In case of engine room of ship, it uses type 2 ventilation system which
supplies outside air forcibly by engine room ventilation fan, and naturally discharges
air to outlet through low-pressed casing. The advantage of type 2 ventilation is that it
makes inside with bi-pressure status to discharge contaminated materials to outside
naturally. However, there is a phenomenon that pressure is greatly different between
outside and inside due to huge amount of air supply by engine room ventilation fan.
Therefore, we went aboard a container vessel which is on test run to analyze
differential pressure with micronanometer by engine load and by combustion air supply
method of engine. As a result, as engine load decreases (50, 75, 100%), the differential
pressure between outside and inside tends to increase by 35% average, and the
difference of pressure was 6.5 times maximum by combustion air supply method of
engine.