Question 145Steam Plants - 1st Asst/Chief

The correct answer is C) alkalinity. Phenolphthalein is a common indicator used to test the alkalinity of boiler water. Alkalinity refers to the ability of the water to neutralize acids, which is an important parameter to monitor in boiler systems. By using phenolphthalein as an indicator, the alkalinity of the boiler water can be determined, allowing operators to make adjustments as needed to maintain proper boiler water chemistry. The other answer choices are incorrect because they do not represent the primary use of phenolphthalein in boiler water testing. Chloride content, hardness, and hydrazine are other water quality parameters that may be tested, but they are not the main purpose of using phenolphthalein as an indicator.