What is the main difference between fire-tube and water-tube boilers?

The distinction between fire-tube and water-tube boilers is fundamentally based on the flow of gas and water within the system. In water-tube boilers, water is contained within tubes and is heated by hot gases that flow outside these tubes. This design allows for high-pressure operation and the ability to handle higher temperatures effectively, making water-tube boilers suitable for larger and more demanding processes.

Conversely, fire-tube boilers work differently; they have hot combustion gases traveling through tubes that are surrounded by water. This configuration limits their ability to operate at very high pressures compared to water-tube boilers.

Therefore, the correct option accurately reflects the operational mechanisms of these two types of boilers, with water-tube designs promoting more efficient heat transfer and adaptability to different industrial applications.