TB Dulpex Filter Housing Dulpex Filter vessel TB duplex filtration systems provide the flexibility and highest filtration quality that your process may require. Available in bag vessel designs, separately valved units operate independently, providing continuous service during media changes. Concurrent operation of both housings doubles the flow rate capacity of a single vessel. Series filtration offers a particular advantage for applications where a process requires filtration for particles with unequal size, coarse filtration in first stages that provides longer service life for subsequent filters, and for improved performance and quality control.