Understanding Steam Pipe Drainage Devices

The question asks to identify the device specifically designed to remove water (condensate) from steam pipes while ensuring that no live steam is lost during this process. Let's analyze the function of each option provided:

Analyzing Device Functions

• Steam separator: While a steam separator removes moisture and impurities from steam, its primary function isn't continuous drainage of condensate without steam loss. It cleans the steam flow.
• Steam trap: This device is specifically engineered to automatically discharge condensate, air, and other non-condensable gases from a steam system. Crucially, it does this without allowing live steam to escape, fulfilling the exact requirements mentioned in the question.
• Pressure reducing valve (PRV): A PRV is used to reduce the pressure of the steam flowing through it to a lower, usable level. It does not primarily function as a drainage device for condensate.
• Injector: An injector uses steam pressure to force water into a boiler. It's a feeding device, not a drainage device for pipes.

Why Steam Trap is the Correct Choice

A steam trap is the correct answer because its core function is to efficiently remove condensate (water formed when steam cools) and air from steam lines and equipment. It achieves this by using various mechanisms (like thermodynamic, mechanical, or thermostatic actions) that respond differently to steam, water, and air. These mechanisms ensure that only water and air are discharged, while the steam is retained within the system. This prevents the loss of valuable steam, which improves energy efficiency and system performance.

Therefore, the device used to drain off water from steam pipes without the escape of steam is correctly identified as a steam trap.