An intumescent is a substance which swells as a result of heat exposure, thus increasing in volume, and decreasing in density. Intumescents are typically used in passive fire protection and, in America, require listing and approval use and compliance in their installed configurations in order to comply with the law.

Types of intumescents

oft char producers

These intumescents produce a light char, which is a poor conductor of heat, thus retarding heat transfer. Typically, these materials also contain a significant amount of hydrates. As the hydrates are spent, water vapour is released, which has a cooling effect. Once the water is spent, it is only the insulation characteristics of the char that was produced, which can slow down heat transfer from the exposed side to the unexposed side of an assembly. Soft char producers are typically used in thin film intumescents for fireproofing of structural steel as well as firestop pillows. Typically, the expansion pressure that is created for these products is very low, because the soft carbonaceous char has little substance, which is beneficial if the aim is to produce a layer of insulation.

Hard expanding char producers

Harder chars are produced with sodium silicates and graphite. These products are suitable for use in plastic pipe firestops as well as exterior steel fireproofing. In those applications, it is necessary to produce a more substantial char, with a quantifiable expansion pressure. In the case of the firestops, a melting, burning plastic pipe must be squeezed together and shut so that there will be no hole for fire to go through an opening in an otherwise fire-resistance rated wall or floor assembly. In the case of the exterior fireproofing, a hydrocarbon fire must be held off with quite potentially more kinetic energy than a house fire. Intumescents that produce hard chars are not typically used for interior spray fireproofing as they are not suitable for that application.

Uses of intumescents in passive fire protection


*gasketing applications


*offshore construction

Problems with intumescents

Some intumescents are susceptible to environmental influences such as humidity, which can reduce or negate their ability to function. DIBt approvals quantify the ability of intumescents to stand the test of time against various environmental exposures. DIBt approved firestops and fireproofing materials are available in Canada and the U.S. [ [ DIBt - Deutsches Institut für Bautechnik ] ]



ee also

* Fire test
* Fire-resistance rating
* Hydrate
* Fire protection
* Passive fire protection
* Firestops
* Putty
* Fireproofing
* Firestop pillow
* Endothermic
* Sodium silicate
* Graphite
* Penetrant
* Bounding
* Construction

External links

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • intumescent — INTUMESCÉNT, Ă, intumescenţi, te, adj. (med.) (Despre ţesuturi) Care începe să se umfle, care prezintă o tumefacţie; umflat. – Din fr. intumescent. Trimis de valeriu, 13.09.2007. Sursa: DEX 98  intumescént adj. m., pl. intumescénţi; f …   Dicționar Român

  • Intumescent — In tu*mes cent, a. [L. intumescens, p. pr.] Swelling up; expanding. [1913 Webster] …   The Collaborative International Dictionary of English

  • intumescent — 1796, from L. intumescentem (nom. intumescens), prp. of intumescere “to swell up,” from in in (see IN (Cf. in ) (2)) + tumescere (see TUMESCENCE (Cf. tumescence)) …   Etymology dictionary

  • intumescent — intumescence [ ɛ̃tymesɑ̃s ] n. f. • 1611; du lat. intumescere → tumeur ♦ Didact. Fait d enfler, de gonfler. Intumescence des chairs, de la rate. ⇒ enflure, gonflement, tuméfaction. Adj. INTUMESCENT, ENTE . ♢ Mécan. Onde de surface dans un canal… …   Encyclopédie Universelle

  • Intumescent — Sur les autres projets Wikimedia : « Intumescent », sur le Wiktionnaire (dictionnaire universel) Terme désignant un matériau dont la particularité réside en une expansion de celui ci en cas de présence prolongée de chaleur excédant …   Wikipédia en Français

  • intumescent — adjective Date: 1953 of paint swelling and charring when exposed to flame …   New Collegiate Dictionary

  • intumescent — n. [L. in, in; tumescere, to swell up] A swelling; being swollen or expanded …   Dictionary of invertebrate zoology

  • intumescent — See intumescence. * * * …   Universalium

  • intumescent — adjective That becomes swollen, especially upon exposure to heat See Also: intumescence …   Wiktionary

  • intumescent — Enlarging; becoming enlarged or swollen. * * * in·tu·mes·cent ənt adj marked by intumescence * * * in·tu·mes·cent (in too mesґənt) [L. intumescens] swelling or becoming swollen …   Medical dictionary

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