What does a filter cage do?
In jet filters air flows from outside the bag to inside, so the bag would collapse inward under suction. To prevent this, a filter wire cage is placed inside each bag. The cage is made of longitudinal wires and rings at set intervals; it holds the bag in a cylindrical shape and lets the compressed-air pulse inflate the bag to throw off the dust cake.
The cage decides bag life
The cage is one of the most common causes of early bag failure:
- Burred weld points cut the bag from inside,
- Bent cages make bags rub against neighbouring bags or the casing,
- Rusty wires abrade and stain the fabric,
- Too few rings let the bag flex too much between them and fatigue.
Choosing the material
Mill filters usually use galvanised steel wire cages. In filters with a high risk of moisture or condensation, stainless steel cages last longer. Cage length and diameter must match the bag and tube sheet exactly; if the cage is shorter than the bag, the bottom of the bag is unsupported.
Maintenance and replacement
Check cages when changing bags: set aside bent, rusty or broken-weld cages. Fitting a new bag on a damaged cage ends with the bag tearing soon. Send us the cage diameter, length and top fitting type and we will prepare the right filter cages.
