Question 11 MODU03 - Ballast Control Operator

The Correct Answer is C **Explanation for C (filling open-circuit breathing systems):** Compressed air used for open-circuit breathing systems (such as SCUBA tanks or self-contained breathing apparatus, SCBA) must meet extremely stringent quality standards because the air is directly inhaled by the user. These standards regulate the levels of contaminants like carbon monoxide, carbon dioxide, oil vapor, particulates, and odor. The term "Grade D" air is a commonly recognized minimum standard specifically defined for **breathing air** in standards established by organizations like the Compressed Gas Association (CGA G-7.1) or military/government specifications. Therefore, filling open-circuit breathing systems requires air certified to Grade D or higher. **Explanation why other options are incorrect:** * **A) bladder-type accumulators:** Compressed air used to pre-charge or charge bladder-type hydraulic accumulators does not need to meet breathing air quality standards. Industrial-grade utility air is typically sufficient, as the gas does not interact with human respiratory systems and the internal components are designed to withstand normal industrial air quality. * **B) high pressure fluid accumulators:** Similar to bladder accumulators, the quality requirements for air used in high-pressure hydraulic fluid accumulators are based on component longevity and system operation (e.g., dryness), not human respiration safety. Standard industrial air quality is generally acceptable. * **D) driving air-powered plunger pumps:** Air used to drive pneumatic tools, motors, or pumps is classified as utility or instrument air. While it must be clean enough to prevent fouling of the machinery, it does not need to meet the strict toxicity and purity limits required for breathing air (Grade D).