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Compressed air foam (CAF) and compressed nitrogen foam (CNF) have been widely used for storage tank fire suppression, benefiting from their highly effective extinguishing performance. Mass loss rate is an important parameter to evaluate the stability of foam and an important factor to influence the suppression efficiency of foam. In this work, mass loss mechanisms including drainage and evaporation of two types of foams under a fixed radiation source were experimentally studied to reflect the foam fire suppression efficiency. It was observed that the foam drain rate is directly proportional to the foam mass, with a slight relation to the irradiance when irradiance is lower than 20 kW/m2. Once the irradiance reaches 30 kW/m2, the drain rate increases significantly. For evaporation, as expected from the established theoretical model, the evaporation rate shows a positive relationship with the irradiance level. However, there is no relationship between foam evaporation rate and the initial foam thickness. Through the experimentally measured evaporation rate, the average foam absorptivity is calculated to be approximately 0.63 ± 0.07 for both foams at an expansion ratio (ER) of 10. A comparative analysis of mass loss characteristics in the two types of foam was also undertaken. It was found that the two types of foam have distinct drain rates due to their different foam stability caused by the different expanded gas properties. However, they have a similar evaporation rate. In addition, the foam destruction rate and time to ignite the underlying fuel were measured, and a linear relationship between ignition time and initial foam height was found with a slope of 1.7 ± 0.2. The results demonstrate that CNF has a better fire suppression efficiency, which can be attributed to the better stability of the foam and the nitrogen released by broken bubbles, which inhibits ignition. The work presented here reveals the different functional mechanisms of compressed air/nitrogen foam and presents useful information that could enhance our understanding of the fire suppression effects of fire extinguishing foam. [ABSTRACT FROM AUTHOR]

The original article can be found online at https://doi.org/10.1007/s10694-022-01332-0.Correction to: Fire Technology https://doi.org/10.1007/s10694-022-01332-0In this article, Sect. 3.2 "The reasons for this are described in Sect. 2.1" should be changed to "The reasons for this are described in Sect. 2.2". The author group information is missing in this article and should have read as in this Correction.The original article has been corrected.By Fengyuan Tian; Kun Wang; Jun Fang; Hassan Raza Shah; Xuqing Lang; Shanjun Mu; Jinjun Wang and Jingwu WangReported by Author; Author; Author; Author; Author; Author; Author; Author [Extracted from the article]

Encapsulation is an effective method for enhancing the reaction to fire of timber structures. Mortar coatings are widely used to encapsulate traditional timber structures due to their excellent mechanical properties. However, there is a significant lack of data on the reaction to fire and fire mechanisms of timber structures with mortar encapsulation, and little is known about the influence of mortar composition on the burning characteristics of timber substrates. This study investigated the fire properties of organic–inorganic composite multilayer mortar coatings with fibre-reinforced layers commonly employed in encapsulating traditional Chinese wooden structures. The burning phases of timber encapsulated by multilayer mortar coatings were examined using thermogravimetric analysis and constant radiation ignition experiments. The fire propagation apparatus was used to measure the critical fire parameters of the encapsulated timber structures, including ignition time, heat release rate, total heat release, and time to peak heat release rate under a constant radiation heat flux of 30 kW/m2. Comparative experiments between finished and semi-finished coating encapsulated samples were conducted to investigate the influence of coating composition. The cracking behaviour of the coating was synchronously observed, with crack length analysis using image recognition techniques. It was found that the topcoat property of the coating mainly influenced the ignition time, and adding the fibre layer can effectively inhibit the bending of the timber substrate. Additionally, reducing the aggregate size may effectively prolong the time to reach the peak of the heat release rate. The relationship between the rise in heat release rate in encapsulation coatings, the appearance of surface cracks, and the maximum crack length with the heat release rate peak has been well established. [ABSTRACT FROM AUTHOR]

• Phenomenological analysis of pilot ignition of cylindrical PMMA was provided. • Theoretical and experimental temperature profiles of varied radius were obtained. • Average absorption heat flux was estimated by two absorption coefficients. • Critical mass flux and mass loss rate were illustrated by absorption heat flux. • Pyrolysis and ignition time and their interval were interpreted in mechanism. The Poly methyl methacrylate (PMMA) material with a cylindrical shape are widely used for the building components. Under external irradiation, it may be ignited by a pilot ignition. Previous studies focused more on a flat surface sample, while for a cylindrical configuration, the heat flux distribution, solid-phase temperature profile and ignition time establishes different aspects induced by the cylinder curvature. Therefore, this study investigated the ignition behaviors of the cylindrical PMMA samples with various radius exposed to an external irradiation by experimental and numerical methods. Firstly, decomposition gases of PMMA samples under the irradiation were observed to evidently accumulate on the top surface of the cylinders, after which an incipient ignition occurred in conjunction with blue flames, quickly followed by sustained ignition. With varied cylinder radius, the characteristic parameters of solid-phase temperature profile and thermal penetration depth changed, which are dependent upon sample radius. While for thermal-thick slabs, these parameters have no changes to be independent of the sample thickness. Furthermore, two absorption heat flux coefficients were introduced to analyze the in-depth heat absorption by considering the effects of angle and sample radius. Finally, the critical mass flux and ignition time were given. The cylindrical samples were easier to be ignited than slab samples. With smaller sample radius, the ignition time is established to be shorter. With increasing sample radius, the critical mass flux is lower. This investigation will provide a tractable way to obtain a comprehensive evaluation of fire risk of the commonly used cylindrical components in construction and buildings. [ABSTRACT FROM AUTHOR]