Minnesota Boiler License Practice Exam

Which two minerals are most common in causing hardness and scale formation in boilers?

1. Lime and salt

2. Calcium and magnesium carbonate

3. Sodium bicarbonate and sodium chloride

4. Iron and aluminum

The correct answer is: Calcium and magnesium carbonate

Calcium and magnesium carbonate are indeed the most common minerals responsible for causing hardness and scale formation in boilers. These two minerals are prevalent in natural water supplies, and when water is heated in a boiler, they can precipitate out of solution. As water temperature increases, the solubility of calcium and magnesium carbonates decreases, which leads to the formation of scale on the boiler's interior surfaces. This scale accumulation can severely impact the efficiency of the boiler by insulating the heating surfaces, leading to increased fuel consumption and potential damage due to overheating. The presence of these minerals is a critical consideration for boiler operation and maintenance, as effective water treatment methods, such as softening and conditioning, are often employed to mitigate scaling and maintain optimal performance. Understanding the role of calcium and magnesium in scaling processes is essential for boiler operators to prevent operational issues and enhance the longevity of the equipment.