Marine Equipment Series: Understanding Marine Compressors

Marine compressors are very important machinery onboard marine vessels as there are many other equipment that depend on the compress air it generates. The compress air is used in many applications, including air filtration, nitrogen generation, offshore drilling exploration and many others. Hence, we need to gain a good understanding of marine compressors for it to work smoothly and efficiently. But fret not, this guide contains everything you need to know about them.

There are 4 types of marine compressors, namely the centrifugal compressor, rotary vane compressor, rotary screw compressor and reciprocating air compressor. On marine vessels, reciprocating air compressors are the ones that are most commonly used. The components in the reciprocating air compressor include piston, connecting rod, crankshaft, wrist pin, suction valve and delivery valves, seen in the diagram below.

Reciprocating air compressor


The piston is connected to the suction line and delivery line. When the crankshaft rotates, it pushes the piston downwards via the connecting rod. This downward motion will reduce the pressure inside the cylinder, and the pressure difference will open up the suction valve to take in air. The delivery valve is closed.

Next, the crankshaft will rotate to push the piston upwards. This closes the suction valve, and builds up pressure in the piston cylinder, compressing the air. When the air is pressurised to a certain point, the discharge valve is opened, and the pressurised air exits via the discharge line to be bottled. This bottled pressurised air can then be injected to engines or any other equipment that requires the compressed air.


There are 4 different types for marine compressors for different uses.

1.      Main Marine Air Compressor

The main air compressor on the marine vessel provides the power required to start the engine by releasing the pressurised air that is stored in the tank. These engines usually require a significant amount of energy from the compressors to start.

2.      Deck Marine Air Compressor

This is a smaller system that has a smaller volume, making it portable to carry around. This allows ship repairs and other operations to be done on the water. This compressor is only frequently use for cleaning and sanitisation.  A deck air compressor can also assist in some safety activities, for example, acting as emergency fire pumps in case of fire. This is essential specifically when ships are out on the water.

3.      Emergency Marine Air Compressor

This can be used to provide a backup supply of energy in case of any emergencies. When there are faults in the main compressor, the emergency air compressor can help to supply the power needed for some time.

4.      Topping up Marine Air Compressor

The topping up compressor will be linked to monitoring devices to monitor the current pressure within a system. When the pressure falls below a set level, the topping up compressor functions will help to restore it back to the set level and compensate for any leaks.

We hope this guide has been helpful and you have learnt a thing or two about marine compressors. You can check out our other guides or consult our friendly engineers if you have any enquiries.

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