21BD8B is a 30" carbon steel duplex filter bag housing with a 3" 150 class ANSI flange pipe size. This filter vessel features a side bottom (2B) outset style and 150 PSI pressure rating with low pressure drops as well as a buna basket seal, DP ports and eye bolt cover. Duplex filter bag housings allow for continuous operation which can reduce overall operating costs as the flow can be switched back and forth between vessels during servicing. Carbon steel is an economic option over stainless steel alternatives. The 316 stainless steel butterfly design valves are soft-seated and offer an effective seal. The legs of this Model 8 duplex bag filter housing are carbon steel and adjustable in height. (D8-30-3F-2B-150-CS-BS-PB-DP)

Key benefits:
  • Continuous operation as the two chambers operate independently
  • Four separate butterfly design valves controlled by a single lever offer bubble-tight closure
  • Mechanical stops to completely open and close valves
  • Minimized pressure drop due to fewer number of elbows in flow path
  • A single-valve pressure balancing vent system is furnished to ease movement of the lever and to fill the just serviced vessel before use
  • O-ring sealed covers
  • Heavy-duty baskets
  • Vents in filter covers and drain ports in filter housing speed evacuation and filling
  • Proudly Made in the USA


Carbon steel (CS) is metal alloy that is made of iron and carbon. It is known as a cost-effective alloying material. There are four types of carbon steel that vary in strength level: low carbon steel, medium carbon steel, high carbon steel, and very high carbon steel. Engine parts, car body panels, and select knives are made of carbon steel. The Cary Company also has carbon steel IBC tanks, filter vessels, and drums that work well with many liquids.


This information has been provided as a general guide. It is the customer's responsibility to select the proper container for product and application compatibility. The Cary Company does hereby disclaim any and all warranties, expressed or implied, including any implied warranty of merchantability or fitness for a particular purpose or use. We are not responsible for consequential damages arising from customer's selection and use of containers, container and label dimensions, and/or closures supplied by us.

Additional Information

More Information
MaterialCarbon Steel
Size2 (7.06" x 32")
Bag/Cartridge QtySingle
Housing Size30"
Pipe Size3" Flange
Outlet StyleSide Bottom
Pressure Rating150 PSI
SealBuna Seal
Basket StyleStandard Basket
Country of ManufactureUnited States
Sieve Diameter3"
Note:Speak to a Filtration Expert - For more information please contact any of our filtration specialists by email at Harold Snyder or by phone at 630.629.6600.
Q & A
Customer Questions
Can you ship internationally? Where are you located?
The Cary Company online ordering platform is only set up to ship within the United States. For international shipments, please contact us at 630.629.6600 or Sales@thecarycompany.com, and we will be happy to process your order. Our main warehouse and office are located in Addison, Ill. We also have warehouses in across the United States that you can see here. Thank you for choosing The Cary Company.
Are duplex bag filter vessels continuous operation?
Yes, duplex filters are continuous operations that will not interrupt your processes.
What if one side of a filter vessel needs to be serviced?
Flow can be switched back and forth between the two vessels, allowing one side to be served on while the other is still in use.
What are dual bag filter vessels made of?
Duplex bag filter vessel housings are constructed of either carbon steel, 304 stainless steel, or 316 stainless steel.
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