Editing Pyrophoricity (section)

{{Short description|Tendency of a chemical compound to ignite in open air}}
{{distinguish|Porphyria|Porphyriticity}}
{{Redirect|Pyrophorus|the bioluminescent beetle genus|Pyrophorus (beetle)}}
{{more citations needed|date=July 2019}}

A substance is '''pyrophoric''' (from {{langx|grc|πυροφόρος}}, {{lang|grc-Latn|pyrophoros}}, 'fire-bearing') if it ignites spontaneously in air at or below {{convert|54|°C|°F}} (for gases) or within 5 minutes after coming into contact with air (for liquids and solids).<ref>GHS, seventh revised version. https://www.unece.org/fileadmin/DAM/trans/danger/publi/ghs/ghs_rev07/English/ST_SG_AC10_30_Rev7e.pdf</ref> Examples are [[organolithium compound]]s and [[triethylborane]]. Pyrophoric materials are often [[water-reactive]] as well and will ignite when they contact water or [[humid]] air. They can be handled safely in atmospheres of [[argon]] or (with a few exceptions) [[nitrogen]]. [[Fire Classes#Metal|Class D]] [[fire extinguisher#Class D dry powder and other agents for metal fires|fire extinguishers]] are designated for use in fires involving metals but not pyrophoric materials in general. A related concept is [[hypergolic propellant|hypergolicity]], in which two compounds spontaneously ignite when mixed.