What is an indicator of excessive alkalinity in boiler water?

Excessive alkalinity in boiler water is often indicated by foaming. When the pH levels are too high, it can lead to the formation of foam on the surface of the water within the boiler. This foam can disrupt the normal operation of the boiler and can result in carryover of water into the steam, which can cause damage to equipment and poor steam quality.

Foaming occurs because high alkalinity can increase the surface tension of the water, creating stable bubbles that do not break as easily as they should. This can lead to operational issues such as reduced efficiency and potential safety hazards if not managed properly.

In contrast, low pressure might indicate other operational issues but does not specifically relate to alkalinity. Color change and odor can signal other chemical imbalances or contaminants in the water but are not definitive indicators of excessive alkalinity. Therefore, foaming is the most accurate indicator of high alkalinity in boiler water.