When the compressed air reservoir is placed in line with an air compressor and is used as an after cooler, the reservoir must be __________.

Correct Answer: Option B — frequently drained of condensed water

When a reservoir acts as an aftercooler, it facilitates the condensation of water vapor from the compressed air. To prevent this moisture from entering the downstream piping, which can cause corrosion and damage to pneumatic equipment, the reservoir must be equipped with a drain valve and be drained frequently during operation.