1. Physical mass per unit area of the bag, thickness, rugged, woven fabric structure, fabric density, bulk density of the nonwoven fabric, porosity, and the like.
2. Filter dust: such as drag coefficient, static dust removal power, dynamic dust removal power, dynamic resistance of filter material, regenerative drag coefficient and dust stripping rate.
3. Special characteristics: such as temperature resistance, corrosion resistance, electrostatic properties, hydrophobicity, etc.
4. Appearance: puncture, defect, black spot, jumper, broken wire, joint number.