1. what is string wound cartridge

String wound cartridge is a depth filter element used for micron filtration field, and installed in a filter vessel for water clearing, removing impurity from 1um to 200um from the water or liquid, Which is widely used as pre-filtration before Reverse osmosis membrane, also called Security filter process.

Widely applications as below:

Prefiltration for RO Desalination

Oil & Gas

Power Generation Condensate System


Food & Beverage


Municipal Water


  1. How is it produced

The string wound filter element is composed of cotton thread wound around the core rod.

Outer diameter normally to be 2.5inch or 4.5inch, length can be selected from 5 to 70 inches, and the micron range is 1um to 200um.


In addition, depending on connection with filter vessel, different end caps may be required. The end cap types are DOE, 222, 226, Fin, and flat.

The end cap and the filter element are combined to form the final product according to the needs.


What’s more, according to the actual application environment, such as temperature, pressure, etc., different materials need to be selected. The winding materials can be pp, gf, cotton, and the core rod can be pp, stainless steel, etc.


Finally, once we decide a cartridge type, the process working flow will be:

Inner core fixed on machine—raw PP material fixed on inner core—auto machine working makes pp wound around the inner core—Once size reach 2.5inch for example, machine stop, cartridge is ready—if need end caps, then use another machine to combine end cap with cartridge—finally packing


  1. How to identify productquality in a easy way?

Smell, to identify the raw material, It smells pungent for not 100% pure PP material. It is easy to be broken for not 100% pure PP material cartridge.

Pinch, to fell the structure tight or not, if it is not tight enough, the filtration performance will not good.

Push, to check whether the pp yarn wound around inner core good or not, if the pp material is easy to be pushed from inner core, there will be a future problem of leak once operation.

Press, to check the strengthen, from which we can learn the inner core is strong or not. As we know, the stronger the inner core, the higher pressure it can bear.


  1. How to choose a reliable supplier?

Producing capacity, with high production capacity, manufacturer can match on time delivery requirement.

Quality control, the manufacturer should have the quality control system to manage the quality to match clients demands all the time.

Certificate for products and company, the certificates to show goods are produced under qualification management.

Case reference, specially with end plant, as we know, normally big plant has the standard checking process, not only for the product itself, but also for the manufacturer. Once a cartridge used in the plant, that is a good voice to show the quality.

After sell service, not only sell products, but also help clients better use it, and even once if there is a problem, manufacturer can offer a solution help to deal.


BF is the best choice to match all above, and can help you to choose the most suitable products in your water treatment system, we work as your partner.

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