Question 140Steam Plants - QMED

The correct answer is D) oil temperature indicated by the bearing thermometer. The oil temperature at the bearing is the best indication of proper lubrication because it directly measures the temperature of the oil film between the bearing surfaces. This temperature is influenced by the viscosity and flow rate of the lubricating oil, which are critical factors for maintaining an adequate oil film and preventing wear or overheating of the bearing. The other answer choices, such as oil temperature leaving the cooler, oil pressure at the pump, or lube oil strainer condition, are indirect indicators that do not directly measure the bearing's lubrication state. The bearing temperature is the most direct and reliable measure of the lubricating conditions at the critical interface where wear and failure can occur.