Minnesota Boiler License Practice Exam

What is the primary cause of foaming in a boiler?

1. Feed water too cold

2. Solids too high

3. Low pH

4. High temperature

The correct answer is: Solids too high

The primary cause of foaming in a boiler is related to the concentration of dissolved solids in the water used for operation. When the concentration of these solids becomes too high, it can lead to the formation of bubbles and foam during the boiling process. This foaming can cause a range of operational issues, including reduced heat transfer efficiency and potential damage to boiler components. Foaming occurs because the dissolved solids create a film on the surface of the water, which traps steam bubbles instead of allowing them to escape. As the steam bubbles accumulate, they expand and rise, creating foam. Managing the levels of dissolved solids through blowdown and water treatment is essential to prevent foaming and ensure the safe and efficient operation of the boiler. The other factors listed—feed water temperature, low pH, and high temperature—can influence boiler operation but are not the primary contributors to foaming in the way that an excess of dissolved solids is. For example, if feed water is too cold, it may affect the thermal efficiency or the shock load on the system rather than directly causing foaming. Low pH levels can lead to corrosion rather than foaming, and while high temperatures are a normal aspect of boiler operation, they do not inherently cause foam formation.