Definition - What does Blowdown mean?

Blowdown is the removal of water from a boiler with the help of a blowdown valve. This valve removes the dissolved solids in the boiler water through the boiler exit port. The term blowdown is associated with fuel-fired boilers common in industry. Blowdown is also associated with heat exchangers or cooling towers in the industrial processes which use water.

Corrosionpedia explains Blowdown

Blowdown maintains boiler water parameters within prescribed limits to minimize corrosion, erosion, carryover and other specific problems. Blowdown helps to remove suspended solid particles from the system. Suspended particles can gather and erode the boiler pipes if they are not removed. The percentage of boiler blowdown is calculated with the formula:

Percentage Blowdown = Quantity of Blowdown Water / Feed Water Quantity x 100

The range of percentage blowdown in a boiler system ranges from 1% to more than 20%, with 1% being the system working at high quality feedwater. In some manufacturing plants that use sodium zeolite softened water, the percentage blowdown is generally estimated with the help of a chloride test.

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