Bag Filter or Cartridge Filter: Choosing the Right Housing

The bag-versus-cartridge question arrives at our desk weekly, usually after a plant has been running the wrong one for years. The choice is not about brand preference; it is about four variables: flow rate, solids loading, target micron rating, and how the plant wants to handle change-outs.

When bags win

High flow, high dirt, coarse to mid-range ratings (roughly 1 to 800 micron nominal), and operators who want fast, cheap change-outs. A single #2 size bag housing passes around 200 GPM of water-like fluid. Bags are the roughing workhorse: cooling water, wash water, paint, and pre-filtration ahead of anything expensive.

When cartridges win

Fine and absolute-rated duty, sanitary service, and streams where bypass is unacceptable. Pleated membrane cartridges reach 0.01 micron absolute; melt blown and string wound cartridges handle the middle ground. Cartridges cost more per element but hold tighter ratings and suit final polishing, food contact, and high-purity chemistry.

The pattern that usually wins

Roughing bags ahead of polishing cartridges. The bag catches the load and extends cartridge life by an order of magnitude; the cartridge holds the final specification. Housing selection follows: ASME code housings for pressure, sanitary housings (NSF, USDA, 3A) for food and pharma, high-flow designs where floor space is short.

Send us the fluid, flow, micron target, and pressure, and we will size the pair, including the change-out cost math, across the Rosedale, Graver, AJR, and Eaton lines we represent.