Exploring new paths in air filter testing

Mann+Hummel, OE equipment supplier to the international automotive industry, has developed an innovative soot particle test rig for intake air filters. With this new test module, contamination of filter elements through superfine soot particles from road traffic can be very accurately simulated in the laboratory.

The outstanding feature of the text rig is its new soot particle generator, which can consistently simulate in the laboratory the actual effect of superfine particles on the filtration behaviour of filter media.

It offers the advantage that air filter elements can be more specifically designed to meet the vehicle manufacturers’ requirements.

Up until now, the test dust used by filter manufacturers to record in the lab the filtration efficiency and dust holding capacity of intake air filter prototypes in accordance with ISO 5011 consisted of quartz particles between 0.3 and 300 microns in size. Filter elements are however exposed to increasing quantities of extremely fine particles of less than 1 micron. These are generated from road traffic, industry and houses and consist primarily of soot. Ingress of this fine dust with the intake air into the engine leads to wear and damage to mechanical and electronic components.

In addition, fine dust significantly reduces the life of air filter elements, as superfine particles of soot clog the filter media far quicker than coarse dust. They block the pores in the media, forcing air to flow through an increasingly narrow cross-section and thus increasing the pressure differential of the filter element. Through the resulting increase in fuel consumption and premature clogging of the filter, service life is reduced and costs are increased.

The core of the testing unit is a PC-controlled soot generator which burns propane to produce soot particles with an average diameter of 80, 95 or 110 nanometres. The generator is linked to a highly sensitive particle measuring system which continuously monitors the size distribution and concentration of the soot particles.