Published: 2026-10-16 · Category: Selection guide
Air filter paper traps dust and particles from the intake air while adding as little restriction as possible. Those two goals pull against each other: finer capture usually costs pressure drop. Selection means finding the balance for a particular filter size, assembly method and working environment.
Start with the filter, not the paper
Basis weight is an outcome, not a starting point. What really drives the choice is the filter geometry (pleat height, element diameter, available media area), the operating environment (dust load, oil or moisture present) and the downstream process (impregnation, pleating, bonding). Fix those first and the parameters become a discussion with a basis.
What each parameter controls
| Parameter | Main effect | Cost of raising it |
|---|---|---|
| Basis weight | Fibre mass per area, initial restriction and dust holding | Higher pressure drop and cost |
| Thickness | Space taken by the pleat pack, dust holding volume | Fewer pleats in the same envelope, less area |
| Air permeability | Initial pressure drop and flow capacity | Too open usually means less capture |
| Stiffness | Pleat shape retention, resistance to crushing | Too stiff turns brittle and cracks when pleated |
| Burst / tensile strength | Resistance to tearing in production and service | Usually moves with weight and resin content |
Read permeability together with media area
Discussions often fix on permeability and ignore media area. For a given pressure drop target, a taller pleat pack or more pleats allows a tighter paper without losing flow - which is the usual way to get both capture and flow. Confirm the available area first, then talk permeability.
Without stiffness, assembly fails
Pleated paper holds its own shape. Insufficient stiffness shows up as crushed elements, uneven pleat spacing and collapse during assembly, followed by local bypass - at which point filtration figures are academic. Stiffness comes from basis weight and resin impregnation together; adding weight alone also raises restriction.
A workable order
- Confirm filter geometry, element size and available media area;
- Confirm the operating environment and target service interval to estimate dust holding needs;
- Set the basis weight and thickness band;
- With the area fixed, choose permeability against the pressure drop target;
- Decide impregnation and resin level for stiffness and pressure resistance;
- Sample and verify on assembly and bench test.