Gas Fitter Practice Test

In a fire tube boiler, where is the water located?

1. Water outside the tube and flue gases outside

2. Water inside the tubes and flue gases outside

3. Water inside the tubes and water outside

4. Water outside the tubes and flue gases inside

The correct answer is: Water outside the tubes and flue gases inside

In a fire tube boiler, the design specifically places water outside the combustion tubes while flue gases travel through the tubes. This configuration allows for efficient heat transfer from the hot gases generated by fuel combustion to the water surrounding the tubes. The flow of flue gases inside the tubes transfers heat through the walls of the tubes directly to the surrounding water, leading to the generation of steam or heated water. Understanding this arrangement highlights the primary function of a fire tube boiler—maximizing heat exchange efficiency by having water in contact with the tube surfaces while the hot gases from combustion move through those tubes. This is fundamental for achieving the desired thermal energy output and operational efficiency in heating applications. In contrast, options suggesting different placements of water and gases do not reflect the conventional design and operational principles of a fire tube boiler.