Cleaning your polymer filter without losing quality. Is it possible?

Filtration is an important step in the production of polymer applications. The aim is to achieve the cleanest possible product while keeping the Total Cost of Ownership low. Thanks to its high porosity, high air permeability metal fiber media has a high dirt holding capacity, a lower pressure drop and therefore a longer lifetime. In other words, it means that your filter will be able to trap and hold a high level of contaminants before reaching the maximum allowable pressure drop.

An advantage of polymer filter candles is that they are re-useable: once the filter is saturated, you can easily remove the filter element, clean it, and therefore extend its lifetime even more, without losing the filtration quality.

The cleaning of filter media is a combination of chemical and mechanical processes, typically used in combination. Those processes will be preceded by some pre-cleaning steps and followed by 3 validation compulsory tests to ensure the effectiveness of cleaning without damaging the parts.

Pre-cleaning steps
The first step of the cleaning process is to remove the polymer or major contaminants. Different methods are available: solvent bath, pyrolysis, and hydrolysis. Each of them has its own advantages.

The method used for contaminant removal will depend on the substrate and the contaminant Please note that other methods exist but I’m not mentioning them as they present more disadvantages.

Final cleaning
After gross contaminant has been removed, filters parts still need to be cleaned. They will go first through a chemical cleaning (caustics and/or acids), before undergoing a final cleaning, this one mechanical (backflush) to get rid of the last remaining dirt/additive.

Validation methods
When the cleaning process is over, it is important to make sure the polymer has been removed safely and effectively from the filters. A quality check will be applied through 3 different tests:

The “Bubble point test” to evaluate possible element damage
The “Backflow test” to evaluate the cleaning quality
The “Weighing test” to conclude element acceptance or rejection
(after cleaning)

Want more information?