Baghouses
Bag cage
Also known as filter bag cage, retainer cage, support cage.
A bag cage is the welded wire frame that holds a filter bag open against the differential pressure of a pulse-jet baghouse. Without the cage the bag would collapse inwards on the dirty-gas side and block flow. Cages are typically galvanised carbon steel, with longer-life options in 304 / 316 stainless for corrosive duty.
Construction
A standard cage has 8–20 vertical wires welded to top, bottom and intermediate rings. The top ring carries the venturi assembly through which the pulse-jet air enters; the bottom is closed with a disc. Cage diameter is fractionally smaller than the bag's inside diameter so the bag slides over it without bunching.
Cage-related failures
- Corrosion — galvanised steel attacked by sulphurous or chloride-rich gas
- Wire breakage — usually at weld points after thermal cycling
- Loss of roundness — distortion under uneven cleaning pulses
- Venturi loss — separates from the cage top, reducing pulse penetration
A failed cage typically destroys the bag within hours of detection.
Related terms
Related terms
- Filter bagA filter bag is the cylindrical fabric sock that traps particulate inside a fabric filter. Media selection depends on temperature, gas chemistry, dust load and cleaning cycle.
- BaghouseA baghouse is the structural enclosure that holds the bags, cages, tubesheet, cleaning system and hoppers of a fabric-filter dust collector. Sized in compartments for online isolation.
- TubesheetThe tubesheet is the perforated steel plate that separates the clean and dirty plenums of a baghouse. Filter bags hang from holes in the tubesheet, sealed by snap-band collars.