What is the proper location for the continuous boiler blowdown takeoff?

The proper location for the continuous boiler blowdown takeoff is indeed 6 inches below the steam drum water level. This positioning is important for maintaining the water quality within the boiler system.

When blowdown occurs, it helps in removing impurities and minimizing the concentration of dissolved solids within the boiler water. By taking the blowdown 6 inches below the water level, it ensures that the water being removed is representative of the overall water quality in the boiler while preventing the removal of water that could lead to foaming and water carryover into the steam system.

This method effectively balances the need to control concentration levels of total dissolved solids (TDS) with the operational integrity and efficiency of the boiler. Proper blowdown practices reduce the potential for scale formation and other related issues, ensuring the boiler operates at optimal performance.

The other options described would not effectively achieve this balance, as drawing from the bottom of the boiler or the bottom of the steam drum might draw water that contains higher concentrations of impurities, while taking from the bottom of the gauge glass would not provide a consistent or representative sample of the boiler's water quality.