Q5
With reference to fuel oil viscosity:
(16)
(a) Explain why correct fuel oil viscosity is necessary
(b) Describe TWO methods for the measurements of viscosity that are suitable for the inclusion into a pneumatic or electronic control system.
(c) State, with reasons, a control action for a viscosity controller.
(16)
Reference Answer
### (a) The Necessity for Correct Fuel Oil Viscosity Correct fuel oil viscosity at the point of injection is critical for the efficient and safe operation of a marine diesel engine. The primary purpose of viscosity control is to ensure optimal atomization of the fuel as it is injected into the combustion chamber. The ideal viscosity for most large two-stroke engines is between 12 and 15 centistokes (cSt). The consequences of incorrect viscosity are severe: * **If Viscosity is TOO HIGH (Fuel is too cold/thick):**
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