Industrial cartridge filters remove suspended solids from liquids before they reach a membrane, pump, spray nozzle, heat exchanger or finished product. They look similar on a shelf, but a melt blown, string wound, pleated or sintered cartridge can behave very differently once it sees real process fluid. Two cartridges with the same micron rating may load, plug and bypass in completely different ways. For procurement and engineering teams, the practical question is rarely “which type is best?” It is “which construction, media, rating and end-cap style fit this liquid, this contaminant load and this housing?” This guide explains the main cartridge types, how they differ, and what to confirm with a supplier before ordering.
Industrial cartridge filters are classified by four independent attributes: construction (how the media is arranged), media material, retention rating, and housing interface (length, diameter, end caps and seals). Treating these as one decision is a common source of specification errors.
MMP Filter’s comparison of melt blown, wound and pleated cartridges makes a useful distinction: melt blown, wound and pleated are constructions, not materials. Polypropylene, polyester, nylon, cotton or glass fiber describes the media. The construction describes how that media is arranged, and the arrangement largely determines dirt-holding behavior, pressure drop and service life.
The most useful first split is depth versus surface filtration:
Dutch Filtration’s selection guidance notes that surface filters are generally preferred when the particle size distribution is narrow. Depth filters have less filter area, which is why most cannot match pleated cartridges on flow rate.
Melt blown cartridges are made by extruding molten polymer, most commonly polypropylene, into fine fibers collected on a rotating mandrel. The result is a graded depth structure. They suit sediment removal, RO pre-filtration and general process liquids where particle sizes vary. Their advantages are low unit cost and good dirt-holding capacity on moderately contaminated feeds. Their limits are lower flow capacity per cartridge than a pleated element, and ratings that vary in meaning between suppliers.
String wound cartridges are yarn wound around a central core in a controlled pattern to form graded layers. Pall’s cartridge overview describes them as depth filters available in materials such as cotton, glass fiber, polypropylene, polyester, nylon and PPS. The core is usually 304 or 316 stainless steel. Yarn and core choice are the main specification levers: they set chemical compatibility, temperature capability and tolerance for heavier sediment or viscous liquids. String wound cartridges are generally treated as disposable prefilters.
Pleated cartridges fold sheet media around a support core. This packs far more filtration area into the same body diameter than a plain cylindrical wall would. Pall’s guidance states that pleated filters suit fluids with a narrower particle size distribution, and applications needing high flow rates with low pressure drop. This is the most varied family. The folded sheet can be a polypropylene or polyester nonwoven, or a membrane such as PES, PVDF, nylon or PTFE. Retention can be nominal or absolute, covered below.
Buyers who want to see how a pleated range is organized by media, length and end style can review Lvyuan’s pleated filter cartridges for industrial liquid filtration. The range includes polypropylene, PES, PVDF, PTFE, polyester, activated carbon fiber and high-flow formats. Customization to match existing housings is also offered.
Pall also describes a pleated-depth hybrid made from thick melt blown media with a tapered pore structure. It aims to combine the dirt-holding capacity of depth filters with the flow capability of pleated ones. Large-diameter high-flow cartridges extend the same logic: more area per housing slot, fewer cartridges, and a smaller housing for a given flow. The trade-off is that high-flow elements use different housings and seals. Moving to them is a system decision, not a cartridge swap.
Activated carbon cartridges address dissolved chlorine, organics, taste and odor, which particulate cartridges do not remove. Sintered metal or porous plastic elements are rigid, can often be cleaned or backwashed, and suit high-temperature, high-pressure or aggressive-media duties, usually at a higher initial cost. Buyers typically choose these for a specific process need, not as general-purpose prefilters.
The table below is qualitative. It describes typical tendencies, not guaranteed performance, and individual products vary by media, rating and manufacturing quality.
| Cartridge type | Filtration mode | Typically suits | Main strengths | Main limits | Verify with supplier |
|---|---|---|---|---|---|
| Melt blown | Depth | Sediment, RO prefiltration, mixed particle sizes | Low cost; good loading on moderate sediment | Lower flow per cartridge; rating basis varies | Nominal or absolute basis; media grade |
| String wound | Depth | Heavy sediment, chemicals, oils, viscous liquids | Wide yarn and core choices; economical | Fiber migration risk in some designs; usually disposable | Yarn, core material, temperature limit |
| Pleated (nonwoven media) | Surface or nominal depth | Higher-flow prefiltration, narrower particle range | Large area; lower pressure drop | Can blind quickly on dirty feeds | Media, rating basis, end style |
| Pleated (membrane media) | Surface | Fine or polishing filtration, chemically demanding liquids | Defined retention; many media options | Higher cost; needs a clean upstream stage | Membrane type, wetting behavior, test data |
| Pleated-depth hybrid | Depth plus pleat area | Wide particle range at higher flow | Strong capacity with good flow | Less common formats | Housing compatibility, rating data |
| Activated carbon | Adsorption plus particulate | Chlorine, VOC, odor, color | Removes dissolved species | Finite adsorption capacity | Carbon type, contact time, particulate load |
| Sintered metal or plastic | Rigid depth | Heat, pressure, aggressive media, reusable service | Cleanable; mechanically strong | Higher initial cost; cleaning validation needed | Pore grade, cleaning method, material grade |
Within the pleated family, media choice matters more than cartridge length. Compatibility depends on the actual liquid, temperature and cleaning chemicals. Treat the table below as a screening guide, not a compatibility chart.
| Media | Common role | Points to confirm |
|---|---|---|
| Polypropylene (PP) | General aqueous prefiltration, RO and DI pretreatment, many compatible process liquids | Temperature, solvent and oxidizer exposure, rating basis |
| Polyester | Sediment and general liquid duty, with a different chemical profile from PP | Fluid chemistry, temperature, construction |
| PES membrane | Fine filtration where a hydrophilic membrane is wanted, such as water and food or beverage lines | Application documentation, extractables expectations |
| PVDF membrane | Fine filtration of aggressive or chemically demanding liquids | Exact membrane grade, temperature and pressure limits |
| PTFE membrane | Very demanding chemical environments, gases or solvents | Hydrophobic behavior in aqueous service; wetting procedure |
| Nylon membrane | Selected process fluids requiring a hydrophilic membrane | Compatibility with acids, oxidizers and the process liquid |
Lvyuan’s 30 inch polypropylene pleated filter cartridge is an example of the all-polypropylene format. It uses PP media, core, cage and end caps for water and compatible process liquids, with 222/Fin ends and optional 226/Fin. The product page notes that allowable differential pressure falls as temperature rises. A headline pressure figure should therefore be read as a design maximum, not a limit that holds across the whole temperature range. That is a sound reading habit for any cartridge datasheet.
For finer retention or more aggressive liquids, the 5 inch compact PVDF pleated cartridge pairs a PVDF membrane with polypropylene support parts in a short body. The pictured version uses a 222/Flat connection with dual O-rings. The page states that actual rating, temperature and pressure limits depend on the specific PVDF membrane and construction. Confirm those values against the chosen specification.
Buyers who have not settled on media can start from a configurable platform such as the 10 inch pleated cartridge with selectable PP, PES, PTFE, PVDF or nylon media. The page makes a point worth repeating: its broad micron range describes the product series, not a rating available with every media type.
A nominal rating means a cartridge removes a manufacturer-stated percentage of particles at or above a given size. An absolute rating implies a much higher and more tightly defined removal efficiency at that size. The Cary Company’s cartridge guide says nominal cartridges may capture only about 75% at the stated micron rating, while absolute-rated cartridges often reach 99% or more. It adds that many systems place nominal filters upstream with absolute filtration at the end.
These terms have no single universal definition. One supplier’s “5 micron nominal” may not match another’s. When comparing quotations, ask for:
Without that data, two quotes at the same micron number are not like-for-like.
No. A pleated or finer-rated cartridge is not automatically the lower-cost option. Pleated media offers a large surface area, but it can blind quickly when the feed carries a wide spread of particle sizes or heavy loading. In that situation a depth cartridge, or a coarser pleated cartridge upstream of a finer one, often gives longer total service life at lower cost per cubic meter filtered.
The right comparison is cost per volume of liquid processed to the target cleanliness. That includes cartridge price, change-out frequency, labor, downtime and disposal, not just the unit price on the quotation. Staged filtration, with a coarse stage taking the bulk of the solids and a fine or absolute stage polishing, is frequently the more economical design. The caveat is that staging adds housings, pressure drop and complexity, so it pays off mainly where contaminant loading is significant.
Frequent plugging is also diagnostic. As Dutch Filtration points out, a filter that plugs earlier than expected can indicate an upstream process problem. Switching cartridge type may then mask the real cause.
The cartridge must fit the housing before it can filter anything. Check these interface points against the existing housing or drawing:
A sample cartridge, a drawing or the housing model number reduces the risk of ordering the wrong interface. This is why OEM and replacement programs often start from a sample.
An accurate RFQ lets the supplier evaluate both the cartridge and the system, instead of matching a catalog size. Provide the following:
| RFQ field | Why it matters |
|---|---|
| Liquid, viscosity and temperature | Determines media, seal and core compatibility and flow behavior |
| Contaminant type and approximate size range | Decides depth versus pleated and whether staging is needed |
| Target micron rating and rating basis | Defines retention and the efficiency data you should request |
| Flow rate, operating and differential pressure | Sets cartridge count, area and replacement trigger |
| Housing model, cartridge length and OD | Prevents fit problems |
| End caps and seal material | Prevents bypass and seal failure |
| Quantity, order pattern and target market | Affects pricing, MOQ discussions and documentation needs |
| Compliance or documentation requirements | Flags food-contact, pharmaceutical or other certification needs early |
| Sample or drawing of the existing cartridge | Speeds compatibility checks for replacement or OEM work |
Ask the supplier to state MOQ, lead time, test data and available documentation in writing against your specification. Request a sample for validation before committing to volume.
The main types are melt blown, string wound, pleated, pleated-depth hybrid, activated carbon and sintered cartridges. Melt blown and string wound are depth filters, pleated cartridges are mainly surface filters, and activated carbon and sintered elements serve specific process needs.
Depth filters trap particles throughout the media thickness and handle mixed particle sizes well. Pleated filters fold the media to create a large surface area, giving lower pressure drop and higher flow. They suit narrower particle distributions and cleaner feeds.
Choose absolute-rated cartridges where defined retention matters, such as final polishing or membrane protection. Nominal cartridges often serve as lower-cost prefilters. Request efficiency percentages and test methods, because definitions vary between suppliers.
They are SOE end-cap connection styles, commonly understood to refer to the O-ring sizes used for sealing, and usually come with a fin or flat tip. They must match the housing adapter, so confirm with a drawing or sample.
Some constructions can be cleaned, but many are disposable. Reusability depends on media, construction and contaminants. Cleaning can change retention or damage the cartridge, so confirm methods and limits with the supplier before planning around reuse.
At minimum: the liquid, contaminant, target micron rating, flow rate, pressure, temperature, cartridge length and OD, end caps, seal material and quantity. A sample cartridge or drawing lets the supplier check compatibility with the housing.
Not unless it includes media designed for adsorption, such as activated carbon fiber. Standard polypropylene or polyester pleated cartridges retain suspended particles and do not remove dissolved chlorine, odor or chemicals.
