Aux 1 Unit 6 Q13

Correct Answer: B) Oil can contaminate and damage sensitive components, leading to malfunctions

Explanation: Compressed air used for control instrumentation must be oil-free because oil can contaminate and damage sensitive components such as valves and sensors, leading to malfunctions and reduced system reliability.

Correct Answer: B) Refrigerated air dryer

Explanation: A refrigerated air dryer is commonly used to remove moisture from compressed air in control instrumentation systems. It cools the air to condense moisture, which is then removed, ensuring the air is dry and suitable for sensitive control equipment.

Correct Answer: B) The control system could become clogged, leading to malfunctions and failures

Explanation: If the compressed air is not properly filtered, contaminants can enter the control system, potentially clogging valves and other components, leading to malfunctions and failures.

Correct Answer: B) 3-5 bar

Explanation: Compressed air for control instrumentation is typically supplied at a pressure of 3-5 bar. This pressure range is sufficient for operating control devices without causing damage or over-pressurization.

Correct Answer: B) To prevent fluctuations that could cause erratic operation of control devices

Explanation: Maintaining a stable air pressure is critical in control instrumentation systems because fluctuations can cause erratic operation of control devices, leading to unreliable performance and potential system instability.

Correct Answer: B) To prevent condensation, which could damage control components and cause corrosion

Explanation: Low humidity in the compressed air is essential to prevent condensation, which can lead to corrosion and damage to control components. Condensation can also cause blockages and reduce the efficiency of the system.

Correct Answer: B) The air must be free of moisture and contaminants

Explanation: Control instrumentation systems require compressed air that is free of moisture and contaminants. Moisture can cause corrosion and freezing in the lines, while contaminants can clog and damage sensitive control devices.

Correct Answer: B) Coalescing filter

Explanation: A coalescing filter is commonly used to remove fine particulate contaminants from compressed air. It captures small particles and aerosols, ensuring the air is clean and safe for use in control instrumentation systems.