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Boiler Blowdown

Proper Boiler Blowdown is essential to prolong your Boiler life. There are two types of blow down.

There are two types of Boiler Blowdown, continuous and manual.

Continuous boiler blowdow utilizes a controlled valve and a blowdown near the boiler water surface. Continuous blowdown  takes water from the top of the boiler at a specified rate.  This is an is optional feature and may not be included in your steam boiler design.   A continuous blowdown can also be automated with a blowdown controller and Automated Solenoid Valve.

Manual blowdowns are performed near the bottom of the boiler. These openings allow for the solids removal that settle at the bottom of the boiler. Manual blowdown keep water level control devices and cutoffs clean of any solids.  Also, if you are using a boiler phosphate chemical, phosphates are designed to capture any hardness in the boiler. The phosphate will sick the hardness to the bottom and thus needs to be released through a bottom Boiler Blowdown. It is a common practice to perform a manual Bottom Blowdown daily.

How do I blow down a boiler?

1) Blowdown should be done with the boiler under a light load.
2) Open the blowdown valve nearest to the boiler. (This should be a quick opening valve.)
3) Crack open the downstream valve until the line becomes warm.
4) Then open the valve at a steady rate to drop the water level in the sight glass _ inch.
5) Close the valve quickly being sure that the hand wheel. Back off slightly from full close to relieve strain on the packing.
6) Shut the valve nearest the boiler.
7) Repeat the above steps if a second valve is located on the boiler.

Depending on your boiler size, the water column should be blown down at least once a shift to keep the bowls clean. Be careful not to release too much water.  Too much water release may set off the low water shut off alarm.

All blowdown piping should be checked once a year for obstructions.

Boiler Blowdown of steam boilers is often neglected or abused. The purpose of boiler blowdown is to control solids in the boiler water.  Boiler Blowdown protects boiler surfaces from scaling and/or corrosion problems. Even if you are using a good steam boiler water treatment program, you will still be required to have some form of boiler blowdown.
For more information, please contact us at 800-658-7716 or email our sales consultant at JZajac@ChemWorld.com.