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Prefiltration for Medical Device Reprocessing

The schematic below shows 2 prefilters. The first is specifically to remove particles. The second, optional filter is to remove either more particles or some of the bacteria that might be in the water. Whether one or two filters are in place, they protect the final, bacteria filter from premature fouling (clogging). Read more below, or go to the product selection table at the bottom of this page to review prefilter options.

Filters for Medical Device Rinse Water

Particle Filtration in Reprocessing

The type and number of filters used by any facility is determined by incoming water quality. In general, water from wells or springs has fewer particles because it has already been filtered by the earth for many years. Water from reservoirs, lakes, rivers and other surface sources is usually from precipitation and often has high levels of organic and inorganic particles. The nature of the particles varies by region. Areas with dry climates may not have much organic content in rivers or lakes, but the amount of sand and sediment probably raises dramatically after rain storms or during the spring snow melt. In wetter climates, leaves and other organic matter in and around the water break down and contribute organic particles and other organic compounds that could affect the water’s taste and odor. If a facility gets its water from a surface source, either directly or after municipal treatment, there will be more particles and more filters may be required to protect the bacteria filter. However, the particle sizes are usually quite small. Municipal water systems do a very good job of removing most particles larger than about 2 microns, so the filters chosen should target particles smaller than 2 microns to be effective in protecting the bacteria filter. For more information on this application, click on the link below to download an Application Summary.

Choosing the Right Filter Media

Almost all particle removal filtration applications are done using depth filtration media. Cartridge filters use two forms of depth media. The standard depth filter is a self-supporting tube made using a polymer, most often polypropylene, and forming the tube using the melt-blown or nano-spun process. The other form of cartridge depth filter uses pleated flat sheet media, most often made with polypropylene or fiberglass.

Standard depth filters will capture a range of particle sizes through the thickness of the media. Pleated media filters have the advantage of a large surface area that can hold a higher quantity of particles on that surface than the standard depth filters.

In pleated depth filters, polypropylene is the most widely used material for water and chemical filtration, but fiberglass has better filter efficiency and generally allows higher flows and throughput than polypropylene in final product prefiltration applications.

The table below shows the filter media in cartridge, capsule and disc filter configurations. We also have sanitary housings for filter cartridges. Click on the PDF Files in the appropriate location to download a data sheet for the filter media and configuration that fits your needs.

Media Code
Filter Media
Filter Grade
Cartridge Data Sheet
Capsule Data Sheet
Disc Filter Data Sheet
Pore Sizes Avail. (µm)
Melt Blown Polypropylene Media
1, 3, 5, 10, 20, 30, 50, 75, 100
Continuously spun bonded polypropylene media for consistent 85% nominal performance.
Nano-spun Polypropylene Media
1, 3, 5, 7, 10, 20, 30, 40, 50
Very high retention efficiency (99%) and high load cpacity to protect downstream processes.
Pleated Polypropylene Depth Media
0.1, 0.22, 0.45, 0.65, 1.0, 3.0, 5.0, 10, 20, 30,40, 60, 100
100% polypropylene construction for high purity.
Melt-Blown Nylon Media
1, 3, 5. 10, 20, 30, 50, 75, 100
Spun bonded for consistency with broad chemical compatibility.
Pleated Fiberglass Depth Media
0.22, 0.30, 0.45, 0.65, 1.0, 2.0, 3.0, 5.0, 10, 20, 30

To estimate the number of filters you will need for your application, use our unique sizing tools.

Contact Critical Process Filtration if you have any questions, wish to discuss a specific application or want to learn more about any of our Products and Services. We look forward to hearing from you!