Moisture in unstandard air can cause which problem?

• A. It can corrode the cylinder
• B. It can overload the regulator
• C. It can freeze the regulator
• D. It can cause the gas to become poisonous

Answer: (C)

Moisture in air that hasn’t been properly dried can freeze inside a regulator when the gas is lowered in pressure. As the air expands through the regulator, it cools rapidly. Water vapor present can condense and then ice can form on the regulator’s valve seats and passages, blocking flow or causing the regulator to seize or free-flow. This freezing risk is why dry, high-quality breathing air is essential, especially in cold environments or during high-demand breathing.

The other options aren’t the direct, typical result of moisture in unstandard air: moisture isn’t the primary cause of cylinder corrosion in normal service, it doesn’t inherently overload the regulator, and it doesn’t make the gas poisonous.