Flashcards in Chapter #16 Fire Streams Deck (110):
The primary way that water extinguishes fire is by absorbing heat which creates what?
A cooling effect
The amount of energy required to raise the temp of a specific unit mass of a material 1 degree in temp.
Quantity of heat absorbed by a substance at the point at which it changes from a liquid to a vapor.
Latent heat of vaporization.
How many more BTU's are required to convert water into steam after it has reached its 212F boiling point?
At 212 F water expands how many times to turn into steam?
Would a solid stream or fog stream nozzle cause water to convert into steam more quickly?
Fog stream. More surface area to absorb more heat.
When water turns to steam from striking a solid object (ceiling) that is 212 F, the steam will expand pushing the smoke layer down. What happens if the water turns to steam while traveling through the smoke layer?
The smoke layer will cool and contract.
T or F There is a practical limit to the velocity or speed at which water can travel through a hoseline. If the velocity is increased beyond this limit, the friction becomes so great that the water in the hoseline is agitated by the resistance.
Name ways that friction loss is reduced.
Increasing hose size. Adding additional parallel lines. Increasing pump pressure. Taking kinks or sharp bends out of the hoseline.
At low flow pressure water hammer is minimal. At higher flow rates the effects of water hammer do what?
What two ways are fire streams classified?
By their size and type.
What are the three sizes of fire streams?
Low-volume stream. Handline Stream. Master Stream.
Discharges less then 40gpm. Supplied by 3/4, 1 or 1 1/2" line.
Low Volume Stream
Supplied by 1 1/2" to 3" hose with flows from 40-350 gpm.
Greater then 350gpm. Supplied by one or more 2 1/2" or 3" lines or LDH. Nozzle pressure of 80-100.
The minimum flow rate at which extinguishment can be achieved.
Critical Flow Rate
This indicates a specific pattern or shape the stream has as it leaves the nozzle.
Name the four types of fire streams.
Solid, Straight, Fog, Broken.
Stream as compact as possible. Has the ability to reach areas that other streams might not reach. Ability to penetrate materials.
What two things determine the performance of a solid stream?
The velocity of the stream caused by the pump and the size of the nozzle orifice.
What nozzle psi can a solid stream handline be increased to when greater reach and volume are needed?
Exposes the max amount of water droplets to absorb heat. Performance is based on the amount of heat the stream absorbs and the rate the water from the stream is converted into steam. Typically has a nozzle pressure of 100 psi. Increases in nozzle pressure do not increase reach but may increase flow.
A semi solid stream that is produced by a fog nozzle.
Stream of water that has been broken into coarsely divided drops.
Name some characteristics of a broken stream.
Absorb more heat per gallon then a solid stream. Greater reach and penetration then a fog stream. Effective on fires in confined spaces. May conduct electricity. Stream may not reach some fires.
Name five limiting factors of fire streams.
Gravity. Water Velocity. Fire stream pattern. Water droplet friction with air. Wind.
Effective forward velocity of the fire stream ranges from what to what? and at what range of nozzle pressure?
60-120 feet per second. 25-100 nozzle pressure.
Under ideal circumstances what angel provides the max horizontal reach of a fire stream?
In actual operation what angle provides the max horizontal reach?
Ideal = 45 degrees. Actual = 30-34 degrees.
Standard for fire hose connections
What are the two categories of fire stream nozzles according to NFPA 1963 ?
Straight tip and Spray Nozzles
What are the three functions of any fire stream?
Controlling water flow. Creating reach. Shaping the fire stream.
The smooth bore nozzle tip should not be larger then what?
1/2 the diameter of the hose.
Can smooth bore nozzles be used to apply compressed-air foam?
The length of a smooth bore nozzle is how many times bigger then its inside diameter?
1 to 1 1/2 times
The flow rate of a smooth bore nozzle depends on what two things?
The pressure at the tip and the size of opening at the tip.
What three patterns can fog nozzles be adjusted to?
Straight stream. Narrow angle fog. Wide angle fog.
Name the four types of fog nozzles used in the fire service.
Basic fog nozzle. Constant Gallonage fog nozzle. Constant Pressure (Automatic) fog nozzle. Constant/Select gallonage fog nozzle.
A adjustable pattern fog nozzle in which the rate discharge is delivered at the designated nozzle pressure and setting.
Basic Fog Nozzle
Discharges a constant discharge rate throughout the range of patterns from the straight stream to a wide fog at a designated nozzle pressure.
Constant Gallonage Fog Nozzle.
The pressure remains relatively constant throughout a range of discharge rates.
Constant Pressure (Automatic) Fog Nozzle.
Allows manual adjustment of the orifice to effect a predetermined discharge rate while the nozzle is flowing.
Typically allows adjustments from 10-250 gpm on handlines and 350-2500 gpm on master streams. Also most have a flush setting.
Constant/Select Gallonage fog nozzle.
Automatic fog nozzles are designed for the following flow rates.
Low flow= 10 - 125 gpm
Mid-range flow = 70 - 200 gpm.
High Flows = 70 -350 gpm
Master streams = 350 - 1250 gpm.
Name three types of broken stream nozzles.
Piercing. Bresnan. Rockwood Cellar Pipes.
Used to access fires in concealed spaces. Can pierce stucco, block, wood, and lightweight steel.
Name two common cellar nozzles.
Bresnan. Rockwood Cellar Pipe.
Name the three types of control valves found on a nozzle.
Ball. Slide. Rotary Control
Most common nozzle control valve. Provide effective nozzle control with minimal effort.
T or F When a ball valve is used on a smooth bore nozzle, the turbulence caused by a partially open valve may affect the quality of the solid stream?
Seats a movable cylinder against a shaped cone to turn the flow of water off. As the handle is pulled back the cylinder slides open permitting water to flow through the nozzle without creating turbulence.
Found only on rotary control fog nozzles. This valve also controls the discharge pattern of the stream. Commonly found in stand pipe cabinets attached to occupant hose. A exterior barrel is rotated around a interior barrel to open flow and close flow. Think- garden hose attachment.
Rotary Control Valve.
How often should nozzles be inspected?
After each use and annually.
Up to what size of hoseline can one firefighter over come the nozzle reaction and maintain control?
Name four ways that firefigthing foam extinguishes and/or prevents ignition.
Separating. Cooling. Smothering. Penetrating
Name two categories of flammable liquids that Class B foam is effective on.
Hydrocarbons and Polar Solvents
Mixture of foam concentrate and water before air is added.
Complete foam product after air is introduced into the foam solution.
The increase in volume of foam when it is aerated.
Name four factors that determine the foam expansion.
Type of foam concentrate used. Accurate proportioning. Quality of foam concentrate. Method of aeration.
Name the three classifications of foam based on there foam expansion.
Low expansion (20-to 1 ratio). Medium expansion (20-to-1 to 200-to-1). High expansion (200-to-1 to 1000-to-1).
Ratio = finished foam-to-foam concentrate.
20-to-1 ratio. Effective in controlling and extingushing most class B fires. Effective for cooling and penetrating class A fires.
Low expansion foam
20-to-1 to 200-to-1 ratio. delivered through hydraulically operated nozzles. Used to suppress vapors from haz mat at ratios of 30-to-1 and 55-to-1.
Medium Expansion Foam
200-to-1 to 1000-to-1. Synthetic foaming agents created by high expansion foam generators. May be used in confined spaces like ships, basements, mines, and aircraft hangers.
High Expansion Foam
Contain surfactants that allow for water penetration. Can be applied using fog nozzles, air-aspirating foam nozzles, medium and high expansion devices, and CAFS. Mildly corrosive. May insulate nearby fuels preventing pyrolysis.
Class A foam
Petro based combustible or flammable liquids that float on water. Examples: Crude oil, Fuel oil, Gasoline, Benzene, Naptha, Jet Fuel, and Kerosene.
Class B hydrocarbon fuels
Flammable liquids that mix readily with water. Examples: Alcohols, Acetone, Lacquer Thinner, Ketones, Esters, and Acids.
Class B Polar Solvent Fuels
Protein and fluoroprotien foams are festive as extinighushing agents and vapor suppressants on hydrocarbon fuels. Why?
Because they float on the surface of these fuels.
Alcohol Resistant foams are specially formulated for what?
Synthetic foam concentrate that, when combined with water, can form a complete barrier over fuel spills and fires and is highly effective extingushing and blanketing agent on hydrocarbon fuels.
Aqueous Film Forming Foam (AFFF)
Foam concentrate that combines the qualities of fluoroprotien foam with those of aqueous film forming foam.
Film Forming Fluoroprotien Foam (FFFP)
Minimum amount of foam that must be applied.
Rate of application.
Name five variables that will affect class B foams rate of application.
Type of concentrate used. If the fuel is on fire. Type of fuel involved (hydrocarbon/polar solvent). Whether the fuel is spilled or contained in a tank. Whether the foam is applied via fixed or portable equipment.
Having a thick sticky, adhesive consistency.
T or F Specialized foams are also for acids spills, pesticide fires, confined or enclosed space fires, and deep seated class A fires. There are also foams designed specifically for un-ignited spills of hazardous liquids.
Mixing of the correct amount of water with foam concentrate to form a foam solution.
How much water is most firefighting foam intended to be mixed with?
What class of foam can be mixed in adjusted proportions to meet the intended needs of the foam. Example: penetration or protection.
Class A foam.
What percent are most class A foams mixed in?
1% or less.
What are most class B foams mixed in?
Some class B foams can be used on both hydrocarbon and polar solvents depending on the foam concentrate. What are most class B foam proportioned at for hydrocarbon fuels? What are they proportioned at for polar solvent fuels?
Hydrocarbon = 3% Polar Solvent = 6%
Name five criteria for the selection of the foam proportioner equipment.
Foam solution flow requirements. Available water pressure. Cost of the foam. Intended use for the foam (truck, fixed, or portable). Foam agent to be used.
Are proportioners and delivery devices designed to work together?
Name four ways that foam is proportioned.
Eduction. Injection. Batch-mixing. Premixing.
What is the simplest method of mixing foam concentrate with water?
What type of foam proportioning system is considered a one time use?
Name three types of foam proportioning systems.
Portable. Apparatus Mounted. Compressed Ai Foam Systems (CAFS).
What are the simplest and most commonly used proportioning devices in use today?
Name two types of portable foam proportioning systems.
Inline foam Eductors and Foam Nozzle Eductors
What is the most common foam proportioner used in the fire service?
Inline foam eductor
The foam concentrate inlet to the educator should not be more then how many feet above the liquid surface of the foam concentrate?
Eductor is built into the nozzle. Can compromise the safety of firefighters.
Foam nozzle eductor.
Name three types of apparatus mounted proportioners.
In-line eductors. Around the pump proportioners. Balanced Pressure Proportioners.
What is unique about a CAFS system?
The hose line contains the finished foam.
Name some advantages of a CAFS system.
Stream reach is longer then with other foam systems. Hoselines are lighter. Foam produced is very durable. Foam produced adheres well to vertical surfaces.
Name some disadvantages of a CAFS system.
CAFS add expense and maintenance cost. Air pressure stored in the hoseline may cause a high nozzle pressure when the nozzle is open. Additional training is required for firefighters and driver/operators.
Limited as a foam nozzle to class A foam. Often used with CAFS.
Smooth bore nozzles
Can be used with foam solution to produce a low expansion short acting foam. Best when used with regular AFFF and class A foam. Can not be used with protein or fluorprotein foam. Can be used with AFFF on hydrocarbon fuels but not polar solvent fuels.
Most effective appliance for the generation of low expansion foam. Inducts air into the foam solution using the venturi principle. Designed to provide the aeration to make the highest quality of foam. Must be used with protein and fluoroprotein foams. Also used with class A foam.
Air-aspirating foam nozzle.
A foam concentrate cartridge is designed to equal how many gallons of foam concentrate? and treat up to how many gallons of water?
5 gallons concentrate. 660 gallons of water.
Name the two types of medium and high expansion foam generators.
Water-aspirating type nozzle. Mechanical blower generator.
Similar to other foam nozzles except the back is open allowing air flow. Foam concentrate also hits a screen or series of screens. Creates medium expansion foam.
Water-aspirating type nozzle
Similar in appearance to a smoke ejector. A powered is fan is used to move air through the foam. Associated with total flooding applications . Limited to high expansion foam.
Mechanical Blower Generator
Name some reasons for failure to create a foam stream.
Eductor and nozzle flow rating do not match. Air leaks at fittings. Improper cleaning causing clogs. Nozzle is not fully open. Hose lay on the discharge side of the eductor is to long, creating excess back pressure and causing reduced foam pick up from the eductor. Hose is kinked or restricted. Nozzle is to far above the eductor. Different types of foam concentrate mixed in same tank causing a mixture that is to viscous to pass through the eductor.
Name the three methods used to apply Class B foam to a liquid fuel fire or spill.
Roll on. Bank Down. Rain Down
Foam application techniques used only on a pool of ignited or unignited liquid fuel on open ground.
Roll On Method
Foam application method used primarily on fires contained in diked pools around storage tanks and fires involving spills around damaged or overturned transport vehicles.
Bank Down Method
Foam application method that is the primary technique used on above ground storage tank fires. Small fires = sweep. Large fires = one area at a time.
Rain Down Method
Why should caution be used in making sure foam doesn't enter bodies of water?
Foam is broken down by environmental bacteria. Bacteria use the available O2. If the bacteria are using the O2, the fish have none.
The less O2 used to degrade a particular foam means what?
The more environmentally friendly the foam is.
Who approves class A foams for environmental suitability in the USA?
U.S. Dept of Agriculture Forest Service.