Flashcards in Chapter # 15 Foam Equipment and Systems Deck (94):
Name three reason that foam and durable agents has increased dramatically in municipal and wild land firefighting.
Increase in HAZ MAT incidents that require foam.
New advancements in foam concentrates have made is easier to use.
Improvements in foam proportioning that have made there inclusion in the construction of a new pump or a addition to a existing pump feasible.
The majority of foams in use today are of this type. they must be proportioned and aerated before they can be used.
The raw foam.
The device that introduces foam concentrate into the water stream.
Mixture of foam concentrate and water.
The completed product after air is introduced into the foam solution.
Foam (finished foam)
Should produce uniformed sized bubbles to provide a long lasting blanket.
What type of fuel should modern fuels with additives be considered?
T or F Some polar solvent foams can extinguish a hydrocarbon fire, but hydrocarbon fuels can never extinguish a polar solvent fire?
Creates a barrier between the fuel and the fire.
Lowers the temp of the fuel and adjacent surfaces.
Prevents the release of vapors.
The three ways foam extinguishes a fire or prevents a fire.
Separating. Cooling. Suppressing.
Most foam concentrates are intended to be mixed with what type of water?
Fresh or salt water.
Most fire fighting foam concentrates are intended to be mix with ........ to ..... water.
94% to 99.9%
Can be adjusted within limits recommended by the manufacturer. (usually 0.1 to 1.0%), to achieve a specific objective.
Class A foam
Name the four ways foam is proportioned.
Induction. Injection. Batch mixing. Premixing.
Uses the pressure energy in a water stream to educate the foam concentrate through a venturi device.
Uses a external pump of head pressure to force foam concentrate into the fire stream at the correct ratio in comparison to the fire stream.
The simplest method of mixing foam concentrate and water. Foam concentrate is poured directly into the water tank. Common for class A foam, but should only be used as a last resort for class B foam. If Class B is used it must be circulate (mixed) in the pump before use. Not effective on large incidents.
One of the more commonly used methods of proportioning. Used with portable extinguishers, wheeled, skid mount twin agent units, and vehicle mounted tank. Typically discharged from a compressed air or a inert gas like nitrogen. One time application.
Name the four common ways that foam concentrate is stored.
Pails. Barrels (drums). 275 gallon tote tanks. Apparatus tank.
Most common container used by municipal fire service to receive and store foam concentrate. Must be a air tight container.
Pail (5 gallons)
More common foam concentrate storage container in industrial applications. Can transfer from this storage devices to another one.
Barrels or drums. 55 gallon plastic or plastic lined.
May be a good choice and money saving if large amounts of foam concentrate are expected to be used.
Totes (275 gallons).
Found on municipal and industrial pumpers, foam tenders, and ARFF apparatus. May also be mounted on a trailer. Has to be airtight, standard vented atmospheric storage tanks are not acceptable. Tank should also be equipped with a pressure vacuum vent. Size on municipal pumpers range from 20-200 gallons. Foam pumpers and tenders may carry 8,000 gallons or more of foam concentrate.
Proven effective in fires in structures, wildland, coal mines, tires storage, and other deep seated fires.
Class A foam
A formulation of hydrocarbon surfactants that reduce the surface tension of the water in the foam solution.
Class A foam
When Class A foam is used with a CAFS system it has what?
Excellent insulating properties.
What can the shelf life of class A foam be?
Common class A foam proportioning for specific types of incidents.
Fire attack and overhaul w/ a standard fog nozzle = 0.2-0.5 %.
Exposure protection with standard for nozzle = 0.5 - 1.0%.
Any application with a air aspirating foam nozzle. = 0.3-0.7%.
Any application with a CAFS = 0.2-0.5%.
Refers to the minimum amount of foam solution that must be applied to a fire, per minute, per square foot of fire.
What is the application rate of class A foam?
The same as the minimum critical flow rate for water.
Elements that affect the breakdown time of finished foam.
Heat of the fire. Height of flames. Ambient air temp and wind.
Used to extinguish fire involving flammable and combustible LIQUIDS.
Class B foam.
What type of class B foam can be applied with a standard for nozzle?
AFFF and FFFP
T or F Class B foam concentrates are made from either a synthetic or protein base. Protein base are derived from animal protein. synthetic is made from a mixture of flurosurfactants.. Some foam is a combination of the two.
Shelf life of class B foam?
Protein base = 10 years. Synthetic = 20-25 years.
Class B foams are mixed in what proportions?
Class B medium expansion foams are usually mixed at what?
1 1/2%, 2%, 3%
Refers to the increase in volume of a foam when it is aerated.
What factors affect the degree of foam expansion?
Type of foam concentrate used. Accurate proportioning. Quality of the foam concentrate. Method of aspiration.
Foam can be low expansion, medium expansion, or high expansion. What are the air/solution ratios for each of these according to NFPA 11?
Low = 20:1 Medium = 20:1 - 200:1 High = 200:1 - 1000:1.
Ratios are parts of finished foam compared to parts of foam solution.
What factors affect the rate of application for foam?
Type of foam concentrate used. Fire or no fire. Type of fuel. Is the fuel spilled or in a tank.
Standard for low, medium, and high expansion foam.
What is the minimum application time for a combustible liquid? For a flammable liquid or crude petroleum?
Combustible liquid = 50 minutes
Flammable liquid or crude petroleum = 65 minutes
What is the equation to determine the application rate available from a nozzle.
Divide the nozzle flow by the square foot area of the fire.
It is important to know the application rate for each type of polar solvent, why?
Because each polar solvent has a different affinity for water.
Has good heat stability and resist burn back, but is not as mobile or fluid on the fuel surface.
Regular Protein Foam
A combination protein based and synthetic based foam, is derived from protein foam concentrates to which fluorochemical surfactants are added. Flows easier then regular protein foam. Strong vapor blanket. Can be made to be alcohol resistant. Still the foam of choice by some departments.
Based on fluoroprotein foam technology with aqueous film forming foam (AFFF) capabilities. Fast fire knock down and long lasting heat resistance. Available in alcohol resistant.
Film forming fluoroprtein foam (FFFP).
Most commonly used foam today. Completely synthetic. Consist of fluorochemical and hydrocarbon surfactents combined with high boiling point solvents and water. Can be made into alcohol resistant.
Aqueous Film forming foam (AFFF)
What three things occur when AFFF or FFFP is applied to a hydrocarbon fire.
An air/vapor excluding film is released ahead of the foam blanket.
The fast moving foam blanket then moves across the surface and objects.
As the aerated (7:1 - 20:1) foam blanket continues to drain its water, more film is released. Can "heal" over areas of disturbed foam blanket.
Proportioning concentrations of Alcohol resistant AFFF.
Most polar solvents = 3% or 6%.
Hydrocarbon fires = 1% or 3%.
Creates a membrane instead of a film over the fuel, which separates the water from the solvent. Should be applied gently so that the membrane can form before the blanket. should be rained down on the fuel.
Alcohol resistant AFFF
Special purpose foam with a detergent base. Low water content which minimizes water damage.
High expansion foams
What are the three basic applications of high expansion foams?
In concealed spaces. In fixed extinguishing systems. In Class A fire applications.
What are the expansion ratios of high expansion foams?
200:1 - 1,000:1 for high expansion use. 20:1 - 200:1 for medium expansion use.
the level of expansion is determined by the application device being used.
In general foam proportioning devices operate by one of two principles,what are they?
The pressure of the water stream flowing through a restricted orifice creates a venturi action that inducts foam concentrate into the water stream.
Pressurized proportioning devices inject foam concentrate into the water stream at a desired ratio and at a higher pressure than that of the water.
Imparts pressure on the foam solution solely by the use of a fire pump. These systems introduce air into the solution when it either reaches the nozzle or is discharged from the nozzle.
Low energy foam systems
Introduce compressed air into the foam solution before it is discharged into the hoseline.
High energy foam systems.
Portable foam proportioners are the simplest and most common foam proportioning device in use. Name the three most common ones in use.
in-line foam eductor. foam nozzle eductor. Self educting master stream nozzle.
The most basic type of foam proportioner used in the fire service. Important to know the max inlet pressure and amount of hose that can be placed between it and the nozzle.
In-line foam eductors
Name some rules that should be followed when using a in-line foam eductor.
-Flow through the eductor should not exceed the rated capacity of the eductor.
-The pressure at the outlet of the eductor (back pressure) must not exceed 65-70% of the eductor inlet pressure. Eductor back pressure is determined by the sum of the nozzle pressure, friction loss in the hose between the eductor and the hose, and the elevation pressure.
-Foam solution concentration is only correct at the rated inlet pressure of the eductor.
-Eductors must be properly maintained and flushed after each use.
-Metering valves must be set to match the foam concentrate percentage and the burning fuel.
-The foam concentrate inlet to the eductor should not be more than 6' above the liquid surface of the foam concentrate.
T or F in order for the nozzle and eductor to operate properly, both must have the same gpm rating. The eductor, not the nozzle must control the flow.
Used where flows of above 350gpm are needed. Are available with flow capabilties of up to 14.000 gpm. Uses a manifold venturi design to draw foam concentrate into the water stream. The pick up tube is located in the center bore of the nozzle. A jet ratio controller can be used to supply foam concentrate to it.
Self educting master stream foam nozzles.
A type of in-line eductor that allows the foam concentrate supply to be as far away as 3,000' from the self educting master stream foam nozzle. Also allows an elevation change of up to 50'. Supplied by a hose line from the same pumper. Proportions the concentrate at a 66.5% solution. The rich solution is then pumped to a self educting master stream foam nozzle where it is further proportioned with the water supplied by the fire pump down to a discharge proportion of 3%.
Jet Ratio controller (JRC)
The JRC and nozzle must match.
Name six different types of apparatus mounted foam proportioning systems.
Installed in-line eductors. Around-the-pump proportioners. Variable-flow variable-rate direct injection systems. Variable-flow demand-type balanced pressure proportioners. Batch-mixing.
Use the sample principles of operation as portable inline-eductors. The only differences is that these are permanently attached to the apparatus. Foam concentrate is provided either by a pick up tube inserted into a 5 gallon bucket, or from foam tanks on the apparatus. May have a bypass mode that will allow a operator to bypass the eductor when using the line without foam. Most commonly used to proportion class B foam. Not effective at proportioning class A foam because of the required low concentrations.
Installed In-line eductor system.
One of the most common types of buit-in proportioners installed in mobile fire apparatus today. Has a small return (bypass) water line that connects from the discharge back to the intake side of the pump. A in-line eductor is installed in the bypass line. Are rated for a specific flow and should be used at this rate. Older models could not take advantage of incoming pressure above 10 psi. Newer models can handle intake up to 40 psi. Another disadvantage is that the pump is dedicated to the foam operation only, and when water is shut down water can still circulate through the eductor adding more concentrate than needed. Close the bypass when no water is flowing.
Uses the apparatus electrical system. Measures flow and uses that measurement to provide the correct amount of foam. Can be used to provide foam concentrations of 0.1% to 3%. Water pressure is not a factor because it measures flow. Can be used with Class A and some Class B foams. Should never be used with alcohol resistant foams. May be used with high energy foam systems. A disadvantage is that the foam enters the piping before any manifolds which means that all lines on the manifold will have foam if they are flowed.
Variable-Flow Variable-Rate Direct Injection System
Also called a pumped/demand system. Includes a motor to drive a concentrate pump to a venturi type device on the specific hoseline. Requires no pumping after use. Water and or foam can be discharged from different lines at the same time. A disadvantage is that pressure drops across the discharge are higher than those on a standard pumper.
Variable-Flow Demand-Type Balanced Pressure Proportioners.
Also call dump in method. Simplest for of mixing foam with water. Only used with regular AFFF and class A foam. Class A foam does not retain its foaming properties if mixed in water for more then 24 hours. Froth may form causing pump cavitaion or priming problems. Should only be used when no other proportioning system is available.
Introduce compressed air into the foam solution prior to discharge in the hoseline. Can be discharged a considerably longer distance then with a regular foam or water fire stream. Formally called Water Expansion Systems or Water Expansion Pumping Systems. Old systems used compressed air cylinders, new systems have a rotary air compressor mounted on the pumper. A direct injection proportioning system is attached to the discharge side of the pump. Used for Class A foam.
High Energy Foam Generating Systems. (Compressed-Air foam systems).
Name some tactical advantages of using a CAFS system.
Longer stream reach. Uniform bubbles and adheres to surfaces. Hoselines weight less. Safer attack from a farther away distance.
Name some limitations of a CAFS system.
Adds expense and maintenance. Hose reaction can be erratic. The compressed air accentuates the hose reaction in the event of a hose rupture. Additional training is required.
Do CAFS systems have edcuctors? Why?
No, because a edcutor can not proportion foam from 0.1% - 1% as is required for class A foam.
With low energy foam systems, the aeration and discharge of the foam are accomplished by the what?
Foam nozzle (Foam maker)
Limited to Class A foam and CAFS systems. When used with a CAFS it can produce a fire stream that is greater then twice the distance of a low energy fire stream. Also when used with a CAFS the standard rule that the tip not be more the 1/2 the size of the hose can be ignored.
Can used a fixed-flow, selective flow or automatic type to produce a low expansion, short lasting foam. Expansion ratios are between 2:1 and 4:1. Best when used with AFFF or Class A foam, can be used with alcohol resistant AFFG on hydrocarbon fires. Can not be used with protein or fluoroprotein fuels. Should not be used on polar solvents Some may come with a attachment or adjustable sleeve to make them air-aspirating nozzles.
Inducts air into the foam solution by a venturi action. Only type of nozzle that can be used with protein and fluoroprotein concentrates. Can also be used with Class A foam in wildland. Provide max expansion of the agent but less reach then a standard for nozzle.
Air-aspirating Foam Nozzle.
May be equipped with special aerating foam master stream nozzles.
Large scale industrial foam apparatus and ARFF vehicles.
Name the two types of medium and high expansion foam generators.
The water-aspirating type and the mechanical blower type.
Very similar to other foam nozzles but much larger and longer. Back of the nozzle is open to allow air flow. End of the nozzle has a screen or series of screens to further break up the foam solution.
Water-aspirating foam nozzle.
Looks like a smoke ejector. Operates on the same principle of the water-aspirating foam nozzle except that air is forced through the foam solution by a powered fan. Produces foam with high air content and is associated with total flooding systems. Limited use is to high expansion foam.
Mechanical blower foam generator.
What should be ensured if connecting a foam eductor directly to the pump panel discharge?
That the ball valve is completely open. Any water turbulence can cause the eductor to not work properly. This may include connecting to a elbow on the discharge.
Name some of the most common reasons that foam is not generated or poor quality foam is generated.
Eductor and nozzle flow don't match. Air leaks at fittings. Improper cleaning that caused clogged passages. Partially closed nozzle. Too long of a hose lay after the eductor. Kinked hose. Nozzle to far above the eductor. Mixing different types of foam in the same tank.
Name the four foam application techniques.
Direct-application. Roll-on. Bank-down. Rain-down.
Class A foam placed directly on the burning material.
Used with Class B foam on a pool of liquid fuel on the open ground.
Used when other application techniques are not feasible or when the fuel is at a elevated area. Used mainly on above ground storage tank fires. Firefighter uses sweeping motions in the air, regardless the size of fire.
What is the main concern of environmental impacts for AFFF concentrates?
Glycol Ethers (Butylcarbitol). and Perfluorooctylysulfonates (PFOS).
Standard on foam chemicals for fire in Class A fuels.