The testing of air filters for use in general ventilation technology and as automotive cabin air filters A comparison of the developments in the field of particle filtration over the last 25 years

摘要

Air filters are subjected to standardised tests agreed upon at national or international levels in order to demonstrate performance to the customers as well as for internal quality assurance purposes.The fundamental meaning and purpose of standardisation is explained in a review article by Ripperger as”Standards are a means of standardising material and immaterial goods [1].They also provide recognised solutions for recurring tasks.One objective of standardisation is to promote national and international exchanges of goods and services”.The primary objective is not to represent”reality”,since standard-compliant filter testing serves only to evaluate a filter under comparable,i.e.reproducible,conditions.It is not possible to confirm the performance of filters in real operation(especially over their entire service life)based on these laboratory results.This requires additional tests with outdoor air.On the other hand,a standard-compliant measurement must not be completely isolated from the actual conditions in practical use,as new media and filter elements are developed specifically with regard to the classification in the standard.Direct comparisons of filter tests,run according to current standards and guidelines,to practical results have been the subject of several application-oriented research projects in recent years [8].In some cases,large differences were found between the results of standard-compliant and practical measurements.In particular,the practical testing of vehicle cabin air filters revealed significantly lower collection efficiencies1 than could be expected from testing according to the standard.Some of these research results were also published in this journal [3]-[7].