What is the preferred application for a float trap?

A float trap is designed specifically for the efficient removal of condensate from steam systems. Its preferred application often focuses on managing the condensate that accumulates in steam lines, which is essential for maintaining system efficiency and reliability. However, in this context, the option indicating the drainage of liquid from air receivers suggests a function that aligns more closely with the design of a float trap.

Float traps operate by utilizing a buoyant float mechanism that activates based on liquid levels, allowing for effective drainage of condensate without significant steam loss. This is particularly valuable in steam heating systems, where maintaining steam quality and efficiency is paramount.

In the context of other options, while draining condensate from steam pipes is a viable function for float traps, it does not represent the primary preferred application when considering the function of air receivers. Purging air from steam lines is more related to general air venting mechanisms rather than a float trap's typical role. Regulating steam temperature in high-pressure systems involves more complex control systems and mechanisms that do not apply to the function of a float trap.