Why must air tanks be drained?

• A. To remove water or oil
• B. To increase pressure
• C. To warm the air
• D. To reduce noise

Answer: (A)

Air tanks need to be drained because moisture and lubricant oil build up inside as air is compressed. When you drain the tank, you’re removing this water and oil so the air you use remains clean and the system stays reliable.

Water in the tank can lead to corrosion and rust inside the cylinder and fittings. In cold conditions, that water can freeze, which may block lines or damage components. Oil from the compressor can contaminate the air and foul regulators, valves, or filters, reducing air quality and performance. Draining releases these liquids through the drain valve at the bottom, typically after use or on a regular maintenance schedule, helping prevent contamination and ensuring smoother operation.

This action doesn’t increase pressure, warm the air, or reduce noise, so those outcomes aren’t the reason draining is done.