String Wound Filters

Depth Filtration with Multiple Filament Media Options

CMI String Wound Filter Cartridges are depth filtration elements manufactured by winding continuous filament yarn around a rigid core in a precise pattern. The controlled winding density creates a graded pore structure, with larger pores on the outside and finer pores toward the inside, enabling effective particle retention and high dirt-holding capacity. Depending on process requirements and chemical compatibility, string wound cartridges are available in polypropylene, absorbent cotton, and glass fiber filament media, making them suitable for a wide range of industrial and process filtration applications.

Key Features

• True depth filtration with graded pore structure
• High dirt-holding capacity
• Stable filtration efficiency throughout service life
• Honeycomb winding structure for improved strength
• Available with spiral or straight winding patterns
• Broad range of micron ratings
• Good chemical compatibility with multiple filament options
• Available in long lengths up to 70 inches
• Ideal for prefiltration and coarse-to-medium filtration

Available Filament Media

Polypropylene (PP) String Wound

• Excellent chemical compatibility
• Suitable for acids, alkalis, and organic solvents
• Widely used in industrial and water treatment applications

Typical Applications: Water treatment, chemicals, RO pretreatment, lubricants, process liquids

Absorbent Cotton String Wound

• Good liquid absorption capability
• Suitable for low-viscosity liquids
• Economical option for general filtration

Typical Applications: Water, food & beverage, light chemicals, low-impurity liquids

Glass Fiber String Wound

• Higher temperature resistance
• Suitable for higher operating temperatures
• Good dimensional stability

Typical Applications: Hot water, process liquids, power plant condensate, industrial utilities

Materials of Construction

• Filter Media: Polypropylene / Absorbent Cotton / Glass Fiber
• Inner Core: Polypropylene / SS304 / SS316L
• Gaskets / Seals: NBR, EPDM, Viton, Silicone

Specifications

• Micron Ratings: 1–150 μm
• Lengths: 5”–70”
• Outside Diameters: 60 mm, 62 mm, 68 mm, 114 mm
• Inside Diameters: 28 mm, 30 mm
• Maximum Operating Pressure: 2.0 bar @ 25°C
• Maximum Operating Temperature: PP media with PP core: ≤ 70°C; PP media with SS core: ≤ 90°C; Cotton media with PP core: ≤ 70°C; Cotton media with SS core: ≤ 120°C; Glass fiber media with SS core: ≤ 200°C
• End Connections: Double Open End (DOE); 222 O-ring (flat / fin); 226 O-ring (flat / fin)

Typical Applications

• Water treatment & RO pretreatment
• Chemical processing
• Power plant condensate filtration
• Food & beverage processing
• Electronics & plating solutions
• Petrochemical and refinery processes
• Hydraulic fluids and lubricants

Advantages of String Wound Cartridges

Feature	Benefit
Depth filtration	High contaminant loading
Graded pore structure	Better particle retention
Multiple media options	Broad chemical compatibility
Long length options	Reduced cartridge change-outs
Simple construction	Cost-effective solution

Why Choose CMI String Wound Cartridges

• Complete filament media portfolio
• Stable and repeatable winding quality
• Long-length manufacturing capability
• Broad application experience
• Competitive alternative to global brands
• OEM and bulk supply capability