas evolution rate

	Test 1	Test 2	Test 3
Physical form	Small pieces & swarf	3 nuggets	1 nugget
Max. gas evolution rate [L/kg/h]	12,000	314	193
Max. gas evolution rate [L/kg/min]	200.0	5.2	3.2

Interpretation of results:

Category 1 (substances or mixtures which in contact with water release flammable gases which may ignite spontaneously) based on GHS criteria

Conclusions:

The test item Strontium emitted gas in contact with water in each of the 4 steps of the test procedure. Based on the chemical reaction, it is assumed that hydrogen, an extremely flammable gas (Flam. Gas 1, H220), evolves upon contact of strontium with water.According to the results of the test for substances which in contact with water emit flammable gases (max. gas evaporation rate of 200 L/kg/min, no self-ignition of the evolved gas, gas assumed to be flammable), the test item in the tested form (i.e. swarf) meets the following classification criteria:UN Transport Regulation:The test item in the tested form (i.e. swarf) meets the classification criteria of Class 4 Division 4.3 “Substances which in contact with water emit flammable gases” according to the UN Transport Regulation.Packaging group Ishould be assigned to the test item in the tested form (i.e. swarf).GHS and EC 1272/2008 (CLP-Regulation)Annex 1: 2.12:The test item in the tested form (i.e. swarf) meets the classification criteria of a “Substance or mixture which in contact with water emit flammable gases”according to GHS and EC 1272/2008 (CLP-Regulation) Annex 1: 2.12,category 1.

Description of key information

Möller (2016) Flammability (solids) A.10: No

Möller (2016) Flammability in contact with water A.12: GHS and CLP-Regulation, Category 1 (H 260).

CRC (2016, 2018) Pyrophoric properties of solids: No

Key value for chemical safety assessment

Flammability:

substances and mixtures which in contact with water emit flammable gases

Additional information

Flammability (solids) A.10:

Strontium in its commercial form (rods) could not be ignited applying a flame as ignition source for 5 minutes, and thus, does not meet classification criteria of a flammable solid according to GHS and EC 1272/2008 (CLP Regulation) Annex 1: 2.7.

Flammability in contact with water A.12:

Strontium (rods) emitted gas in contact with water in each of the 4 steps of the test procedure. According to the results of the test for substances which in contact with water emit flammable gases (max. gas evaporation rate of 200 L/kg/min, no self-ignition of the evolved gas, gas assumed to be flammable), strontium in its commercial form (rods) meets the classification criteria of a “Substance or mixture which in contact with water emit flammable gases” according to GHS and EC 1272/2008 (CLP-Regulation) Annex 1: 2.12,category 1.

Pyrophoric properties of solids A.13:

According to Regulation (EC) No 1907/2006, Annex XI, Section 1, the study does not need to be conducted since strontium metal rods did not show any phyrophoric properties in contact with air in the flammability studies according to UN Test N.1 and N.5. Thus, it may be assumed not to be pyrophoric under the conditions given in EU-Method A.13.

In the literature (Merck, 2006), the following is stated: The finely divided metal ignites spontaneously in air. However, the particle size of strontium was not stated. The smallest commercial form of strontium are rods with the size of approximately 20 mm x 15 mm. Even at smaller size of approximately 2 mm diameter, a spontaneous ignition in air was not observed in the UN Test N.5. Thus, pyrophoric properties of strontium in its smallest commercial form can be excluded.