NSTM 555 - Firefighting Flashcards
What are the components of the Fire Tetrahedron?
Oxygen, Heat, Fuel, Chemical Reaction
What is a Class “A” fire?
Combustible materials that produce ash - wood, cloth, paper, etc
What is the primary and secondary agents for class A fires
Water in straight or fog patterns, or AFFF for deep seated fires
What are Class “B” fires?
Fuel, liquid, flammable oils and fluids, and flammable gases
What are the primary agents to combat a class “B” fire?
AFFF, Halon, Water mist
What is the most important step to combating a Gas “B” fire?
Securing the source of the leak/gas
What is a class “C” fire?
Electrical fire - once power is secured it becomes an “A”
What are the primary agents to combat a “C” fire?
CO2, Halon, Water spray
Why should PKP only be a last resort for “C” fires?
It is highly corrosive
What is a class “D” fire?
Combustible metals such as magnesium and titanium
What is the primary agents for a “D” fire?
Water, used in a fog from a safe distance as there may be small explosions when applied
How does water put out a fire?
Heat is removed in the form of steam, providing a cooling effect
Describe the use of a straight stream water pattern
Aimed from a distance at the base of a fire, used to break up the burning material and apply cooling at source of heat
What are the hazards of using a straight stream water pattern?
Can cause flooding below decks due to increased flow, more electrically conducive - don’t use on electrical fires
Why are fog patterns more effective than straight streams?
More effective cooling and heat absorption, and provides protection to the firefighters
What types of fuel is water effective at combating fires in?
High flashpoint fuels (over 140 F) such as F-76
How do you employ water as an agent in a “B” fire?
Use narrow angle fog pattern to the leading edge of the flames in a sweeping pattern
What is the Water to AFFF ratio?
94:6
What are three advantages to using AFFF?
- Prevents fuel vapors from escaping
- Removes Oxygen from the fire
- Provides cooling effect
Is AFFF or Water the better agent for “A” fires?
AFFF
Discharge of AFFF to the sea is only allowed at what distance from shore?
12 NM
How does CO2 put out fires?
It is 1.5 times heavier than air, so it smothers the fire and removes Oxygen
How does Halon 1301 extinguish fires?
Chemically inhibits the fire
What should happen upon inadvertent activation of Halon?
Evacuate spaces
What is PKP primarily used for?
Class “B” Fires (smaller ones)
How does PKP extinguish a fire?
It inhibits the combustion chain - it does not have a cooling effect
What ship class is the Water Mist system found on and why?
LPD-17 class. It is a replacement for Halon since Halon is an Ozone Depleting Substance
What PSI is the water mist system deployed at?
1000 PSI
Advantages to Water mist over Halon?
No need for 30/60 sec delay time, non-ozone depleting, Non-toxic to personnel
When is HFP used in place of Water Mist?
On newer class ships in unmanned spaces
How is AFFF activated at each hosereel?
There is an electrical pushbutton that activates the system
How is AFFF turned off from a hosereel?
There is no off button, the flow can be turned off at the nozzle
What color boxes are AFFF Sprinkler activation switches contained in?
Red/Green striped boxes
If a major oil leak is detected, what immediate actions can reduce the possibility of a fire?
Secure the oil source and cover surfaces with AFFF
If you cannot stop the oil leak, what is another action that can help reduce the possibility of ignition?
Deflect the oil away from hot surfaces
What types of fire prevention systems are installed in Gas Turbine and Diesel Engine Enclosures?
Halon, HFP, and CO2
