Jul. 21, 2025
About depth filtration and the porous filter elements used in fuel filters
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Read Part 1 to find out more about sintered porous bronze filter elements and their use in small plastic inline fuel filters >>
Part 3 has an FAQ about sintering and sintered porous bronze fuel filters, plus a list of references and other applications using porous bronze filter elements >>
Some Details About Bronze, Depth Filtration, Porous Bronze Filter Elements and How to Make Them
What is bronze?
Bronzes and tin bronze
Traditionally, bronze is an alloy of copper and tin. Tin bronze is still the most common bronze alloy, and it usually has about 10 to 12% tin with copper making up most of the balance. Quite a few modern bronzes do not contain any tin at all.
Bronze alloys vary by the metals or non-metals added to the copper. Metallurgy groups different types of bronzes by the primary metal added to the copper. Some examples of this are aluminum bronze, phosphor bronze and silicon bronze.
The tin bronze alloy used for small sintered metal filters tends to be around 89 to 91% copper and about 9 to 11% tin.
Find out more about the differences between copper, brass and bronze at Metal Supermarkets >>
What are sintered porous metals?
When small openings in metals are not defects
Fine, uniform metal powders are formed into useful shapes and then fused to make porous sintered bronze filter elements. The sintering powders are shaped by dies and fused by heat.
Carefully controlled particle fusion causes enough metal to diffuse between particles without allowing the part to become dense and solid. The result is a single piece of porous metal explicitly designed for filtration applications.
These porous metal filter elements are mechanically strong but have a capillary-like network of interconnecting pores running through the metal.
Why use sintered porous bronze as a filter element?
Porous bronze benefits
Sintered porous bronze filter elements are extremely tough and able to provide both surface and depth filtration. They provide
Greater particle-holding capacity
Depth filtration and particle capture
Porous sintered bronze filters provide both surface filtration and depth filtration. Depth filtration is all the interconnecting and winding pores and passages within the filter element's walls. Filter elements use depth filtration to capture and hold smaller particles not stopped at the filter element's outside surface.
Depth filtration captures smaller particles and holds onto more of them. It also does this without diminishing flow too much. Depth filtration is what makes sintered porous filter elements more efficient.
Over time though, the buildup of fine particles reduces flow through the filter element.
Sintered porous bronze depth filtration is efficient because of
What is porosity?
Porosity is the ratio of open space in a filter element compared to its total volume. Typically, a filter with high porosity has a more open structure and a higher flow rate. Together these increase its efficiency.
What is tortuosity?
Depth filtration is also efficient because of tortuosity. Tortuosity is the complex network of winding, interconnecting pores or passages through the filter material (filter media).
What are the advantages of porosity and tortuosity for depth filtration?
A larger number of interconnecting winding passages through the porous bronze (tortuosity) creates more opportunities for a filter element to capture small particles that would otherwise pass through the filter.
Particles small enough to not be captured on the filter's outer surface encounter many more potential obstacles down inside the filter media. Tortuosity gives depth filtration its higher particle holding or loading capacity.
Get more information about the and other polymer treated paper ITW Fastex® Visu-Filters in the ISM catalog >>
Higher porosity means lower pressure drops across the filter
Porosity provides depth filters with lower pressure drops across the filter elements even as they hold onto more particles. They are considered efficient because of this.
Paper, actually polymer treated cellulose, and porous sintered bronze filter elements take advantage of depth filtration to capture finer particles. Porous sintered bronze is especially good at doing this while still allowing a relatively good flow rate through the filter.
Bronze filters are relatively compact, but paper filter elements need larger filter bodies. The surface area of paper elements needs to be large enough to provide usefully high fuel flow rates while still capturing fine particles.
Metal and plastic mesh screen filters only stop particles on the filter element surface. They cannot capture finer particles than their micron rating, but they do provide very good flow rates.
What is the process used to make sintered porous bronze filters?
Pressureless sintering
Sintered porous bronze filter elements are made with bronze powders using the pressureless sintering process. Pressureless sintering is a type of powder metallurgy.
Sintered bronze filter elements start with a specific type of metal powder:
The powder is poured into dies and placed in specialized furnaces. Precisely controlled sintering conditions fuse the particles into porous but mechanically strong finished parts.
Some General Information About Plastic Inline Filters That Use Porous Sintered Bronze Filter Elements
Can sintered porous bronze filter elements be cleaned?
Engineers design small plastic inline fuel filters for easy replacement
Generally, plastic inline fuel filters need to be changed out regularly. The need to replace them is why OE small engine manufacturers and OEM aftermarket distributors provide so much support for OE replacement parts. They know the importance of protecting sensitive components that could be clogged or damaged by contamination. They also know that end users need replacement filters over the lifetimes of their machines.
Many manufacturers and aftermarket distributors recommend replacing plastic inline fuel filters at least once a year. Some go further and recommend replacing fuel filters as a part of routine maintenance after an internal combustion engine-powered machine comes out of storage.
Backwashing can extend the useful lives of both screen and sintered porous bronze filter elements, a definite design advantage for end users.
ITW (natural) and (red) Visu-Filters use a stainless steel mesh screen
Get more information about the , and other ITW Fastex® Visu-Filters in the ISM catalog >>
Backwashing plastic inline fuel filters
What is backwashing?
Backwashing or backflushing is reversing flow through a filter or filtration sub-system to clean it and restore flow.
Backwashing a fuel filter can blow out accumulated particles and debris. This backwashing is an attempt to temporarily restore or at least improve fuel flow through the filter. Generally, backwashing with fuel or pressurized cleaning solvent successfully dislodges loose debris on the surface of both mesh screen and porous sintered bronze filter elements.
How well does backwashing a plastic inline fuel filter work?
Backwashing a mesh screen or sintered metal filter may restore much of its filtering capability. Because sintered metal filters are depth filters, there is always a gradual buildup of finer particles that, bit by bit, clog up more and more of the tiny passages in a porous metal filter.
For this reason, plastic inline fuel filters with sintered bronze filter elements should be considered consumable items that end users must replace at some point. Recommended best practice is to replace plastic inline fuel filters as part of routine preventive maintenance.
Still, the ability to backwash a mesh screen or porous sintered bronze fuel filter and restore flow, even a reduced flow, reassures end users that they won't get stuck. Many Powersports users ride their machines into the backcountry. Backwashing a filter to restore or improve fuel flow means there is a much better chance they can return from the wild even if a filter begins to clog up.
Transparent and semi-transparent inline filter housing materials make it easier to inspect fuel filters for particle buildup. The benefits of visually inspecting filters are why many small plastic inline fuel filters use plastics that make it pretty easy to see particle accumulation on the filter element.
For more information, please visit sparger ring.
End users can tell just by looking if they should probably replace a filter. If necessary, they can backflush it to provide a temporary hold-over until they can find and install a replacement.
Because backwashing is useful, at least in the short run, sintered bronze fuel filter elements tend to be considered more practical than paper filter elements for off-road Powersports and Outdoor Power Equipment (OPE) used in remote locations.
ITW and Visu-Filters use a stainless steel mesh screen
Get more information about the , and other ITW Fastex® Visu-Filters in the ISM catalog >>
Cross-section of flexible tubing pushed over a hose barb
Connection type is important for small plastic inline fuel filters
Why use hose barb connections on inline fuel filters?
Most plastic inline fuel filters use hose barb connections. These easily replaceable filters have hose barb connections (barbed inserts) designed to work with flexible hose and plastic tubing.
Get some insight into hose barb design plus tips about matching hose barbs to the right flexible tubing and hose at the ISM blog >>
What about the fuel lines?
General-purpose gas-powered internal combustion engines and Powersports machines are likely to be exposed to gasohol (gasoline-ethanol blends) and even methanol now and then. Because of this, machine designers know it is probably best if their flexible fuel lines use materials that can stand up to a variety of fuels and fuel additives.
Find out more about gasohol (gasoline-ethanol) blends and outdoor power equipment from OPEI, the Outdoor Power Equipment Institute >>
Flexible fuel line choice and durometer
Flexible fuel lines also need to be soft enough that the barbed hose connections can grip the fuel line's inner surface and create a tight seal.
Engine and machine design engineers are familiar with durometer ratings. They choose the right fuel line durometer and inner diameter (ID) to match the power system's barbed fittings. And they also opt for material compatibility with a variety of fuels and fuel additives.
Find out more about what durometer is, how it's measured and why it is an important specification for hose barbed connections at the ISM blog >>
Flexible fuel line fuel resistance
Experienced small engine designers and manufacturers build their engines always with the end user in mind. This perspective extends to their choice of fuel line tubing or hose. It is usually Tygon or a comparable fuel-resistant transparent tubing that does not turn brown and brittle after extended use.
Find out more about materials and chemical compatibility with the ISM Chemical Compatibility Chart >>
The style of hose clamp matters
Most original equipment (OE) manufacturers provide pre-installed plastic inline fuel filters with hose barb connections. Their installation should include properly sized spring band clamps.
This clamp style ensures a durable leak-free connection because it can compensate for the fuel line's compression around the hose barb shank.
Spring band clamps also do a good job coping with the fuel line and hose barb diameter changes caused by temperature swings.
Get more information about hose barb or barb connector design and function at the ISM blog >>
Original equipment small engines and high-quality OEM filters
Why plastic fuel filter quality matters
Original equipment (OE) machine manufacturers want to offer plastic inline fuel filters made by highly reputable original equipment manufacturers (OEM). Consistently high-quality replacement parts provide manufacturers with an economical way to increase end-user satisfaction.
Manufacturers do this by ensuring users can find the correct and best quality replacement parts when they need them. Using high-quality, consistent replacement parts and making them widely available enhances both the machine manufacturer and their engines' reputations.
Aftermarket distributors and original equipment replacement part suppliers have access to the same lineup of OEM plastic inline fuel filters as the OE manufacturers. This range of choice allows them to market OEM filters both as replacement parts and as aftermarket add-ons. They do this knowing they are offering highly reliable, durable parts that are less likely to fail unexpectedly.
Find out more about ANSI-OPEI B71.10- compliant inline plastic fuel filters and shut-off valves from ITW Fastex Filtration and ITW Powertrain Components >>
Quality plastic inline fuel filters marketed as replacement and aftermarket parts provide
Plastic inline fuel filters that incorporate porous sintered bronze filter elements meet all of these requirements.
There is a bonus with fuel filters manufactured to meet industry standards like ANSI/OPEI B71.10-. Industry standards like this provide even greater assurance of sturdiness and durability in real operating conditions.
Get more information about ANSI/OPEI B71.10- Off-Road Ground-Supported Outdoor Power Equipment - Gasoline Fuel Systems - Performance Specifications and Test Procedures >>
About this three-part series on sintered porous bronze fuel filters
Sintered Porous Bronze Fuel Filters - Part 1: Benefits of porous sintered bronze filter elements and how they are made >>
An overview of porous bronze filter elements, why they are so effective in small plastic inline fuel filters and what it takes to produce high-quality sintered porous bronze fuel filters.
Sintered Porous Bronze Fuel Filters - Part 2: About depth filtration and the porous filter elements used in fuel filters >>
More detail about bronze, porous sintered bronze filter elements as depth filtration, how to make them, and their installation and use.
Sintered Porous Bronze Fuel Filters - Part 3: Porous sintered bronze elements FAQ, applications beyond filtration plus references >>
An FAQ about sintering, sintered porous bronze fuel filter elements and depth filters. It also includes an overview of other applications that use porous bronze filter elements, plus a list of references.
Selected ITW Fastex Filtration Visu-Filter fuel filters
ITW Fastex Filtration and ITW Powertrain Components Visu-Filter fuel filters are compliant with ANSI/OPEI B71.10-.
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Sintered Porous Metal Filter Element
The advantages of having a sintered porous metal filter element are just enormous. I can assure you that you stand to gain a lot by using these filters on your application. Among the various benefits that you can gain include the following.
Better filtration
When filtering, you want to get the best of your filtration which involves removing all the contaminants that are present in your fluid.
You can achieve this by using a sintered porous metal filter element for your filtration.
A sintered porous metal filter element offers quality filtration for your fluid with the results being fluid that is free of contaminants.
By adjusting the porosity of the filter element depending on the fluid means that you can achieve the perfect filtration that you want.
Since there will be no corrosion of your filter, no contaminants will be present in your fluid as a result of the reaction of the filter.
Corrosion resistance
What a sintered porous metal filter element offers for your application is a corrosion-free filter that will provide you with quality service.
Various reactions take place in your filter.
These reactions can either be chemical, mechanical, or physical reactions.
Such reactions can hurt the condition of your filter as well as the fluid that you are filtering.
However, by using a sintered porous metal filter element, you are sure that there will be no corrosion of the filter.
Also, you can be sure of the fluid that you are filtering won’t be affected by the filter element.
Sintered Porous Metal Filter Element
Reasonable pressure drop
If there is one aspect of your filtration that you need to ensure that is constant is the pressure of your fluid in your application.
That is precisely what a sintered metal filter offer.
A sintered metal filter can maintain the pressure of your fluid within your application thus ensuring maximum operation.
A slight drop in pressure might hurt your application.
For instance, you may not be able to achieve the filtration that you want to due to there not being the relevant force to filter your fluid.
Also, drop-in pressure results in a drop in the fluid requirement of your application.
You will, therefore, find that your application may not get the fluid that it needs for your filtration.
High thermal shock
The advantage of a sintered porous metal filter element is that it has a high thermal shock.
This is mainly an advantage when you are dealing with applications that have a high thermal shock.
During the manufacturing process bonding of various metals happens while maintaining the physical properties of the metals.
It is these physical characteristics of these metals that aid in absorbing the high thermal shock of your filter.
You can, therefore, use these filters in a wide range of applications depending on the thermal range of your application.
High thermal shock also ensures that you can filter your fluid efficiently without having to worry about the thermal heat of the application.
Temperature and pressure resistance
You can easily maintain the temperature and pressure resistance of the individual metals.
This is because you can mix different metals by bonding without necessarily having to melt the metals.
The advantage of this is that the resulting sintered porous metal filter element has a high temperature and pressure resistance.
You can, therefore, use this filter in applications that have a higher temperature and pressure without having to worry about your filter element.
Among applications that have a higher temperature and pressure resistance include chemical reaction and gas treatment plants.
The use of sintered metal filters in such applications ensures that you obtain the best results for your filtration.
Sintered Porous Metal Filter Element
Advantage of sintered mesh filter cartridges comparing to wire mesh filter
Comparing to non-metallic and ordinary wire mesh filter cartridges, sintered metal mesh filter cartridge is superior in:
ㆍfixed and stable pore size under high temperature and pressure
ㆍsuitable for temperature applications higher than 300 degree Celsius
ㆍwashable and reusable
ㆍall welded structure, no risk of failure of spot welding or adhesive
ㆍself-support, easy to form cartridge
As the mechanism of the sintered wire mesh is stop and restrain the impurities in the working fluid, there are chances that the impurities accumulated and form the filter cake. The filter cake can increase the filtering accuracy at certain degree before the cake is cleaned or removed by backwashing or offline cleaning.
Sintered metal mesh filter cartridge is suitable for applications of micron level filtration and separation. Such as particle candle filter for chemical, pharmaceutical, oil & gas, petrochemical; strainer for food & beverage, fuel, hydraulic.
Why sintered filters?
We spoke ad nauseam about the application of sintered filters but why sintered filters are used in the above-mentioned industries, instead of any other type of filter? There are a few vital reasons why people from such industries trusted a sintered product over all else.
The porosity of sintered filter dictates the outward or inward flow of liquid or gas. The controlled flow of filtering material can be managed without the help of a pressure gauge.
Sintered filters and high-pressure situations go hand in hand. When applied in a pressure-rich environment, most other filter material tends to fail. You cannot use plastic or paper when the psi is extremely high. That is why sintered filters are trusted.
It can operate in a high-temperature environment. A sintered filter steel mesh can resist the heat of up to 480°C. If the material or the alloy is changed, the heat resistance also sees changes, which is not possible in any other type of filter.
Know about Jintai
Shijiazhuang Jintai Purification Equipment Co., Ltd. has been committed to the development of metal porous materials and related technologies and applications. As early as more than 20 years ago, Jintai began to focus on the development and production of metal porous powder sintered porous metal filter elements. It has 15 invention patents and utility model patents. It has been a high-tech enterprise and has passed ISO quality management system certification. After more than 20 years of technical accumulation, Jintai can now provide customers with a variety of product materials and specifications to meet customer needs. If you need our products, please feel free to contact us.
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