- (a) Explain the need for fitting, location, and operation of an engine room fire main isolation valve.(4)
(b) State the type of valve used in part (a).(1)
(c) Describe, with the aid of a sketch, the construction of a sprinkler head.(5)
What is an engine room fire main isolation valve?
An engine room fire main isolation valve is a crucial safety component found in a ship’s fire-fighting system. It is a valve strategically placed in the fire main piping, specifically designed to isolate the section of the fire main within the machinery space (engine room) from the rest of the fire main system.
Purpose:
The primary purpose of the engine room fire main isolation valve is to:
- Preserve Firefighting Capability: In the event of a fire or other emergency in the engine room that causes damage to the fire main piping within that space, closing the isolation valve prevents the loss of water pressure and flow to the rest of the ship. This ensures that firefighting efforts can continue on deck and in other areas, even if the engine room fire main is compromised.
- Limit Fire Spread: By isolating the engine room section of the fire main, the valve helps contain the fire and prevent it from spreading to other parts of the ship through the fire main piping.
Location:
- As per SOLAS (Safety of Life at Sea) regulations, the engine room fire main isolation valve must be:
- Outside the Machinery Space: It is located in an easily accessible and tenable position outside the engine room, typically on deck or in an adjacent compartment.
- Easily Accessible: The valve should be readily accessible to crew members even in emergency situations, allowing for quick and easy operation.
Operation:
- The valve is typically a large, manually operated gate valve or butterfly valve.
- In normal operation, it is kept open to allow water flow throughout the entire fire main system.
- In case of a fire or emergency in the engine room, the valve is closed to isolate the affected section and maintain water pressure for firefighting in other areas.
Additional Points:
- Clear Marking: The isolation valve should be clearly marked and identified to ensure easy recognition and access during emergencies.
- Regular Testing and Maintenance: The valve should be regularly inspected, tested, and maintained to ensure its proper functioning in critical situations.
- Crew Training: Crew members should be trained in the operation of the isolation valve and its role in the ship’s fire safety plan.
In summary, the engine room fire main isolation valve serves as a critical safety barrier, protecting the ship’s firefighting capabilities and limiting the spread of fire in the event of an engine room emergency. Its strategic placement and proper operation are essential for ensuring the safety of the vessel and its crew.
Type of valve used
The type of valve typically used for an engine room fire main isolation valve is a non-return gate valve or a butterfly valve.
- Non-Return Gate Valve:
- This type of valve allows water to flow in only one direction, preventing backflow. 1. Spot the difference – Check valves or Non-return valves… – Water Regs UK www.waterregsuk.co.uk
- In the context of fire main isolation, this ensures that if there is a rupture or damage in the engine room section of the fire main, water from other parts of the system cannot flow back into the engine room and worsen the flooding.
- Gate valves provide a tight shut-off when fully closed, minimizing any leakage.
- They are robust and reliable, suitable for high-pressure applications like fire mains.
- Butterfly Valve:
- Butterfly valves are also commonly used for fire main isolation due to their quick operation and compact design. 1. How does a Butterfly Valve Work? www.dombor.com
- They provide good flow control and can be easily operated manually or with actuators. 1. What is a Butterfly Valve? | Tameson.com tameson.com
- While they may not offer the same level of leak tightness as gate valves, they are generally sufficient for fire main isolation purposes.
Key considerations for choosing the valve type:
- Size of the fire main: The valve size should match the diameter of the fire main piping to ensure proper flow and pressure.
- Pressure rating: The valve should be rated for the maximum pressure expected in the fire main system.
- Accessibility and ease of operation: The valve should be located in an easily accessible and tenable position outside the machinery space and be easy to operate quickly in an emergency.
- Maintenance requirements: The chosen valve type should be relatively low-maintenance and suitable for the marine environment.
Additional points:
- Remote operation: In some cases, the isolation valve may be remotely operated from the bridge or a fire control station for added convenience and safety.
- Redundancy: Depending on the ship’s design and safety requirements, there may be multiple isolation valves installed to provide redundancy and ensure that the fire main can be isolated even if one valve fails.
Ultimately, the choice of valve type for the engine room fire main isolation depends on various factors, including the specific ship design, regulatory requirements, and operational considerations. However, both non-return gate valves and butterfly valves are commonly used and effective options for this critical safety application.Sources and related content
Contruction of a sprinkler head
let’s break down the construction of a typical sprinkler head, a critical component of fire protection systems on ships and in buildings.
Main Components:
- Frame:
- This is the body of the sprinkler head, typically made of brass or other corrosion-resistant metal. It provides structural support and houses the other internal components. 1. Fire Sprinkler Heads: Types, Parts & Differences [Guide] | RCI www.rcifire.com
- It also connects to the sprinkler piping system via a threaded or soldered joint.
- Deflector:
- This is the flower-shaped or dome-shaped component located just below the orifice (opening) of the sprinkler head. 1. Definition: Fire Sprinkler Head | Firewize firewize.com.au
- Its function is to distribute the water spray in a specific pattern, ensuring even coverage of the protected area. 1. Types of Sprinklers | NFPA www.nfpa.org
- Heat-Sensitive Element:
- This is the crucial component that triggers the sprinkler head in response to a fire. There are two main types:
- Fusible Link: A metal link that melts at a predetermined temperature, usually around 68°C (155°F). When the link melts, it releases the plug, allowing water to flow. 1. Did you know? Sprinkler Head Operation & Types www.firesecurity.co.uk
- Glass Bulb: A small glass bulb filled with a heat-sensitive liquid or a pressurized gas. The liquid expands or the gas pressure increases with rising temperature, causing the bulb to shatter at a specific temperature, typically between 57°C and 182°C (135°F and 360°F) depending on the hazard classification of the area. 1. What are the Differences Between Fusible Link vs Glass Bulb Sprinkler Heads? – Kinetix Fire kinetixfire.com2. How does a automatic fire sprinkler head work? – Firewize firewize.com.au
- Plug:
- This is a disc or cap that seals the orifice of the sprinkler head, preventing water flow until the heat-sensitive element is activated.
- Once the fusible link melts or the glass bulb shatters, the plug is released, allowing water to flow. 1. Sprinkler head – Designing Buildings Wiki www.designingbuildings.co.uk
- Orifice (Opening):
- This is the opening through which water is discharged once the sprinkler head is activated.
- The size of the orifice determines the flow rate and spray pattern of the water.
- Cap and/or Escutcheon:
- The cap or escutcheon is the decorative or protective cover that surrounds the sprinkler head. 1. What are Escutcheons and Are They Required for Fire Sprinklers? blog.koorsen.com
- It may also serve to deflect or direct the water spray pattern. 1. Sprinkler head – Designing Buildings Wiki www.designingbuildings.co.uk
Construction Process:
- The frame is manufactured using casting or machining processes, creating the body and internal structure to house the other components. 1. Fire Sprinkler Head Types: Pendents, Uprights, Sidewalls & Concealed – Blog | QRFS.com blog.qrfs.com
- The deflector is typically stamped or molded from metal and attached to the frame.
- The heat-sensitive element (fusible link or glass bulb) is assembled and installed within the frame.
- The plug is fitted into the orifice, sealing it securely.
- The cap or escutcheon is attached to the frame, completing the assembly. 1. Fire Sprinkler Heads: Types, Parts & Differences [Guide] | RCI www.rcifire.com
Types of Sprinkler Heads:
- Pendent Sprinkler: Hangs down from the ceiling and sprays water downwards.
- Upright Sprinkler: Points upwards and sprays water upwards towards the ceiling. 1. Types of Sprinklers | NFPA www.nfpa.org
- Sidewall Sprinkler: Mounted on a wall and sprays water horizontally. 1. Types of Sprinklers | NFPA www.nfpa.org
- Concealed Sprinkler: Hidden behind a decorative cover that releases upon activation.
Remember: The construction of sprinkler heads is strictly regulated to ensure their reliability and performance in fire emergencies. Different types and designs are available to suit various applications and hazard classifications.