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Physical & Chemical properties

Flammability

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Description of key information

Flammability properties of zirconium are highly depend on the form and particular size of the metal.
A test performed on zirconium metal (sponge) shows that it is highly flammable according to 67/548/EEC
In the powder form and according to its size, Zirconium can be pyrophoric, under specific conditions of moisture (3% to 25% water content) .
As stated in the harmonised Classification and Labelling (CLP 1272/2008, annex VI): zirconium powder is classified "pyr sol.1" and "water react 1"
zirconium powder dry is classified "self heat 1"

Key value for chemical safety assessment

Flammability:
contact with water liberates highly flammable gases

Additional information

Flammability is usually seen as the ease with which the substance can burn or be ignited. However it also includes spontaneously flammability (pyrophoricity) and ignition on contact with water.

PYROPHORICITY

POWDER FORM:

The various studies show that zirconium in the powder form presents a risk of explosion in contact with air according to its particle size, especially if particles have a diameter lower than 62 µm.

Furthermore, zirconium powder in contact with water (humidity between 3 % and 25 %) can ignite spontaneously.

According to annex VII, section 7.13 column 2 of the REACH regulation on standard information requirements, the study does not need to be conducted when the substance ignites spontaneously with air at room temperature. Zirconium powder presents risks of spontaneous ingnition, therefore, the test for zirconium powder is not conducted.

As stated in the harmonised Classification and Labelling (CLP 1272/2008, annex VI):

zirconium powder is classified "pyr sol.1"

zirconium powder dry is classified "self heat 1"

SPONGE:

In the daily use and handling of Zirconium sponge during which continuous exposure to air can occur, no spontaneous ignition is observed. The absence of structural alerts furthermore confirms that Zirconium sponge is not expected to have pyrophoric properties.

FLAMMABILITY IN CONTACT WITH WATER

POWDER FORM:

Zirconium powder may ignite in contact with moist air or moisture (3%-25% humidity) with liberation of flammable gases (H2). It is to be noted that combustion of zirconium dust in air is enhanced by the presence of limited amounts of water (5 -10%)

As stated in the harmonised Classification and Labelling (CLP 1272/2008, annex VI):

zirconium powder is classified "water react 1"

SPONGE:

Under conditions where Zirconium sponge is in contact with water no ignition and/or liberation of flammable gases is observed. The absence of structural alerts furthermore confirms that it is highly unlikely that Zirconium sponge is flammable in contact with water.

 

FLAMMABILITY

A test has been performed by EUROFINS on zirconium shot (>0.5mm, <2.8mm), following EEC Method A10. This test shows that zirconium shot is highly flammable according to 67/548/EEC regulation. This result is chosen for this endpoint and on the basis of expert judgement it is considered as relevant also for the sponge form.


Flammability additional key value for CSA: highly flammable, spontaneously flammable in air (pyrophoric)

Justification for classification or non-classification

Zirconium powder is listed on Annex VI of regulation n°1272/2008 of 16 December 2008 :

zirconium powder is classified "pyr sol.1" (H250: Catches fire spontaneously if exposed to air) and "water react 1" (H 260: In contact with water, releases flammable gases which may ignite spontaneously).

zirconium powder dry is classified "self heat 1" (H 251: Self-heating; may catch fire)

No change to this classification is proposed.

According to the results (method A 10, 440/2008/CEE regulation), zirconium sponge is considered as highly flammable (R11) following 67/548/EEC regulation.

According to the 1272/2008/CEE regulation (CLP), proposition for classification of zirconium sponge as "flammable solid" (H 228), category 1.

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