Pleated vs String Wound Filter cartridge: A Comparison in Structural, Performance and Applications

In the field of water treatment and industrial filtration, pleated cartridge cartridge and string wound filter cartridge, as two mainstream technologies, occupy the market with the core advantages of “precision interception” and “deep purification” respectively. In this article, from the structural design, filtration mechanism, performance parameters, application scenarios and other 7 dimensions to start the comparison, combined with authoritative data and industry standards (such as JB/T 7218-2004), analysis of the differences between the two, and quantitative analysis of the table, to provide a scientific basis for engineering selection.

I. Structural design: deep honeycomb vs pleated membrane layer

String wound filter cartridge using textile fibers (such as polypropylene, skimmed cotton thread) in the porous skeleton precision winding, the formation of sparse outside and inside the dense honeycomb rhombic channel (Figure 1). Its structural features include:

• Gradient density design: the outer layer has large pore size (20-100 μm) and the inner layer has small pore size (1-10 μm), which extends the filtration path by bending the scattering-like channel to realize deep interception.
• Multi-layer composite: polypropylene or stainless steel backbone, compatible with organic solvents and high-temperature liquids (up to 120°C).

Pleated filter cartridges, on the other hand, fold the microfiber membrane into a fan or wave shape by means of hot-melt technology, significantly increasing the effective filtration area . For example, a single pleated cartridge can provide up to 20 times the filtration area of a conventional cartridge. Its innovative membrane pleat structure combines a support layer with a flow-conducting layer to ensure stable accuracy (0.1-50μm) at high flow rates.

II. Filtration Mechanism: Deep Interception vs Surface Retention

1. The principle of “triple purification” of string wound filter cartridge:

   • Pore size grid interception: physically block particles through diamond-shaped holes.
   • Fiber hook effect: the channel wall of the fiber fluff adsorption of suspended matter.
   • Dynamic deposition: particles in the curved path due to inertial collision deposition.
     Experiments show that the retention rate of 10μm string wound filter cartridge on 3μm particles can still reach 99.5%.

2. “Surface sieving” mechanism of pleated cartridge:

   • Relying on a dense membrane layer to retain particles directly, the accuracy is determined by the membrane pore size (e.g. 0.1μm absolute accuracy). The advantage is that there is no risk of fiber migration, and it is suitable for use in a variety of applications.
   • Advantage is that there is no risk of fiber migration, suitable for sterile pharmaceuticals, electronic ultrapure water and other highly sensitive scenarios.

III. Comparison of Performance Parameters: 

IV. Material and Chemical Compatibility: Scenario Adaptation

• String wound filter cartridge material:

  • Polypropylene (PP): acid and alkali resistant (pH 1-13), applicable temperature ≤ 60℃.
  • Degreased cotton fiber: resistant to organic solvents, 120 ℃ high temperature sterilization.
  • Glass fiber: resistant to corrosive gases, 200℃ working condition.

• Pleated filter cartridge material:

  • Polytetrafluoroethylene (PTFE): hydrophobic, for gas filtration.
  • Polyethersulfone (PES): high biocompatibility, suitable for pharmaceuticals.
  • Stainless steel sintered mesh: pressure resistance 0.4MPa, food grade certified.

V. Application: Industrial vs High Precision Fields

1. String wound filter cartridge applicable scenes:

   • Pre-treatment: power plant circulating water, food grease filtration (such as chocolate slurry).
   • High viscosity liquids: resin, paint, relying on deep structure to avoid rapid clogging.

2. Pleated filter cartridge core area:

   • Pharmaceutical sterilization: terminal filtration of pharmaceutical liquids, complying with FDA standards.
   • Microelectronics manufacturing: ultrapure water preparation (particles ≤ 0.1μm).
   • Food and beverage: juice clarification, sterilization before filling.

VI. Economic analysis: cost and maintenance comparison

• Initial cost: String wound filter cartridge  unit price is low (about $20-$50), pleated cartridge is higher ($80-$200).
• Maintenance frequency: wire-wound cartridges require regular backwashing (1 time per week), pleated cartridges can be sterilized online and have a long replacement cycle.
• Comprehensive energy efficiency: pleated cartridge differential pressure is reduced by 20%-60%, energy saving effect is remarkable.

VII. Industry standards and quality control

• String wound filter cartridge: It needs to meet the standard of “JB/T 7218-2004 Cartridge Pressurized Liquid Filtration Cartridge” to test the permeability and pressure resistance.
• Pleated filter cartridge: ISO 9001 certified, 100% integrity test (e.g. blister point method).

Conclusion

Pleated filter cartridges and string wound filter cartridges complement each other in structure, performance and application: the former is characterized by precision interception and is suitable for high hygiene standard scenarios; the latter is characterized by in-depth purification and high dirt-holding capacity, and is suitable for industrial pre-treatment. When selecting a model, it is necessary to consider the water quality parameters (particle distribution, viscosity), cost budget and ease of maintenance. In the future, with the integration of new materials (such as graphene coating) and intelligent monitoring technology, the two types of cartridges will be iterated in the direction of “long life + adaptive”.