Coast Guard Exams
Question 79Steam Plants - Assistant Engineer70% to pass

Boiler water hardness is increased by _______________.

AI Explanation
The correct answer is D) scale forming salts in the feed water. Boiler water hardness is increased by the presence of scale-forming salts, such as calcium and magnesium ions, in the feed water. These dissolved salts can precipitate out and form hard mineral deposits (scale) on the inside of the boiler, which increases the boiler water hardness. The other options are incorrect because zero alkalinity, improper DC heater operation, and dissolved gases do not directly increase boiler water hardness, which is primarily caused by the presence of scale-forming salts in the feed water.