What role do steam traps play in a boiler system?

Steam traps play a crucial role in a boiler system by preventing the flow of condensate back to the feed-water pump. They are designed to allow the passage of steam while blocking the return of condensate without allowing steam to escape. This function is essential because condensate, which is water formed from condensed steam, can cause damage to the boiler system if it flows back into the feed-water supply. By effectively managing condensate flow, steam traps help maintain the operational efficiency and safety of the boiler system, ensuring that the feed-water remains as pure and in optimal condition as possible for the generation of steam.

The other options, while relevant to the functioning of a boiler system, do not specifically describe the primary purpose of steam traps. For instance, promoting efficient steam flow and recovering heat from condensate are important aspects of overall boiler efficiency, but they are not the direct functions of steam traps. Similarly, while steam traps can help manage pressure in a system, releasing excess pressure is not their main role. Thus, the correct answer highlights the specific and critical function of steam traps within the boiler system.