9. Describe, with the aid of a sketch, a multiple bottle CO, gas system suitable for the protection of machinery spaces.
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Multiple Bottle CO₂ System for Machinery Spaces
Description:
- A CO₂ smothering system is used to extinguish large machinery space fires by displacing oxygen.
- Because of the volume required, multiple high-pressure CO₂ bottles (cylinders) are used.
Main Features:
- CO₂ Cylinder Bank
- Cylinders are stored together in a dedicated, ventilated CO₂ room outside the protected machinery space.
- Each bottle has its own valve, fitted with bursting disc safety relief.
- Manifold and Distribution System
- Cylinders are connected via flexible hoses to a common manifold.
- The manifold supplies CO₂ into distribution pipes leading to the machinery space.
- The piping network ends in discharge nozzles arranged to ensure uniform flooding.
- Operating Mechanism
- Cylinders are normally held shut by pilot valves.
- Activation is via a pilot cylinder (smaller CO₂ bottle) released first; its pressure operates the main cylinder valves simultaneously.
- Operation is from a remote control station outside the protected space, with local back-up controls.
- Safety Features
- Audible and visual alarms in the engine room warn of impending release.
- A time delay (typically 30–60 seconds) allows evacuation before CO₂ discharges.
- Lock-off arrangements prevent accidental release.
- Capacity and Regulation
- The system must be able to release 85% of the required CO₂ volume within 2 minutes.
- CO₂ volume is calculated to give at least 35% concentration of the gross machinery space volume.
Sketch (exam style)
Draw a block diagram with the following:
- CO₂ Bottle Room (bank of cylinders).
- Each connected via hoses → Common Manifold.
- Pilot cylinder + release mechanism shown.
- Manifold → Distribution piping → Nozzles inside the machinery space.
- Remote release station outside engine room.
- Alarm bell/light on engine room side.