Blowdown Separators


(9 Models for Boilers up to 300 PSI)

  • COST EFFECTIVE – One of the least expensive ways to legally and safely dispose of boiler blowdown.
  • FAST LEAD TIMES – Madden keeps our most frequently purchased models in stock.
  • PREDESIGNED – 9 standard models conveniently pre-sized per boiler blowdown pressure and line size. Custom models available upon request.
  • CONSTRUCTION – ASME Div I, Section VIII Vessels, 150 PSI DWP @ 500+ deg. F, with National Board serial number.
  • Check out our most up to date BROCHURE for an overview, selection guide, cooling water parameters, and more.
  • CONTACT US for sizing assistance and pricing.

The purpose of blowdown separators for boilers is to cool off the intermittent boiler blowdown flow so the wastewater can be safely discharged into a public sewer system and so that the flash steam can be safely vented into the atmosphere. All Madden boiler blowdown separators are pressure vessels made to ASME Section VIII, Divison 1 standards.

High temperature and high pressure blowdown water impacts the striking plate inside the separator. 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.

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 Datasheet 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 2-1/2″ and smaller are NPT, 3″ and larger are 150 psi RF flanged. See page 3 in the below dimensional and installation drawing PDF. See the Datasheet below, or click here to view it on our Literature page.

Part NumberMaximum Boiler
Operating Pressure
Diameter X Height, Inlet, Drain, Vent
BD130A2215010″ X 30″, 3/4″ NPT, 2-1/2″ NPT, 2-1/2″ NPT
*BD130B2315010″ X 30″, 1″ NPT, 2-1/2″ NPT, 3″ NPT
*BD230C4415016″ X 30″, 1-1/4″ NPT, 4″ 150# flg, 4″ 150# flg
BD230D4515016″ X 30″, 1-1/2″ NPT, 4″ 150# flg, 5″ 150# flg
*BD230E5615016″ X 30″, 2″ NPT, 5″ 150# flg, 6″ 150# flg
BD242B4430016″ X 42″, 1″ NPT, 4″ 150# flg, 4″ 150# flg
BD242C4530016″ X 42″, 1-1/4″ NPT, 4″ 150# flg, 5″ 150# flg
BD242D5630016″ X 42″, 1-1/2″ NPT, 5″ 150# flg, 6″ 150# flg
BD242E6830016″ X 42″, 2″ NPT, 6″ 150# flg, 8″ 150# flg
*Note: These vessels are normally stocked at our Elkhart, IN facility.

Madden also builds BD Separators or general flash tanks to order. Please use our contact or RFQ form to start an inquiry.