Fire Testing of Experimental Siloxane-Based AFFF. Results from New Experiments

Transcription

1 Fire Testing of Experimental Siloxane-Based AFFF Results from New Experiments SupDet

2 AFFF AFFF = Aqueous Film Forming Foam 2

3 The Aqueous Film The Aqueous Film cools the fuel surface acts as vapor barrier operates in areas without foam autonomously closes perforations of the foam works as buffer between fire and foam AFFF is the most effective agent for pool fires! 3

4 Environmental Problems Environmental Problems of AFFF: - AFFF use PFC (polyfluorinated compounds) to establish the water film. - PFC are persistent. - PFC are strictly regulated in Germany. Quelle: abgerufen am

5 Definition of the spreading coefficient S = SFT F - (SFT A + IFT) S SFT F SFT A IFT Spreading Coefficient Surface Tension of the Fuel Surface Tension of the Extinguishing Agent Interfacial Tension between the Fuel and the AqueousPhase If S > 0, an aqueous film is formed. (S > 0 is a necessary, but not a sufficient condition.) 5

6 Militarily Important Fuels Fuel SFT F (24 C) Sample Origin Diesel 28,3 mn/m BP Refinery Emsland, Germany Jet fuel 26,7 mn/m BP Refinery Emsland, Germany F-34 25,8 mn/m Bundeswehr (NATO Standard Fuel) Cyclohexan 24,9 mn/m Reference substance S = SFT F - (SFT A + IFT) => (SFT A + IFT) < 25 mn/m 6

7 Surfactant Types Surfactant Type min. SFT A (20 C) 1. Fluorosurfactants (PFC) 15 mn/m 2. Siloxane surfactants 20 mn/m 4. Alkylsurfactants 28 mn/m 5. no surfactant (pure water) 73 mn/m S = SFT F - (SFT A + IFT) (SFT A + IFT) < 25 mn/m => SFT A <<25 mn/m 7

8 Siloxane Surfactant T-C3-Malt T-C3-Malt 8

9 Synthesis of T-C3-Malt Problems: time consuming and low yields. 9

10 Interfacial Characteristics T-C3-Malt Chemical Composition 0.25 g/l T-C3-Malt 0.50 g/l T-C3-Malt 1.00 g/l T-C3-Malt 2.00 g/l T-C3-Malt SFT A [mn/m] # : based on Cyclohexane (SFT F =25.0 mn/m); *: small area film formation, recontracting after a short term. IFT # [mn/m] S # [mn/m] Film on Cyclohexa ne Film on F No No No Yes* Yes Yes Yes Yes Yes Yes 10

11 Foam Characteristics Experimental Setup Foaming Device: Micro Foam Unit, MFU V-25, (Jürgen Arens, Cologne, Germany). Nozzle: Low Expansion (also Jürgen Arens). Discharge Rate: 1.06 Kg/min. Working Pressure: 4,5 bar. Graduated Cylinder : 2000 ml nominal volume, 2330 ml total volume. Electronic Balance and Stop Watch. 11

12 Foam Characteristics of T-C3-Malt Chemical Composition 0.25 g/l T-C3-Malt 0.50 g/l T-C3-Malt 1.0 g/l T-C3-Malt 2.00 g/l T-C3-Malt Expansion Factor 50%-Drainage Time [min] ± :39 ± 0: ± :44 ± 0: ± :36 ± 0: ± :00 ± 0: ± :05 ± 0:03 12

13 Commercially Available Foams Commercial Firefighting foam PFCcontaining Concentration in Water [%] Expansion 50%-Drainage Time [min] 1 AFFF 1 Yes ± :38 ± 0:04 2 AFFF 2 Yes ± :09 ± 0: PFC-free 50%-Drainage Time Chemical Composition Expansion Factor No ± :21 ± [min] 0:21 Class B Foam 6.8 g/l 1 Glucopon 215 CS UP ± :39 ± 0:03 PFC-free 6.8 g/l GlucoponNo 215 CS UP ± :16 ± 0:22 Class B 2 Foam 2.5 g/l 2 BDG ± :44 ± 0:02 PFC-free 0.25 g/l T-C3-Malt 6.8 g/l GlucoponNo 215 CS UP ± :26 ± 0:06 Class B 3 Foam 2.5 g/l 3 BDG ± :36 ± 0: g/l T-C3-Malt ± :00 ± 0: g/l T-C3-Malt ± :05 ± 0: g/l T-C3-Malt 13

14 Experimental Setup Small Scale Fire Tests Pan: EN 3-7, 55B ( kg/min m²) 21B (>1.8 kg/min m²). Water Buffer: 3 cm Fuel: F-34 (10 l) Nozzle: Low Expansion Foam: Premixed Solution Discharge Rate: 1.06 Kg/min Foam Solution Reservoir: 25 l (premix) Working Pressure: 4,5 bar Burn Back Pot: Height: 10.0 cm Radius: 5.8 cm Fuel: Heptane 14

15 99% Extingusihing Time [s] Small Scale Fire Tests 99% Extinguishing Time Application Rate [kg / (min x m²)] AFFF 1 AFFF 2 PFC-free Class B Foam 1 PFC-free Class B Foam 2 PFC-free Class B Foam g/l Glucopon, 6.8 g/l Glucopon,, 0.25 g/l T-C3-Malt 6.8 g/l Glucopon,, 0.50 g/l T-C3-Malt 6.8 g/l Glucopon,, 1.00 g/l T-C3-Malt 15

16 100% Extingusihing Time [s] Small Scale Fire Tests 100% Extinguishing Time Application Rate [kg / (min x m²) AFFF 1 AFFF 2 PFC-free Class B Foam 1 PFC-free Class B Foam 2 PFC-free Class B Foam g/l Glucopon,, 1.00 g/l T-C3-Malt 6.8 g/l Glucopon,, 0.50 g/l T-C3-Malt 6.8 g/l Glucopon,, 0.25 g/l T-C3-Malt 6.8 g/l Glucopon, 16

17 25% Reignition Time [s] Burn Back Experiments Application Rate [kg / (min x m²)] AFFF 1 PFC-free Class B Foam 1 PFC-free Class B Foam 2 AFFF g/l Glucopon,, 1.00 g/l T-C3-Malt 6.8 g/l Glucopon,, 0.50 g/l T-C3-Malt 6.8 g/l Glucopon,, 0.25 g/l T-C3-Malt 6.8 g/l Glucopon, 17

18 Revised ICAO Test Protocol Source: ICAO AIRPORT SERVICE MANUAL, Doc 9137-AN/901 Part 1 ( ). 18

19 ICAO Fire Test Experimental Set-Up Start Foam Application 99%-Extinguishing Time (only flickers left) Burn Back Experiment 19

20 Results of ICAO B Fire Tests Type of Foam Solution Chemical Composition / Commercial Foam Extinguishing Time [s] 25%-Burn Back Time [s] Requirements 60 (99%) 120 (100%) 300 PFC-free siloxane based foam solution PFC-containing AFFF according to TL g/l new siloxane surfactant 2.0 g/l new siloxane surfactant 0.15 g/l Xanthan gum AFFF 1 AFFF 2 AFFF n.d n.d

21 Conclusions Conclusions The new siloxane surfactants form aqueous films on cyclohexane and militarily important fuels. These siloxane surfactants are compatible with foam forming glyscoside surfactants. In fire test the perfomance of the siloxanes based foams is only surpassed by the fluorine-containing AFFF. Fluorine-free Class B foams are clearly performing less good than the siloxane-containing blends. Future work Further fire tests according to international standards, e.g. ICAO B and C. Formulation of a long-term storable concentrate based on the experimental siloxane 21

22 AFFF Thank you for your kind attention. Questions? 12 February

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