How to Blow Down a Boiler Water Column

When a boiler is operating, mineral impurities dissolved in the free water stream continuously enter the boiler water column. Water is converted into steam that goes to the vapor drum and the impurities are left behind. Once the boiler water reaches saturation level for dissolving the impurities, sludge formation and scaling start in the boiler. To remove the sludge, blow down is required at periodic intervals depending upon the rate of formation of the sludge. Timely blow down increases boiler life and reduces the heating costs. Performing a manual blow down is not a rigorous task and can be accomplished with some technical know-how.

Things You'll Need

  • Boiler manual (if available)
  • Protective gloves
  • Protective glasses
  • Safety boots
  • Hard hat
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Instructions

    • 1

      Wear the protective safety gloves, hard hat, safety boots and protective glasses. Direct contact with hot water can cause burns.

    • 2

      Locate the boiler blow down valve at the bottom of the boiler water column. The valve should be a quick opening valve with a lever on the top for fast operation. Refer to the boiler schematic in the boiler manual to locate the exact position of the valve. Usually it is the valve closest to the water column.

    • 3

      Locate a slow opening drain valve installed in the water line after the blow down valve. The slow opening valve is a ball or gate valve with a circular flange on the top.

    • 4

      Release the quick opening blow down valve to start the blow down.

    • 5

      Open the slow opening drain valve in the line to drain the water containing the sludge and scale.

    • 6

      Wait for 5 to 8 seconds for blow down or for the blow down time period listed in the boiler manual.

    • 7

      Check the water level in the tank through the level indicator provided in the column. Do not drain more than 25 percent of the water.

    • 8

      Close the slow opening drain valve.

    • 9

      Close the blow down valve to cut the water supply from the water column.

    • 10

      Open the slow opening drain valve again to drain the line between the blow down valve and the drain valve.

    • 11

      Close the slow opening drain valve and ensure all the valves are tightly shut.

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