Chapter 16: Fire Streams

Broken stream

A broken stream is a fire stream that has been broken into coarsely divided water droplets by specialized nozzles such as cellar nozzles, pierc- ing (penetrating) nozzles, and chimney. While a solid stream may become a broken stream past the breakover point, a true broken stream takes on that form as it leaves the discharge device. In some cases, the effects of a broken stream can be produced by deflecting solid or straight streams off a wall or ceiling so they break up over the fire. This type of stream is used to extinguish fires in attics, cocklofts, basements, and other confined spaces.

Foam nozzle educators

A foam nozzle eductor operates on the same basic principle as an in-line eductor; however, this eductor is built into the nozzle rather than into the hoseline. As a result, its use requires the foam concentrate to be available where the nozzle is operated. If the foam nozzle is moved, the foam concentrate container must also be moved. The size and number of concentrate containers required magnify the logistical problems of relocation. Use of a foam nozzle eductor can also compromise firefighter safety. Firefighters cannot always move quickly, and they may have to leave their concentrate supplies behind if they are required to retreat for any reason.

Fog stream

A fog stream is a fine spray composed of tiny water droplets. Fog nozzles are used to produce fog streams and designed to permit adjustment of the tip to produce different fog-stream patterns. Water droplets, in either a shower or spray, are formed to expose the maximum water surface for heat absorption. The desired performance of a fog stream is characterized by the amount of heat that it absorbs and the rate by which the water is converted into steam or vapor.

Mechanical blower foam generator

A mechanical blower generator is similar in ap- pearance to a smoke ejector. It operates on the same principle as the water-aspirating nozzle except that a powered fan is used to force air through the foam spray instead of water movement. This device produces foam with high air content and is typically associated with total-flooding applications. Its use is limited to high- expansion foam.

Straight stream

A straight stream pattern is a semi-solid steam that is produced by a fog nozzle. This is done by rotating the stream shaper until a straight stream is produced. Characteristics of straight stream patterns are similar to those of the solid stream.

Specialized application system

Advances in foam technology have created an application system that uses a solid foam/wetting agent. The solid agent container is inserted into the specially perforated foam sleeve between the hoseline and an ad- justable fog nozzle. The concentrate is designed for use on Class A and Class B fires. Each 11⁄2-pound (0.68 kg) cartridge of solid agent is equal to 5 gallons (18.93 L) liquid agent and will treat approximately 660 gallons (2 498.37 L) of water.

Polar solvents

Alcohol Acetone Lacquer thinner Ketones Esters Acids

Air aspirating foam nozzle

An air-aspirating foam nozzle is the most effective appliance for the generation of low-expansion foam. The air-aspirating foam nozzle inducts air into the foam solution using the Venturi Principle. This nozzle is especially designed to provide the aeration required to make the highest quality foam possible. These nozzles must be used with protein and fluoroprotein concentrates. They may also be used with Class A foams. These nozzles provide max- imum expansion of the agent. The reach of the stream is less than that of a standard fog nozzle.

What flow are automatic master streams designed for?

Automatic master stream fog nozzles are typically designed to flow between 350 gpm (1 400 L/min) and 1,250 gpm (5 000 L/min).

Ball valve characteristics

Ball valves are the most common nozzle control valves. They provide effective nozzle control with a minimum of effort. The ball, perforated by a smooth waterway, is sus- pended from both sides of the nozzle body and sealed against a seat. The ball can be rotated up to 90 degrees by moving the valve handle or bale backward to open it and forward to close it. With the valve in the closed position, the waterway is perpendicular to the nozzle body, blocking the flow of water through the nozzle. With the valve in the open position, the waterway is in line with the axis of the nozzle, allowing water to flow through it.

Batch mixing method of proportioning

Batch-mixing is the simplest method of mixing foam concentrate and water. It is commonly used to mix foam within a fire apparatus water tank or a portable water tank. Batch-mixing is common with Class A foams but is less common with Class B foams.

Disadvantages of batch mixing

Batch-mixing may not be effective on large incidents because when the tank be- comes empty, the foam attack lines must be shut down until the tank is completely filled with water and more foam concentrate is added. Another drawback of batch- mixing is that Class B concentrates and tank water must be circulated for a period of time to ensure thorough mixing before the solution is discharged. The time required for mixing depends on the viscosity and solubility of the foam concentrate. Another disadvantage to the method is that it can be difficult to refill an apparatus water tank due to excessive bubbling from residual solution.

Class B foam proportioning

Class B foams are mixed in proportions from 1 percent to 6 percent. Some mul- tipurpose Class B foams designed for use on both hydrocarbon and polar solvent fuels can be used at different concentrations, depending on which of the two fuels is burning. These concentrates are normally used at a 3 percent rate for hydrocarbons and 6 percent for polar solvents. Newer multipurpose foams may be used at 3 percent concentrations regardless of the type of fuel. Always follow the manufacturer's rec- ommendations for proportioning.

What are hydrocarbon fuels

Crude oil Fuel oil Gasoline Benzene Naphtha Jet fuel Kerosene

Low volume stream

Discharges less than 40 gpm (160 L/min). Typically sup- plied by 3⁄4-inch (20 mm), 1-inch (25 mm), or 11⁄2-inch (38 mm) hoselines.

Master streams

Discharges more than 350 gpm (1 400 L/min) and is fed by one or more 21⁄2- or 3-inch (65 mm or 77 mm) hoselines or large-diameter hoselines connected to a master stream nozzle. Nozzle pressures of 80 to 100 psi (560 to 700 kPa) are common with master stream devices. Master streams are large-volume fire streams created by master stream appliances such as apparatus-mounted deck pipes and ladder pipes.

Apparatus mounted proportioner

Foam proportioning systems are commonly mounted on structural, industrial, wild- land, and aircraft rescue and fire fighting apparatus (ARFF), as well as on fire boats. Three types of the various apparatus-mounted foam proportioning systems are installed in-line eductors, around-the-pump proportioners, and bal- anced pressure proportioners

Class A foam characteristics

Foams specifically designed for use on Class A fuels (ordinary combustibles) are in- creasingly used in both wildland and structural fire fighting. Class A foam is a special formulation of hydrocarbon-based surfactants. These surfactants reduce the surface tension of water in the foam solution, allowing better water pen- etration into the fuel, thereby increasing its effectiveness. Aerated Class A foam coats and insulates fuels, preventing pyrolysis and ignition from an adjacent fire.

High expansion foam

High-expansion foams are synthetic foaming agents created by high-expansion foam generators at ratios from 200-to-1 to 1,000-to-1. They are typically used in confined spaces such as shipboard compartments, basements, mines, and enclosed aircraft hangars.

What is latent heat vaporization?

Latent heat of vaporization is the amount of heat required to convert unit mass of a liquid into a vapor without a temperature change. Water has a latent heat of va- porization of 970 Btu/lb (2 257 kJ/kg) at its boiling point. For example, when water is heated to its boiling point of 212oF (100oC) additional energy is required to change it from liquid phase to gas phase, but the temperature of the water remains 212oF

Low expansion foam characteristics

Low-expansion foam has an air/solution ratio up to 20 parts finished foam for every part of foam solution (20-to-1 ratio). Low-expansion foams are effective for control- ling and extinguishing most Class B fires. They are also effective for cooling and penetrating Class A fires.

Medium expansion foam

Medium-expansion foam is most commonly used at a ratio of between 20-to-1 to 200-to-1 through hydraulically operated nozzle-style delivery devices. These foams are used to suppress vapors from hazardous materials spills when applied at expan- sion ratios of 30-to-1 and 55-to-1.

What are most foams proportioned at?

Most fire fighting foam concentrates are intended to be mixed with 94 to 99.9 percent.

What NFPA standard pertains to foam manufacturing?

NFPA 11

What NFPA standard categorizes nozzles?

NFPA® 1963, Standard for Fire Hose Connections (2009), establishes two general categories of fire stream nozzles: straight tip nozzles and spray nozzles.

How large of a hoseline requires more than one operator?

One and three quarter inch (45 mm) and larger hoselines require additional personnel to overcome the reaction and maneuver the hoseline

How large of a hoseline can one person operate?

One person can usually operate a smooth bore nozzle on a 11⁄2-inch (38 mm) or smaller hoseline.

Premixing

Premixing is one of the more commonly used methods of proportioning. Premeasured portions of water and foam concentrate are mixed in a container. Typically, the premix method is used with portable extinguishers, wheeled extinguishers, skid- mounted twin-agent units, and vehicle-mounted tank systems. In most cases, premixed solutions are discharged from a pressure-rated tank using either a compressed inert gas or air. An alternative method of discharge uses a pump and a non-pressure-rated atmospheric storage tank. The pump discharges the foam solution through piping or hose to the delivery devices. Premix systems are limited to a one-time application. When used, the tank must be completely emptied and then refilled before it can be used again. Since most Class A foam solutions are biodegrad- able, premixing the solution and storing it for long periods can result in decreased foaming ability.

Characteristics of a rotary control valve

Rotary control valves are found only on rotary control fog nozzles. They consist of an exterior barrel guided by a screw that moves the exterior barrel forward or backward, rotating around an interior barrel. Rotary control valves also control the discharge pattern of the stream. This type of nozzle is commonly found in standpipe cabinets attached to occupant-use hoselines

What is specific heat?

Specific heat is the amount of energy required to increase the temperature of a substance by one degree. In the customary system used in the United States, this would be expressed in terms of the number of British thermal units (Btu) required to raise the temperature of 1 pound (lb) of water by 1oF. In the Standard International System of Units (SI), specific heat is expressed in joules (J) per kilogram (kg) per Kelvin. In the SI system, water has a specific heat of 4 200 J/kg K.

Characteristics of steam

Steam production during fire fighting is necessary for effective and efficient use of water as an extinguishing agent. However, care must be taken to apply the appropri- ate amount of water in the right place to achieve the desired effect. When steam is produced on contact with hot surfaces such as burning fuel or walls and ceiling ma- terials that are hotter than 212oF (100oC), water is vaporized into steam which adds to the total volume of the upper layer of hot smoke and fire gases. As this total volume increases and the room fills with the mixture of hot smoke and steam, the upper layer of smoke expands downward, potentially making conditions uncomfortable or even dangerous for firefighters inside the room

Handling stream

Supplied by 11⁄2- to 3-inch (38 mm to 77 mm) hose, with flows from 40 to 350 gpm (160 L/min to 1 400 L/min). Nozzles with flows in excess of 350 gpm (1 400 L/min) are not recommended for handlines.

Fog stream velocity

The angle of fog streams range from narrow to wide. A narrow-angle fog pattern has the highest forward velocity and its reach varies in proportion to the pressure applied. A wide-angle fog pattern has less forward velocity and a shorter reach than the other fog settings. Like all fire streams, any fog pattern will have a maximum reach. A nozzle pressure of 100 psi (700 kPa) is the standard for fog nozzles. Once the nozzle pressure has produced a fire stream with maximum reach, further increases in nozzle pressure have little effect on the stream except to increase the volume.

Bank down method

The bank-down method may be employed when an elevated object is near or within the area of a burning pool of liquid or an unignited liquid spill. The object may be a wall, tank shell, or similar vertical structure. The foam stream is directed onto the object, allowing the foam to run down and onto the surface of the fuel. As with the roll-on method, it may be necessary to direct the stream onto various points around the fuel area to achieve total coverage and extinguishment of the fuel. This method is used primarily on fires contained in diked pools around storage tanks and fires involving spills around damaged or overturned transport vehicles.

Characteristics of a cellar nozzle

The cellar nozzle consists of a rotating head with multiple outlets that distribute water in a circular pattern. The nozzle may be supplied by a 11⁄2-inch (38 mm) or 21⁄2-inch (65 mm) supply hose with a control valve located one section of hose from the nozzle. The nozzle and hose are lowered into the cellar, attic, cockloft, or confined space through a hole cut in the overhead surface. Two commonly used cellar nozzles are the Bresnan distributor and the Rockwood cellar pipe

Slide valve characteristics

The cylindrical slide valve control seats a movable cylinder against a shaped cone to turn off the flow of water. When the shutoff handle is in the forward position, the cylinder is closed preventing water flow past the shaped cone. As the handle is pulled back, the cylinder slides open permitting water to flow through the nozzle without creating turbulence.

Education method of proportioning

The eduction (induction) method of proportioning foam uses the pressure energy in the stream of water to induct (draft) foam concentrate into the fire stream. This is achieved by passing the stream of water through an eductor, a device that depends on the Venturi Principle to draw the foam through a hose connected to the foam concentrate container and into the water stream. In-line eductors and foam nozzle eductors are examples of foam proportioners that use this method

In-line Foam educators

The in-line eductor is the most common type of foam pro- portioner used in the fire service. It is designed to be directly attached to the pump panel discharge outlet or connected at some point in the hose lay. When using an in-line eductor, it is very important to follow the manufacturer's instruc- tions about inlet pressure and the maximum hose lay between the eductor and the appropriate discharge nozzle. In-line eductors use the Venturi Principle to draft foam concentrate into the wa- ter stream. The eductor pickup tube is connected to the eductor at this low-pressure point. A pickup tube submerged in the foam concentrate draws the concentrate into the water stream, creating a foam/water solution. The foam concentrate inlet to the eductor should not be more than 6 feet (2 m) above the liquid surface of the foam concentrate. If the inlet is too high, the foam concentration will be very lean or foam may not be inducted at all.

Injection proportioning method

The injection method of proportioning foam uses an external pump or head pressure to force foam concentrate into the fire stream at the correct ratio for the water flow. These systems are commonly employed in apparatus-mounted or fixed fire protec- tion system application

Solid stream velocity

The performance of a solid stream depends on the velocity of the stream resulting from the pump pressure and the size of the nozzle orifice. A nozzle pressure (NP) of 50 psi (350 kPa) will produce fire streams from smooth bore nozzles with good reach and volume. If greater reach and volume are needed, the nozzle pressure may be in- creased to 65 psi (450 kPa). Above this pressure, the nozzle and hoseline will require more personnel to handle safely.

How does water extinguish fire primarily?

The primary way that water extinguishes fire is by absorbing heat which creates a cooling effect.

Class A foam proportioning

The proportioning percentage for Class A foams can be adjusted (within limits recommended by the manufacturer) to achieve specific objectives. To produce a dry (thick) foam suitable for exposure protection and creating fire breaks in wildland fires, the foam concentrate can be adjusted to a higher percentage. To produce wet (thin) foam that rapidly penetrates a fuel's surface, the foam concentrate can be adjusted to a lower percentage. Most Class A foams are mixed in proportions of 1 percent or less.

Rain down method

The rain-down method is used when the other two methods are not feasible because of the size of the ignited or unignited spill area or the lack of an object from which to bank the foam. The rain-down method is also the primary manual application tech- nique used on aboveground storage tank fires. This method directs the stream into the air above the fire or spill and allows the foam to float gently down onto the sur- face of the fuel. On small fires, the nozzle operator sweeps the stream back and forth over the entire surface of the fuel until the fuel is completely covered and the fire is extinguished. On large fires, it may be more effective for the firefighter to direct the stream at one location to allow the foam to collect there and then float out from that point.

Roll in method

The roll-on method directs the foam stream on the ground near the front edge of a burning liquid spill. The foam then rolls across the surface of the fuel. Firefighters continue to apply foam until it spreads across the entire surface of the fuel and the fire is extinguished. It may be necessary to move the stream to different positions along the edge of a liquid spill to cover the entire pool. This method is used only on a pool of ignited or unignited liquid fuel on the open ground.

What influences a fire stream?

The size of the nozzle opening or orifice and nozzle pressure determines the quan- tity of water flowing from the nozzle. At the same time, the size of the opening also influences the reach or distance of the fire stream. Finally, the type of nozzle deter- mines the shape of the fire stream. A smooth bore nozzle produces a tightly-packed solid stream of water. A fog nozzle produces a fog or straight stream. The sections that follow provide more detailed information about fire streams.

Water aspirating nozzle

The water-aspirating type nozzle is very similar to the other foam-producing nozzles except it is much larger and longer. The back of the nozzle is open to allow air flow. The foam solution is pumped through the nozzle in a fine spray that mixes with air to form moderate-expansion foam. The end of the nozzle has a screen or series of screens that break up the foam even more while mix- ing it with air. These nozzles typically produce foam with lower air volume than do mechanical blower generators.

What must a water stream do to effectively extinguish a fire?

To be effective, a fire stream must deliver a volume of water sufficient to absorb heat faster than the fire generates it. If the heat-absorbing capability of a fire stream does not exceed the heat output from the fire, extinguishing the fire by cooling is impossible

What is needed to produce an effective stream?

To produce an effective fire stream, regardless of type and size, several things are needed. All fire streams must have an agent (water), a pressuring device (pump), a means for the agent to reach the discharge device (hoseline), and a discharge device (nozzle). The following sections more closely examine the char- acteristics of different types of fire streams.

Ideal vs. realistic fire stream reach

Under ideal circumstances, the greatest horizontal reach for a fire stream is at- tained at 45 degrees from the horizontal plane. In actual operation, fire stream angles between 30 degrees and 34 degrees provide the maximum effective horizontal reach

Piercing nozzle characteristics

Used to access fires in concealed spaces. This nozzle can be used to pierce material such as stucco, block, wood and lightweight steel. The nozzle con- sists of a piercing tip, shaft, hose connection, and striking plate at the end. A nozzle control valve can be attached between the hose connection and the supply hose. The nozzle is usually driven into place with a mallet, sledgehammer, or flathead axe

What is vaporization?

When heated to its boiling point, water absorbs heat and converts into water vapor or steam in a process called vaporization.

What pressure are smooth bore nozzles operated at?

When smooth bore nozzles are used on handlines, they are usually operated at 50 psi (350 kPa) nozzle pressure. Most smooth bore master stream appliances are operated at 80 psi (560 kPa).

What is pressure loss and gain?

When the nozzle is below the pump, there is a pressure gain. These changes in pressure caused by gravity must be compensated for by adjusting the pressure at the pump.

Water hammer characteristics

When the nozzle is closed quickly and suddenly, a shock wave is produced when the moving water reaches the closed nozzle and bounces back. The resulting pressure surge is referred to as water hammer. This sudden change in the direction creates excessive pressures that can cause considerable damage to water mains, plumbing, fire hose, hydrants, and fire pumps. At low flow rates, water hammer is minimal. At higher flow rates, the effects of water hammer increase significantly. To prevent water hammer, slowly close nozzles, hydrants, control valves, and hose clamps

Why are fog nozzles more effective?

When the water is broken into small particles or droplets, such as the discharge pattern that a fog nozzle produces, it absorbs heat and converts into steam more rapidly than it would in a compact form. This occurs because more of the water's surface is exposed to the heat

solid stream

solid stream is a fire stream produced from a fixed orifice, smooth bore nozzle. Smooth bore nozzles are designed to produce a stream as compact as possible with little shower or spray. A solid stream has the ability to reach areas that other streams might not reach. It can also penetrate and saturate burning materials or debris. The reach of a solid stream can be affected by gravity, friction of the air, and wind

Straight streams are

solid stream of water has a smaller surface area and absorbs heat less efficiently.

Compressed air foam systems

• A standard centrifugal pump supplies the water • A direct-injection foam-proportioning system mixes foam solution with the water on the discharge side of the pump • An onboard air compressor adds air to the mix before it is discharged from the apparatus

What are fire streams used for?

• Apply water or foam directly onto burning material to reduce its temperature • Apply water or foam into open flames to reduce the temperature so that firefighters can advance handlines • Reduce the temperature of the upper gas layers • Disperse hot smoke and fire gases from a heated area • Create a water curtain to protect firefighters and property from heat • Create a barrier between a fuel and a fire by covering the fuel with a foam blanket

What are the four types of fog nozzles?

• Basic fog nozzle — An adjustable-pattern fog nozzle in which the rated discharge is delivered at a designated nozzle pressure and nozzle setting • Constant gallonage fog nozzle — An adjustable pattern fog nozzle that discharges a constant discharge rate throughout the range of patterns from a straight stream to a wide fog at a designed nozzle pressure • Constant pressure (automatic) fog nozzle — An adjustable-pattern fog nozzle in which the pressure remains relatively constant through a range of discharge rates • Constant/select gallonage fog nozzle — A constant discharge rate fog nozzle with a feature that allows manual adjustment of the orifice to effect a predetermined discharge rate while the nozzle is flowing

Characteristics of a broken stream

• Coarse droplets absorb more heat per gallon (liter) than a solid stream. • They have greater reach and penetration than a fog stream. • They can be effective on fires in confined spaces. • May have sufficient continuity to conduct electricity. • Stream may not reach some fires.

Foam production failure

• Eductor and nozzle flow ratings do not match, preventing foam concentrate from inducting into the fire stream. • Air leaks at fittings cause a loss of suction. • Improper cleaning of proportioning equipment causes clogged foam passages. • Nozzle is not fully open, restricting water flow. • Hose lay on the discharge side of the eductor is too long, creating excess back pres- sure and causing reduced foam pickup at the eductor. • Hose is kinked and restricts or stops flow. • Nozzle is too far above the eductor, which causes excessive elevation pressure. • Mixing different types of foam concentrate in the same tank results in a mixture too viscous to pass through the eductor.

Characteristics of a fog stream

• Fog-stream patterns can be adjusted to suit the situation. • Fog streams can be used for hydraulic ventilation. • Fog streams can be used for vapor dispersion. • Fog streams can be used for crew protection. • Fog streams reduce heat by exposing the maximum water surface for heat absorption • Fog streams may be used to cool the hot fire gas layer as well as hot surfaces. • Fog streams have shorter reach or penetration than solid or straight fire streams. • Fog streams are more affected by wind than are solid or straight fire streams. • Fog streams may disturb thermal layering in a room or compartment if applied incorrectly. • Fog streams may intensify the fire by pushing fresh air into the fire area if used incorrectly

Characteristics of a solid stream

• Good reach and stream penetration • Stream produced at low nozzle pressure • Produces less steam conversion • Provides less heat absorption per gallon (liter) • More likely to conduct electricity

What are factors that limit the reach of fire streams?

• Gravity — Gravity not only limits the verticle and horizontal distance the fire stream will travel, it also causes solid streams to separate and lose their compact shape. • Water velocity — Effective forward velocity of the fire stream ranges from 60 to 120 feet per second (18.3 to 36.6 meters per second). This velocity is generated by nozzle pressures of 25 to 100 psi (175 kPa to 700 kPa). • Fire stream pattern — Solid stream patterns have greater reach than straight, fog, or broken patterns. • Water droplet friction with air — Air friction has greater effect on the multiple finely-formed water droplets in a fog stream than it does on the outer surfaces of a compact solid stream. • Wind — Wind direction and speed can shorten the reach and deteriorate the shape of the fire stream considerably. The negative effect is increased on fog streams.

What should be inspected on nozzles?

• Inspect the swivel gasket for damage or wear. Replace worn or missing gaskets. • Look for external damage to the nozzle body, coupling, and tip. • Look for internal damage and debris. • Check for ease of operation of the nozzle parts. • Ensure that the pistol grip (if applicable) is secured to the nozzle. • Ensure that all parts are in place and in good condition.

What flow rates are automatic fog nozzles designed for?

• Low flows such as 10 gpm (40 L/min) to 125 gpm (500 L/min) • Mid-range flows such as 70 gpm (280 L/min) to 200 gpm (800 L/min) • High flows such as 70 gpm (280 L/min) to 350 gpm (1 400 L/min)

Characteristics of smooth bore nozzles

• Operate at low nozzle pressures • Are less prone to clogging with debris • Can be used to apply compressed-air foam • May allow hoselines to kink due to less pressure • Do not allow for selection of different stream patterns

What contributes to friction loss?

• Rough linings in fire hose • Damaged hose couplings • Sharp bends in hose • Number of adapters • Length of hose lay • Hose diameter Friction loss is overcome by increasing the hose size, adding additional parallel hoselines, or increasing the pump pressure. It can also be reduced by taking any kinks or sharp bends out of the hoseline.

How does foam extinguish fires?

• Separating — Creates a barrier between the fuel and the fire • Cooling — Lowers the temperature of the fuel and adjacent surfaces • Smothering — Prevents air from reaching the fuel and mixing with the vapors and prevents the release of flammable vapors reducing the possibility of ignition or reignition • Penetrating — Lowers the surface tension of water and allows it to penetrate fires in Class A materials

What are advantages of compressed air foam systems

• Stream reach is considerably longer than with other foam systems. • Hoselines are lighter than those full of water or foam solution. • Foam produced is very durable. • Foam produced adheres well to vertical surfaces. Some of the disadvantages include: • CAFS add expense to the purchase and maintenance of the apparatus. • The stored energy created by the compressed air pressure in the hose can create a high nozzle reaction when the nozzle is opened that may throw the nozzle operator off balance. • Additional training is required for firefighters and driver/operators.

Characteristics of fog nozzles

• The discharge pattern can be adjusted. • Fog nozzles can provide protection to firefighters with a wide fog pattern. • Fog nozzles can be used for a variety of applications. • They offer a variety of nozzle choices. • Fog nozzles can be used to apply certain types of foam.

Care of nozzles should include?

• Thoroughly cleaning nozzles after each use with soap and water using a soft bristle brush. • Following manufacturer's recommendations for cleaning and lubricating any moving parts that are sticking. • Storing nozzle with the control valve bale in the closed position. • Never dropping or dragging nozzles. • Using the flush setting on fog nozzles to remove any internal debris. If debris re- mains, shut off the water supply, remove the nozzle and physically remove the debris.

What has an effect on fire streams?

• Velocity of the water • Gravity • Wind direction and velocity • Air friction • Operating pressure • Nozzle design and adjustment • Condition of the nozzle opening