Presentation on theme: "Nozzles, Fire Streams, and Foam"— Presentation transcript:
1 Nozzles, Fire Streams, and Foam Chapter 11Nozzles, Fire Streams,and Foam
2 Introduction Fires usually extinguished by water Foam added to improve water’s extinguishment abilityFor fires where water ineffectiveWater and foam delivered using nozzles and fire streamsNozzle selection importantEach fire situation requires different appliance
3 Definition of Fire Stream Fire stream: extinguishing agent that leaves the nozzle and flows toward its targetFour elements affecting the stream:PumpWaterHoseNozzleProper stream has sufficient volume, pressure, and direction to reach its target
4 NozzlesNozzles: appliances that allow application of extinguishing agentTwo types: solid stream and fogCombination nozzles: straight stream or adjustable spray patternsNozzle pressure: pressure required for effective nozzle operationRelates to flow and reachNozzle flow: amount of water a nozzle provides at a given pressure
5 Figure 11-1 Nozzles showing the stream shape for straight, solid, and wide pattern streams.
6 Nozzles (cont’d.)Nozzle reach: distance the water will travel after leaving the nozzleNozzle reach a function of water pressureAffected by stream shape, water pressure, wind direction, gravity, air frictionStream shape (stream pattern): configuration of droplets of water as they leave the nozzleNozzle reaction: nozzle moves in opposite direction of water flow
7 Solid Tip or Stream Deliver unbroken stream of water Solid stream nozzle delivers water as a solid cone of waterLarge droplets when bounced off wall, ceilingFlow a factor of tip size at a certain nozzle pressureMinimal effect of room’s thermal balanceDisadvantages: lack of volume control, lack of fog protection, higher nozzle reaction
8 Fog NozzlesDeliver fixed spray pattern or variable combination patternStraight stream and spray patternsFog provides better heat absorption, but can change to steamExcellent tools for hydraulic ventilationLarge quantities of smoke removed by aiming fog cone out an open windowCan also draw heat from the fire
9 Figure 11-6 Variable combination fog nozzle patterns Figure Variable combination fog nozzle patterns. From top to bottom: straight stream, narrow fog, and wide fog.
11 Straight Stream Creates a hollow type stream Similar to solid stream patternStraight stream pattern must pass around the baffle of the nozzleCreates an opening in the patternMay allow air into the stream and reduce its reachNewer designs have hollow effect from the tipShort distance to refocus the stream to create solid stream with good reach and penetration
12 Figure 11-11 Comparison of (A) straight and (B) solid streams at tip.
13 Special Purpose Not often used Cellar nozzles and Bresnan distributors:Fight localized fires in basements when firefighters cannot make direct attackPiercing nozzles originally designed to penetrate the skin of aircraftModified to pierce through building walls and floorsWater curtain nozzleSprays water to protect against heat exposure
14 (A)(B)Figure (A) Cellar nozzle and (B) Bresnan distributor.
15 Figure 11-13 Piercing nozzle. Figure Water curtain nozzle.
16 Nozzle Operations Solid tip nozzles easy to operate Nozzle size and tip selected to match desired flowCarry smaller nozzle tips in pocketFog nozzles with rotating valves common for wildland firefightingGallonage and pattern adjustments detected in the dark because nozzle clicks at each positionFog nozzles have more applications than smooth bore nozzlesConsidered more effective
17 Operating Hoselines Chapter 10 covers: Advancing hoselines, initial nozzle operationStraightening the hoseProperly spacing firefighters on same side of lineBleeding off air from hose and nozzleSelecting proper patternMost hoselines operated from crouching or kneeling positionLying, standing, or sitting positions also used
18 Small-Diameter Handlines Typically 1½, 1¾, or 2 inches in diameterFlow from 100 to over 250 gpmWhen flowing at lower volumes, operated by one personLarger volumes require two peopleFog and solid tip nozzles can be used for small linesSmall lines popular because of ease of mobility, number of personnel, extinguishing ability
19 Medium-Diameter Handlines Medium-diameter hose for handlines:2½-inch or 3-inch hoseSolid tip and fog nozzlesFlow from 165 to 325 gpm2½-inch hose is standard size hoselineMany departments use 1¾-inch and 2-inch for attackIncreased maneuverabilityLarge commercial structures or buildings with high fire loading require increased gpm flow of 2½-inch lineRequire two or more personnel to operate
20 Master Stream Devices Master stream devices capable of 350 gpm Main artillery of fire serviceUsed when large volumes of water requiredMust be apparatus-mounted or secured properlyRequire only one person to operateLack of mobility
21 Stream Application, Hydraulics, and Adverse Conditions Applications of fire streams vary according to method of fire attack, conditions encounteredIncluding environmental factors and water supplyFire streams must have proper pressure and flowFirefighters must understand hydraulicsImproper hydraulic calculations are the leading cause of poor fire streams
22 Direct, Indirect, and Combination Attack Direct fire attackAim the flow of water directly at the seat of the fireUsed on deep-seated fires that require penetrationIndirect fire attackApply a fog stream into a closed roomConvert water into steam to extinguish the fireCombination attackTypical attack in structural firefighting
23 Figure 11-20 Firefighter directly attacking a fire.
24 Figure Firefighter using indirect attack by applying water into room and then closing the door.
25 Figure One cubic foot of water in liquid form expands 1,700 times when converted to steam at 212°F.
26 Figure Firefighter using combination fire attack directing the stream from the ceiling to the fire with a circular, “Z” or “T” motion.
27 Basic Hydraulics, Friction Loss, and Pressure Losses in Hoselines Hydraulics: study of fluid in motionPressure: force divided over an areaFlow: rate and quantity of water deliveredFriction loss: loss in pressure due to frictionDischarge pressure of a pump:EP = NP + FL ± E + SA
28 Figure 11-27 Example for friction loss and engine pressure calculations.
29 Adverse Conditions Two types: natural and man-made Natural: Wind and wind directionBreaks up stream and deflects it from its targetRain, snow, hail, tree branches, wires, etc. deflect and break up hose streamsGravity and air friction:Move closer to the target or to a better position
30 Types of Foam and Foam Systems Class B foam: specially formulated concentrated liquid foaming agentsCreates a blanket that cools and smothers the fireSeals in vaporsClass A foam: detergent or soap-based surfactantsPenetrate ordinary combustible materialsKeeps fuel wet and reduces its ability to burn
31 Foam CharacteristicsProtein foam: natural protein materials with metallic saltsFluoroprotein foam: improved protein foam with fluorinated surfactant addedAlcohol-resistant foam: contains a polymerForms a layer between burning surface and foamFluoroprotein film-forming foam (FFFP):Combines protein with film-forming fluorosurfactantsDetergent-type foams: synthetic surfactants break surface tension of water
32 Classification of Fuels Foams used for Class A and B firesSpecific considerations affect their use
33 Class A Piles of Class A materials extinguished using a wetting agent Foamy water solution has the ability to cling to sides of objectsUsed to protect homes in urban interface areas during wildland firesDisadvantages:Cost of equipment and agent, environmental effectsFire investigation lab tests, difficult salvage operations
34 Class B Class B fuels: hydrocarbons and polar solvents Hydrocarbons: Firefighters do not use foamHydrocarbons:Examples: heating oil, gasoline, paraffin, asphaltNot miscible; foam is best method to extinguishPolar solvents:Examples: alcohols, lacquer thinners, acetoneNormal foams break down when used on fires involving these mixturesSpecial foams create a polymeric barrier
35 Figure 11-29 (A) AFFF applied on Class B fuel Figure (A) AFFF applied on Class B fuel. Note the film barrier on the surface.
36 Figure Polar solvent or alcohol-type foam applied on Class B polar solvent fuel. Note the polymeric film barrier on the surface.
37 Application of FoamRequires a device to proportion, meter, or mix foam concentrate into the waterAir added to foam solutionEductor: common proportionerWorks on Venturi principleMust have proper gpm flow, correct pressure, be clean, not have back-pressure situationsCompressed air foam systems (CAFS):Concentrate in separate foam tankConcentrate metered by microprocessor
38 Figure 11-33 Foam eductor using the venturi principle.
39 Bank-In TechniqueFigure The bank-in technique of foam application.
40 Bank-Back TechniqueFigure The bank-back technique of foam application.
41 Raindown TechniqueFigure The raindown technique of foam application.
42 Fog Nozzles versus Foam Nozzles Some nozzles combined all foam-making stepsModern foam nozzles aspirate air and apply foam to the fuelAir vents built into the nozzleDesigned for low and medium expansionRecommended with protein and fluoroprotein foamsFog nozzles can be used with foamClip-on foam nozzle adapters attach to the fog nozzleThree techniques: bank-in, bounce-off, raindown
43 Nozzle and Foam Equipment Maintenance Nozzles and foam appliances must be cleaned and maintained regularlyFollow manufacturer guidelines and department policiesGuidelines and policies should include:Cleaning and maintenance scheduleNecessary skill level of firefighterDocumentation proceduresReplacement and repair process
44 Lessons LearnedFire streams: water that leaves a nozzle and heads toward the targetSolid tip and fog nozzlesNozzle should match fire conditions and department resourcesCorrect hydraulics calculations require understanding pressure and friction lossWhen fuels not compatible with water, other agents are usedFoam requires special equipment