What is one primary difference between a fire-tube boiler and a water-tube boiler?

The primary difference between a fire-tube boiler and a water-tube boiler lies in their design and the flow of fluids. In a fire-tube boiler, the combustion gases produced by the burner travel through tubes that are surrounded by water. This means that the hot gases pass through the tubes, transferring heat to the water that surrounds them. Conversely, in a water-tube boiler, water flows through the tubes, and the hot gases surround the tubes, allowing heat to be transferred from the gases to the water.

This fundamental difference in construction has implications for the performance and application of the boilers. Fire-tube boilers are generally simpler and often used for applications with lower pressures, while water-tube boilers can handle higher pressures and are capable of generating steam more efficiently. The design influences aspects such as response time in steam generation, maintenance requirements, and heat transfer efficiency.

The other choices may touch on characteristics of the boilers, but they do not capture the essential distinction regarding the flow of hot gases and water between the two types.