Substance profile
Zirconium powder (pyrophoric)
Zirconium powder (pyrophoric) is bluish-black, amorphous powder or grayish-white lustrous metal (platelets or flakes) of.
01 · Identification
What Zirconium powder (pyrophoric) is
Zirconium powder (pyrophoric) is bluish-black, amorphous powder or grayish-white lustrous metal (platelets or flakes) of. Its molecular formula is Zr and its molecular weight is 91.22 g/mol. It boils at 4406 °C, melts at 1854 °C, is soluble in water.
Under the GHS it carries the signal word Danger. It is classed as flammable agents - 4th degree.
02 · Identifiers
Zirconium powder (pyrophoric) identifiers and molecular data
Zirconium powder (pyrophoric) CAS number and EC number
Zirconium powder (pyrophoric) molecular formula and molecular weight
03 · GHS classification
Zirconium powder (pyrophoric) hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Zirconium powder (pyrophoric) pictograms and signal word
Zirconium powder (pyrophoric) hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Pyrophoric liquids or Pyrophoric solids | Category 1 | H250 | GHS02 |
| In contact with water emits flammable gases GHS chapter 2.12 | Category 1 | H260 | GHS02 |
Where two values are shown with “or”, the hazard statement is shared by more than one category or by more than one class, and the code alone does not say which. H272, for example, belongs to oxidising liquids and to oxidising solids — the physical state decides. The binding answer for a specific entry is in the CLP Annex VI table itself.
Zirconium powder (pyrophoric) hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H250 | Catches fire spontaneously if exposed to air. |
| H260 | In contact with water releases flammable gases which may ignite spontaneously. |
This page lists only the codes assigned to Zirconium powder…. The full reference lives on the hazard statements hub, the precautionary statements hub and the GHS pictograms hub.
Safety Data Sheet
Getting an SDS for Zirconium powder…
A Safety Data Sheet is written for a product, not for a substance: the supplier of the grade you actually buy issues it, so two suppliers of Zirconium powder… issue two different sheets. That is why there is no single authoritative SDS for a substance to download — what there is, is the job of collecting the sheets for the products you hold and keeping them current as suppliers revise them.
04 · Precautionary statements
Zirconium powder (pyrophoric) precautionary statements
CLP Annex VI assigns 6 precautionary statements to Zirconium powder…. They are grouped the way a label groups them: what to do before handling, what to do when something has already happened, how to store it and how to dispose of it.
Prevention
What to do before and during handling so the hazard never happens.
Disposal
What has to happen to the contents and the empty container.
Reading the notation. … is a blank the supplier fills in — not a truncated sentence.· [square brackets] mark a part printed only when it applies.
05 · Names in the regulation
Zirconium powder (pyrophoric) name in 23 EU languages
CLP Annex VI Part 3 is published in every language edition of the regulation, and the identification column is written out in each of them. Nothing below is translated by us: each line is the name as that edition prints it. Under Art. 18(2) the substance name from Annex VI is a lawful product identifier, so this is the wording to put on a label going to that market — and where the cell lists several designations, any one of them qualifies.
| Language | Name in CLP Annex VI Part 3 |
|---|---|
| Bulgarian български | циркониев прах (пирофорен) |
| Spanish español | Circonio en polvo (pirofórico) |
| Czech čeština | zirkonium práškové (nestabilizované) |
| Danish dansk | zirconiumpulver (ustabiliseret) |
| German Deutsch | Zirconiumpulver (pyrophor) |
| Estonian eesti | tsirkooniumipulber (pürofoorne) |
| Greek ελληνικά | κόνις ζιρκονίου (πυροφόρος) |
| English English | zirconium powder (pyrophoric) |
| French français | poudre de zirconium (pyrophorique) |
| Croatian hrvatski | cirkonijev prah (piroforni) |
| Italian italiano | zirconio in polvere (piroforica) |
| Latvian latviešu | cirkonija pulveris (pirofors) |
| Lithuanian lietuvių | cirkonio milteliai (piroforas) |
| Hungarian magyar | cirkóniumpor (pirofóros) |
| Maltese Malti | trab taż-żirkonju (piroforiku) |
| Dutch Nederlands | zirkoniumpoeder (pyrofoor) |
| Polish polski | proszek cyrkonowy (piroforyczny) |
| Portuguese português | zircónio em pó (pirofórico) |
| Romanian română | zirconiu pudră (piroforică) |
| Slovak slovenčina | práškové zirkónium (pyroforické) |
| Slovenian slovenščina | cirkonijev prah (piroforen) |
| Finnish suomi | zirkoniumjauhe (pyroforinen) |
| Swedish svenska | zirkoniumpulver (pyrofort) |
All 23 language editions of Annex VI carry this entry. Irish is the twenty-fourth official EU language and has no line here for a different reason: no consolidated CLP text has ever been published in Irish, so there is no Irish edition of Annex VI to quote a name from. Source: consolidated CLP, CELEX 02008R1272, language editions. © European Union, https://eur-lex.europa.eu — only the electronic Official Journal of the European Union is authentic.
06 · Label elements
Zirconium powder (pyrophoric) GHS label elements
Everything CLP Annex VI fixes for Zirconium powder…, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Zirconium powder (pyrophoric)
- Catches fire spontaneously if exposed to air.
- In contact with water releases flammable gases which may ignite spontaneously.
- Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
- Do not allow contact with air.
- Handle and store contents under inert gas/…
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- In case of fire:
- Dispose of contents/container to …
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Zirconium powder… in the GHS label constructor →
07 · Health hazards
Zirconium powder (pyrophoric) health hazards and exposure limits
Zirconium powder (pyrophoric) hazard summary
Other than the skin and respiratory irritant effects of zirconium chloride, work-related diseases caused by zirconium have not been documented. [ACGIH] Zirconium compounds, both soluble and insoluble, have the following notation, Danger of sensitization of the airways and the skin. [MAK] Repeated inhalation of zirconium tetrachloride mist by dogs for 2 months at 6 mg/m3 as zirconium caused slight decreases in hemoglobin and in erythrocyte counts, with some increases in mortality over that of controls; these effects may have been due to the liberation of hydrogen chloride. [NIOSH Guidelines for Chemical Hazards] Generally considered to be of low toxicity. Zirconium chloride (ZrCl4) can cause acute pneumonitis. No lung changes were found in 32 workers with 1-17 years of exposure to zirconium metal reactor parts. A lens grinder who mixed zirconium oxide powder and polished optical lenses developed interstitial fibrosis after a latency of 15 years. [Harber, p. 479, 487, 506] Soluble zirconium compounds include nitrates, acetates, sulfates, chlorides, bromides, iodides, and salts of Na, K, and ammonium; Insoluble zirconium compounds include hydroxides, carbonates, and phosphates; [Nordberg, p. 19]
Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
Zirconium powder (pyrophoric) occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 5.0 [mg/m3], as Zr (compounds) | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 5 mg/m³ | Occupational Safety and Health Administration (OSHA) |
| PEL | TWA 5 mg/m3 See Appendix G | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 5 mg/m³ | Occupational Safety and Health Administration (OSHA) |
| REL | 10 mg/m³ | Occupational Safety and Health Administration (OSHA) |
| REL | TWA 5 mg/m3 ST 10 mg/m3 [*Note: The REL applies to all zirconium compounds (as Zr) except Zirconium tetrachloride.] | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 25 mg Zr/m3 (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 25.0 [mg/m3], as Zr | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| IDLH | 50 mg/m³ | Occupational Safety and Health Administration (OSHA) |
These are United States values. The European Union sets its own indicative and binding limits, and the figure that applies at a given workplace is the one in the local regulation — not the one shown here.
08 · Physical and chemical properties
Zirconium powder (pyrophoric) properties
Every value is shown with the conditions it was measured under and the source it came from. Where sources disagree, all values are listed rather than one being picked — the difference is usually a different form of the substance, not an error.
Zirconium powder (pyrophoric) boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 4406 °C (7962.8 °F) | HSDB | |
| 3577 °C (6471 °F) | NIOSH | ||
| 3577 °C (6471 °F) | at 760 mmHg | CAMEO |
Zirconium powder (pyrophoric) melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 1854 °C (3369.2 °F) | HSDB | |
| 1857 °C (3375 °F) | NIOSH |
Zirconium powder (pyrophoric) density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 6.52 g/cm³ | HSDB | |
| 6.51 g/cm³ | Metal | NIOSH |
Zirconium powder (pyrophoric) solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Soluble in hot concentrated acid | HSDB | |
| Insoluble | NIOSH | ||
| Insoluble (NIOSH, 2024) | CAMEO |
Zirconium powder (pyrophoric) vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 0 mmHg | HSDB | |
| 0 mmHg | approx | NIOSH |
Zirconium powder (pyrophoric) autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 330 °C (626 °F) | HSDB |
Zirconium powder (pyrophoric) lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | Sponge zirconium is pyrophoric when pure, and violently explosive when impure. | HSDB | |
| Metal: Combustible, but solid form is difficult to ignite; however, powder form may ignite SPONTANEOUSLY and can continue burning under water. | NIOSH |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Zirconium powder… fire and explosion behaviour
These are descriptions rather than measured values, so they are kept out of the table above and quoted here with the source that reported them.
Zirconium powder (pyrophoric) fire potential
Zirconium metal dust dispersed with uranium and uranium hydride as a cloud ignites under certain conditions.
Source: Hazardous Substances Data Bank (HSDB)
Fire and explosion
Zirconium metal dust is extremely flammable and can cause explosions. It burns with a brilliant flame, forming oxides and nitrides of the metal. Burning zirconium also reacts with halon and carbon dioxide fire-extinguishing agents.
Source: HSDB
Corrosivity
Zirconium is a very reactive metal that, in air or aqueous solution, immediately develops a surface oxide film. This stable, adherent film is the basis for zirconium's corrosion resistance.
Source: HSDB
10 · Handling and storage
Zirconium powder (pyrophoric) storage and handling
Zirconium powder (pyrophoric) storage conditions
Conditions for safe storage, including any incompatibilities: Keep container tightly closed in a dry and well-ventilated place. Storage class (TRGS 510): Non Combustible Solids.
Source: Hazardous Substances Data Bank (HSDB)
Zirconium powder (pyrophoric) incompatible materials
Incompatible materials: Hydrofluoric acid, fluorine, fluorine nitrate, chlorine, bromine, iodine, halogenated hydrocarbon.
Source: Hazardous Substances Data Bank (HSDB)
Zirconium powder (pyrophoric) reactivity
When a mixture of alkali hydroxides and zirconium is heated, the liberated oxygen reacts explosively with zirconium [Mellor 7:116 1946-47]. Chromates, dichromates, sulfates, molybdates, and tungstates of lithium, sodium, potassium, rubdium, and cesium will react violently, even explosively, with an excess of zirconium powder [Ellern 1968. p. 249]. A mixture of hydrated borax and zirconium explodes when heated [Mellor 7:116 1946-47]. An explosion occurred when zirconium sponge was placed in a beaker of carbon tetrachloride [Allison 1969]. Zirconium explodes violently with cupric oxide or lead oxide [Mellor 7:116 1946-47]. A mixture of powdered zirconium and potassium nitrate explodes when heated above the melting point [Mellor 7:116 1946-47].
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Zirconium powder… in the storage compatibility matrix →
11 · Transport
Zirconium powder (pyrophoric) UN number and transport classification
Transport classification is a separate system from the GHS classification above. It decides how a package is marked and how a load may be carried; it does not follow from the workplace label, and the workplace label does not follow from it. The entries below are linked by CAS number, never by name.
The same CAS number is shipped under more than one UN number. Which entry applies follows from the form and the concentration of the consignment — read the proper shipping name, not the CAS.
Zirconium powder (pyrophoric) under UN 1358 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| ZIRCONIUM POWDER, WETTED with not less than 25 % water | 4.1 | F3 | II | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 4.1 is “Flammable solids, self-reactive substances, polymerizing substances and solid desensitized explosives” (ADR 2.1.1.1).
United States · 49 CFR 172.101 Hazardous Materials Table
| Proper shipping name (column 2) | Class or division | PG | Labels (column 6) |
|---|---|---|---|
| Zirconium powder, wetted with not less than 25 percent water (a visible excess of water must be present) (a) mechanically produced, particle size less than 53 microns; (b) chemically produced, particle size less than 840 microns | 4.1 | II | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 4.1 is “Flammable solid” (49 CFR 173.2).
Zirconium powder (pyrophoric) under UN 2008 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| ZIRCONIUM POWDER, DRY | 4.2 | S4 | I | |
| ZIRCONIUM POWDER, DRY | 4.2 | S4 | II | |
| ZIRCONIUM POWDER, DRY | 4.2 | S4 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 4.2 is “Substances liable to spontaneous combustion” (ADR 2.1.1.1).
United States · 49 CFR 172.101 Hazardous Materials Table
| Proper shipping name (column 2) | Class or division | PG | Labels (column 6) |
|---|---|---|---|
| Zirconium powder, dry | 4.2 | I | |
| Zirconium powder, dry | 4.2 | II | |
| Zirconium powder, dry | 4.2 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 4.2 is “Spontaneously combustible material” (49 CFR 173.2).
12 · Questions
Zirconium powder (pyrophoric) — frequently asked questions
What is the CAS number of Zirconium powder (pyrophoric)?
The CAS number of Zirconium powder (pyrophoric) is 7440-67-7. Its EC number is 231-176-9.
What is the chemical formula of Zirconium powder (pyrophoric)?
The molecular formula of Zirconium powder (pyrophoric) is Zr and its molecular weight is 91.22 g/mol.
What does a Zirconium powder (pyrophoric) label have to show?
Under CLP Annex VI the label for Zirconium powder (pyrophoric) carries the pictogram Flame and the signal word is Danger.
Is Zirconium powder (pyrophoric) flammable?
Yes. CLP Annex VI assigns Zirconium powder (pyrophoric) H250 and H260 — catches fire spontaneously if exposed to air.
Is Zirconium powder (pyrophoric) a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Zirconium powder (pyrophoric). Annex VI is a list of agreed classifications, not a list of substances found safe, so this is an absence of a classification rather than a clean bill of health.
What is the exposure limit for Zirconium powder (pyrophoric)?
The US occupational exposure limit reported for Zirconium powder (pyrophoric) is 5.0 [mg/m3], as Zr (compounds) (Haz-Map, Information on Hazardous Chemicals and Occupational Diseases). Limits differ by country: the EU sets its own indicative and binding values, and the figure that applies at a given workplace is the one in the local regulation.
What is the boiling point of Zirconium powder (pyrophoric)?
The boiling point reported for Zirconium powder (pyrophoric) is 4406 °C (7962.8 °F) (HSDB).
What is the melting point of Zirconium powder (pyrophoric)?
The melting point reported for Zirconium powder (pyrophoric) is 1854 °C (3369.2 °F) (HSDB).
How should Zirconium powder (pyrophoric) be stored?
Conditions for safe storage, including any incompatibilities: Keep container tightly closed in a dry and well-ventilated place. Storage class (TRGS 510): Non Combustible Solids. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Zirconium powder…
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