What is Stainless Steel Filter?

 

Stainless steel filter cylinder is a filter element mainly made by 304 or 316 stainless steel wire mesh which has different sizes of mesh to get the best performance of filtering. Different kinds of structures can be chosen based on various requirements, such as epoxy bonded structure, pressure welding structure and all welded structure. The stainless steel filter can be completely reused through backwashing, ultrasonic washing, and other non-abrasive washing methods.

Stainless steel filter can be classified based on its structure in the manufacturing process:

• Epoxy bonded construction
• Crimped construction（used in industrial process）
• All welded structure

Epoxy Bonded Construction

Stainless steel filters made through the epoxy bonding technique can be sold at a competitive price. Its strength is enough to be applied in high-pressure conditions with the epoxy bonding element, which is an ideal option for most fluids.

Crimped Construction

It can be used to clarify and filter fluids especially suitable for filter core used in the industrial process. It’s generally accessible for batch applications. The filter elements are usually pleated or columniform (covered) with light core and support rings in it. The industrial process filter element is made of stainless steel by using crimping and welding. Instead of brazing or bonding with epoxy so that it can overcome the limitations of temperature and compatibility brought about from cellulose filter elements or the synthetic cellulose ones.

All welded Construction

The metal mesh filter element is all made from stainless steel assemblies including end caps, central tubes, and metal mesh. During the applications of filtering dangerous fluids, the element is easy to clean with processing costs greatly reduced.

The metal mesh element with an all-welded structures is very suitable for the extreme environment. For example, it can be applied in the severe environment of high pressure or corrosive fluids. It can eliminate the harmful effect caused by media migration and filter out particles larger than the micron-scale precisely. Through backwashing or other technologies, the element can be easily cleaned to restore its working life.

It is an ideal option for many high-pressure applications due to its robust component and welded structure. We also provided elements used in the collapse pressure rating. When it comes to the applications in the extremely high temperature which may destroy the traditional epoxy structural element, the metal mesh filter element can be ideal.

All metal mesh elements with the welded structure are treated through annealing to minimize the possibility of elements failure caused by the interaction of intergranular corrosion and high pressure.

How Does the Stainless Steel Filters Work?

Stainless steel filter works based on the principle that it will retain all dirt whose diameter is larger than that of mesh. As a result, it has an absolute rating.

The stainless steel filter made of sintered metal fiber felt is a kind of deep stainless steel filter element, which can deeply intercept the polluted particles when the fluid passes through the filter element.

The polluted fluids can be formed from inside to outside or vice versa according to different applications of stainless steel filter.

Stainless steel filter works to remove particulate pollutants through the following mechanisms:

Inertial impaction: Large and dense particles are usually captured by inertial impaction. Particles will be separated from airflow and then impact with cellulose filter elements under the inertia effect.

Interception: Through interception, the medium size of particles will be removed because they are too small to be affected by inertia. So, they will follow the route of airflow. These pollutions will be suspended in the air. When they are in contact with the fiber, they will be adhered to the medium and then be captured.

Diffusion: The smallest particles will be captured through diffusion. Just like gas molecules, they travel along an irregular path, which is called the Brownian movement. Through stochastic motion, the possibility of particle impaction and adherence to the surface of the medium will increase.

High pressure differential

It’s a filter element with the resistance of high pressure. It is often used in filtering high pressure fluids to help ensure the long time operation of instruments in the high-pressure pipeline.

High temperature resistance

Stainless steel material can work for a long time at high temperatures. Compared with other materials that are out of shape easily if, under the condition of high temperature, the stainless steel filter core will maintain its stability.

Easy to clean

The material of stainless steel is very easy to clean and reuse. The process of cleaning involves the effort to remove dirt and re-install the instrument to have the next operation done. It can be rewashed to make sure that there is no polluted particle remaining on the surface of the stainless steel filter core.

Long-life

The filtering area is increased with the pleated stainless steel filter core. Longer replacement cycles are available and its working life is also prolonged. At the same time, the element is resistant to corrosion, which makes it available not to pollute fluids passing though secondarily.

Customizable size

It has a different size so that it can be applied extensively in the industries. Different size of elements is easily suitable for different types of instruments. It also provides various kinds of seal rings or gaskets for different applications.

A fixed bore diameter

The filter medium has a fixed pore structure, which will prevent polluted particles to go back to the clean fluid. The fixed absolute rating of pore will lead to more efficient filtering.

The metal filter cores are available for applications in a severe environment where solid materials are required. They can be used in the condition of high pressure differential and extreme temperature. Besides, they are used to filter fluids which have special compatibility requirements.

Automobile industry:

• Air filter
• Lubricating oil filter
• Airbag inflator filter

Chemical reagent and catalyst recovery:

• Hot liquid
• Cryogenic liquid
• Solvent，ketone，ester，liquid hydrocarbon
• Water supply and make-up water
• glycol
• The efficient solid or liquid recovery

Foods and drinks：

• Steam filtration
• Recovery of catalyst from the hydrogenation reactor
• Polishing of syrup, wine, and other liquids
• Removal of catalysts from flavor components and other food specialties
• Removal and decolorization of activated carbon

Polymer filtration: Polyamide，Kevlar®，Polyester，Polypropylene，Polyamide

HEPA and ULPA filtering

Burner: Sintered metal fibers are made of high temperature resistant alloys and are used as radiation materials for burners

Refinery: High flow rates typical of continuous operation in refinery applications

Nonwoven metal fibers are used in liquid-liquid separation (coagulation and liquid-gas separation (demisting) systems)

Spinning polymer

Hot-gas filtration

The medical and pharmaceutical sector

Hydraulic and fuel field

Nuclear emissions

The stainless steel filter barrel brings great convenience for experiments that require a large area and highly efficient filtration through using stainless steel sinter fiber web and stainless steel wire mesh as the major filter medium. To keep its outstanding performance, the filter core needs to be maintained on a regular basis. Three cleaning methods are as follows:

Ultrasonic cleaning

It uses longitudinal waves as cleaning fluid to produce a certain number of vacuum bubbles which are also small enough. These bubbles will be broken when they fail to suffer from pressure. And the impact force will be used to clean the stainless steel filter barrel.

Backwashing

It backwashes the stainless steel filter in the opposite direction utilizing inert gas such as nitrogen.

Solution cleaning

The method is to soak the stainless steel filter barrel with a 5% sodium hydroxide solution or nitric acid solution for an hour. The soak time can be prolonged or shortened according to the pollution level. And finally, the filter will be dried naturally using clean air.

When the stainless steel filter works for a long time, the accumulation of polluted particles will be a burden to the filter core element with its efficiency reduced. The method to ease the burden is to demount the stainless steel filter barrel and clean it correctly or change it.

The stainless steel filter can be used until it’s not available after cleaning. When it can’t meet the requirements that it should meet, the only choice is to demount the old filter and change a new one.

1. Receive the production order to replace the stainless steel filter element to ensure that the system has already not been in operation;
2. Confirm the replaced stainless steel filter element (specification, material, size, O-ring material, model, etc.), disassembly tools, collection bucket, dishcloth, etc.;
3. Clean the stainless steel filter housing thoroughly, empty the filter area, and leave the operation area. All process needs to be done with protective equipment taken;
4. Close the filter system which is in operation, open the exhaust port at the top of the filter slowly to release the pressure. Check the pressure gauge to ensure that the pressure is minimum or completely closed. Pay attention to safety during the process to prevent material or liquid splashing;
5. Drain the materials in the stainless steel filter, open the sealing cover of the filter with tools, take out the stainless steel filter element to be replaced from the filter housing, and pack the stainless steel filter element with plastic bag for cleaning or scrapping.
6. Clean the inside of the stainless steel filter with cleaning tools and rags, and install the updated stainless steel filter element.
7. Open the plastic bag of the stainless steel filter element and check whether the O-ring is intact and in place.
8. Hold the stainless steel filter element close to one end of the O-ring, connect the socket of the stainless steel filter element vertically and completely with the corresponding place on the base, remove the packing bag after installation, and then install the sealing cover of the filter in place, and tighten the stainless steel filter with tools.
9. Close the discharge port of the stainless steel filter, open the vent valve on the top of the shell, and open the fluid inlet valve slowly to make the fluid enter the shell at a constant speed until the fluid overflows from the vent valve on the top of the shell, and then close the vent valve. Pay attention to check the disassembly for leakage.
10. Slowly open the outlet valve of stainless steel filter until it is completely opened, indicating that the replacement is completed.

The working life of stainless steel filter, as well as its high quality and high performance, will depend on its manufacturing process including filter material selection, pleating, welding, gluing, and dust-free assembly.

First, we choose appropriate filter material with the main structure determined. And then we simulate its structure through digital media. The next step is to perfectly present the design through accurate manufacturing and processing with the help of experienced teams and advanced instruments.

Professional material is a precondition for a quality stainless steel filter. Coupled with high quality manufacturing processes, good quality control, and strict operation procedures, we ensure each step is in fastidious detail to make the product of high quality.

Pleating

First the medium of stainless steel filter core is pleated to achieve a larger filtering area within a small surface. And it can be used as compact units such as filter element and filter.

Modern pleating machines can be used to process gasket made of multi-layer media which is composed of different metal fiber webs and/or wire mesh, and the height of the stainless steel filter element can be up to 1500 mm. Therefore, there will be stable components, which can operate stably for a long time under a high mechanical load.

Welding

The pleated stainless steel layer or smooth filter medium in the cylindrical filtration system will be connected through welding. The same operation will be done in the connection at the outlet or inlet interface of the filter medium. To achieve this, there are many welding methods. These methods will be chosen correspondingly according to the materials, thickness, and the appearing shape of the weld.

The welds in the filter element must be 100% sealed and must also be fine enough not to be coated. Because they can’t block too much filtering area, and fluid barrier shouldn’t appear in the shell. The finer and smoother the welds are, the higher their corrosion resistance will be.

The most common welding method is plasma welding and gas tungsten arc welding (GTAW or TIG). Metal inert gas welding (MIG) and metal active gas welding (MAG) are also used in rare cases.

High-alloy steel and all nonferrous metal can be welded using GTAW or TIG. Titanium welding is also included.

A high quality weld is available through resistance welding technology such as spot welding and roller welding. It can be reproduced without the surface of the materials affected.

Through using low current intensity, plasma welding is a welding method especially suitable for metal film and wire welding. For those very fine filter media which need to be welded, plasma welding will be a good choice.

Bonding

Apart from welding technology, another approach to connect metal or other materials is to use reactive adhesives or epoxy. If we use the right adhesive with a bonding position professionally treated (cleaned, degreased), the joint will be completely sealed. It can suffer high mechanical and chemical load and can be used under a high temperature of 150 ℃. Because many products are used in the areas with high hygiene conditions such as in the pharmaceutical and food processing industries, the adhesive chosen must be authorized to prevent pollution caused by unavoidable contact.

Dust-free assembly

To manufacture and assemble a high-quality stainless steel filter element or system, a dust-free environment must be required.

The solid structural material is needed in a poor operating environment. No matter what kind of severe environment your applications will be in, high operating pressure, high pressure differential, extreme temperature, or compatible fluid needed, it’s of great importance for system protection to use structural materials. Since the stainless steel filter element has its own material advantages, it is easy to customize the design to meet the requirements of material, strength, flow, thickness, micron grade, and environment.

It’s a filter element with extremely high compressive strength. So, it is used for the filter in industries which use high pressure fluids.

Stainless steel material can resist high temperature and keep in operation for a longer period of time. The stainless steel filter maintains stable while other materials are easy to be out of shape under high temperatures.

It’s very easy to clean and reuse the element due to its material of stainless steel. To clean the instrument, dirt should be removed and the instrument will be re-installed to have the next operation done. Usually, there is no dirt remaining on the stainless steel material. Not too much cleaning is required. So, it’s a more cost-effective option.

The stainless steel filter has high mechanical strength and can resist high pressure. High mechanical strength will help the element to resist high pressure and high temperature with its shape kept during the whole operating process.

The pleated stainless steel filter increases the filtering area. It will be more durable and can be used for a long time before changing.

It has different sizes available for extensive industrial applications. Different sizes of elements can be easily suitable for various instruments with different O-rings or gaskets provided for applications.

It has a fixed pore structure, which can prevent dirt to go back to the clean fluid. It has an absolute rating to ensure consistent, reliable, and repeatable fluid filtration. Due to the material of stainless steel, it resists to corrosion and can be used for a longer time. Corrosion resistance makes it a suitable filter element without fluid passing through polluted.