Question 27 QMED01 - Junior Engineer

The Correct Answer is B **Explanation for Option B (2):** Greases used for most marine applications, particularly general-purpose lubricating greases for bearings, couplings, pumps, and stern tubes (where traditional grease is applicable), typically require an NLGI Grade 2 consistency. An NLGI 2 grade is the industry standard for a firm, yet easily dispensable, general-purpose grease. This consistency is thick enough to stay in place under typical operating conditions, resist water wash-out (especially important in the marine environment), and effectively seal the bearings, while still being soft enough to be pumped and distributed through standard centralized or manual lubrication systems. **Explanation for Incorrect Options:** * **A) 00:** NLGI Grade 00 grease is semi-fluid (like applesauce or thick oil). It is too soft for general-purpose marine bearing applications where mechanical stability and resistance to water ingress are critical. It is primarily used in specialized applications like enclosed gearboxes or centralized systems requiring extremely long pump lines. * **C) 4:** NLGI Grade 4 grease is very stiff (like a firm block of cheese) and has a consistency much harder than required for most standard marine applications. It is typically too hard to be easily pumped or effectively distributed into bearings without specialized, high-pressure equipment, making it impractical for general marine use. * **D) 6:** NLGI Grade 6 grease is extremely hard (almost solid, like a wax block). This grade is used only in highly specialized, usually non-pumpable applications (often block greases) and is far too stiff for typical lubricating systems found in marine engines, shafts, or deck machinery.