Exam Question
Write short notes to explain the following fittings/devices used in engine room, and their applications. (16)
(a) Low sea suction
(b) Fretting corrosion
(c) Caustic embrittlement
(d) Air starting motor
Class 4 (4th Engineer)
MEKG
📅 Jan 2025
Reference Answer
### (a) Low Sea Suction
**1. Principle and Application:**
The Low Sea Suction is a secondary sea water intake connection to the ship's sea water cooling system, located at a much lower position on the hull than the main or 'High' sea suction. Its primary application is to ensure a continuous and reliable supply of cooling water when the vessel is operating in light ballast condition or in shallow waters (e.g., rivers, ports, canals).
* **Shallow Draft Operation:** In light ballast condition, the ship's draft is reduced. The high sea suction, placed for optimal operation at design draft, may come too close to the water surface. This poses a risk of drawing in air (vortex formation), causing the sea water pumps to lose suction, cavitate, and potentially leading to an engine blackout due to overheating.
**1. Principle and Application:**
The Low Sea Suction is a secondary sea water intake connection to the ship's sea water cooling system, located at a much lower position on the hull than the main or 'High' sea suction. Its primary application is to ensure a continuous and reliable supply of cooling water when the vessel is operating in light ballast condition or in shallow waters (e.g., rivers, ports, canals).
* **Shallow Draft Operation:** In light ballast condition, the ship's draft is reduced. The high sea suction, placed for optimal operation at design draft, may come too close to the water surface. This poses a risk of drawing in air (vortex formation), causing the sea water pumps to lose suction, cavitate, and potentially leading to an engine blackout due to overheating.
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