fuel Flashcards
how can ships be refuled
replenishment at sea (RAS)
road bowser/tanker
jetty storage tanks
lighter barge
fixed jetty pipeline
explain RAS
RAS is where fuel is taken from a supply ship (Usually RFA). This is a whole ship operation (massive spillage and fire risk) (All personnel above decks will be wearing anti-flash) This is a very hazardous way of re-fuelling due to the close proximity of the two ships and will be kept to a minimum time.
what is a road bowser /tanker
When the ship is alongside, we can receive fuel via a Road Bowser (Tanker). Fuel is taken at a slower rate so the fuelling operation will take longer than that for RAS but is safer.
explain fuel storage
Fuel enters the filling trunk and continues to fill up until it reaches the weir height. Continued fuelling will cause fuel to cascade over the weir and down into the fuel filling manifold
what is a displacement tank
A fuel tank that will contain some salt water. They act as fuel storage and ballast for ship stability. Only ever filled to 90%
what is a un displaced tank
A fuel storage tank that only holds fuel (could be dirty fuel) - never filled with water as ballast. The fuel then passes through a centrifuge.
what is a centrifuge
Separates oil/fuel from water, using centrifugal force. Once the fuel is clean it is stored in a service tank for use.
when testing for fuel what should you look for
- Water – may contain sodium and will encourage Micro Biological Growth (MBG)
- Dirt
- Surfactants - detergents/degreasers/anti-waxing agents/chemical additives
what are the reasons for fuel testing
- Good quality fuel is clear and bright
- Sodium (Salt) can cause corrosion
- Water in a tank can encourage MBG
- MBG is a fungus and is found in most fuels. Moisture and warmth encourage multiplication of the spores.
- Dirt in the fuel will cause filtration devices to become blocked.
what are the fuel tests
- Visual test – fuel must appear “clear and bright” at all times
- Water Reaction test – carried out at embarkation – a mixture of 20ml distilled water and 80 ml fuel is left to settle. There must be no more than a maximum 2ml cloudy area “Interface” (80% - 20% - 2%)
- Colour test - “Lovibond colour comparator” - gives an indication of fuel age – darker fuel is older
- Diesel Filtration Test Kit (DFTK) - gives an indication of how quickly filters will block/clog - must pass 250ml of fuel before pressure reaches 15 PSi
what is the fuel boost system
Service tank – motor driven centrifugal pump – pressure relief valve – pre-filters (remove very fine particles down to 5 microns) - Coalescer (Water Seperator) (removes water droplets down to 10ppm) - pressure maintaining valve – Boost Ring Main (Supplying main engines) supply to auxiliary machinery – supply into Boost ring main from duplicate fuel boost system
what auxiliary machinery do the RN use
Auxiliary boiler, diesel generators, emergency supply for gas turbines, upper deck fuelling points (for boats and vehicle transport)
what are the hazards and safe working practices?
- Fire and Explosion – fire and explosion risk due to highly flammable vapours, especially during embarkation or transferring of fuel
- Toxicity – Fumes given off by Dieso/Avcat are toxic, therefore during embarkation, cleaning or inspection ventilation must be maintained and warning pipes made. Where fumes are unavoidable respirators must always be worn and risk assessments must be carried out.
- Dermatitis – POL products can be harmful to the skin so precautions to prevent skin contact must be taken e.g. Gloves, barrier cream.
- Pollution – care must be taken during any evolution to prevent pollution overboard. Minor spill kits should always be ready to deploy when fuelling is taking place. Speedy deployment can prevent fuel/oil spilling overboard.
