Filtering cartridges are very common products used in many industrial processes to clarify/decontaminate a broad variety of liquids (beverage, pharmaceutics, chemicals, paints, varnishes, blood, drinking water,…) and on as many types of machines (aircrafts, engines, boats, fluid power systems, road and off-road vehicles, machine tools,…).
If efficient, all filtering cartridges, whatever their type, clog, what means their differential pressure increases and/or flowrate decays. Then they cannot fulfil their function correctly and need being replaced. This creates a huge market of renewable products with plenty of suppliers offering very diverse cartridges.
Criteria to choose a cartridge and its supplier rather than another one strongly depend on its application. But in all cases, the key criterion is filtration efficiency. another one possibly being retention capacity.
Filtration efficiency guarantees the quality of the filtered liquid. It is specified/expressed by a percentage of efficiency in percent or a filtration ratio (e.g. ß) at a given particle size or by a rating, i.e. a particle size supposed to correspond to a given, often not claimed, efficiency.
Since the efficiency measurement method, equipment and products directly impact the values of efficiency, many professional sectors, including filter cartridge manufacturers and their end users agree on standard methods, often a compromise between technical and cost requirements, such as ASTM, NFPA, SAE or ISO standards.
All standard procedures allow variations of different details, e.g. accuracy of measuring instruments, variations in test conditions, type of equipment, validation criteria, etc. This means that performances claimed according to any standard by any manufacturer may not be comparable to those claimed by a competitor for the same application.
Thus only independent third party testing centre results can really be trusted when evaluating competing products.