Question 42 QMED03 - Oiler

The Correct Answer is B *** ### Explanation for Option B (Correct) **B) operate the lube oil purifier on the main lube oil sump** This is the common and intentional method for preheating lube oil. Lube oil purifiers (or conditioning units) are equipped with dedicated electric heaters necessary to lower the viscosity of the oil, making the separation of water and contaminants more efficient. By running the purifier in recirculation mode on the main sump, the heater slowly and safely transfers heat into the large volume of oil. Circulating the oil through the purifier's heated circuit ensures that the main turbine lube oil is brought up to the required startup temperature (typically around 90–110°F or higher, depending on the unit design) before the main shaft is rolled over. *** ### Explanation of Incorrect Options **A) slightly increase gland sealing steam pressure** Gland sealing steam is used to prevent air from leaking into the turbine casing and steam from leaking out along the shaft. While gland steam does contribute to heating the turbine casing (a separate pre-startup requirement), it has a negligible and indirect effect on the bulk temperature of the lube oil in the main sump, which is typically located far away and separated by oil coolers. **C) run both the lube oil pumps simultaneously** Running the main lube oil pumps (often AC and DC emergency pumps) circulates the oil through the primary cooling circuit (lube oil coolers). If cooling water is flowing, running these pumps simultaneously could actually increase heat removal rather than providing controlled preheating. While pumping generates some frictional heat, the system is designed to remove heat, making this an inefficient and uncontrolled heating method. **D) bypass the lube oil gravity tank** The lube oil gravity tank (or overhead tank) is a vital part of the emergency lubrication system, providing temporary oil flow in the event of pump failure until the DC emergency pump can engage. Bypassing this tank would remove a critical safety feature and would not introduce any heat into the lube oil system.