Question 2 QMED01 - Junior Engineer

The Correct Answer is B A **check valve** (also known as a non-return valve) is specifically designed to allow fluid (or steam, in the case of the auxiliary exhaust) to flow in only one direction. In a deaerating feed tank (DFT) system, the check valve is installed on the auxiliary exhaust line where it enters the DFT. Its function is to prevent steam and potentially high-level water (if the DFT floods) from flowing backward out of the tank and into the auxiliary exhaust steam system, thereby protecting components connected to that line (like main turbines or auxiliary turbines) from water damage or back-pressure issues. Here is why the other options are incorrect: * **A) Exhaust piping:** The piping itself is merely the conduit for the flow; it has no mechanism to prevent backflow. * **C) Pumps:** Pumps are used to move water from the tank to the boilers (feed pumps) or other areas. They operate on the fluid side of the system and are not positioned on the exhaust steam line to control backflow into the auxiliary exhaust system. * **D) Reverse-acting relief valve:** A relief valve is designed to vent excessive pressure, opening when system pressure exceeds a set point. A reverse-acting relief valve is typically a rupture disk assembly designed to fail when pressure on the non-process side exceeds that of the process side, but it is not the standard component used to prevent liquid backflow on a steam line; that function belongs to a check valve.