Question 7 QMED05 - Machinist-Pump Technician

The Correct Answer is D **Explanation for Option D (Control Air System) being correct:** When an air compressor is specifically designated to supply highly filtered, dry air primarily to pneumatic instrumentation—such as the combustion control system (which relies on pneumatic signals to modulate fuel and air flow) and other pneumatic controllers (e.g., those governing temperature, pressure, or level)—the entire setup is correctly termed the **Control Air System**. This system is critical for precise operation of automated control loops and requires higher quality air than general utility (service) applications to prevent corrosion and blockage of small orifices within the instruments. **Why the other options are incorrect:** * **A) ships service air system:** This system supplies general utility air (often called 'ships service air' or 'utility air') for non-critical, high-volume applications like operating pneumatic tools, cleaning equipment, general deck services, and sometimes starting main engines (though dedicated starting air systems are common). This air is usually lower pressure and less rigorously filtered or dried than control air. * **B) supply air system:** This term is too general. While the compressor supplies air, the specific *function* (supplying pneumatic controllers) is what defines the system's specialized name. * **C) forced draft air system:** This system refers to the mechanical equipment (fans/blowers) used to push combustion air into a boiler or furnace. It deals with large volumes of ambient air for combustion itself, not the small, precise volumes of filtered air used for pneumatic signaling and control mechanisms.