Question 6 QMED04 - Boiler Technician-Watertender

The Correct Answer is B **Explanation for Option B (Correct Answer):** A chain-operated valve is specifically designed to allow personnel to operate a valve from a location that is safely and easily reachable, typically a deck or platform, when the valve itself is physically situated too high up. The chain wheel is attached directly to the valve stem, and the endless chain hangs down to the operating level. Pulling the chain rotates the wheel, which in turn opens or closes the valve. Therefore, the primary and most common application for this mechanism is when **the valve is located too far directly above the deck where it is operated from** (e.g., in overhead pipe racks, high bulkheads, or tank tops). **Explanation for Other Options (Incorrect):** * **A) The valve is located too far directly across from the location where it is operated:** While remote operation is a goal, a simple chain wheel mechanism operates based on gravity and vertical rotation. If the valve is horizontally distant (across a space), a geared linkage system, flexible shaft, or remote control actuator is typically used, not a simple hanging chain. * **C) The valve is located too far directly below the deck where it is operated from:** If the valve is below the deck (e.g., in a bilge or pump room), an extension spindle (or reach rod) that extends vertically up through the deck to a handwheel is the standard and simpler solution. A chain mechanism is not necessary or practical for this orientation. * **D) A chain-operated valve can be used in any of the applications listed above:** This is incorrect because, as explained, the chain mechanism is specifically optimized for valves located high overhead (Option B). Other orientations (A and C) require different standard remote operating solutions.