A water leg is found on a/an ____________ boiler.

A water leg is a specific design feature commonly associated with locomotive boilers. In this type of boiler, the water leg refers to the vertical sections that hold water and are designed to help maintain proper water levels and distribution within the boiler. This feature is significant in locomotive boilers because these boilers need to generate steam quickly and efficiently under variable loads, which is crucial for their operation in trains.

Locomotive boilers must manage the heat generated from the combustion of fuel effectively. The water legs assist in maintaining sufficient water volume, which not only acts as a coolant for the internal components but also contributes to overall steam generation capacity.

In contrast, Scotch, watertube, and HRT (Horizontal Return Tubular) boilers utilize different configurations and principles for heat and water management, making the water leg a distinctive characteristic of locomotive boilers. This context helps emphasize the functionality and importance of water legs within the specific design that features them.