What is a String Wound cartridge filter?

String wound filter cartridge is a type of depth cartridge filter that is made by weaving yarn around a core. Microfibers are twisted and twined together to form a yarn. This yarn is woven in a honeycomb-shaped weave around the core such that it forms a gradient structure to allow better filtration. The quality of a wound filter cartridge hugely depends on the type of yarn that is used to make the filter. The material of the core and a controlled manufacturing mechanism that produces a precise micron rating also contribute. One should bear in mind the filtration application and other involved physical and chemical parameters before choosing a string wound filter cartridge.

How does a string wound cartridge filter work?

The string wound filter cartridge is woven to form a gradient density – tighter at the core and lighter on the outside. This means that bigger sediments are filtered out at the onset, and as the liquid passes through the medium, the finer particles get gradually filtered out at every layer. The winding pattern and controlled thickness of the cartridge results in higher dirt holding capacity and increases the life and efficiency of the filter.

Where Are String Wound Filter Cartridges Used?

String wound variants are popularly used for liquid filtration in industries like Food and beverage, pharmaceuticals, water treatment, mining, chemical, oil & gas, gas and air, flue gas, Desalination and automotive.

Best Used For Filtration Of:

Water
Alkalis
Dilute acids and Alkalis
Organic acids and solvents
Potable liquids
Petroleum oils
Mineral acids

What are the advantages of string wound cartridge filter and why string wound cartridge filter is the best?

The string wound cartridge filter is widely used across industries and for various types of liquid filtration requirements because of its filtration capabilities, high dirt holding capacity, and ability to keep form and last longer. If manufactured to good quality, these types of filters do not collapse under pressure differentials. Additionally, most of the filter housings use ‘knife-edge sealing’ to inset and seal the filter cartridges inside the housing. While other cartridges may be susceptible to poor edge sealing resulting in by-pass problems, good quality string wound cartridges hold their shape and are sturdy.

What happens When you use run-of-the mill cartridge filter housing?

knife-edge sealing - Gopani Product Systems

If you have overlooked the importance of knife-edge sealing while purchasing cartridge filter housings, then you know how regret looks like! Sometimes overlooking the minutest detail can lead to huge problems. Product Quality Matters.

Poorly designed run-of-the-mill products have no arrangement for inside sealing. This leads to the seepage of water from the infiltration area. In some cases, the rubber gaskets degrade over time. And sometimes the disk sealing the cartridge filter moves from its place, leaving huge gaps for contaminants to seep in. The fitment of the cartridge inside the housing is not right and the product quality is compromised. While making a purchase it is a common tendency to be lured by the extremely cheap pricing, and overlook the minute quality details. What is a filtration system that allows contaminants to pass through? – it is not doing the work it is designed to do. So, if you have ever settled for a poor-quality product for its price, you know well not to repeat the mistake.

How to select a string wound cartridge filter?

There are four components in a string wound cartridge filter

Core
Yarn
Endcap
Gasket

A perfect filter is the one that uses appropriate materials and is woven to perfection to fulfil the filtration application requirements. A sturdy core, a premium quality yarn, and high precision manufacturing are some desirable qualities to look for in a cartridge filter. Good quality materials used in the manufacturing of the wound filter cartridge, give it higher filtration capabilities and longer life.

Buy from a string wound filter cartridge manufacturer who has excellent manufacturing capabilities and access to the latest technology. Go local. If you need filtration equipment for a unit based in India, look for a manufacturer who will provide string wound cartridge filter at best price in India. Additionally, a local string wound filter cartridge manufacturer in India will be able to provide faster delivery, and after-sales support will be easy.

Features to look for in a good quality string wound cartridge:

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

Not using a good quality wound cartridge filter? Here’s what can happen…

• Tunneling

If the yarn used to manufacture a string wound filter cartridge is rounded and smooth, it can easily shift and roll. This displacement/rolling of yarn can happen during ‘knife-edge sealing’ or due to pressure and flow fluctuations. This dismantles the honeycomb structure and creates gaps between the yarn weave and compromises the filtration efficiency. In this case, achieving a precise micron rating is a challenge.

• Chemical leaching

Chemical leaching is a serious concern as it compromises the quality of the filtrate. Often chemicals, resin binders, lubricants, antistatic, and release agents start leaching out as soon as the filter is put to use. they mix with the filtrate and reduce the efficiency of the filtration process. The solution is a) prewash the filter cartridge, and b) let the liquid flow through for some time before using the filter.
However, to ensure minimum leaching it is the best to use filters that are 100% free of resin binders, lubricants, antistatic, and release agents.

• Media Migration

Quality of yarn is one of the important factors that account for the quality of a wound cartridge filter. Short chopped fibers tend to loosen and migrate into the filtration liquid. Rough handling, bad packaging, wear and tear during knife-edge sealing, and inconsistent flows may further cause quality deterioration.

A Complete Guide to Selection of a String Wound Filter Cartridge

What Are The Different Types Of End Caps Used In A String Wound Cartridge Filter?

What are the various types of cores for a string wound cartridge?

Polypropylene
Gas-filled polypropylene
Stainless steel
Tinned steel

What are the different yarn types used in a string wound cartridge filter?

Natural cotton
Bleached cotton
Glass fiber
Polypropylene
Nylon, Rayon
Polyester and other

What is a Micron Rating?

Micron rating indicates the ability of the filter to remove contaminants by the size of particles. The quality of the yarn and the manufacturing quality have a significant impact on achieving a perfect micron rating. A filter with a 10-micron rating can capture and filter out contaminants as small as 10 microns.

Contaminants as thick as a human hair – 50 Microns
Contaminants not visible to human eye – 40 Micron
Contaminants of the size of white blood cells – 25 Micron
Contaminants of the size of red blood cells – 8 Micron
Contaminants of the size of Bacteria – 2 Micron

What Is A Micron Rating - Gopani Product Systems

Nominal Micron Rating: Nominal micron rating means that the filter has the ability to capture 50% to 90% of the contaminants of the specified micron size. For example, if the filter has a nominal rating of 50% at 25 microns, it will capture 50% of all the contaminants of size 25 micron.

Absolute Micron Rating: absolute micron rating signifies absolute filtration. Filters with an absolute micron rating are capable of removing 98. 7% or more than 98.7%contaminants of specific microns.