Influence of fuel on foam degradation for fluorinated and fluorine-free foams

Hinnant, Katherine M.; Conroy, Michael; Ananth, Ramagopal

doi:10.1016/j.colsurfa.2017.02.082

Cited by 70 publications

(47 citation statements)

References 31 publications

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“…In addition to repulsion towards fuel, foam stability and lamella thickness are also important to reduce fuel flux through the lamellae. Surfactants can affect the thinning dynamics of lamellae, thereby affecting foam degradation directly [25]. A synergy between the fluorocarbon and hydrocarbon surfactants contained in AFFF was shown to be important for forming stable foams, despite reduced repulsion towards fuel by the presence of hydrocarbon surfactants in the AFFF formulation [27].…”

Section: Resultsmentioning

confidence: 99%

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Measuring fuel transport through fluorocarbon and fluorine-free firefighting foams

Hinnant

Giles

Ananth

2017

Fire Safety Journal

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A flux chamber was designed to measure the transient fuel transport through a foam layer before significant degradation of foam occurred. The fuel transport rate through AFFF (fluorinated foam) was much slower than through RF6 (fluorine-free foam) with breakthrough times being 820 s and 276 s respectively over n-heptane. The fuel flux through AFFF covering three fuel pools (n-heptane, iso-octane, and methyl-cyclohexane) was also measured. AFFF had the smallest flux over iso-octane with a breakthrough time over 1900 s and the highest flux over methyl-cyclohexane with a breakthrough time under 80 s even though the fuels have similar vapor pressures at room temperature. Despite the lack of aqueous film formation on an iso-octane fuel pool, the fuel vapor flux through AFFF was much smaller relative to the methyl-cyclohexane pool, which enables film formation due to its higher surface tension than iso-octane. Our measurements of transient fuel flux show that the foam layer is a significant barrier to fuel vapor transport. The data suggest a transient mechanism based on the suppression of fuel adsorption onto bubble lamellae surfaces due to the oleophobicity of fluorocarbon surfactants, which is consistent with fuel solubility data. This suggests that surfactants that suppress fuel adsorption and solubility into bubble lamellae surfaces may reduce fuel transport through foams.

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Section: Resultsmentioning

confidence: 99%

“…ImageJ software was used to calculate the initial, average, diameter of 300 bubbles from the digital image. The bubble diameter distribution was reported elsewhere [25]. The initial expansion ratio was determined by weighing 250 mL of foam immediately after foam generation and dividing the volume of the foam by the weight of the foam.…”

Section: Fuelsmentioning

confidence: 99%

Measuring fuel transport through fluorocarbon and fluorine-free firefighting foams

Hinnant

Giles

Ananth

2017

Fire Safety Journal

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“…Foams were generated from the three candidate AFFF formulations using a sparging method for bench‐scale evaluations as detailed by Hinnant, Conroy, and Ananth (). Air flows through a circular sparger disc (1 cm diameter, 25–50 μm pore size) placed 3‐cm deep in the surfactant solution at a constant rate to generate bubbles.…”

Section: Methodsmentioning

confidence: 99%

An Analytically Defined Fire‐Suppressing Foam Formulation for Evaluation of Fluorosurfactant Replacement

Hinnant

Giles

Snow

et al. 2018

J Surfact & Detergents

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A 4‐component, analytically defined, reference fluorosurfactant formulation (Ref‐aqueous film forming foam [AFFF]) composed of 0.3% fluorocarbon‐surfactant concentrate (Capstone 1157), 0.2% hydrocarbon‐surfactant concentrate (Glucopon 215 UP), and 0.5% diethylene glycol mono butyl ether by volume in distilled water was found to have rapid fire extinction comparable to a commercial AFFF in tests conducted on a bench scale and a large scale (28 ft2, part of US Military Specification, MIL‐F‐24385F). The Ref‐AFFF was analytically characterized to provide the identity and quantity of the chemical structures of the surfactant molecules that were lacking for commercial AFFF formulations. To arrive at an acceptable Ref‐AFFF formulation, 3 candidate formulations containing different hydrocarbon surfactants in varying amounts were evaluated and ranked relative to a commercial AFFF using a bench‐scale fire‐extinction apparatus; varying the hydrocarbon surfactant was found to affect the fire‐extinction time. The ranking was confirmed by the large‐scale tests suggesting that the bench‐scale apparatus is a reasonable research tool for identifying surfactants likely to succeed in the large‐scale test. In the future, replacing the fluorocarbon surfactant with an alternative surfactant in the Ref‐AFFF enables a direct comparison of fire extinction and environmental impact to identify an acceptable fluorine‐free formulation.

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“…To determine the foam stability, the authors of [16] conducted experiments to quantify the degradation of foam caused by fuel, the application of foam to liquid fuel and water (for comparison). It was found that foams without fluoride decomposed much faster than AFFF.…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

Establishing regularities in the insulating capacity of a foaming agent for localizing flammable liquids

Tsapko¹,

Rogovskii²,

Titova³

et al. 2020

EEJET

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Influence of fuel on foam degradation for fluorinated and fluorine-free foams

Cited by 70 publications

References 31 publications

Measuring fuel transport through fluorocarbon and fluorine-free firefighting foams

Measuring fuel transport through fluorocarbon and fluorine-free firefighting foams

An Analytically Defined Fire‐Suppressing Foam Formulation for Evaluation of Fluorosurfactant Replacement

Establishing regularities in the insulating capacity of a foaming agent for localizing flammable liquids

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