Question 192Steam Plants - QMED

The correct answer is B) Close the top shut off valve and open the drain valve to clear out the bottom connection to the gauge glass. The reasoning for this is that when performing a periodic gauge glass blow down, the top shut off valve is closed first to isolate the gauge glass from the system pressure. This allows the bottom connection to the gauge glass to be cleared out by opening the drain valve, ensuring the glass is free and operating correctly. Closing the bottom valve first would not clear out the top connection, and closing the wrong valve entirely would not accomplish the intended purpose of the blow down. Therefore, option B is the correct procedure to follow.