A Comprehensive Look at the Structure and Functionality of String Wound Filter Cartridges

string wound filter cartridge-likefilter

Table of Contents

Overview of String Wound Filter Cartridge

A string-wound filter cartridge serves as a depth filter, commonly used across various industries to extract particulates from liquids.

These cartridges are meticulously fashioned by winding a continuous filament or yarn around a central core in a distinct pattern. This design establishes a filter media filled with intricate channels, ensuring the efficient capture and retention of diverse particle sizes throughout its depth.

string wound filter cartridge structure likefilter

Composition of a String Wound Filter Cartridge

The construction of a string-wound filter cartridge is a meticulous process that balances the need for durability with the necessity for effective filtration. Here’s a closer look at how these cartridges are constructed and the elements that make them unique:

Yarn Constituents:

Wrapped around the core is the actual filtering material: the yarn. This yarn can be made from various materials depending on the application, including:

  • Polypropylene: Celebrated for its resistance to chemicals and adaptability to numerous liquids.
  • Cotton: Renowned for its superior absorbency.
  • Nylon: Boasts high tensile strength and is frequently chosen for high-temperature operations.
  • Fiberglass: A preferred choice in industrial applications due to its resilience against a plethora of chemicals.
string wound filter cartridge with inner core likefilter

Inner Core Elements:

At the center of every string-wound filter cartridge is a core. This core provides mechanical strength and ensures the cartridge retains its shape, especially under pressure. Typical core materials include:

  • Polypropylene: Its resistance to many chemicals renders it suitable for diverse uses.
  • Stainless Steel: Favoured for its robustness, particularly in elevated temperatures.

End Caps and Adapters:

For a snug fit within filter enclosures, cartridges often come with tailored end caps or specific adapters, minimizing any chances of leakage.

Design Specifications of a String Wound Filter Cartridge


The inner and outer diameters of a cartridge play a role in determining its flow rate and contaminant holding capacity.


While there are standard lengths available, cartridges can often be customized to fit specific filtration systems.

Winding Techniques:

The manner in which the yarn is wound around the core is of prime importance:

  • Winding Density: This refers to how closely the yarn is wound. A higher winding density means finer filtration but can reduce the flow rate. Conversely, a looser winding will allow for a higher flow rate but may not trap the finest particles.
  • Winding Pattern: There are different ways to wind the yarn around the core:
    • Spiral Winding: Creates a tight matrix ideal for capturing fine particles.
    • Cross Winding: This method introduces broader spaces, suitable for larger contaminants.

Principles of Operation

At the heart of the cartridge’s efficiency lies its operation mechanism. Several particle capture methods are employed:

  • Sieving: This mechanism stops larger particles.
  • Interception and Diffusion: These processes target smaller particles.
  • Inertial Impact: This captures tiny particles moving at high speeds.

Depth filtration stands as a hallmark feature. As fluids traverse the cartridge’s depth, contaminants get trapped at different levels, optimizing filtration and extending cartridge life. The winding density’s tightness directly impacts filtration accuracy, with tighter winding enabling finer filtration. Understanding the winding pattern’s role in clogging, alongside the significance of pressure drops, becomes essential for efficient operation.

string wound filter cartridge yarn likefilter 1

Factors Influencing Cartridge Performance

Yarn Quality:

Consistency in yarn production is vital for filter efficacy.

Production Consistency:

Uniform winding tension and precise machinery are non-negotiable for optimal cartridge performance.

Chemical Compatibility:

Factors such as pH levels can degrade materials over time, underscoring the importance of matching yarn material with the intended fluid.

Operational Parameters:

Parameters like pressure, temperature, and flow rate influence cartridge longevity and efficiency. Awareness of potential media migration or off-gassing is vital for ensuring safety.

string wound filter cartridge likefilter 1

Applications and Industry Standards

Beneficial Industries:

  • Food and beverage
  • Prefiltration for RO system
  • Petrochemical
  • Water treatment and purification
  • Chemical processing
  • Pharmaceutical and biotech

Compliance, Certifications, and Standards:

Upholding standards such as NSF and FDA guarantees cartridges operate safely, meeting industry benchmarks.

Maintenance and Lifespan

Spotting signs of wear, like dwindling flow rates or escalating pressure drops, is imperative. Although some cartridges support backwash to extend their lifespan, routine upkeep and timely replacements are essential for continuous efficient performance.


LikeFilter String Wound Filter Cartridge Options

LikeFilter offers a range of cartridges tailored for diverse filtration needs, standing out due to their distinctive features and advantages.

Options & Specifications

Material:Polypropylene/Cotton Yarn/Glass Fiber
Inner Diameter:28mm/30mm
Outer Diameter:64mm;114mm
Inner core:Polypropylene/SS304/SS316L
Micron Rating:1um to 200um
End cap:DOE; 222/fin; 226/fin; 222/flat; 226flat
Seal Ring/Gasket:EPDM/Viton/Silicone/Buna N
DP change-out:1.5-1.6bar
MAX Temp:80℃/120℃/370℃

Feathers and Advantages

  • Broad Particle Retention: The unique winding pattern allows the filter to retain a wide range of particle sizes, from larger particles on the outer layers to finer particles in the inner layers.
  • Gradient Density: The unique winding pattern allows for varying densities throughout the cartridge, meaning larger particles are captured near the surface while finer particles are trapped deeper within, optimizing filtration efficiency.
  • Extended Lifespan: Their construction often results in longer service life, reducing the frequency of replacements and the associated costs.
  • Chemical Resistance: Depending on the chosen material, these cartridges can be resistant to a wide range of chemicals, making them suitable for harsh industrial applications.
  • Temperature Resilience: Certain materials allow the cartridge to operate effectively in high-temperature environments without degradation.
  • Versatility: Suitable for various applications due to its availability in different materials and micron ratings.
  • High Dirt Holding Capacity: Can retain a significant amount of contaminants before needing replacement.
  • Cost-Effective: Often more affordable than many other types of depth filters.
  • Easy Installation and Replacement: Their design often allows for easy installation and quick replacement, reducing downtime.
  • Customized: Can be tailored in terms of length, diameter, core, and winding material to suit specific requirements.
  • Reliable Performance: Consistent manufacturing standards ensure predictable and dependable filtration results.
  • Scalability: Suitable for both small-scale operations and larger industrial applications, thanks to the customized nature and available sizes.
  • Eco-friendly: Many string-wound cartridges can be made from sustainable or recyclable materials, minimizing environmental impact.
string wound filter cartridge 3 likefilter 2


In summary, string-wound filter cartridges are a versatile and efficient solution for removing particulates from liquids in various industries. Their design, which leverages depth filtration, allows for superior contaminant retention, making them a preferred choice in many filtration applications.

Reach out to the LikeFilter team for more insights.

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