Which of the following is a clear sign of a steam leak?

• A. Fogging lens
• B. Increased temperatures only
• C. Visible vapor, whistling noise, and increased temperatures
• D. Decreased humidity

Answer: (C)

Recognizing a steam leak relies on noticing a characteristic combination of signs produced by high‑pressure steam escaping. When steam leaks, you often see a plume of white visible vapor as hot steam rapidly cools and condenses in the surrounding air. The escaping steam also creates a distinct whistling or hissing sound as it blasts through a small opening. And because the steam carries a lot of heat, the area near the leak tends to feel warmer than its surroundings. The combination of visible vapor, the telltale hiss, and the temperature rise is a clear indicator that steam is escaping.

Fogging a lens or surface can happen with moisture, but it’s not a reliable sign of a steam leak by itself. Increased temperatures alone don’t pinpoint a leak since equipment can be hot for other reasons, and decreased humidity contradicts what steam release does (it adds moisture to the air).