{"id":38000,"date":"2023-02-22T11:40:56","date_gmt":"2023-02-22T10:40:56","guid":{"rendered":"https:\/\/www.gt-engineering.it\/?post_type=approfondimento&p=38000"},"modified":"2025-07-17T11:04:52","modified_gmt":"2025-07-17T10:04:52","slug":"dangerosite-des-substances","status":"publish","type":"approfondimento","link":"https:\/\/www.gt-engineering.it\/fr\/approfondissement\/risque-atex\/dangerosite-des-substances\/","title":{"rendered":"Dangerosit\u00e9 des substances"},"content":{"rendered":"\n\n \n \n \n
\n\n \n \n \n \r\n\r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n <\/picture>\r\n\r\n \r\n\r\n \r\n \r\n <\/div>\n \n
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Ce qui provoque une explosion, c’est la combustion d’un gaz. Pour ce faire, trois \u00e9l\u00e9ments sont n\u00e9cessaires :<\/p>\n

– Combustible : le gaz<\/p>\n

– Comburant : l’air (oxyg\u00e8ne)<\/p>\n

– Allumage : il peut \u00eatre de diff\u00e9rentes natures<\/p>\n

La concentration du combustible et du comburant d\u00e9termine si la combustion peut avoir lieu ou non. Il existe une fourchette de concentration entre le combustible et le comburant \u00e0 l’int\u00e9rieur de laquelle la combustion est possible. Les limites inf\u00e9rieure et sup\u00e9rieure de cette plage sont appel\u00e9es respectivement la limite inf\u00e9rieure d’explosivit\u00e9 (LIE) et la limite sup\u00e9rieure d’explosivit\u00e9 (LSE). En dessous de la LIE, la concentration de combustible dans le m\u00e9lange n’est pas suffisante pour permettre \u00e0 la r\u00e9action de se produire, tandis qu’au-dessus de la LSE, la concentration de combustible est tr\u00e8s \u00e9lev\u00e9e au d\u00e9triment d’une concentration r\u00e9duite d’oxydant, auquel cas la r\u00e9action ne peut pas non plus avoir lieu.<\/p>\n

En fonction de la concentration volum\u00e9trique de l’air, l’\u00e9nergie n\u00e9cessaire que l’allumage doit fournir pour qu’il y ait combustion varie, on parle dans ce cas d’\u00e9nergie d’allumage et elle d\u00e9pend du combustible consid\u00e9r\u00e9. Le graphique ci-dessous montre l’\u00e9nergie d’allumage n\u00e9cessaire pour le propane et l’hydrog\u00e8ne en fonction de la concentration de l’air.<\/p>\n

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\n Temp\u00e9rature d’auto-inflammation et point d’\u00e9clair <\/h2>\n <\/div>\n <\/div>\n \n \n
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On d\u00e9finit deux temp\u00e9ratures qui caract\u00e9risent les substances inflammables :<\/p>\n

– Temp\u00e9rature d’inflammabilit\u00e9 ou point d’\u00e9clair : c’est la temp\u00e9rature la plus basse \u00e0 laquelle des vapeurs se forment en quantit\u00e9 telle qu’en pr\u00e9sence d’oxyg\u00e8ne (air) et d’une source d’inflammation, elles donnent lieu au ph\u00e9nom\u00e8ne de combustion (le gaz devient inflammable et peut donc exploser).<\/p>\n

– Temp\u00e9rature d’auto-inflammation : la temp\u00e9rature la plus basse \u00e0 laquelle la substance commence \u00e0 br\u00fbler spontan\u00e9ment en pr\u00e9sence d’oxyg\u00e8ne, sans source d’inflammation externe.<\/p>\n

Chaque substance a son propre point d’\u00e9clair et sa propre temp\u00e9rature d’auto-inflammation. Sur la base de la temp\u00e9rature d’inflammabilit\u00e9, les diff\u00e9rents liquides inflammables sont class\u00e9s :<\/p>\n

– Cat\u00e9gorie A (Ti<21\u00b0C) : essence, alcools ; ce sont les produits les plus dangereux car ils sont extr\u00eamement inflammables m\u00eame \u00e0 temp\u00e9rature ambiante et doivent \u00eatre tenus \u00e0 l’\u00e9cart de toute source d’ignition possible ;<\/p>\n

– Cat\u00e9gorie B (21 \u00b0C \u2264 Ti \u2264 65 \u00b0C) : carburant diesel ;<\/p>\n

– Cat\u00e9gorie C (Ti > 65 \u00b0C) : glyc\u00e9rine, bitume.<\/p>\n

Les liquides inflammables des cat\u00e9gories A et B sont \u00e0 leur tour divis\u00e9s en (Classification des substances inflammables selon la directive 67\/548\/CEE) :<\/p>\n

– R10 Inflammable : Substances et pr\u00e9parations liquides ayant un point d’\u00e9clair t > 21\u00b0C et < 55\u00b0C.<\/p>\n

– R11 Facilement inflammable : Substances et pr\u00e9parations liquides ayant un point d’\u00e9clair t > 0 \u00b0C et < 21 \u00b0C.<\/p>\n

– R12 extr\u00eamement inflammable : Substances et pr\u00e9parations liquides ayant un point d’\u00e9clair T < 0 \u00b0C.<\/p>\n

La temp\u00e9rature d’auto-inflammation d\u00e9termine la classe de temp\u00e9rature \u00e0 laquelle appartient un gaz. Le tableau 5.5-A indique les classes associ\u00e9es aux valeurs de la temp\u00e9rature d’auto-inflammation.<\/p>\n

 <\/p>\n<\/div> <\/div>\n \n \n

<\/div>\n \n\n <\/div>\n <\/section>\n\n \n\n\n\n\n \n \n \n
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\n La classe de temp\u00e9rature <\/h2>\n <\/div>\n <\/div>\n \n \n
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La temp\u00e9rature d’auto-inflammation d\u00e9termine la classe de temp\u00e9rature \u00e0 laquelle appartient un gaz. Le tableau 5.5-A indique les classes associ\u00e9es aux valeurs de la temp\u00e9rature d’auto-inflammation.<\/p>\n

 <\/p>\n<\/div> <\/div>\n \n \n

<\/div>\n \n\n <\/div>\n <\/section>\n\n \n\n\n\n\n \n \n \n
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\n Groupe gaz <\/h2>\n <\/div>\n <\/div>\n \n \n
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En fonction de leur dangerosit\u00e9, li\u00e9e aux endroits o\u00f9 ils sont g\u00e9n\u00e9ralement pr\u00e9sents ou \u00e0 l’\u00e9nergie minimale d’inflammation, les gaz sont \u00e9galement divis\u00e9s en groupes :<\/p>\n

– Groupe I : Grisou – Gaz de mine (~80% de m\u00e9thane). E.M.I. = 0,28mJ<\/p>\n

– Groupe IIA : Propane, essence, m\u00e9thanol. E.M.I. = 0,16 mJ<\/p>\n

– Groupe IIB : \u00e9thyl\u00e8ne. M.I.E.=0,06mJ<\/p>\n

– Groupe IIC : hydrog\u00e8ne, ac\u00e9tyl\u00e8ne. M.I.E.=0.02mJ<\/p>\n

Le gaz est ensuite identifi\u00e9 par la classe de temp\u00e9rature et le groupe. Ces informations figurent sur le marquage CE des produits utilis\u00e9s dans une zone ATEX particuli\u00e8re.<\/p>\n<\/div> <\/div>\n \n \n

<\/div>\n \n\n <\/div>\n <\/section>\n\n \n","protected":false},"excerpt":{"rendered":"

Ce qui provoque une explosion, c’est la combustion d’un gaz. Pour ce faire, trois \u00e9l\u00e9ments sont n\u00e9cessaires<\/p>\n","protected":false},"author":182,"featured_media":48508,"parent":0,"menu_order":111,"template":"","meta":{"_acf_changed":false,"footnotes":""},"tipologia_approfondimento":[162],"class_list":["post-38000","approfondimento","type-approfondimento","status-publish","has-post-thumbnail","hentry","tipologia_approfondimento-risque-atex"],"acf":{"sottotitolo":"","allegati":null},"yoast_head":"\nDangerosit\u00e9 des substances - Gt-Engineering<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.gt-engineering.it\/fr\/approfondissement\/risque-atex\/dangerosite-des-substances\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Dangerosit\u00e9 des substances - Gt-Engineering\" \/>\n<meta property=\"og:description\" content=\"Ce qui provoque une explosion, c'est la combustion d'un gaz. 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