8. (a) State THREE dangers arising from the use of LPG open flame appliances.(3)
(b) Describe the requirements for a Gas Detector suitable for a LPG installation.(7)
(a) THREE dangers arising from the use of LPG open flame appliances (3 marks)
- Fire and explosion risk
- LPG is highly flammable and heavier than air. Leaks can accumulate in bilges or low spaces, creating a serious explosion hazard if ignited by a spark or flame.
- Asphyxiation (oxygen depletion)
- Burning LPG consumes oxygen. In confined spaces with poor ventilation, oxygen levels can fall below safe limits, leading to asphyxiation or loss of consciousness.
- Toxic fumes and carbon monoxide (CO) production
- Incomplete combustion due to faulty burners or poor ventilation produces carbon monoxide, a colourless, odourless, poisonous gas that can cause headache, dizziness, or death.
(1 mark each — total 3 marks)
(b) Requirements for a Gas Detector suitable for an LPG installation (7 marks)
- Type and sensitivity
- The detector must be suitable for LPG, capable of detecting butane or propane vapours, and sensitive to concentrations well below the lower explosive limit (LEL).
- Location
- LPG vapour is heavier than air; detectors must be fitted low down, close to the deck or bilge level, and near potential leak sources such as cookers, regulators, or cylinder lockers.
- Alarm indication
- The detector must have both audible and visual alarms, clearly audible throughout the accommodation, to provide early warning of a leak.
- Power supply
- The system should be permanently powered from the vessel’s DC supply, preferably with battery backup to ensure continuous operation during power failure.
- System testing
- A test function must be provided to check the operation of sensors and alarms at regular intervals.
- Automatic control (recommended)
- The system should ideally shut off the gas supply automatically via a solenoid valve when gas concentration exceeds safe levels.
- Installation and maintenance
- Detectors must be marine-approved equipment, installed and maintained according to the manufacturer’s instructions, and replaced or recalibrated as per service schedule.
(1 mark each — total 7 marks)