Question 322Steam Plants - 1st Asst/Chief

The correct answer is B) successive pressure drops through the seal stages. Labyrinth seals used on rotating steam turbine shafts work by creating a series of small clearances between the rotating shaft and the stationary seal housing. As the steam passes through these clearances, the pressure is reduced in a stepwise manner, preventing external leakage. The successive pressure drops through the seal stages are the key mechanism that makes labyrinth seals effective in reducing leakage. The other options are incorrect because they do not accurately describe the primary function of labyrinth seals. Increased turbulence (A) is a secondary effect, and temperature drops (C) and pressure increases (D) are the opposite of how labyrinth seals actually operate.