Fire Streams Module II & III

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

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

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.

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

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.

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.

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

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

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

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.

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.

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

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

Ways Fire Fighting Foam Extinguishes/Prevents Fire Separating Cooling Smothering Penetrating

Terms Associated With Foam Foam concentrate Foam proportioner Foam solution Foam (finished foam)

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

How Foam is Generated Elements needed to produce fire fighting foam Foam concentrate Water Air Mechanical agitation (Continued)

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

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

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

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

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

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

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

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)

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)

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

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

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

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)

Proportioning

Proportioning Methods Induction Injection (Continued)

Proportioning Methods Batch-mixing Premixing Courtesy of Ansul.

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

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

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

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

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)

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

Handline Nozzles Solid-bore nozzles Fog nozzles Air-aspirating foam nozzles

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

Reasons for Poor-Quality Foam/ Failure to Generate Foam Eductor, nozzle flow ratings do not match so foam concentrate cannot induct into fire stream Air leaks at fittings cause loss of suction (Continued)

Reasons for Poor-Quality Foam/ Failure to Generate Foam Improper cleaning of proportioning equipment causes clogged foam passages Nozzle not fully open, restricting water flow (Continued)

Reasons for Poor-Quality Foam/ Failure to Generate Foam Hose lay on discharge side of eductor is too long Hose is kinked and stops flow Nozzle is too far above eductor (Continued)

Reasons for Poor-Quality Foam/ Failure to Generate Foam Mixing different types of foam concentrate in same tank results in mixture too viscous to pass through eductor

Roll-On Foam Application Method Directs foam stream on ground near front edge of burning liquid spill Foam rolls across surface of fuel (Continued)

Roll-On Foam Application Method Firefighters continue to apply foam until spreads across entire surface of fuel and fire extinguished Used only on pool of liquid fuel on open ground

Bank-Down Foam Application Method May be employed when elevated object is near/ within area of burning pool of liquid or unignited liquid spill Object may be wall, tank shell, similar vertical structure (Continued)

Bank-Down Foam Application Method Foam stream directed onto object, allowing foam to run down onto surface of fuel Used primarily in dike fires, fires involving spills around damaged/ overturned transport vehicles

Rain-Down Foam Application Method Used when other two methods not feasible because of size of spill area or lack of object from which to bank foam (Continued)

Rain-Down Foam Application Method Primary manual application technique on aboveground storage tank fires Directs stream into air above fire/spill, allows foam to float gently down onto surface of fuel

Foam Hazards to Humans Foam concentrates pose minimal health risks to humans May be mildly irritating to skin, eyes (Continued)

Foam Hazards to Humans Affected areas should be flushed with water Some concentrates, vapors may be harmful if ingested/inhaled Consult MSDS for specific information

Foam Hazards to Equipment Most Class A, Class B foam concentrates are mildly corrosive Follow proper flushing procedures to prevent damage

Foam Hazards to Environment Primary impact is effect of finished foam after application to fire/liquid spill Biodegradability of foam determined by rate at which environmental bacteria cause decomposition (Continued)

Foam Hazards to Environment Environmental impact of foam concentrates varies In the U.S., Class A foams should be approved by USDA Forest Service (Continued)

Foam Hazards to Environment Chemical properties of Class B foams and environmental impact vary on type and manufacturer Protein-based foams safer for environment (Continued)

Summary Firefighters must know the differences between the classes of foam, how to generate foam, and how to apply foam most effectively