Question 193Steam Plants - Assistant Engineer70% to pass
After a boiler has been taken off the line and is cooling, the air cock is opened to _______________.
AI Explanation
The correct answer is D) prevent the formation of a vacuum within the boiler.
When a boiler is taken off the line and begins to cool, the air cock is opened to allow air to enter the boiler. This prevents the formation of a vacuum inside the boiler, which could occur as the steam condenses and the volume decreases. Allowing air to enter through the open air cock ensures that the boiler cools evenly and without creating a dangerous vacuum condition.
The other answer choices are incorrect because they do not accurately describe the purpose of opening the air cock during boiler cooldown. Purging air from the steam drum (A), guarding against gas pockets in the superheater (B), and allowing even cooling of the steam drum (C) are not the primary reasons for opening the air cock in this situation.
Related Questions
#191 When a boiler has been secured and is being initially cooled, the water level showing in the steam drum gage glass should be _______________.#192 If a boiler is brought on the line with its steam pressure much higher than that of the boiler already on the line, there is danger of _______________.#194 Which of the following is the best reason for opening the air cock when draining a water-tube boiler? #195 The steam separator as used in conjunction with a steam whistle normally drains to which of the listed drain systems? #196 The items labeled "A" in the illustration are the _______________. Illustration SG-0025