The Aramid Filter Media Family Explained: Nomex vs. Conex vs. Kermel

Technical comparison of meta-aramid and para-aramid fiber types used in industrial hot-gas filtration, examining mechanical modulus, thermal shrinkage, and cost differences.

Aramid fibers (aromatic polyamides) are renowned for thermal stability and mechanical toughness. In the dust filtration market, engineers frequently encounter diverse trade names: DuPont Nomex, Teijin Conex, and Kermel polyamide-imide.

1. Meta-Aramid Chemistry and Operating Envelope

Meta-aramid fibers (poly-m-phenylene isophthalamide) operate continuously at 200°C with non-melting flame resistance (Limiting Oxygen Index LOI > 28%). When exposed to direct flame, they form an insulating char layer without dripping.

2. Brand Comparisons: Nomex vs. Conex

DuPont Nomex represents the historical industry standard, offering outstanding fiber crimp and thermal stability (< 1% shrinkage at 200°C). Teijinconex (Conex) provides equivalent heat resistance and mechanical elongation at a competitive procurement price point. Kermel, a polyamide-imide copolymer, offers superior softness and dimensional stability.

3. Application Guidelines and Acid Moisture Warnings

While aramid excels in dry, high-temperature abrasive dust streams (asphalt plants, metallurgy, cement dryers), it is sensitive to strong acid hydrolysis when moisture exceeds 10% and SOx is present. In acidic flue gases, PPS or PTFE should be chosen.