Fire Streams

1. Fire Streams Module II & III

2. Fire Hydraulics • Deal with properties of energy, pressure, and water flow as related to fire suppression.

3. Flow • Volume of water that is being moved • Measured in gallons per minute (gpm) • Metric measured in liters per minute (lpm)

4. Pressure • Amount of energy in a body or stream of water • Measured in pounds per square inch (psi) • Metric measured in kilopascals (kPa) • Required to push water through a hose or to a higher level • Pumps usually provide the pressure.

5. Friction Loss • Loss of pressure as water moves through a pipe or hose • Loss represents the energy required to push the water. • Greater flow in same hose, greater friction loss • Smaller hose with same flow, greater friction loss • All else equal, loss proportional to distance

7. Elevation Pressure • Elevation affects water pressure. • Elevated water tanks supply pressure to pipes due to elevation. • Difference between nozzle elevation and engine elevation affects pressure. • Hoses laid downhill have greater pressure. • Hoses laid up stairs will have less pressure.

9. Water Hammer • Surge in pressure caused by sudden stop in the flow of water • Shock wave is transmitted back through the hose. • Can damage hose, couplings, and plumbing • To prevent, open and close valves slowly.

11. Foam • Used to fight several types of fires • Used to prevent ignition of materials • Used to neutralize hazardous materials • Produced by mixing foam concentrate with water and air

12. Foam Classifications (1 of 2) • Class A foam • Used to fight fires involving ordinary combustible materials • Increases effectiveness of water by reducing the surface tension of water • Can be added to water streams and applied with several types of nozzles

14. Foam Classifications (2 of 2) • Class B foam • Used for class B fires • Specific foam varies by type of flammable liquid • Separates fuel from the fire • Foam blanket must not be disturbed • Can be applied to flammable liquid spills to prevent fire

16. Class A Foam Concentrates • From 0.1% to 1% solution • “Wet” foam has good penetration properties. • “Stiff” foam is more effective when applied for protecting buildings.

17. Class B Foam Concentrates (1 of 3) • Used as either 3% or 6% solution • Types of foams should not be mixed. • Brands of the same foams should not be mixed. • Incompatible mixtures may congeal and plug foam systems. • Older foams have environmental hazards.

18. Class B Foam Concentrates (2 of 3) • Protein foams • Made from animal byproducts • Effective on hydrocarbon fires • Fluoroprotein foams • Made with same base materials as protein foam • Includes a flurochemical surfactant • Produce fast-spreading membrane • Provide a greater seal against edges of objects

19. Class B Foam Concentrates (3 of 3) • Aqueous film-forming foam (AFFF) • Synthetic base • Particularly suited for gasoline • Seals across surface quickly • Excellent vapor suppression ability • Alcohol-resistant foam • Properties similar to AFFF • Won’t dissolve in alcohols and other polar solvents

23. Ways Fire Fighting Foam Extinguishes/Prevents Fire • Separating • Cooling • Smothering • Penetrating

24. Terms Associated With Foam • Foam concentrate • Foam proportioner • Foam solution • Foam (finished foam)

25. How Foam is Generated • Foams used today are of mechanical type and before use must be • Proportioned • Aerated (Continued)

26. How Foam is Generated • Elements needed to produce fire fighting foam (Continued)

27. How Foam is Generated • All elements must be present and blended in correct ratios • Aeration produces foam bubbles to form effective foam blanket

28. Foam Expansion • The increase in volume of foam when aerated • Method of aerating results in varying degrees of expansion • Types of foam

29. Foam Concentrates — General Considerations • Foam concentrates must match fuel to which applied • Class A foams not designed to extinguish Class B fires • Class B foams designed solely for hydrocarbon fires will not extinguish polar solvent fires

30. Class A Foam • Increasingly used in both wildland and structural fire fighting (Continued)

31. Class A Foam • Special formulation of hydrocarbon surfactants • Aerated Class A foam coats, insulates fuels, preventing pyrolysis and ignition • May be used with variety of nozzles

32. Class B Foam • Used to prevent ignition of or extinguish fires involving flammable and combustible liquids Courtesy of Williams Fire & Hazard Control, Inc. (Continued)

33. Class B Foam • Used to suppress vapors from unignited spills of these liquids • Several types of Class B foam concentrates available (Continued)

34. Class B Foam • Manufactured from synthetic or protein base • May be proportioned into the fire stream through fixed system, apparatus-mounted system, or by portable foam proportioning equipment (Continued)

35. Class B Foam • Foams such as AFFF and FFFP foam may be applied with standard fog nozzles or air-aspirating foam nozzles Courtesy of Harvey Eisner. (Continued)

36. Class B Foam • Rate of application depends on several factors • Unignited spills do not require same application rates as ignited spills • To be most effective, blanket of foam 4 inches (100 mm) thick should be applied to fuel surface

37. Specific Application Foams • Numerous types of foam available for specific applications • Properties of foams vary

38. Proportioning • Mixing of water with foam concentrate to form foam solution • Most concentrates can be mixed with fresh/salt water (Continued)

39. Proportioning • For maximum effectiveness, foam concentrates must be proportioned at designated percentage • Most fire fighting foams intended to be mixed with 94 to 99.9 percent water (Continued)

40. Proportioning

41. Proportioning Methods • Induction • Injection (Continued)

42. Proportioning Methods • Batch-mixing • Premixing Courtesy of Ansul.

43. Foam Proportioners — General Considerations • May be portable or apparatus-mounted • Operate by one of two basic principles Courtesy of Conoco/Phillips.

44. Portable Foam Proportioners • Simplest, most common form of proportioning devices • In-line foam eductors • Foam nozzle eductors

45. Apparatus-Mounted Proportioners • Mounted on structural, industrial, wildland, and aircraft rescue and fire fighting apparatus, as well as on fire boats • Three types

46. Compressed-Air Foam Systems (CAFS) • Newer structural engines are equipped with CAFS (Continued)

47. Compressed-Air Foam Systems (CAFS) • Standard centrifugal pump supplies water, direct-injection foam-proportioning system mixes foam solution with water on discharge side of pump, onboard air compressor adds air to mix before discharging from engine (Continued)

48. Compressed-Air Foam Systems (CAFS) • Unlike other systems, hoseline contains finished foam • Advantages • Disadvantages

49. Handline Nozzles • Solid-bore nozzles • Fog nozzles • Air-aspirating foam nozzles

50. Medium- and High-Expansion Foam Generating Devices • Produce foam that is semistable with high air content • Medium-expansion foam • High-expansion foam • Water-aspirating type nozzle • Mechanical blower generator