Question 14 QMED04 - Boiler Technician-Watertender

The Correct Answer is C ### Explanation of Correct Option (C) **Option C: Quickly opening and then reclosing the gauge glass drain valve.** This is the standard and most effective operational test (often called a "blow-down" or "blow-through"). 1. **Test Mechanism:** When the drain valve is opened (while the top steam root valve and bottom water root valve remain open), the pressure differential forces a rapid discharge of water and steam through the gauge glass system. 2. **Confirmation of Proper Operation:** If the gauge glass is operating properly, the water level will drop violently and rapidly when the drain is opened, and then immediately and vigorously return to the true boiler level once the drain is closed. 3. **Why it Works:** A vigorous return confirms that both the steam connection (top path) and the water connection (bottom path) are completely clear and unobstructed, allowing the gauge glass to accurately display the boiler water level. If the level is slow to return or stops short, it indicates a partial blockage in one or both connecting pipes. --- ### Explanation of Incorrect Options **Option A: Quickly opening and then reclosing the gauge glass lower root valve.** The lower root valve is the isolation valve for the water side and should always be fully open during normal operation. Opening and reclosing a valve that is already open accomplishes nothing. If you were to close it, the gauge would become isolated and the level would become static, which is the opposite of testing its functionality. **Option B: Watching for the level to fluctuate in the glass corresponding to ship movements such as pitching.** While minor fluctuations due to ship movement (on marine boilers) or boiler load changes are normal, this is a passive observation, not an active test. A gauge glass with severely restricted connections could still show small fluctuations or could appear steady even if clogged, especially if the ship movements are minimal. It does not actively prove the patency of the connecting pipes. **Option D: Quickly opening and then reclosing the gauge glass upper root valve.** Similar to the lower root valve (A), the upper root valve isolates the steam connection and must be open during normal operation. Opening and reclosing an already open root valve is meaningless for testing operational accuracy. The gauge is tested by *draining* the contents to ensure pressure and water levels rapidly re-establish themselves through both open root valves.