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Blowdown Separators for Boilers

Blowdown Separator with aftercooler
Blowdown Separator

Features and Quick Spec's

  • One of the most cost effective ways to legally and safely dispose of boiler blowdown
  • 10 standard models available
  • Can be custom built to user specifications
  • ASME Section VIII, Div 1, 150 psi DWP, with National Board serial number
  • Quick ship options available for some models. Get a blowdown separator in as little as 2 weeks! Contact the factory if you need one in a rush.

The purpose of blowdown separators for boilers is to cool off the intermittent boiler blowdown flow so the waste water can be safely discharged into a public sewer system and so that the flash steam can be safely vented into the atmosphere.


High temperature and pressure blowdown water impacts the striking plate. Flash steam is created and the remaining 212°F hot water drains into the aftercooler. The Flash steam exits to the atmosphere through the vent connection. In the aftercooler the hot water is mixed with cooling water to instantaneously cool the blowdown to a safe temperature. A baffle is placed to assist the mixing of the two liquids. Both the blowdown and cooling water are then sent off to the public sewer.

Selecting a Blowdown Separator

To select the proper blowdown separator for your application, you need to know both the boiler operating pressure and the size of the bottom blowdown connection. Using those two figures, you can match the bottom blowdown inlet on the blowdown separator to the boiler blowdown connection size from the table in our dimensional and installation drawing PDF File. See the Data sheet below, or click here to view it on our Literature page.
For example, the proper blowdown separator connection for a 125 psi. boiler with a 1-1/2" bottom blowdown connection, you'll need part number BD230D45. The aftercooler size is determined by the size of the drain in the blowdown separator. The temperature regulating valve sizing is dependent on the cold water inlet on the aftercooler selected. For sizing on blowdown tanks, or for blowdown separators for boilers over 300 psi, contact the factory. All connections 2-2/1" and smaller are NPT, 3" and larger are 150 psi RF flanged. See page 2 in the below dimensional and installation drawing PDF. See the Data sheet below, or click here to view it on our Literature page.

blowdown tank brochure
Blowdown Separator Brochure

Product Line

Part Number Maximum PSI Description
Diameter X Height, Inlet, Drain, Vent
BD130A22 150 10" X 30", 3/4" NPT, 2-1/2" NPT, 2-1/2" NPT
BD130B23 150 10" X 30", 1" NPT, 2-1/2" NPT, 3" NPT
BD230C44 150 16" X 30", 1-1/4" NPT, 4" 150# flg, 4" 150# flg
BD230D45 150 16" X 30", 1-1/2" NPT, 4" 150# flg, 5" 150# flg
BD230E55 150 16" X 30", 2" NPT, 5" 150# flg, 5" 150# flg
BD242A34 300 16" X 42", 3/4" NPT, 3" 150# flg, 4" 150# flg
BD242B44 300 16" X 42", 1" NPT, 4" 150# flg, 4" 150# flg
BD242C45 300 16" X 42", 1-1/4" NPT, 4" 150# flg, 5" 150# flg
BD242D56 300 16" X 42", 1-1/2" NPT, 5" 150# flg, 6" 150# flg
BD242E68 300 16" X 42", 2" NPT, 6" 150# flg, 8" 150# flg

To learn more about our Blowdown Separators for boilers or to find out pricing and availability, click here to contact us.

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Celebrating 65 years of business

Madden Manufacturing has been designing and producing industrial steam equipment and diaphragm metering pumps for over 65 years now. We take great pride in the fact that our simple, rugged designs have been around since 1952 with only a few changes since.

With our smaller, family owned company, you can always expect responsive customer service and to receive some of the most durable products on the market. Thank you to all our distributors, reps and end users for helping us thrive for the past 65 years. 

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