When picking or selecting a filter, there is a lot of misunderstanding and differing expert views - and the frequently requested question is, "should I choose string wound or melt blown filter cartridges?"
Both filters have distinct advantages and disadvantages, and the application and filtration requirements should help determine the decision. Here are some key facts and differences between string wound and melt blown filter cartridges.
What Is A String Wound Filter Cartridge?
A string wound filter cartridge is a water-filtering device that reduces sediment, dirt, sand, and other particles from water. The filtration cartridge aims to provide clean, secure drinking water by reducing impurities and contaminants from the water source.
The string used to wind the cartridge changes in diameter by layer, which aids in capturing particles of varying sizes within the filter. Impurities and contaminants in the water are caught in the gradient spaces between the string strands as water passes through the cartridge. It must be changed regularly to ensure the filtration cartridge continues successfully reducing contaminants from the water. Frequency of change-outs depends on the flow rate and concentration of dirt in the filtration stream.
These filters are beneficial in regions with high amounts of sediment or other particles in the water supply. A string wound filter cartridge can help improve the water quality while protecting plumbing fittings and appliances from sediment accumulation.
What Is A Melt Blown Filter Cartridge?
A melt-blown filter cartridge is constructed from a fine mesh of thermoplastic fibers that have been melted and blown onto a central core to create a filter matrix. Impurities in the water are trapped in the gradient spaces between the fibers as water passes through the cartridge. Change-out frequency is also based on flow rate and the amount of dirt in the flow stream.
Melt blown filter cartridges are widely used in domestic, commercial, and industrial environments. They are especially effective at removing fine particles such as sediment, rust, and other types of debris from the water supply.
Melt blown filter cartridges have a high dirt-holding capacity, which means they can hold a lot of debris before changing it. They are also reasonably priced and simple to install, making them a standard option for water filtration applications.
What Are The Differences Between Melt Blown Filters and String Wound Filters?
Even though they are both commonly used to remove contaminants in water filtration systems, melt blown filters and string wound filters have some key differences.
Filter Media
Melt blown filters are created by melting and extruding thermoplastic resin into a fibrous matrix and blowing it onto a revolving core. The resulting fine fiber matrix is shaped into a filtration cartridge.
String wound filters, however, are created by wrapping a piece of string around a core, resulting in a tight, dense filter matrix. Cotton, polyester, and polypropylene are some of the materials that can be used to make the thread.
Filtration Efficiency
Melt blown filters have a higher filtration efficiency than string wound filters in general, particularly when it comes to capturing smaller particles. Because fine fibers in melt blown filters produce a denser matrix with more surface area for particles to adhere to, the capture rate is higher.
Melt blown filters are highly efficient at removing fine particles from fluids because they can capture particles as small as 0.3 microns in diameter. String wound filters, on the other hand, are better adapted for removing larger particles and sediment and are less effective at capturing tiny particles.
Dirt-Holding Capacity
String wound filters have a great dirt-holding capability. This is because the string used in string wound filters produces a denser matrix with bigger void spaces than fine fibers used in melt blown filters. Because of the bigger void spaces, string wound filters can collect much dirt before needing to be replaced.
In contrast, melt blown filters have fibers that were blown onto the core as a hot liquid polypropylene and as the fibers cool, they are fixed in place. These fibers are not movable and allow the melt blown to collect dirt more uniformly throughout the filter. Dirt holding capacity comparisons between the melt blown and string wound vary based on applications.
Cost
The cost of melt blown and string wound filters vary based on factors such as filter size, the material used, and the manufacturer. Cost comparisons in the past have put string wound filters at a lower price point, but due to advancements in melt blown technology the price gap is minimal.
The string wound filter manufacturing process is more straightforward and less costly than the melt blown filter manufacturing process. String wound filter materials are usually less expensive than melt blown filter materials, lowering the cost of string wound filters even further.
When comparing costs, it is essential to evaluate the overall performance and efficiency of the filters. While string wound filters are less costly, they may not be as effective as melt blown filters at capturing small particles. The better efficiency of melt blown filters may outweigh the higher expense in some applications.
Applications
Melt blown and string wound filters are used in various applications but are usually better suited for specific filtration requirements.
Melt blown filters are commonly used in uses requiring high-efficiency filtration. They are frequently used in pre-filters for reverse osmosis (RO) and chemical filtration applications because polypropylene is compatible with many chemical fluids.
String wound filters, however, are better suited to applications requiring high dirt-holding capacity, such as those in the industrial, agricultural, and municipal water treatment sectors. String wound filters are excellent at removing larger particles and sediment from fluids, making them ideal for well water filtering, irrigation, and industrial fluids.
Understanding the differences between these two types of filters and considering the application's specific requirements allows you to choose the filter that will provide the best performance and value. The filtration requirements and purpose determine the appropriate filter. To make an informed decision, consider particle size, efficiency, dirt-holding ability, flow rate, temperature, and cost.