Fire-fighting foam

Fire-fighting foams greatly reduce the density of water and allow it to spread easily over the fuel. These foams kill fires through a combination of the following [44,796-799]  

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The release of oil into the dike was due to boilover, that is, production of steam from the fire-fighting foam by the hot oil. As the steam leaves the tank, it brings oil with it. Boilover usually occurs when the heat from the burning oil reaches the water layer at the bottom of the tank, but in this case it occurred earlier than usual when the heat reached pockets of water trapped on the sunken roof [14]. 

Before welding is allowed on tanks that have contained heavy oils, the tanks should be filled with inert gas or with fire-fighting foam generated with inert gas, not with fire-fighting foam generated with air (see Section 12.3.2). Filling the tank with water can reduce the volume to be inerted. 

Perfluoroalkylethanols are widely used to prepare useful materials such as oil and water repellants, surfactants, and fire-fighting foams These alcohols are... 

AFFF, AQUEOUS FILM-FORMING FOAM Fire-fighting foam which flows on burning liquid as a film, providing rapid knock-down. 

Operation of detectors with their associated alarm panels should be checked and calibrated after installation. Detector performance can be impaired in a hostile environment by blockages to the detector (i.e., ice, salt crystals, wind blown particles, water or even fire fighting foam, or by inhibition of the catalysts by airborne contaminants such as compounds of silicon, phosphorus, chlorine or lead. It is essential that detectors and alarm panels be checked and re-calibrated on a routine basis. 

The trend of discovering the analytical field of environmental analysis of surfactants by LC-MS is described in detail in Chapters 2.6-2.13 and also reflected by the method collection in Chapter 3.1 (Table 3.1.1), which gives an overview on analytical determinations of surfactants in aqueous matrices. Most methods have focused on high volume surfactants and their metabolites, such as the alkylphenol ethoxylates (APEO, Chapter 2.6), linear alkylbenzene sulfonates (LAS, Chapter 2.10) and alcohol ethoxylates (AE, Chapter 2.9). Surfactants with lower consumption rates such as the cationics (Chapter 2.12) and esterquats (Chapter 2.13) or the fluorinated surfactants perfluoro alkane sulfonates (PFAS) and perfluoro alkane carboxylates (PFAC) used in fire fighting foams (Chapter 2.11) are also covered in this book, but have received less attention. 

Two independent analytical methods—LC-MS-MS and 19F-NMR— for the determination of perfluorinated anionic surfactants in environmental water samples were presented. Perfluorinated alkanesulfonates and perfluorocarboxylates were determined qualitatively and quantitatively because of an accidental release of perfluorosurfactant contaminated fire-fighting foam [55]. Ci8-SPE was applied for concentration of the compounds from water samples. Methanol was used for elution prior to ESI-LC-MS(—) analysis. The negatively recorded LC-MS-MS TIC for the determination of PFOS, PFHxS, PFOA, perfluor-oheptanoic acid (PFHpA), perfluorododecanoic acid (PFDoA internal standard) in water samples was presented [55]. 

The most widespread large-scale application of gas-liquid foams is in fire fighting, where air is excluded from the combustible material by a thick blanket of foam [320]. These fire-fighting foams are supplied as liquid concentrates, which can be diluted on-site to the required strength. The foam is formed from this premixture by an aerating device. Several studies have been undertaken to investigate the suitability of foams for bioremediation applications, as follows ... 

The PFAS are used in the production of stain-repelling agents, and fluoropolymers, such as Teflon, pesticides, lubricants, paints, medicines, and fire-fighting foams. PCNs are used in cable insulation, wood preservatives, engine oil additives, electroplating masking... 

One well known application concerns the fire fighting foam-agents (A3F), as well as the use of fluorosurfactants in emulsions (for fluoromonomers) and microemulsions. 

Figure 12.4 Illustration of a fire fighting foam. From reference [800], Copyright 2005, Reliable Fire Equipment Company.

Corrie, J.G. Experimental Methods for the Study of Fire-Fighting Foams in Foams,... 

The role of surfactants in stabilization/destabilization of foam (air/liquid dispersions) is similar to that for emulsions. This is due to the fact that foam stability/instability is determined by the surface forces operative in liquid films between air bubbles. In many industrial applications, it is essential to stabilize foams against collapse, e.g., with many food products, foam in beer, fire-fighting foam, and polyurethane foams that are used for furniture and insulation. In other applications, it is essential to have an effective way of breaking the foam, e.g., in distillation... 

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