When it comes to the filtration world there are endless types of material you can use: metal, paper, fiber, polymer, ceramic, etc. All of these different materials can be formed or treated differently depending on your application or your specific filtration needs.
At W.S. Tyler, we specialize in woven wire mesh for the filtration world but we get a lot of questions about other types of stainless steel filtration media. One of the most asked questions is: “What is the difference between woven wire and wedge wire screens?”
These two metals can seem very similar to the naked eye but they are truly very different. Both have their pros and cons depending on what type of application you are using it for and what your needs are.
In this article, we are going to take a look at both woven wire and wedge wire as filter media. We will cover the advantages and disadvantages and then compare the two in the following categories:
-Pore Size/Micron Rating
-Open Area/Flow/Pressure Drop
What is Wedge Wire?
Wedge wire is a metallic filter media made up of v-shaped wires that are lined up against or wound around support or structure. The wires are attached through welding.
The material being filtered flows through these formed slots. Most often, the surface facing the liquid is the flat/smooth side while the “v” shape is on the bottom.
The support structure for this material is located opposite of the incoming material, which allows it to support the media while staying out of the path of flow. Flow direction can be either outside-to-inside or inside-to-outside and the filter is constructed accordingly.
Top Applications for Wedge Wire:
- Filtering foods that have a high level of purity
- Oil filtration
- Brewing industry filtration (microbreweries and bottled teas)
- Fertilizer industry
- Solids from wastewater
Wedge wire is most typically formed into cylinders or panels. Typical cylinder size and slot opening/micron ranges include:- Diameter: between 1” - 36”
- Length - Virtually any length is possible
- Micron - As low as 30 micron or as large/open as necessary
Benefits of Wedge Wire:
- Resistance to clogging - The wide slot allows for less clogging due to fewer contact points while retaining an accurate opening size for efficient filtration.
- Precisely-sized slots/openings - Specified opening sizes or micron ratings are held with great accuracy due to the robust nature of the construction.
- Easily-cleaned surface filtration - The smooth filtration surface allows for easy and complete cleaning, whether through physical cake removal or by back-flushing
- Low pressure drop - The wide but precise slots allow for good flow and an acceptable amount of pressure drop when these filters are part of a system.
- High strength - Wedge wire is a self-supporting structure and inherently robust because of the cross-section of the wires, the sub-structure, and the fact that those items are welded together at many points throughout the fabrication.
- Service life - This media can be cleaned and reused indefinitely and the high strength nature resists damage, leading to a filter media with a long service life.
What is Woven Wire Mesh?
This type of filtration media can go by a few different names: Woven wire cloth, woven wire mesh, woven wire fabric.
As it’s name implies, this type of wire is woven on a loom and is very similar to how cloth is woven. The wires go in two directions, warp and shute wires. Woven wire is typically manufactured on rolls and then either cut or formed into desired shape and size.
The woven material creates a very stable but flexible filtration media that is almost like fabric or cloth.
The material can be made up of wires of different thicknesses or woven into different patterns depending upon the specified application.
Due to its labor-intensive production, Woven wire is generally used in more complex or technical applications compared to welding wire mesh.
Typical Applications for Woven Wire:- Sifting and sizing
- Architectural applications where aesthetic appeal is desired
- Pest control and livestock cages
- Ventilation screens
- Air and water filters
- Waste water
- Filters for air, fuel, oil and hydraulic systems
Benefits of Woven Wire Mesh:
- Customizations: Because the media is woven there are many customizations available like opening size, specific weave type and even the thickness of each wire. These changes will affect price and usage, but there are lots of ways to get the specific results you need for your filtration
-Ventilation: Woven wire mesh allows for steady, uninterrupted flow in a ventilation application. Air can be allowed to pass in and out of an area or it can be used to keep impurities out of the vessel that needs ventilation. It can also act as pre-filtration, which will provide good flow while helping the life of finer filtration that is located downstream.
- Precise openings/Accuracy: This material is woven on very precise high-speed looms and high-quality wires with tight dimensional tolerances are used. This leads to pore sizes that are very precise, accurate, and repeatable.
- Flexibility: The wires being woven but not welded together allow the material to be formed to all kinds of shapes and specifications without damaging the material or losing accuracy.
- Fabrication: This material is able to be cut, formed, or fabricated into nearly any shape imaginable by the use of typical sheet metal fabrication techniques. The end product can be small and simple or very large and very complex.
- Cleanable/Reusable: The nature of the material being metallic and offering surface filtration rather than depth filtration leads to a filter that is cleanable and reusable, offering a much longer service life than a typical disposable filter.
- Harsh Environments: Woven wire mesh offers fine filtration in environments that other fine filters simply cannot withstand. Woven wire mesh can be produced in specifications that will perform well when a low micron rating is required in an application that involves high pressure, high temperature, or corrosive chemicals.
Wedge Wire VS Woven Wire
Now that we have reviewed both materials on their own, we are going to take a look at each material in the following 9 categories: Durability, Pore Size/Micron Rating, Fabrication Options, Cleanability, Strength, Weight, Service Area, Life span, Open Area/Flow/Pressure Drop, and Cost.
When it comes to durability, wedge wire is inherently more durable due to the fact that it is made up of heavier wire & components than the finer specifications of woven wire mesh would be.
However, woven wire mesh itself may not be as durable but it can be made to be as strong as necessary through additional processes like laminating into multiple layers or by combining it with an additional support or protection structure.
In the bigger world of filtration, both wedge wire and woven wire mesh are go-to types of filter media when the filter is exposed to harsh environments.
Pore Size/Micron Rating
The pore size or micron rating of wedge wire typically goes down to about 30 micron (.030mm).
Woven wire mesh can be produced that has a micron rating of 5 micron.
If very fine metallic filtration that maintains acceptable flow is required, woven wire mesh will have the edge in this situation. The woven material allows for precise control over opening sizes that can’t even be seen by the naked eye.
On the other end of the spectrum, either material can be made with openings as large as necessary. Both types of media can be made with accurate openings, so both can provide very accurate filtration it depends on what your needs are in terms of pore size.
Wedge wire is typically formed into larger (in excess of 1” diameter x inches in length) cylinders, plates, or cones/funnels. In this regard, fabrication options are relatively limited.
Woven wire mesh can be more easily formed into many different kinds of shapes and configurations. This is what makes woven wire such a great material for filtration. Typical sheet metal forming techniques are generally used for woven wire mesh, so the options are practically endless.
Woven wire mesh can also be combined with plastic over-molding, different filter media, and can be made into a wider variety of sizes - from very small (⅛” in diameter) to extremely large (the size of small car).
Both woven wire mesh and wedge wire and typically used as “surface filtration”, meaning that the filter cake, or buildup of material, being filtered from a liquid resides on the surface of the filter. This allows the filter to be easily cleaned and reused.
While both types of media are cleanable and reusable, wedge wire usually proves to be more easily cleaned due to a surface structure that is a bit smoother than woven wire mesh. There is also a bit less risk of damaging the material when cleaning with wedge wire than with woven wire.
When talking about strength, wedge wire is going to take the win on this one. The very nature of wedge wire promotes strength - the wires are thick & robust, the substructure is strong, and everything is resistance welded together.
However, if finer filtration or a smaller footprint is required, woven wire mesh fabrications can also be quite strong with the addition of added value services like our Porostar or a support structure. While wedge wire is inherently very strong, woven wire mesh can also operate in high-pressure environments if the correct steps are taken to ensure this type of durability.
The great strength of wedge wire comes at the cost of weight. The relatively thick & wide filtration wires located closely together along with the robust support structure result in a filter that is nearly all solid metal.
If your micron rating and pressure needs will allow for the use of woven wire mesh, your filter will weigh less overall. This could lead to a further reduction of system weight if less-robust components are necessary to support the filter media.
Life span could refer to how long a filter can run between cleanings, how many times can that filter be cleaned, and how long will the filter last in the conditions where it operates.
Wedge wire is typically more robust and can sometimes be cleaned easier, so these filters will typically have a longer service life.
The more delicate nature and finer wires within woven wire mesh could lead to a shorter service life when compared to wedge wire. Woven wire can still be cleaned and maintained but there is a higher risk of wear and tear. The wedge wire will simply hold up to more abuse for a longer period of time.
Open Area/Flow/Pressure Drop
Open area or flow rates are always a concern with any filtration system. This critical characteristic becomes even more of a concern when strength requirements increase and micron ratings decrease.
There is a delicate balance between strength, flow, and micron rating that needs to be paid attention to. Expectations need to be realistic when deciding on a design where these characteristics are important.
Wedge wire that has larger openings and will flow very well. That flow is going to slow down substantially when the wedge wire is constructed with lower micron ratings. Strength is maintained, but undue pressures result when attempts are made to maintain the desired flow rate.
This is where moving to a woven wire mesh can be beneficial. Flow is maintained at lower micron ratings and strength can be added through lamination or support.
Metallic filter media is never a “low-cost option,” but it is used because of special requirements pertaining to micron rating, pressure, or harsh environments.
While both wedge wire and woven wire mesh are both on the upper end of filter media costs, wedge wire will typically be a bit more expensive than a woven wire mesh fabrication.
This is due to the volume of metal involved, the slow speed of production, and the cost of the equipment involved to produce this type of filter.
Woven wire mesh has a wider variety of costs depending on what processes are involved, but a wedge wire fabrication will typically be more expensive than a comparable woven wire mesh fabrication.
To Sum It Up
Even though woven wire and welded wire are similar in their nature and use, there are a lot of differences between the two as well.
There isn’t one filtration media out there that is perfect for everyone’s needs. Which filter media is right for you is going to depend on your application, your needs and your parameters of your system.
It is important that you know the benefits and capabilities of each so that you can choose the best one for your filtration system or needs. We hope this article helped you in your search for the right filter media for you.
If you are looking for more information on woven wire mesh in terms of terminology, added-value services or cost you can check out our Guide to Woven Wire mesh to learn more.
As always, if you have any questions about either material you can reach out to us with your questions and we will be happy to help in any way we can.