🔍 Key Concepts

• Function of the boiler air cock (or vent) during shutdown and cooling • What happens to steam and water volume as the boiler cools down • Possible problems if the boiler is sealed tight while cooling

💭 Think About

• Think about what happens to the pressure and volume of steam when temperature drops inside a closed boiler. • Which choice best matches the main safety concern when a hot, pressurized vessel is isolated and allowed to cool? • Ask yourself: is the air cock used more to remove something from the boiler, or to let something in as conditions change?

✅ Before You Answer

• Consider how steam pressure changes as the boiler cools and condenses. • Decide whether the air cock is meant to release pressure, admit air, or both in this situation. • Eliminate any choices that describe a function that normally occurs during operation, not after the boiler is taken off the line and cooling.