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Low Expansion Foam

Low Expansion Foam. NFPA 11 class B flammable liquids, FP < 100 0 F combustible liquids FP > 100 0 F forms blanket 2-D horizontal surface tank farms, airports etc. . Expansion Ratio. Classification Range Low expansion up to 20:1 Medium 20:1 to 100:1 High 200:1 to 1000:1.

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Low Expansion Foam

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  1. Low Expansion Foam • NFPA 11 • class B • flammable liquids, FP < 1000F • combustible liquids FP > 1000F • forms blanket • 2-D horizontal surface • tank farms, airports etc.

  2. Expansion Ratio Classification Range Low expansion up to 20:1 Medium 20:1 to 100:1 High 200:1 to 1000:1

  3. Components of Foam Air • within bubbles • most of volume Concentrate • to be mixed with water • final concentration 3% or 6% Water • water + concentrate = solution

  4. Types of Foam Protein • older type • no film • from animal protein • little in use now

  5. Types of Foam Fluoroprotein • better than protein • forms film

  6. Types of Foam Aqueous Film Forming Foam • AFFF • most common for fuels • thin film • not for alcohols

  7. Types of Foam Alcohol Resistant • also “Alcohol type” • for small alcohols • methanol, ethanol etc • from membrane bewteen water and foam

  8. Types of Foam Chemical • chemically generated foam • obsolete

  9. Proportioning Methods • To mix concentrate with water • either 3% or 6% concentrate in water • 3 mechanisms • Venturi proportioner • Pressure proportioner • Balanced pressure proportioner • skip details

  10. Types of Systems Mobile • fire dept. trucks Semi-Fixed • permanent piping, foam makers • mobile concentrate and pump

  11. Types of Systems Fixed • Subsurface injection • Surface application • seal protection for floating roofs • dike protection

  12. Sub-Surface Injection • Fixed roof storage tank • foam applied below surface • floats to surface • gentle, uniform application • fluoroprotein foam • has good fuel-shedding properties

  13. Sub-Surface Injection-design 1. Calculate fuel surface area A =( )( r)2 2. Determine application rate (R) and discharge time (T) • see 3.8

  14. Sub-Surface Injection-design 3. Calculate discharge rate (D) and foam concentrate quantity (Q) D = (A) x (R) Q = (A) x (R) x (T) x (%) 4. Determine the number of subsurface application outlets • see 3.9

  15. Sub-Surface Injection-design 5. Determine supplementary requirements • number of hoses (see 3-10) • discharge time (see 3-11) 6. Calculate supplementary discharge rate (Ds) and foam quantity (Qs) Ds = (N) x (50 gpm) Qs = (N) x (50 gpm) x (Ts) x (%)

  16. Sub-Surface Injection-design Total requirement for concentrate Qtotal = Q + Qs see example 3.1

  17. Surface Application • Fixed discharge units • on rim of tank

  18. Surface Injection-design 1. Calculate fuel surface area A =( )( r)2 2. Determine application rate (R) and discharge time (T) • see 3.14 • note difference between types I and II

  19. Surface Injection-design 3. Calculate discharge rate (D) and foam concentrate quantity (Q) D = (A) x (R) Q = (A) x (R) x (T) x (%) 4. Determine the number of surface application outlets • see 3.15

  20. Surface Injection-design 5. Determine supplementary requirements • number of hoses (see 3-10) • discharge time (see 3-11) 6. Calculate supplementary discharge rate (Ds) and foam quantity (Qs) Ds = (N) x (50 gpm) Qs = (N) x (50 gpm) x (Ts) x (%)

  21. Surface Injection-design Total requirement for concentrate Qtotal = Q + Qs see example 3.2

  22. Seal ProtectionFloating Roof Tanks • No vapour space • gap at edge of roof a problem • seal spans gap

  23. Floating Roof Tanks-design 1. Calculate fuel surface area A = total roof area - unprotected roof area A =( )( r1)2 -( )( r2)2 2. Determine application rate (R) and discharge time (T) • R = .30 gpm/ft2 • T = 20 min.

  24. Floating Roof Tanks-design 3. Calculate discharge rate (D) and foam concentrate quantity (Q) D = (A) x (R) Q = (A) x (R) x (T) x (%) 4. Determine the spacing of outlets • see text

  25. Floating Roof Tanks-design 5. Determine number of discharge devices N = C/S N = number C = circumference ( x diameter) S = maximum spacing

  26. Floating Roof Tanks-design 6. Determine supplementary requirements • number of hoses (see 3-10) • discharge time (see 3-11) 7. Calculate supplementary discharge rate (Ds) and foam quantity (Qs) Ds = (N) x (50 gpm) Qs = (N) x (50 gpm) x (Ts) x (%)

  27. Floating Roof Tanks-design Total requirement for concentrate Qtotal = Q + Qs see example 3.3

  28. Dike Protection • To contain tank farm

  29. Dike Protection- Design 1. Calculate dike surface area A = dike length x dike width 2. Determine application rate (R) and discharge time (T) R = .10 gpm/ft2 fixed outlets R = .16 gpm/ft2 monitors T = 30 min., flamm. liquids T = 20 min., comb. liquids

  30. Dike Protection- Design 3. Calculate discharge rate (D) and foam concentrate quantity (Q) D = (A) x (R) Q = (A) x (R) x (T) x (%) 4. Determine the number of discharge devices • every 30 ft N = (2L + 2W)/30 see 3.4

  31. Aircraft Hangers • omit

  32. Truck Loading Rack

  33. Truck Loading Rack Hazards

  34. Truck Loading Rack Strategy

  35. Truck Loading Rack Design

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