FAQ Orals (FFA)

How Does A Foam Nozzle Work?
The Foam Nozzle Works On The Venturi Principle Where Air Is Drawn Into The Nozzle Aerating The Foam Solution For Good Quality Fire Fighting Foam.
 
Why Is An Alarm Sounded When CO2 Is Released Into The Engine Room?
An Alarm Is Sounded To Inform Personnel In The Engine Room That The Release Of CO2 Is Imminent.  The Type Of Alarm Will Be Visual And Sound Different From Engine Room Alarm And General Alarm.CO2 Cannot Support Life So Everybody Should Vacate Engine Room Before Releasing It.
 
Explain  A Exhaust Inert Gas System.
In A Boiler Funnel Inert Gas System, Exhaust Gas Is Taken From The Boiler Uptakes And Passed Through A Scrubber Tower Where The Gas Is Cleaned With Sulphur And Excess Carbon Being Removed.
The Gas Which By Then Is Considered Inert And Mainly Contains Nitrogen And Carbon Dioxide With Less Than 5% Oxygen, Is Then Supplied Via Blowers And Deck Seal Which Acts As A Non-return Valve, Along Deck Pipes To Cargo Banks.
The Inert Gas Being Used To Blanket The Oil Cargo During Discharging Operations.  Empty Tanks Are Filled With Gas And The Inert Gas Is Blown Out When Oil Is Loaded.
 
Describe And Sketch A Soda Acid Extinguisher.
The Container Of The Extinguisher Holds A Sodium Bicarbonate Solution.  The Screw On Cap Contains A Plunger Mechanism Covered By A Safety Guard.  Below The Plunger Is A Glass Phial Containing Sulphuric Acid.  When The Plunger Is Struck, The Glass Phial Is Broken And The Acid And Sodium Bicarbonate Mix.  The Resulting Chemical Reaction Produces Carbon Dioxide Gas, Which Pressurises The Space Above The Liquid, Forcing It Out Through The Internal Pipe To The Nozzle.
 
 On What Type Of Fire Would You Use A Dry Powder Fire Extinguisher?
The Dry Powder Can Be Used On All Classes Of Fire, But It Has Poor Cooling Effect.
 
What Advantage Do Inert Gas Producing Units Used For Fire Fighting Installations Have Over CO2 And Halon Systems?
Inert Gas Producing Units Have The Advantage Of Being Able To Continuously Produce Inert Gas.  A Bottle Storage System, Such As CO2 Or Halon Flooding Is A "one Shot" Fire Extinguisher Which Leaves A Ship Unprotected Until Further Gas Supplies Can Be Found.
 
What Can You Tell Me About Halon Systems, With Regards To New Installations And Existing Ones?
SOLAS Prohibits The Installation Of New Or Portable Systems In All Ships From 1st October 1994 And Providing Existing Fixed Installations And Portable Extinguishers Remain Serviceable And Fit For Purposes, They May Remain In Place.
 
What Does The Opening Of The CO2 Release Cabinet Do?
It Sets Off An Alarm In The Engine Room To Warn Personnel That The Release Of CO2 Is Imminent.
In Some Ships  stops All Ventilation Fuel Oil Circulation And Supply Pumps.
 
 What Are The Advantages Of CO2 Systems Compared To Halon Systems?
CO2 Is More Environmentally Friendly Also Halon Systems Are Being Phased Out.
 
 What Is A Water Fog Based Fire-fighting Installation?
Unlike Conventional Sprinkler Systems Utilising Water Under Low Pressure In Heavy Large Diameter Pipes, The Water Fog Extinguishing System Operates By Using Water Under Very High Pressure In Small Bore Pipes.  This Reduces The Weight And Volume Of The System And Permits Easy Installation On Board.
The Water Fog System Produces Micro-droplets Of Water; Thus A Very Large Cooling Surface Is Created With Only Small Quantities Of Water.  With This System The Amount Of Water Required For Successful Fire Extinguishing Is Much Less Than Conventional Sprinkler Systems.  This Allows For The Use Of Fresh Water As The Medium.  Also With The Water Fog System, The Water Fog Is Propelled Into Hidden Spaces Just Like Halon Or CO2, Providing The Most Reliable Fire-extinguishing.
In Accommodation Areas This System Can Use A Dual-purpose Nozzle Which Incorporates A Quartazoid Bulb For Detection And Extinguishing.
The Water Fog System Is Also Suitable For Engine Rooms.
 
What Is The Gas Analysis After The Scrubber Tower On An Inert Gas System.
Oxygen:  0-1% (Alarm At 5%)
Carbon-monoxide:  0
Carbon Dioxide:  14-15%
Nitrogen:  85%
 
Where Would You Expect To Find A Foam Extinguisher?
It Would Be Located In The Engine Room, In The Vicinity Of Flammable Liquids, Also Bunker Stations.
 
On What Type Of Fire Would You Use A Soda Acid Extinguisher?
This Type Of Extinguisher Would Be Used On Class A Fires:  Fires Burning Wood, Glass Fibre, Upholstery And Furnishings
 
What Are The Requirements Of A Fixed CO2 Fire Fighting Installation?
The System Must Give 40% Saturation Of The Compartment To Be Filled.
85% Of The CO2 Charge Must Be Discharged Into The Compartment Within The First Two Minutes.
 
What Testing And Maintenance Is Done Regarding Soda Acid And Foam Extinguishers?
The Extinguisher Containers Are Pressure Vessels, Therefore Require Testing.
Containers Are Initially Tested To 25 Bar Every Year For Five Years And Thereafter At Four Yearly Intervals To 20 Bar.
On Soda Type Extinguishers 20% Of Contents Should Be Discharged Per Year And Replenished With Foam Type 50%.
Where Practical The Operating Mechanism Of Portable Extinguishers Should Be Examined Every
Three Months.
 
What Happens To The CO2 System In Drydock?
In Drydock The CO2 System Must Be Made Inoperable.
 
What Are The Four Principle Types Of Portable Fire Extinguishers Found On Board Ships?
Water/Soda Acid Type Extinguishers
Foam Extinguishers
Dry Powder Type Extinguishers
Carbon Dioxide Extinguishers.
 
How Much Foam Is Produced From A 9L Foam Extinguisher?
72 Litres Of Foam.
 
What Is The Re-entry Procedure Once A Machinery Space Has Been Flooded With  CO2 Or Halon?
Once CO2 Or Halon Flooding Has Taken Place, The Space Should Be Continued To Be Boundary Cooled.
Only When The Extinguished Fire Has Been Left Long Enough To Cool Down, Can The Space Be Re-entered.  Note:  Early Re-entry Can Lead To Re-ignition.
Re-entry Should Be Done By Personnel Wearing Breathing Apparatus, Taking Water Spray Hoses With Them To Cool Down Any Hot Surfaces.  Note:  Re-entry Should Also Take Place From The Lowest Point Remote From The Seat Of The Fire, If Possible.
Cooling And Smoke Dispersal Are The First Priorities To Provide An Atmosphere In Which Others Can Operate And Gradually Bring Machinery Back Into Service. 
Where The Machinery Space Fire Involves Electrical Equipment Then Only Dry Powder Of Carbon Dioxide Extinguishers Can Be Used Until The Equipment Is Isolated.
 
On What Type Of Fire Would You Use A CO2 Extinguisher?
Class B And C Fires And Electrical Fires.
 
State The Regulations Regarding The Emergency Fire Pump.
The Emergency Fire Pump Is To Be Located Remote From The Machinery Space And With Independent Means Of Power, Which Could Be A Diesel Engine Or From The Emergency Switchboard.
 
Describe An Inert Gas Generator.
The Inert Gas Generator Burns Fuel In Designed Quantities To Produce Perfect Combustion.  This Produces An Exhaust Gas, Which Is Largely Nitrogen And Carbon Dioxide With A Very Small Oxygen Content.
The Exhaust Gases Pass To A Cooling And Washing Chamber To Remove Sulphur And Excess Carbon.  The Washed Or Scrubbed Gas Is Now Inert And Passes To A Distribution System For Fire Fighting.  The Complete Unit Is Arranged To Be Independently Operated In Order To Supply Inert Gas For As Long As The Fuel Supply Lasts.
On Tankers The Inert Gas Can Be Supplied And Used To Blanket The Oil Cargo During Discharging Operations.  Empty Tanks Are Filled With Gas And Inert Gas Is Blown Out When Oil Is Loaded.
  
Briefly Explain How High Expansion Foam Is Produced.
High Expansion Foam Is Produced By Means Of A Foam Generator, Where From Foam Concentrate And Seawater, 1000 Times Quantity Is Achieved.  The Generator Blows Air Through A Net Sprayed With Foam Concentrate And Water.  The Vastly Expanded Foam Is Then Diverted Away To The Space To Be Protected.  The Foam Is An Insulator And An Absorber Of Radiant Heat; It Also Excludes Oxygen From The Fire.
 
What Is The Purpose Of The Deck Seal On An Inert Gas System?
The Purpose Of The Deck Seal Is To Act As A Non-return Valve And Prevent The Back Flow Of Gases.
  
What Is Boundary Cooling And The Reasons For It?
It Should Be Remembered That A Fire Exists In Three Dimensions And Therefore Has Six Sides, Therefore Can Be Transmitted Through Bulkheads Due To Radiant Heat, I.e. Causing Combustible Materials In Adjacent Compartments To Catch Fire. Therefore, This Radiant Heat Is Prevented By Boundary Cooling Of All Sides Of The Compartment On Fire, Using Water Spray Hoses.
 
What Does AFFF Stand For And Where Would You Use This Type Of Extinguisher?
AFFF Stands For:  Aqueous Film Forming Foam.
This Would Be Used On Class B Fires, Fires Burning Liquids Such As Lubricating Oils And Fuels
 
What Action Would You Take In The Event Of Fire Breaking Out In The Machinery Space?
If A Fire Breaks Out, The Alarm Should Be Raised And The Bridge Informed Immediately.  If The Ship Is In Port, The Local Fire Authority Should Be Called.  If Possible, An Attempt Should Be Made To Extinguish Or Limit The Fire By Any Means Possible (a Fire In Its First Few Minutes Can Usually Be Readily Extinguished).
Ventilation Fans Should Be Stopped (should Stop Automatically On Activation Of Fire Alarm).  Openings To The Space Should Be Sealed To Reduce The Supply Of Air To The Fire And To Prevent It Spreading.  Any Fuel Lines Feeding The Fire Or Threatened By It Should Be Isolated.  If Practicable, Combustible Materials Adjacent To The Fire Should Be Removed.
After The Fire Has Been Extinguished, Precautions Should Be Taken Against Spontaneous Re-ignition.
Personnel, Unless Wearing Breathing Apparatus, Should Not Re-enter A Space In Which A Fire Has Occurred Before It Has Been Fully Ventilated.