At tens or hundreds of cubic metres per hour, a skid full of small cartridges quickly becomes impractical. High flow filter cartridges solve this with large-diameter pleated elements that each handle up to 100 m³/h. This guide explains how they differ from standard 2.5″ cartridges, how to choose the right medium and micron rating, and how to size a system that runs reliably between change-outs.
What are high flow filter cartridges?
High flow filter cartridges are large pleated elements with a 6″ (152 mm) core diameter, supplied in 20″, 40″ and 60″ lengths (508, 1,016 and 1,524 mm). The pleated medium gives them about ten times the surface area of a wound cartridge, so a single 60″ element can carry up to 100 m³/h and replace up to 40 standard 10″ cartridges.
Standard cartridges, by contrast, have an outer diameter of 2.5″ (63 mm) and come in 10″, 20″, 30″ and 40″ lengths. They fit almost every standard housing, but each element carries only a small share of the flow, so large flows mean big multi-cartridge housings and long change-outs.
The main advantages of high flow cartridges for large-volume filtration are:
- Fewer elements – a handful of large cartridges instead of dozens of small ones.
- Smaller housings – fewer and more compact filter vessels and less floor space.
- Longer service life – the large pleated surface spreads the dirt load and keeps the pressure drop low.
- Reliable retention – absolute-rated media protect downstream membranes and equipment.
- Faster maintenance – changing a few elements takes a fraction of the time.
Pleated vs depth media, absolute vs nominal ratings
Pleated high flow cartridges
Pleated cartridges filter mainly at the surface of a thin, folded filter medium. Because the folded area is very large, they combine an absolute rating with a high flow per element and a low clean pressure drop. That makes them the first choice for large, continuous flows with a moderate solids load, for example RO pre-filtration.
Depth cartridges
Depth cartridges, such as melt-blown or spun polypropylene elements, hold particles throughout a thick layer of fibres. They offer a high dirt-holding capacity and cope well with heavy or variable solids loads. High flow depth cartridges are usually nominal-rated and allow a lower flow per element than pleated designs.
Absolute vs nominal micron ratings
A nominal rating means the element retains a certain percentage of particles of the stated size; some larger particles can still pass. An absolute rating describes a much higher, consistent retention efficiency at the stated size. Where membranes, nozzles or product quality depend on particle removal, an absolute rating is the safer design basis. Always compare like with like: 5 µm nominal and 5 µm absolute do not perform the same.
Choosing the filter medium
High flow cartridges are available with ratings from 0.1 to 70 µm absolute in four media:
- Polypropylene (PP) – general water filtration and RO pre-filtration, with wide chemical compatibility.
- Glass fibre (GF) – high-temperature service up to 80 °C.
- Polyethersulfone (PES) – fine filtration of food, beverage and process water.
- PTFE – aggressive chemicals and demanding process liquids.
End caps are available in polypropylene, stainless steel 316 or PTFE-coated versions. For drinking water and food applications, cartridges with FDA 21 CFR and NSF 61 compliant materials are available.
How to size a high flow cartridge filter
Sizing starts from the process data, not from the cartridge catalogue. Work through these steps:
- Design flow – use the maximum flow the filter will see, including peaks, not just the average.
- Liquid and temperature – viscosity and temperature affect pressure drop and determine which medium is suitable.
- Required micron rating – set by the equipment you need to protect or the product quality you need to achieve.
- Solids load – the amount and type of particles determine service life and whether a coarse pre-filter is needed.
- Flow per element – this depends on the micron rating, the liquid and the allowed clean pressure drop. Finer ratings and more viscous liquids mean less flow per element.
- Number of elements and housings – divide the design flow by the permissible flow per element and add a safety margin.
Sizing example
With up to 100 m³/h per 60″ element, a 300 m³/h RO pre-filtration stage typically needs 3 to 4 elements including a safety margin. The same duty with standard 10″ cartridges would require more than a hundred elements spread across several large housings. For small flows, the picture is reversed: standard cartridges or bag filters are often the more economical option.
Pressure drop and change-out
A generously sized filter starts with a low clean pressure drop and takes longer to reach its change-out point. Fit a differential pressure gauge to each housing and replace the elements at the recommended change-out value, well below the maximum of 4.1 bar at 20 °C. Because service life depends on the solids load, trending the pressure drop is more reliable than fixed intervals.
Housings for high flow and standard cartridges
The cartridge and the housing must be chosen together. Cartridge filter housings are available in stainless steel 304/316L, carbon steel and PVC, from a single element up to 72 cartridges, for standard 10″ to 40″ cartridges and for 60″ high flow elements. Stainless steel housings are rated up to 10 bar and 120 °C, PVC housings up to 6 bar and 5–50 °C. Connections range from ½” to 12″ NPT or ANSI flanged.
For flows above about 50 m³/h, high flow cartridges need far fewer elements and can reduce the number of housings by up to 90%. Our high flow cartridges also fit existing high flow housings from Parker, Pall and Pentair, so an upgrade does not necessarily mean replacing the vessel.
When bag filters or spun cartridges are better
High flow cartridges are not the answer to every filtration task. For small and medium flows, PP spun cartridges in standard 2.5″ format are often the simpler choice. They are available in 1 to 100 µm absolute, in 10″ to 40″ lengths, with a graded density structure for high dirt-holding capacity, and they work as drop-in replacements in all major housing brands. Note their temperature limit of 50 °C for standard PP and a maximum differential pressure of 3.5 bar at 20 °C.
Where the liquid carries a heavy load of coarse solids, bag filter housings are usually the better first stage. Filter bags cover 1 to 800 µm, multi-bag housings with up to 12 bags handle up to 800 m³/h, and the side-entry design allows tool-free bag changes. A bag filter upstream removes the coarse fraction and extends the life of the finer high flow cartridges downstream.
High flow cartridges as RO pre-filtration
Reverse osmosis membranes must be protected from particles. Cartridge filtration is a standard part of the pre-treatment for industrial reverse osmosis systems, together with multimedia filtration, softening and antiscalant dosing as required. RO pre-filtration commonly uses 5 µm absolute cartridges, and sometimes 1 µm where the feed water contains fine particles; the final choice depends on the water analysis and the membrane manufacturer’s requirements.
In large brackish water and seawater RO plants, high flow cartridges replace dozens of standard cartridges in the pre-filtration stage and reduce the time needed for routine maintenance.
Typical mistakes when selecting cartridge filters
- Sizing on average flow – ignoring peaks means a high pressure drop from day one.
- Choosing finer than necessary – an unnecessarily fine rating shortens service life without improving the process.
- Mixing up nominal and absolute ratings – comparing cartridges on different rating bases leads to poor protection of downstream equipment.
- No coarse pre-filtration – with a high solids load, fine cartridges block quickly unless a bag or depth stage is installed upstream.
- Ignoring temperature and chemistry – the medium, end caps and seals must suit the liquid and its operating temperature.
- Running to the maximum pressure drop – a fully blocked element risks damage and bypass.
Comparison: high flow cartridges, standard cartridges and bag filters
| Criterion | High flow pleated cartridges | Standard PP spun cartridges | Bag filters |
|---|---|---|---|
| Format | 6″ (152 mm) core, 20″, 40″, 60″ | 2.5″ (63 mm) OD, 10″–40″ | No. 1 (7″×16″) and No. 2 (7″×32″) bags |
| Flow capacity | Up to 100 m³/h per 60″ element | Small flow per element; many elements for large flows | 5–800 m³/h per housing (up to 12 bags) |
| Filtration rating | 0.1–70 µm absolute | 1–100 µm absolute | 1–800 µm |
| Media | PP, glass fibre, PES, PTFE | Melt-blown polypropylene | PP, polyester, nylon, PTFE |
| Max temperature | Up to 80 °C (media dependent) | 50 °C (standard PP) | Housing up to 120 °C (EPDM seal) |
| Max differential pressure | 4.1 bar at 20 °C | 3.5 bar at 20 °C | Change at specified limit |
| Best suited for | Large continuous flows, RO pre-filtration | Small to medium flows, final filtration | High solids load, coarse pre-filtration |
Frequently asked questions
Which micron rating is used before reverse osmosis?
RO pre-filtration commonly uses 5 µm absolute cartridges, and sometimes 1 µm where the feed water contains fine particles. The right rating depends on your water analysis and the membrane manufacturer’s requirements.
How many high flow cartridges do I need?
Divide your maximum design flow by the permissible flow per element, which depends on the micron rating, the liquid and the allowed pressure drop, and add a safety margin. As a guide, a 300 m³/h RO pre-filtration typically needs 3 to 4 elements of 60″ length.
When should high flow cartridges be replaced?
Replace them when the differential pressure reaches the recommended change-out value, which lies well below the maximum of 4.1 bar at 20 °C. Service life depends on the solids load, so monitoring the pressure drop is the most reliable indicator.
Do high flow cartridges fit my existing housing?
Our high flow cartridges fit high flow housings from Parker, Pall and Pentair. Send us the housing make and model and we will confirm the matching element.
Planning a new filtration stage or replacing an existing one? Send us your flow, liquid and filtration data and we will prepare a proposal within 48 hours.