Air Marine Starter

A marine air starter is a pneumatic system that uses highpressure compressed air to turn and start large marine diesel engines Because electric starters would be impractically large and heavy for these engines air starters are the standard method for ships including cargo vessels tankers and yachts 

How a marine air starter works

There are two primary methods for starting a large marine engine with compressed air 

Direct air injection

This method is used for very large slowspeed twostroke engines 

Air compression and storage Onboard compressors fill large air receivers also known as air bottles with air pressurized to around 30 bar 435 psi

Timed distribution When the engine is commanded to start an air distributorcontrolled by a camshaftdirects the highpressure air to the engine cylinders in the correct firing order

Piston movement The compressed air forces the piston in the selected cylinder downward beginning the rotation of the crankshaft

Continuous rotation The distributor continues to inject air into subsequent cylinders maintaining the engines rotation Once the engine reaches a certain speed fuel is injected and the engine begins to run under its own power 

Air motor start

This method is used for smaller but still large marine diesel engines 

Motor activation Compressed air is delivered from the storage tanks to a powerful air motor

Flywheel engagement The air motor rapidly spins causing a gear pinion to engage with the engines flywheel

Engine cranking The starter motor cranks the engine until it reaches ignition speed and starts running 

Key components of an air start system

Air Compressor The equipment used to pressurize air from the atmosphere and store it

Air Receiver A large tank that stores a sufficient volume of highpressure air for multiple engine starts

Air Distributor A device timed to the engines camshaft that ensures air is delivered to the correct cylinders in the proper firing sequence

Air Start Valve A valve on each cylinder head that opens to admit compressed air into the combustion chamber

Control Valves and Interlocks Various safety mechanisms that prevent accidental starts and ensure proper system function 

Advantages of marine air starters

High torque The system provides the high torque necessary to start massive engines that electric starters cannot

Safety By using compressed air instead of electricity there is no risk of sparks which is critical in marine environments where fuels or gases may be present

Reliability The system is highly reliable and less susceptible to the effects of moisture and saltwater corrosion that can affect electrical systems

Simplicity Air starters have fewer complex electrical components than electric starters making them durable and easier to maintain

Environmental tolerance They operate effectively in a wide range of temperatures and harsh conditions