nozzles and streamsmembers.wabash.net/~lfender/ncfpd_web/basic_ff_mod_b/nozzles and streams.pdf–...

Nozzles and Streams

Define Fire Stream

• A stream of water, or other extinguishing agent, after it leaves the fire hose and nozzle until it reaches the desired point

Identify the Purposes of a Fire Stream

• Applying water or foam directly to burning material to reduce its temperature

• Applying water or foam over an open fire to reduce the temperature so firefighters can advance hand lines closer to effect extinguishment

• Reducing high atmospheric temperature • Dispersing hot smoke and fire gases from a heated area by using a

fire stream • Creating a water curtain to protect firefighters and property from

heat • Creating a barrier between a fuel and a fire by covering with a

foam blanket

Identify the Various Uses of Water as an Extinguishing Agent

• Advantages – Water is an efficient, plentiful, and inexpensive extinguishing agent. – Greater heat absorbing capacity than other common extinguishing

agents • One BTU is the amount of heat required to raise the temperature of one

pound of water one degree F • Cools fuel below ignition temperature

– A relatively large amount of heat is required to vaporize water to steam

• 970 BTU’s are required to vaporize water, changing it to steam – The greater the surface area of the water exposed, the more rapidly

heat will be absorbed – Water converted to steam occupies 1700 times the original volume

occupied by the liquid – Displaces hot gases, smoke and other products of combustion

Water as Steam

• At 212ºF (100ºC) water expands to approximately 1,700 times its original volume. • Steam absorbs more heat faster, cooling fuel below ignition temperature. • Steam displaces hot gases, smoke, and other products of combustion. • In some cases, steam may smother fire by excluding oxygen.

20 cubic feet (0.57 m3) of water @ 500°F

(260°C) converts to 48,000 feet (1 359 m)

of steam

96 feet (29 m)

10 fe

et (3

m)

Identify the Various Uses of Water as an Extinguishing Agent

• Disadvantages – Water has a considerable amount of surface tension – Will not readily penetrate certain porous materials – Will react with certain combustible materials – Freezing will occur at 320 F (00C) – Water has low viscosity; it will not cling or readily

coat materials – May conduct electricity under certain conditions

Identify the Types of Fire Stream Nozzles

• Solid Stream

Discharge Orifice No Greater Than Half Size of Hoseline

Smooth, Cylindrical Bore Length One to One and One-half

Times its Diameter


• Solid Stream – Flow rate is dependant on the velocity of the stream and size of

discharge opening • Increase of size of discharge orifice or velocity will increase flow

– Longer reach than other types of streams; • The greater the discharge pressure, the greater the reach • Maximum horizontal reach is attained at an angle of 32 degrees • Vertical reach into structures is best at a 70-75 degree angle • Greatest vertical reach is a 90 degree angle • Wind will affect stream shape and reach

– Reduced problem of steam burns to firefighters and trapped civilians as a result of disturbance to the normal thermal layering of heat and gases during interior structural attack

– Operating pressures • 50 psi on handlines • 80 psi on master stream devices


• Fog Stream / Straight Stream


• Fog Stream / Straight Stream – A fog stream is a patterned stream composed of fine water

droplets – Greater heat absorption due to more surface area of water – May be used in close proximity to energized electrical

equipment – Has less reach and penetrating power than solid streams – Improper use during interior attacks can

• Spread the fire • Create heat inversion • Cause steam burns to firefighters and trapped civilians


• Fog Stream / Straight Stream – Flow rate is dependent on type of nozzle, pressure and stream

pattern • Constant gallonage nozzles

– One flow rate at a given discharge pressure • Adjustable gallonage nozzles

– Allows one of several preset gallon settings to be selected • Automatic nozzles

– Discharge a wide range of flows depending on the pressure being supplied to the nozzle


15° to 45°

45° to 80°

• Fog Stream / Straight Stream – Can produce variable stream patterns

• Wide angle fog

• Narrow angle fog

• Straight stream – A very narrow fog pattern with broken water dropets – Not to be confused with a solid stream


• Fog Stream / Straight Stream – Wider the pattern, shorter the reach – Low nozzle pressure will reduce velocity, reach and

volume – Once maximum reach is attained, increases in nozzle

pressure have little effect on reach and volume


• Broken stream


• Broken stream – Limited to special applications – Designed for a specific use – Solid stream broken into coarsely divided water

droplets – Droplets are larger than fog stream droplets and have

better penetration

Identify the Water Flow/GPM of Handlines and Master Streams

• Hand Lines - Generally range from 40 – 350 GPM – ½” to 1” diameter hand lines (small) 40-100 GPM – 1” to 2” diameter hand lines (medium) 100-250 GPM – 2½” - 3” diameter hand lines (medium/large) 165-350 GPM

• Master Stream - Discharge is greater than 350 GPM

Identify the Safe Operation of Fire Stream Nozzles

• Watch for over-pressurization • Operate hand lines with minimum of two firefighters • Remain aware of fire conditions • Follow personal safety procedures • Hand lines should be operated with two or more firefighters • Methods of preventing damage • Open nozzles and other appliances slowly • Close nozzles and other appliances slowly • Avoid dropping nozzles and appliances • In cold weather, leave nozzles cracked open to prevent freezing

Define Nozzle Reaction

• The force of nature that makes the nozzle move in the opposite direction of the water flow. The nozzle operator must counteract the thrust exerted by the nozzle to maintain control – Newton’s Third Law: For every action, there is an

equal and opposite reaction – The greater the nozzle discharge pressure, the

greater the nozzle reaction

Define Water Hammer and Techniques for Its Prevention

Sudden stopping of water flow resulting in surge of energy in the opposite direction

Define Water Hammer and Techniques for Its Prevention

• Effects – Broken pipes, hoses, pumps and hydrants

• Prevention – Open and close valves slowly

• Cause – Rapid/sudden closing of nozzles or valves

Identify results that are obtained when the proper application of a fire stream is accomplished

• Thermal layer is maintained • Steam conversion • Temperature reduction • Fire reduction / extinguishment (darkens down)

Identify Methods of Water Application

• Direct – Apply water directly on burning fuels: Most efficient

use of water – Should be applied in short bursts – Application of water until the fire "darkens down"


• Indirect – Fog stream directed at ceiling, into superheated atmosphere

results in the production of large quantities of steam – Not desirable when victims may yet be present – Used where spread of fire into uninvolved spaces cannot be

contained


• Combination – A ceiling level attack combined with an direct attack

on burning materials at the floor level – Nozzle is rotated with stream edge reaching the

ceiling, wall, floor and opposite wall

T O Z

Identify the Use of Various Nozzles Carried on Fire Apparatus

• Fog – Immediate reduction of heat – Helps to avoid flashover – Adjustable stream pattern

• Wide Angle Fog • Narrow Angle Fog • Straight Stream

• Smooth bore nozzle – Longer reach than a combination nozzle – Capable of deeper penetration into burning material – Operate at a lower pressure – Less disturbance of the thermal layering – Easier to see the pathway than a fog stream

• Piercing nozzle – Used to make holes in sheet metal, aircraft, or building walls – Extinguish behind these surfaces

• Cellar nozzle/Bresnan distributor nozzles: – Fires in cellars and other inaccessible places

• Water curtain – Deliver a flat screen of water to form a protective sheet of water

Identify the Procedures for Cleaning, Maintaining and Inspecting Nozzles

• Inspecting – Check the gasket – Check for external damage – Check for internal damage and debris – Check for ease of operation

• Cleaning and Maintaining – Clean with soap and water using a soft bristle brush – Replace the gasket – Clean and lubricate any moving parts that stick

according to manufacturer’s recommendations

Identify the Principals of Both Class A and Class B Foam as an Extinguishing Agent

• Components of foam – Air – Water – Concentrate – Mechanical Agitation

Foam Proportioner

Water

Foam Solution

Finished Foam

Foam Concentrate


• Types of foam concentrate – Class A

• Are used on wildland and structural fires • Contain hydrocarbon surfactants • Reduce water tension in foam solution • Coat and insulate fuels • May be applied with a variety of nozzles, expansion

devices, and CAFS • Have supercleaning characteristics • Are mildly corrosive


• Types of foam concentrate – Class B

• Are used on fires involving flammable and combustible liquids

• Are used to suppress unignited vapors • Are made from fluorosurfactants, animal proteins, and

combinations of these • Are generally formulated for either hydrocarbons or

polar solvents

Class B Fuels

Hydrocarbon Fuels • Petroleum based • Float on water • Examples

– Crude oil – Fuel oil – Gasoline – Benzene – Naphtha – Jet fuel – Kerosene

Polar Solvent Fuels • Flammable liquids • Mix with water • Examples

– Alcohols – Esters – Acids – Acetone – Lacquer thinner – Ketones

Class B Foam Types

• Protein • Fluoroprotein • Film Forming Fluoroprotein

– Contain natural proteins – Bio-degradable – Better used on deep pools of fuel

Class B Foam Types

• Aqueous Film Forming Foam (AFFF) • Alcohol Resistant Film Forming Foam (AR-AFFF)

– Synthetic foaming agents – Film is formed on the surface of the flammable

liquid by the foam solution as it drains from the foam blanket

– Best used on spills

How AFFF Works

• Water drained from foam blanket floats on hydrocarbon fuel spills. • This “light water” send an air-excluding film ahead of foam blanket.

Foam

Fuel

Aqueous Film

Identify the Methods by Which Foam Prevents or Controls a Hazard

• Separates – barrier between fuel and fire • Cooling – reduces the temperature of the fuel • Suppressing – holds down flammable vapors • Tension / Penetration – reduces surface tension

allowing for greater penetrating ability (Class A)

Proportioning Concentrations • 3% foam = 97 parts of water + 3 parts foam concentrate

• Class B foams are normally mixed in proportions of 1% to 6%.

• Class A foams can be mixed across a wider range of proportions than Class B foams.

• 3% concentrate is normally used for hydrocarbon fuels.

• 6% concentrate is normally used for polar solvent fuels.

• Multipurpose foam is often mixed at 3% concentration regardless of the fuel.

• Dry (thick) foam used for exposure protection and fire breaks can be produced by increasing the percentage of foam concentrate.

• Wet (thin) foam that will sink below the surface of the fuel can be produced by decreasing the percentage of foam concentrate.

Identify the Necessary Equipment for the Application of Class A and Class B Foam

• Eductors – Venture principle to pick up the foam – In-line – water always piped through the eductor – By-pass – separate waterway to by-pass the

waterway


• Proportioner – The device that mixes the foam concentrate into

the fire stream in the proper percentage • Fixed • Portable

– Should be located less then 6’ from foam tank/source


• Nozzles – Smooth Bore – Fog – Air Aspirating

• Water Aspirating • Mechanical Blower

– Compressed Air Foam Systems (CAFS)

Identify the Principle by Which Foam is Generated

• Picked up (educted) – Pressure energy in the water stream drafts

concentrate into the fire stream

• Proper mixture (proportioned) – An external pump or head pressure forces

concentrate into the fire stream

• Mixed with air (aerated)(nozzle) – Nozzle designed to draw air into the foam mix to

allow for a greater expansion of the foam mixture

Identify the Techniques of Applying Class B Foam

Bank-in or Roll-On

Rain-Down or Snowflake

Bank-Back, Bounce-Off, Bank-Down or Deflection

Identify Common Causes for Poor Foam Generation and How to Correct It

• Eductor and nozzle flow ratings do not match

• Air leaks at fittings cause a loss of suction

• Foam passages are clogged due to improper cleaning

• Nozzle is not fully open

• Hose lay on discharge side of eductor is too long

• Hose is kinked and stops flow

• Nozzle is too far above eductor

• Mixture is too viscous to pass through eductor

Identify the Procedures for Inspecting, Cleaning and Maintaining Foam Appliances

• Inspecting; – Check the gasket – Check for external damage – Check for internal damage and debris – Check for ease of operation

• Cleaning and Maintaining – The foam appliance should be flushed with water at the

end of each use – Clean with soap and water using a soft bristle brush – Replace the gasket – Clean and lubricate any moving parts that stick according

to manufacturer’s recommendations

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