With reference to tank quick closing valves:
(a) describe, with the aid of sketches, TWO methods for remote actuation;(6)
(b) state where they would be fitted;(2)
(c) explain why they are fitted.(2)
Mainly well answered. Candidates loose marks by not how the valve closes after it has been tripped.
How can quick closing tank valves be actuated?
Quick closing tank valves on superyachts, especially those used for fuel or other hazardous liquids, can be actuated using a few different methods, each with its own advantages and potential drawbacks.
1. Emergency Fuel Shut Off, Quick Closing Valves | WO Supply Catalog
Here are the main ways they can be operated:
- Hydraulic Actuation:
- Mechanism: Hydraulic fluid under pressure is used to move a piston or actuator that triggers the valve’s closing mechanism.
- Advantages: High force, reliable, can operate multiple valves from a single hydraulic power unit.
- Disadvantages: Requires a hydraulic system with pumps, piping, and maintenance, potential for leaks.
- Pneumatic Actuation:
- Mechanism: Compressed air is used to drive a piston or actuator to close the valve. 1. Quick closing valve systems / Emergency Shut-Off – FJ | Fernández Jove fernandezjove.com
- Advantages: Simple, fast acting, no risk of fluid leaks, can operate multiple valves from a central air supply. 1. Quick closing valve systems / Emergency Shut-Off – FJ | Fernández Jove fernandezjove.com
- Disadvantages: Requires a compressed air system, potential for air leaks, may be less powerful than hydraulic systems for large valves.
- Electrical Actuation:
- Mechanism: An electric motor or solenoid is used to activate the valve’s closing mechanism.
- Advantages: Precise control, can be easily integrated with electronic control systems, no fluid or air leaks.
- Disadvantages: Dependent on electrical power, potential for electrical faults, may require backup power sources.
- Manual Actuation:
- Mechanism: A local handle or lever is used to manually close the valve.
- Advantages: Simple, no external power required, can be used as a backup in case of remote system failure.
- Disadvantages: Requires crew members to be physically present in potentially hazardous areas during an emergency.
- Fail-Safe Mechanisms:
- Fusible Link: A heat-sensitive fusible link melts at a specific temperature, releasing a spring-loaded mechanism to close the valve in case of fire. 1. 6 Typical Applications of Fusible Link Valves and How It Work | THINKTANK cncontrolvalve.com
- Spring Return: The valve is held open by pressure or an electrical signal. If this is lost, a spring automatically closes the valve.
Choosing the Actuation Method:
The choice of actuation method for quick closing tank valves depends on several factors, including:
- Valve Size and Application: Large valves may require more powerful hydraulic or pneumatic actuation.
- Vessel Systems: Existing hydraulic or pneumatic systems on the vessel may make those options more convenient.
- Safety Requirements: Critical valves may require redundant actuation systems or fail-safe mechanisms for added security.
- Maintenance and Cost: Each system has different maintenance requirements and associated costs.
Testing and Maintenance:
Regular testing and maintenance are essential to ensure that quick-closing valves and their actuation systems are always ready to function properly in an emergency. This includes checking for leaks, verifying operating pressures, and testing both local and remote operation.
1. Operation and Inspection of Fuel Oil Quick Closing Valves (QCV) – Irclass.org
Where would the tank quick closing valves be fitted?
Tank quick closing valves, especially those remotely operated, are strategically fitted at critical points in a superyacht’s fuel and other liquid storage systems to provide swift and effective control in emergency situations.
Here are the most likely locations where you’d find them:
- Tank Outlets:
- Main Outlet: The primary outlet where fuel or liquid is drawn from the tank for normal operations. A quick-closing valve here allows isolation of the entire tank in case of a leak, damage, or fire.
- Other Outlets: Some tanks may have additional outlets for transferring fuel or other purposes. These would also likely have quick-closing valves for similar reasons.
- Tank Vent Lines:
- Vent Valve: A quick-closing valve on the vent line can prevent the release of flammable vapors in case of fire or damage, minimizing the risk of explosion.
- Crossover Lines (If Applicable):
- Inter-Tank Connections: If tanks are interconnected for fuel transfer or balancing purposes, quick-closing valves would be fitted at these crossover points to isolate individual tanks in an emergency.
- Manifold Systems (If Applicable):
- Manifold Inlet/Outlet: In complex fuel systems with manifolds, quick-closing valves may be located at the manifold inlet and outlet to isolate specific tanks or groups of tanks.
The specific placement and number of tank quick closing valves on a superyacht will depend on factors like:
- Tank Configuration: The number and size of tanks onboard.
- Fuel System Complexity: The presence of manifolds, crossover lines, etc.
- Safety Regulations: Requirements based on the vessel’s flag state, classification society, and its intended operation.
Additional Considerations:
- Accessibility: Valves should be readily accessible for manual operation in case of remote system failure.
- Clear Labeling: Valves should be clearly labeled to indicate which tank or line they control.
- Regular Testing: Quick-closing valves should be regularly tested as part of a planned maintenance program to ensure they are always in good working order. 1. Operation and Inspection of Fuel Oil Quick Closing Valves (QCV) – Irclass.org www.irclass.org
Understanding the placement of these valves is crucial for the safe and effective operation of a superyacht. In an emergency, quick access and operation of the right valves can make a significant difference in preventing the spread of fire, mitigating pollution, and protecting the crew and vessel.