🔍 Key Concepts

• surface blow / skimming purpose in boiler operation • Effect of changing water level before blowing • How a surface blow removes foaming, oil, and scum from the water surface

💭 Think About

• Which part of the boiler are you trying to clear during a surface blow — the bottom or the top water layer? • If you want to remove impurities that float on the surface, would you want more water at the surface outlet or less? Why? • What boiler condition (temperature/pressure) is normally required so the blow line sees flow and carries away surface impurities effectively?

✅ Before You Answer

• Confirm what ‘surface blow’ actually targets compared to a bottom blow • Think about where the surface blow line/nozzle is located relative to normal water level • Verify what most boiler operation manuals say about water level adjustment immediately before a surface blow