NCCER Millwright Practice Exam 2025 – The Comprehensive All-in-One Guide for Exam Success!

A mechanical seal is designed to prevent fluid leakage in rotating equipment, such as pumps and mixers. When mechanical seals fail, specific signs often indicate a malfunction. Leakage of fluid, increased mechanical resistance, and changes in pressure are all common indicators of a failed mechanical seal.

If a mechanical seal is functioning correctly, it will hold pressure and prevent fluid from leaking. However, when there is leakage of fluid, it signifies that the seal has lost its ability to contain the fluid, typically due to wear or damage.

Increased mechanical resistance can indicate that the seal is binding or has become too tight or misaligned, leading to excessive friction or wear on the seal surfaces. Furthermore, noticeable changes in pressure can suggest that the mechanical seal is no longer able to handle the pressure levels, often leading to leak paths forming.

In contrast, a vibration-free operation is not a sign of a failed mechanical seal. In fact, excessive vibrations usually indicate other potential issues unrelated to the seal itself. A properly functioning mechanical seal should allow for smooth operation, meaning that a lack of vibration is actually a positive indication of operational integrity rather than a sign of failure. Thus, the absence of vibration suggests that the equipment is running smoothly, which is contrary to the symptoms of seal failure.