Flanders B1 Swing Bolt Frames

Flanders B-1 Frames are permanent holding frames for field or OEM assembly of built-up HEPA/ULPA filter banks. They may be used to hold Alpha 95, Alpha Cell and Alpha 2000 filters with gasketed frames. Standard sizes include the three widely used filter face sizes: 24 in. x 24 in., 24 in. x 12 in. and 12 in. x 24 in., as well as less common sizes: 24 in. x 30 in. and undersize versions of the common face sizes. Separate locking arm and screw assemblies are used to retain the nominal 12 in. depth filter casings. The entire assembly will have the same efficiency as the filters themselves without leaks or bypass when the filters and frames are installed as recommended by Flanders. Clips to hold prefilters are available.


  • All-welded 14 gauge galvaneal steel construction for corrosion resistance and rigidity
  • Stainless steel locking arm and screw assemblies secure and seal the HEPA filter
  • Factory-drilled alignment holes facilitate field assembly of built-up filter banks.
  • Optional prefilter assembly is available for direct attachment to the frame