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EK 1 > Module 6: Fire Fighting systems > Flashcards

Module 6: Fire Fighting systems Flashcards

1
Q

What is a fire main?

A

A fire main system is a critical component of a ship’s firefighting infrastructure. It provides a centralized distribution network for seawater or freshwater, used to suppress fires onboard.

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2
Q

What are the main parts of a fire main?

A

fire pumps
fire mains
fire hydrants
fire hoses

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3
Q

What is the purpose of an international shore connection?

A

Emergency Backup
Standardization
Flexibility
Regulatory Compliance

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4
Q

What are the advantages of a smothering gas system?

A

Effective Fire Suppression
Minimal Damage
Suitable for Enclosed Spaces
Safety for Sensitive Cargo and Equipment
Compliance with Regulations
Minimal Maintenance Requirements
Cost-Effectiveness

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5
Q

List five (5) rules that apply to smothering gas systems

A

*audible warning
*automatically stop ventilation fans
*all openings can be closed off
control valves that clearly indicate the compartment
*avoid the possibility of inadvertent or malicious use
*All piping, valves and fittings must be constructed of ferrous materials
*Instructions displayed near
*Smothering system control gear
located not inaccessible by fire
*whole charge enter the space in no more than two minutes
*diffuser nozzles in areas where not harm crew
*cylinders stored safely and well ventilated area

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6
Q

What calculations are used to determine the minimum amount of free smothering gas in a machinery space?

A

*40% of the gross volume of the largest space
*35% of the entire volume of the largest space including the casing.

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7
Q

What considerations are given for air receivers

A

Air receivers must be included in total volume. You have to have enough CO2 to fill that area as well.

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8
Q

In reference to the actuating valves on top of CO2 cylinders: why are they made of brass

A

Corrosion Resistance
Durability
Machinability
Non-sparking
Cost-effectiveness

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9
Q

Why is a siphon tube fitted to the valve?

A

To ensure that liquid CO2 is discharged from the cylinder, rather than CO2 in a gaseous state.
If CO2 were to evaporate from the surface of the liquid CO2 in the cylinder, it would absorb latent heat and cause the remaining CO2 in the cylinder to freeze

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10
Q

How are the actuating valves on CO2 cylinders operated?

A

●Remotely by an electronic switch
●Remotely by a manual pull chain
●Locally by a manual release

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11
Q

What type of indicating alarms are fitted to a space protected by a smothering gas system

A

*Gas Detection Alarms
*Audible Alarms
*Visual Alarms
*Pressure or Flow Alarms
*Temperature Alarms
*Time Delay Alarms

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12
Q

Describe how the CO2 system is activated

A

Activation
Control Stop Valve
CO2 Distribution
Pressure Monitoring
Delay and Release
Main Gas Flow
Safety Mechanisms

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13
Q

Describe the steps taken before the CO2 system is activated

A
  1. Alarm is sounded and all personnel are evacuated from the space.
  2. Roll call sounded.
  3. All ventilation dampers and openings are covered to prevent entry of air into the space.
  4. All ventilation fans, fuel pumps, engines etc are shut down. This is done manually (emergency stops) or automatically (pressure switch connected to the CO2 System)
  5. After a 30 second delay, the bulk of the C02 will flood the space.
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14
Q

In reference to sprinkler systems: What is the capacity of the sprinkler tank equal to?

A

The sprinkler tank in a sprinkler system must have a capacity equal to one minute of discharge from the sprinkler pump. This ensures there is an immediate supply of fresh water available for fire suppression when the system is activated.

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15
Q

In reference to sprinkler systems: What special considerations are given for the power supplied to the sprinkler pump ?

A

The sprinkler pump is typically a centrifugal pump with two sources of power: the main switchboard and the emergency switchboard.

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16
Q

In reference to sprinkler systems: What must be fitted at the start of each protected zone?

A

At the start of each protected zone in a sprinkler system, an isolation valve must be fitted. This valve allows for the isolation of individual zones for maintenance or in the event of a problem in that zone. Adjacent to each isolation valve, a pressure gauge and a drain valve must also be fitted.

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17
Q

What are the advantages of a water mist system?

A

*Localized Fire Suppression
*No Need for Evacuation or Space Isolation
*Effective Cooling and Smothering
*Reduced Risk of Re-ignition
*environmentally friendly
*pose less risk to personnel

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18
Q

What are the disadvantages of a water mist system

A

High Installation Cost
Complexity
Lower effectiveness on Large Fires
Water Supply Requirements
Corrosion Risk
Limited Industry Acceptance

19
Q

Briefly describe how foam suppresses a fire

A

Foam Blanket Formation
Smothering Effect
Cooling Effect
Sealing the Surface
Film Formation

20
Q

What is the purpose of a proportioning valve in a foam system

A

*Mixing Foam Concentrate and Water
*Maintains Consistent Ratio
*Optimizes Foam Performance
*Accommodates Variable Flow
*Prevents Over- or Under-Proportioning

21
Q

In reference to foam discharge devices, what is meant by the term aspirating?

A

Air Entrapment
Produces Fine Foam
Application
Effective for Vapor Suppression

22
Q

In reference to foam discharge devices, what is meant by the term non aspirating?

A

No Air Entrapment
Produces Heavier Foam
Application
Effective for Surface Fires

23
Q

In reference to Inert Gas Systems: What is meant by the term inerting?

A

Purpose: The process of introducing inert gas (such as nitrogen or CO2) into a space to reduce the oxygen concentration below the level required for combustion.

Application: Used to prevent the risk of fire or explosion in environments containing flammable materials.

24
Q

In reference to Inert Gas Systems: What is meant by the term purging?

A

Purpose: The removal of air (especially oxygen) from a confined space by replacing it with inert gas.

Application: Ensures that the space is safe for operations by lowering the oxygen content before work begins, particularly in hazardous environments.

25
Q

In reference to Inert Gas Systems: What is meant by the term gas freeing?

A

Purpose: The process of removing harmful gases, vapors, or flammable substances from a space and ensuring that the space has been safely purged to allow for human entry or maintenance.

Application: Common in tanks, holds, and other confined spaces after they have been used for transporting or storing hazardous substances.

26
Q

In reference to Inert Gas Systems: What is meant by the term topping up?

A

Purpose: The replenishment of inert gas in a system or space to maintain the desired inert gas concentration after some loss.

Application: Ensures that the inert gas level remains sufficient to maintain safety, especially after purging or due to natural leaks.

27
Q

What are the three (3) sources of inert gas commonly found on an oil tanker

A

*Exhaust gasses from a main or auxiliary boiler
*Exhaust gasses from an internal combustion engine (main or auxiliary) or a gas turbine
*A dedicated inert gas generator powered by gas oil or heavy fuel oil

28
Q

Describe the purpose of a scrubber.

A

Gas Cleaning: Cools exhaust gases and removes pollutants like Sulphur dioxide and particulate soot.

Environmental Protection: Reduces harmful emissions from the inert gas system, ensuring compliance with environmental regulations.

Efficiency: Removes at least 90% of Sulphur dioxide and all solids from the exhaust gas.

29
Q

Describe the purpose of deck water seals.

A

Prevent Gas Leakage: Ensures no inert gas leaks into the atmosphere from the inert gas system when the scrubber is open for inspection.

Safety: Acts as a safety device to maintain a sealed environment in the system during maintenance.

Maintains Pressure: Prevents backflow or loss of inert gas from the system by providing a water barrier.

30
Q

Describe the purpose of a pressure vacuum breaker

A

Regulates Pressure: Protects the tank or system from overpressure or vacuum conditions by allowing air in or out as needed.

Prevents Damage: Ensures the system does not experience excessive pressure or vacuum, which could damage equipment or compromise safety.

Maintains Tank Integrity: Keeps the system within safe operating pressure limits during inerting or venting.

31
Q

What are the key elements that control pressure in an inert gas system?

A

*Pressure/Vacuum (P/V) Breakers:
*Pressure Control System
*Blower Capacity
*Isolation Valves
*Non-Return Devices (e.g., Deck Water Seal)

32
Q

What are the Pressure/Vacuum (P/V) Breakers?

A

Crucial Safety Devices:
Prevent over-pressurization or vacuum conditions in the inert gas system.

Types:
Can be liquid-filled or mechanical designs.

Function:
Vent excess pressure to prevent damage or failure.
Allow air intake if a vacuum develops, maintaining system stability.

33
Q

What are the Pressure Control Systems?

A

Automatic Adjustment:
Uses a pressure transmitter and regulator to manage inert gas flow to cargo tanks.

Recirculation Control:
Regulates the amount of gas recirculated back to the scrubber for efficiency.

Regulating Valves:
Installed in both the main flow line and the recirculation line to control gas distribution.

34
Q

What is the Blower Capacity?

A

Primary Function:
Deliver inert gas to cargo tanks.

Capacity Requirement:
Must meet 125% of the vessel’s maximum cargo discharge capacity.

Purpose of Excess Capacity:
Ensures adequate pressure is maintained during peak demand and operational needs.

35
Q

What alarms must be fitted to an inert gas system

A
  1. High oxygen content in the inert gas main.
  2. Low gas pressure in the inert gas main (Alarm point is 50 mm H20).
  3. Low pressure in the supply water to the deck seal.
  4. High temperature of gas in the inert gas main (Alarm point is 65 degrees Celsius).
  5. Low water pressure to the scrubber.
36
Q

When would nitrogen be used to inert a tank

A

Nitrogen is used to inert tanks on ships, particularly chemical tankers, when a higher level of purity and a lower oxygen level is required than can be achieved with standard inert gas systems that use boiler exhaust gas.

37
Q

Why would nitrogen be used to inert a tank

A

Sensitivity to Moisture
Sensitivity to Carbon Dioxide
Sensitivity to Low Oxygen Levels

38
Q

describe the principle of pressure swing adsorption systems

A

Uses a solid adsorbent material (usually zeolite) to separate nitrogen from air by adsorbing oxygen under high pressure.

39
Q

describe the process of pressure swing adsorption systems

A

Compression
Adsorption
Pressure Reduction
Regeneration

40
Q

describe the principle of hollow fibre membrane systems.

A

Uses semi-permeable membranes to separate gases based on their molecular size and diffusion rate.

41
Q

describe the process of hollow fibre membrane systems.

A

Air Feed
Separation
Product Nitrogen

42
Q

What are the advantages of pressure swing adsorption systems?

A

*High purity nitrogen production.
*Continuous operation with relatively simple maintenance.

43
Q

What are the advantages of hollow fibre membrane systems?

A

*Compact design with low energy consumption.
*Simple and reliable operation with minimal maintenance requirements.
*Can operate effectively at lower pressures compared to PSA systems.

EK 1 (10 decks)

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