Service compressed air circuit
Heavy 2 stroke engines - Specific features and fields of application

Slow-moving engines commonly use two pressure levels, one at 30 bar (figure 36 ) to start the engine by blowing air into the cylinders, and another between 7 and 9 bar for various actuations, such as exhaust valve retraction and control of valves or other equipment in ATEX zones or requiring high forces. The logic parts of the compressed air circuits are minimized or non-existent in favor of electronic logic. The ship also uses low-pressure air for other on-board purposes (tools, cleaning, etc.). Even if 30-bar air can be expanded to feed the low-pressure circuit, specific low-pressure compressors are used instead, so as not to overtax the 30-bar compressors.