Maine State Boiler Practice Test 2025 - Free Boiler Exam Practice Questions and Study Guide

When feedwater is too hot, it can lead to the phenomenon known as vapor lock in the feedwater pumps. Vapor lock occurs when the temperature of the liquid is high enough to create vapor bubbles within the pump, which can disrupt the flow of the liquid. This issue arises because as water approaches its boiling point, it can begin to turn into steam or vapor, leading to a reduction in the effective flow through the pump. Vapor lock can severely impair the operation of the feedwater pump, potentially causing it to lose prime and ultimately fail to deliver the necessary water to the boiler.

In contrast, while bearing failure, pressure loss, and corrosion are all significant concerns in boiler operations, they are not directly caused by the temperature of the feedwater in the same way that vapor lock is. For instance, bearing failure usually results from dry operation or improper lubrication rather than simply from hot feedwater. Pressure loss typically occurs due to blockages or restrictions in the system rather than the temperature of the feedwater alone. Corrosion, while a crucial consideration for maintaining system integrity, is more related to the chemical composition of the water rather than its temperature in this specific context.