Engineering model for intumescent coating behavior in a pilot‐scale gas‐fired furnace

Abstract

In the event of a fire, intumescent fire protective coatings expand and form a thermally insulating char that protects the underlying substrate from heat and subsequent structural failure. The intumescence includes several rate phenomena, which have been investigated and quantified in the literature for several decades. However, various challenges still exist. The most important one concerns mathematical model validation under realistic exposure conditions and/or time scales. Another is the simplification of advanced models to overcome the often‐seen lack of a complete set of input and adjustable model parameters for a given coating, thereby providing models for industrial applications. In this work, these two challenges are addressed. Three experimental series, with an intumescent coating inside a 0.65 m3 gas‐fired furnace, heating up according to so‐called cellulosic fire conditions, were conducted and a very good repeatability was evident. The experiments were run for almost 3 h, reaching a final gas temperature of about 1100°C. Measurements include transient temperature developments inside the expanding char, at the steel substrate, and in the mineral wool insulation placed behind the substrate. A mathematical model, describing the intumescent coating behavior and temperatures in the furnace using a single overall reaction was developed and validated against experimental data. By including a decomposition front movement through the char, a good qualitative agreement was obtained. After further validation against experiments with other coating formulations, it has potential to become a practical engineering tool. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3947–3962, 2016

Interactions between calcium carbonate and ammonium polyphosphate in low‐borate concentration hydrocarbon intumescent coatings

“…Depending on the fire characterization (ie, cellulosic or hydrocarbon), intumescent coatings can be classified accordingly into cellulosic or hydrocarbon types 7‐9 . The former, due mainly to their high demands in residential or commercial buildings, has dominated the commercial market and research investigations on intumescent coatings in the past decades 1,8,10,11 .…”

Exposure of hydrocarbon intumescent coatings to the UL1709 heating curve and furnace rheology: Effects of zinc borate on char properties

“…Above 350 o C, gelation and consolidation of the expanded mixture occur, giving rise to a multicellular char with a low thermal conductivity (e.g. for an epoxy-based coating below 0.4 W•m -1 •K -1 [11]). At still higher temperatures, thermal degradation of the char (mainly oxidation of carbon) takes place.…”

Correlating the Performance of a Fire-Retardant Coating across Different Scales of Testing

“…There are publications that proposed experimental procedures or setup to simulate heat flux [ 25 ] or gas pressure [ 26 ] in a structural-scale furnace, but certain limitations apply with the reduction in scale, and the focus has largely been on the temperature development of the substrate. Correlating numerical simulations with cone calorimeter results [ 18 , 27 , 28 ] and furnace test results [ 29 ] obtained at the bulk scale are also proposed, but beyond bulk-scale tests, there seems to be little information in the literature [ 30 , 31 ]. Even so, we consider the following questions.…”