Submicron cartridge filters are broadly used to clarify,purify or decontaminate many liquids in several industrial fields.Such applications are the processing of ultrapure liquids for making electronic components,the cold sterilisation of wines,bioliquids and pharmaceutical solutes,and the decontamination of industrial solvents and washing liquids.Microfiltration cartridge filters,with ratings below 3 urn,are installed as prefilters and are pleated,agglomerated or wound.The performance and ability to use these prefilters are determined in laboratory conditions according to standard methods adopted by filter makers and large end users.For instance,the rating is determined using water or a mineral oil as the test fluid,ISO MTD according to ISO 12103 as a test powder,and online particle counting with light extinction instruments to count particles at various sizes upstream and downstream of the test filter to calculate its instantaneous efficiency.Reading technical brochures of submicron filters show they are mainly characterised by their microbial rating (they are regarded as sterilising if they reduce to a given ratio the number of standard microorganisms).Very few brochures state a micron rating based on particle size and when they do,they do not refer to any test method.To answer the need of several large end users,IFTS has developed a new protocol to measure filtration efficiency during the clogging of submicron and microfiltration cartridges.This paper describes the test powder chosen,the test circuit designed,validation results,criteria and typical test results obtained for several cartridges bought on the market.
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