New filter media protects against respirable silica dust

New filter media for cabin air filters from MANN+HUMMEL meets the US requirements for the MERV 16 filter class. That means it effectively protects drivers in cabs of construction machines against respirable silica dust.

The dust levels on construction sites, in mines, and in tunnels can be very extreme. Depending on the work operation, building sites generate kilos of dust per hour. This represents the hardest conditions for machines and their operators. The cabs of construction vehicles therefore have to be comfortable and also effectively protect the driver against harmful dust particles. This includes, for example, respirable silica dust particles. The breathing in of these particles can lead to serious lung diseases including silicosis. For this reason, the US Occupational Safety and Health Administration has published the 1926.1153 standard. This defines the procedure for dealing with dangerous concentrations of respirable crystalline silica dust.

 

Stress test for filters

If the machine operator is exposed to an average concentration of more than 25 micrograms per cubic meter of air within 8 hours, the cab must be pressurized and the intake air must be filtered to separate particles in the range of 0.3 to 1 micrometers with an efficiency of 95 percent. That corresponds to the MERV 16 filter class in accordance with the US ASHRAE 52.2 standard. MERV stands for "Minimum Efficiency Reporting Value". A standardized test procedure for the filter class verifies the effectiveness of the filter to protect against silica dust. In this process a solution of potassium chloride is atomized in a test channel. The number and size of the crystals formed as a result are measured upstream and downstream of the filter in order to determine the separation efficiency. Due to its similar particle sizes and characteristics, the test aerosol is comparable to silica dust. This test is performed on new filters and filters filled with dust. The lowest measured value is then decisive for the definition of the filter class. For MERV 16 this means that the filter must have a separation efficiency of at least 95 percent for potassium chloride with particles between 0.3 and 1 micrometer. That corresponds approximately to the F9 filter class according to the European EN779:2012 standard.

In use all over the world

The MANN+HUMMEL product range now includes a new synthetic filter media designed especially for this performance class which can be used in all common cabin air filter designs for construction machines. It reliably protects operators in cabs worldwide against harmful silica dust particles even under the most dustiest operating conditions.