I need to filter very high-viscosity products. Which filters should I choose?

Viscosity of a fluid characterizes its resistance to flow. It is related to the friction forces between the fluid particles themselves and against the walls when the fluid is set in motion. The more viscous a liquid is, the more difficult it is for it to flow.

Viscosity must be taken into account, for example, when selecting pump power, as well as for the sizing, geometry, and choice of filter media. At an equivalent flow rate, a viscous product will require a larger filtration surface than a low-viscosity fluid. Fluid viscosity is classically expressed in centipoise (cP).

In practice, in industry, fluids with high viscosity include resins, inks and paints, polymers, oils, creams, food pastes, coatings, and adhesives.

It should be noted that fluid viscosity generally depends on temperature and pressure—a parameter that must be taken into account on production lines.

A high viscosity (several hundred to several thousand cP) is not without consequences for filters. When a viscous fluid flows, pressure losses—that is, pressure drops along the entire production line, and particularly during filtration stages—are significant. Filter cartridges can deteriorate under the effect of differential pressure, meaning the pressure difference between the inlet and the outlet of the filter. They may undergo mechanical deformation, rendering them ineffective. Their filter media can also be damaged and release particles or fibers into the filtered fluid.

To prevent deformation of filter cartridges used to purify very high-viscosity liquids, you can install cartridges featuring a one-piece central core.

This component provides higher mechanical strength than conventional designs. More robust, central-core cartridges remain effective for a longer time. Their service life can be 45 to 50% longer than that of cartridges without a monolithic core.

You can also favor thermally bonded fiber media to minimize fiber migration and release into the fluid under the effect of differential pressure.

Another option is to act on the very structure of the filter media itself, for example by installing cartridges whose media has been manufactured using a meltblown process.

Finally, as is always the case in industrial filtration, when choosing your filter, take into account the chemical nature of the product to be purified. In the case of viscous materials such as PET (polyethylene terephthalate), PP (polypropylene), cellulose acetate, or nylon, metallic filter media are, for example, excellent candidates.

For very high viscosities (above 10,000 cP), synthetic media are too fragile (risk of tearing or bursting). Stainless steel filter media are then the only viable option.

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