Things to Know About String Wound Filter Cartridges

String wound filter cartridges are the type of depth cartridge filters made by weaving yarn on a core.
Microfibers are twined and twisted together to form the yarn, which is woven in a honeycomb-pattern around the core so that it forms gradient structure to facilitate better filtration. 
The string wound filter cartridge quality depends significantly on the kind of yarn that is employed to make the filter.
Apart from that, the core material as well as a controlled making mechanism that forms a precise micron rating contribute as well.
When you purchase string wound filter cartridges, you should consider the chemical and physical parameters along with the filtration application.

How Do String Wound Filter Cartridge Work?

As mentioned above, the string wound cartridge filter is woven to make a gradient density, which means tighter at the core but lighter on the outside.
So, bigger sediments are eliminated when the liquid flows through the medium as well as finer particles get filtered gradually at every layer.
The controlled thickness and winding pattern of the cartridge enhance dirt holding capacity as well as increases the efficiency and life of the filter.

Where Is String Wound Filter Cartridge Used?

A string wound filter cartridge is popularly utilized for liquid filtration in automotive, desalination, flue gas, air and gas, oil and gas, chemical, mining, water treatment, pharmaceuticals, and food and beverage industries.
It is commonly used for filtration of: 

  • Alkalis 
  • Water 
  • Alkalis and dilute acids
  • Potable liquid 
  • Organic acids and solvents
  • Mineral acids
  • Petroleum oils


Advantages of Good-Quality String Wound Filter Cartridges

The string wound filter cartridges are widely used across various industries and for varying liquid filtration requirement types due to its filtration capabilities, ability to keep form, long life, and high dirt holding capacity.
If you buy from reputable sellers and these filters are of high-quality, they would not collapse even under pressure differentials. 
Additionally, the majority of filter housings utilize knife-edge sealing to seal and insert the filter cartridges in the housing.
While other filter cartridges may be prone to poor edge sealing causing by-pass problems, high-quality string wound filter cartridges are sturdy and hold their shape. 
If you overlook the importance of the knife-edge sealing while buying the filter cartridge, it can ultimately cause huge problems.
Poorly made average items have no arrangement for sealing inside.
This causes seepage of liquid from the infiltration area.
The rubber gasket may degrade over time too.
At times, the disk sealing cartridge filter may shift from its place leaving big gaps for particles to seep in.
This would happen if the cartridge does not fit correctly or is of poor quality. 
While buying the string wound filter cartridge, you should pay attention to its quality more than its price.
After all, what is the filtration system that lets contaminants pass through?
The system is not doing what it is made for. 

Importance Of Selecting The Right String Wound Filter Cartridge

A string wound filter cartridge has four components – core, yarn, endcap, and gasket.
The right filter would use appropriate materials and would be woven to perfection for fulfilling the filtration application needs.
A premium quality yarn, a sturdy core, and high precision manufacturing are amongst the desirable qualities to seek in a cartridge filter.
Top-notch quality materials utilized in making the wound filter cartridge ensures longer life and higher filtration capabilities. 
So, you should choose a manufacturer who uses the latest technologies and has excellent manufacturing capabilities.
Apart from them, look for supportive after-sales service and warranty for the product. You should also look for these features – 

  • Structural stability 
  • Long service life 
  • High dirt holding capacity 
  • Minimum media migration 
  • Precise micron rating 
  • Graded density winding 
  • Chemical-free

If you do not use the right wound filter cartridge, the following things may happen:

1. Chemical leaching

It is a serious concern because it compromises the filtrate’s quality.
Often resin binders, chemicals, antistatic, lubricants and release agents begin leaching out just as the filter is used.
These contaminants mix with filtrate and decrease the filtration process’s efficiency.
The solution to this problem is rewashing the filter cartridge, letting the fluid flow through for a few minutes before you use the filter.
To ensure minimum leaching, you must use filters that are completely free of lubricants, release agents, antistatic, and resin binders.

2. Media migration

If the quality of the yarn is not considered, short chopped fibres of the yarn would loosen and flow with the filtration liquid.
Bad packaging, rough handling, inconsistent flows, and wear and tear during sealing would lead to quality deterioration. 

3. Tunnelling

In case the yarn used is smooth and rounded, it can shift and roll easily.
The rolling/displacement of yarn can occur due to flow and pressure fluctuations and during knife-edge sealing.
This would dismantle the honeycomb pattern and form gaps between the yarn weaves.
As a result, filtration efficiency would be affected. 


String wound filter cartridges are effective in filtering fluids.
However, the yarn used in the filter should be woven rightly and made using high-quality material so that the filter is able to perform its job. 


Navrajvir Singh
Navrajvir Singh
Entrepreneur. Strategist. Think Tank.

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