Italian Submarines
Class "600"

by Cristiano D'Adamo


Air Systems
The compressed air system was one of the most important systems on the submarine. It was used to blow the ballast tanks, fire torpedoes, and to start the main engines. Without a functional air system the submarine became inoperable. Docking facilities were usually provided with the necessary high-pressure air supply so that the submarine would not have to produce its own. Air tanks tended to accumulate condensed moisture (water), thus they were regularly drained for maintenance. On the “600” class the primary air compressor was installed in the auxiliary room. It was build by San Giorgio and capable of pressurizing air up to 200 kg.cm2 (2845 psi) and producing 9 liters per minute (0.31 cubic feet per minute). The compressor was powered by an electric motor.


R. Smg. Neghelli of the Adua Series the day of its launch on November 7th, 1937 in Muggiano.
(Photo courtesy Erminio Bagnasco and Achille Rastelli)

There were also two super compressors capable of boosting air pressure to 200 kg.cm2 (2845psi). They were driven by the main diesel engines. This system received air from the two compressors built into the diesel engines and air was stored into tanks with a total capacity of 8,020 liters (282.5 ft3). These compressors could only be used when the submarine had at least the cunning tower out of the water so that the hatch could be open to supply external air.

The air was stored in six groups of tanks, two located in the forward torpedo room, two in the auxiliary room, and two in the engine room. The tanks in the engine room were more numerous than the ones in the forward torpedo room, and the auxiliary room had the least number.

Air Filtering System
The “600” were equipped with an air filtration system for the removal of CO2 (Carbon Monoxide). There were also 10 oxygen tanks used to oxygenate the depleted air while submerged. The submarine was equipped with external hookups so that, in case of malfunction, a support ship could blow the ballast tank and also provide breathable air. Due to primitive nature of the air circulation system, when submerged, the crew would experience very uncomfortable conditions and the air was reportedly foul within a very few minutes.

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