(The air receiver relief valve opening could either open outside the engine room through the ship’s funnel or inside the engine room itself.
In case of an Engine Room fire when CO2 flooding is required, this valve is to be opened before evacuating the engine room. It is provided as over-pressure protection and as a back-up of the fusible plug. It is fitted to release the compressed air in the event of abnormally high compressed air temperature. Melting Point: 220deg F (104.4deg cel) Fitted at the reservoir’s bottom or on the reservoir at the ship side when a relief valve (safety valve) is not directly fitted on the reservoir. Air Reservoir MountingsĮach air reservoir should be equipped with the following mountings:Ĭomposition – Bismuth 50%, Tin 30%, Lead 20% There must be 2 identical main air receivers and 1 emergency air bottle for every vessel. The total capacity of air reservoirs must be sufficient to give at least 12 consecutive Main Engine starts for a reversible engine, and at least 6 consecutive starts for a non-reversible engine without refilling of the reservoirs. They may be of the vertical or horizontal type.Īir reservoirs are hydraulically pressure tested to 1.5 times its working pressure. The marine boilers and exhaust gas economizers on certain ships are soot blown with air, these ships may be employed with higher capacity air compressors at the design stage depending on ship owners.Īs per SOLAS requirements, a ship’s main air compressors should be able to fill its air reservoirs from 0 to maximum pressure (30bar) within 1 hour.Įach ship is equipped with a set of 2 air reservoirs. The discharge of the main air compressor is led into a main air bottle or reservoir which stores this pressurised air at a maximum of 30-32 bar.Ī ship may have 2 or 3 main air compressors depending upon many factors such as each air compressor capacity, amount of volume of air needed for starting of the Main Engine, demand of air on that particular ship etc.
The capacity of the main air compressor is expressed in terms of Free Air Delivery (FAD) and is stated in cubic mtrs /hour.įree Air Delivery can be defined as the volume of air actually discharged by the compressor in 1 hour, that would occupy if expanded down to atmospheric pressure and cooled to atmospheric temperature. Most modern merchant vessels are employed with multi-stage reciprocating air compressors having intercoolers & aftercoolers with auto-draining and unloading arrangements. The air compressor compresses air by means of reducing its volume so as to raise its pressure. The main air compressor is the heart of the air-line onboard. The complete pneumatic air line on a ship includes the Main High-pressure airline, the service air line and the control air line.
This article throws light on the air line of a Ship in general, its important components and working. This makes the air line on a ship a very important aspect of ship operations. This controlled air is used for pneumatic controllers and is important for the operation of machinery onboard ships. The control air is a filtered branch of the service air which is made free of any moisture and oil carry-over.
One more important branch of this 7-8 bar compressed air is used as control air. Some of these include starting of Auxiliary Engines, Emergency Generators, Charging of freshwater and drinking water hydrophores, blowing the fog horn, spring air for exhaust valves of the Main Engine, dry washing of Main Engine turbochargers, for use in sewage treatment plants for aerobic sewage breakdowns, soot blowing of boilers, pneumatic pumps for oil transfers and many more applications such as service air for the use of cleaning, painting operations, chipping and operation of pneumatic tools such as grinders, chisels etc. The air at reduced pressures of 7-8 bar is used as service air for a number of applications. This high-pressure air is reduced to lower working pressures through pressure reduction valves and is used for other important purposes. High-pressure air of 30 bar is mainly used for the main engine starting. Compressed air on ships is used for different purposes.