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Engineer School > Chp 14 > Flashcards

Chp 14 Flashcards

1
Q

Foam used more because

A

Bigger hazmats
New foam is easier to use by structure and wildland
Proportioners are better, easier to put in pumpers
Helps reduce water if water is limited

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2
Q

Mechanical foam

A

Produced by physical agitation of concentrate, water and air

Most common

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3
Q

Aeration

A

Put air into foam solution to create bubbles that give finished foam

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4
Q

Foam concentrate

A

Starting point

Can be protein, synthetic, aqueous film forming, high expansion or alcohol

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5
Q

Foam proportioner

A

Second step
Injects correct amount of foam concentrate into the water stream
Makes foam solution

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6
Q

Foam

A

Completed product after air is introduced
Foam solution + air
For use on Class A or B
Protein,

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7
Q

Class B fuels

A

Hydrocarbons: crude oil, benzene, kerosene, specific gravity <1
Polar Solvents: alcohol, acetone, ketones, esters, miscible and conduct electricity
Modern fuels with 15% solvent additives treat as polar solvents
Class B foam only works on hydrocarbons

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8
Q

Foam works by

A

Separating: fuel and fire
Cooling: the fuel and adjacent surfaces
Smothering: vapors
Initial blanket excludes oxygen then as it breaks down into water it cools and runs off, taking product with it

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9
Q

Proportioning

A

Can mix with fresh or salt water
Mix per mfg
Mix from 0.1 - 6%
Class A 0.1 - 1%

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10
Q

Proportioning Methods

A

Induction: Pressure of water to draft concentrate by passing through a venturi device called an eductor, through a pickup tube
Injection: External pump forces concentrate into firestream at correct amount (fixed systems)
Batch mixing: Dumping concentrate (usually A) into a tank. Inaccurate and shuts down lines when tank is empty. B has to be stirred
Premixing: mixed in the container, portable and wheeled extinguishers, can use with CAFS

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11
Q

Foam storage

A

Pails: 5 gal, non corrosive, airtight, easy to store
Barrels: 55 gal, usually just for storage, can put on a trailer
Totes: 275 gal, storage for ARFF or wildland, can be on a trailer
Apparatus tanks: 20-200 gal, tender up to 8000 gal and no water

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12
Q

Foam concentrates

A

Some are A and B but most are one or the other

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13
Q

Class A foam

A

Hydrocarbon based surfactants or wetting agents that reduce surface tension
Used on structure, wildland, coal, tire storage and others
When used with CAFS (entrains lots of air) makes excellent insulation
20 yr shelf life, buy in bulk
Don’t flow directly into lakes
Corrosive on skin
0.1 - 1.0 %

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14
Q

Class A foam nozzles

A

Fog
Aerating foam
Medium and high expansion devises
CAFS with most nozzles including solid stream
Produce more stable foam at 1.0% than 0.5%

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15
Q

Class A proportioning

A

Fire attack and overhaul with fog: 0.2 to 0.5
Exposure protection with fog: 0.5 to 1.0
All with air aspirating foam nozzle: 0.3 to 0.7
All with CAFS: 0.2 to 0.5

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16
Q

Application rate definition

A

Minimum amount of foam solution applied to unignited fire, spill, or spill fire to control vapor emission or extinguish the fire
Take GPM/square ft to calculate
Determine in pre incident planning

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17
Q

Application of class A

A

Areas needing max penetration
Vertical surfaces: dry foam clings well
Surface of fuel: cling and penetrate

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18
Q

Foam breakdown affected by

A

Heat of fire
Size of flames
Ambient temp
Prevailing winds

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19
Q

Class B Foam

A

Made of synthetic (Fluorosurfactants) or protein (animal) base
Store in cool place, 10 yr life protein, 20-25 for synthetic
Usually cant mix but AFFF and fluoroprotein can be mixed immediately before use, mil spec mixed anytime

20
Q

Class B proportioning

A

1 to 6 %

Can depend on fuel hydrocarbon 1 to 3%, polar solvents 3 to 6%

21
Q

Foam expansion

A 
Low medium or high depends on
Type of concentrate
Accurate proportioning
Qualify of concentrate
Method of aeration
NFPA 11 finished foam to solution, low: 20:1, medium 20:1 to 200:1, high 200:1 to 1000:1
22
Q

Rate of class B application

A 
Set by NFPA 11, Depends on:
Type of concentrate
If the fuel is on fire (requires more)
Hydrocarbon or polar solvent
If fuel is contained or not
Once you start, mus apply continuously from uphill upwind so make sure at the beginning that you have enough, or fire may consume a portion of the blanket
Apply uphill upwind
23
Q

1-Regular protein foams

A

Protein hydrosolate plus additives to prevent freezing
From hooves, horns and feathers
Good heat stability and burnback resisitance
Not as fluid
Shorter shelf life
More rare

24
Q

2-Fluoroprotein Foam

A

Protien foam with synthetic fluorchemical surfactant added
Makes it flow better and has longer lasting vapor suppression
Popular
Add Ammonia salts to work with alcohol for 15 min

25
Q

3-Film forming fluoroprotein foam

A

Combines 2-fluroprtein foam’s long heat resistance with 5- AFFF’s for quick knockdown
Can be alcohol resistant

26
Q

4-Aqueous film forming foam

A

Most common synthetic
Fluorochemical and hydrocarbon surfactants for high boiling point
Creates thin film over fuel specifically:
Vapor suppression film is released before the blanket
Fast Moving blanked spreads across fuel for insulation
Drains and fill in holes where blanket was disturbed

27
Q

4.5-Alcohol resistant AFFF

A

For use on polar solvents
Creates a membrane over the fuel, separates water in the foam from alcohol in the product
3 to 6% concentrate
Also used on hydrocarbons at 1 to 6%
Aspirating nozzles are best to create and preserve membrane
Put on gently to help membrane form first

28
Q

High expansion foam

A 
Detergent base, low water content
Less runoff, less water damage
Used in cellars and coal mines
Class A
Industrial hazards
29
Q

Two types of proportioners

A

Venturi

Pressurized injects set ratio into water

30
Q

In line foam eductor

A

Low energy proportioner
Mfg for pressure and distance
Gpm must not exceed rated capacity
Pressure at discharge side can’t exceed 70% of inlet pressure (back pressure)
Too high or too low pressure makes lean or rich mixture
Flush for 1 minute
Eductor inlet within 6”
Nozzle and eductor must have same gpm rating

31
Q

1-Foam nozzle eductor

A

Low energy proportioner
Nozzle with an eductor
Foam must be at the nozzle

32
Q

2-Self educting master stream foam nozzle

A

Low energy proportioner
For flows >350 gpm up to 14000 gpm
Lower pressure drop
Jet ratio controller can locate 3000’ from nozzle and elevation of 50’, proportions at 66.5% then in line eductor from MS drops it to 3%

33
Q

3-App mounted in line eductor

A

Same as portable
Foam can come from bucket or onboard tank
Bypass proportioner can reduce FL across eductor when just flowing water
Usually for class B

34
Q

4-Around the pump proportioner

A

App mounted, Most common
10-40 gpm of water from the tank flows through an inline proportioner to create venturi to get foam then dumped back to pump inlet
Old ones can only work off tank water

35
Q

5-Bypass type balanced pressure proportioner

A

Large mobile app like ARFF
Monitors demand for foam and adjusts concentrate supplied by a separate foam pump for each discharge
Most accurate

36
Q

6-Variable flow variable rate direct injection system

A

Positive displacement foam pump injects concentrate into the water flow so supplies all discharges with foam
Monitors hoselines to maintain consistent quality of foam
0.1 to 3%
Class A or B, not alcohol resistant
Atmospheric pressure fed foam tanks

37
Q

7-Variable flow demand type balanced pressure proportioner

A

Both fixed and mobile
Variable speed drives foam pump and monitors the flow of foam
Ready to pump, no flushing and can go to any number of discharges

38
Q

Batch mixing

A

Only done with Class A
Not good 24 hrs after mixing
Foam can remove lube
Last resort

39
Q

CAFS

A 
High energy
Stream reaches farther
Small, uniform, durable bubbles
Good adherence good heat resistance
More expensive, maint, training
0.1 to 1%
10:1 expansion ratio
40
Q

Smooth bore nozzles

A

Only work with CAFS

Good reach

41
Q

Fog nozzles

A

Apply low expansion short duration foam blanket
2:1 to 4:1 expansion
Best for AFFF and Class A not fluoroprotein or polar solvents

42
Q

Air aspirating foam nozzle

A

Induct air into the foam solution
Good for Class A and only ones for protein and fluoroprotien concentrates
Max expansion, worst reach

43
Q

Medium and high expansion foam generators

A

Water aspirating: same as other foam nozzles just bigger with screens
Mechanical Blower: uses a fan instead of water, good for total flooding
Create high air content from 20:1 to 200:1
For high expansion foam 200:1 to 1000:1

44
Q

Problems with foam fire streams

A 
Not matching eductor and nozzle flow
Air leaks, lack of suction
Clogged proportioning equipment
Attack line too long
Too much elevation to nozzle
Mixed concentrates
45
Q

Foam application techniques

A 
Direct application: class A
Roll on: Class B
Bank down: Class B
Rain down: Above ground storage tanks
46
Q

Durable agents

A

gelling agents: superabsorbent liquid polymers absorb 100x their weight in water
Slippery
Expensive
Trap water instead of air in the bubbles
Non toxic
Can stick to walls for 24 hrs and be rehydrated with a fine mist

47
Q

Class A application rate

A

Same minimum required flow rate for water

Engineer School (21 decks)

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