Read the NIOSH white paper:
The Effectiveness of Several Enclosed Cab Filters and Systems for Reducing Diesel Particulate Matter
by James Noll, Andrew Cecala, John Organiscak
The National Institute for Occupational Safety and Health has researched filtration methods for effectively removing Diesel Particulate Matter (unburned diesel fuel) and Respirable Crystalline Silica (RCS) from the air in an enclosed operator cab. The development of the Sy-Klone RESPA® Cab Air Quality System came from this research. While not directly endorsing a product or company, NIOSH is very interested in scientifically demonstrating the effectiveness of known technologies in solving air quality problems. The goal is to provide the cleanest air with the lowest concentration of respirable particulate (particulate between .3 and 10 microns) into an operator cab on fixed or mobile equipment.
NIOSH tested the highest efficiency filters that are available today. The filters in this test were Sy-Klone filters and are the standard filter options available in the RESPA® Cab Air Quality System.
Test results showed that the lower cost, High-efficiency MERV 16 filter, was an acceptable alternative to the HEPA filter. The test evaluated the filters in the laboratory under strict test conditions which used carbon particles typical of DPM to evaluate the effectiveness of each of the filters. The initial test was performed on clean filters. The test was then redone after the filters were exposed to a constant stream of particulate for a short period of time. The difference in performance between the higher efficiency HEPA filter and the MERV 16 filter was so similar as to be beyond the test equipment’s ability to tell the difference in efficiency.
The conclusion was that it is not necessary to use the HEPA filter to obtain the desired result of particulate removal from an enclosed operator cab. In fact, the recommendation is to save the money and enjoy the longer filter life associated with the MERV 16 filter with the confidence that you are doing all that is required and necessary to provide clean air to the operator cab.
This test was not done to validate any regulatory issue or particular application. The research validates the effectiveness of the MERV 16 filter in the removal of DPM and elemental carbon sufficient to comply with industry Permissible Exposure Limits (PEL’s), Time Weighted Averages (TWA’s)and Occupational Exposure Limits (OEL’s).
Particulate filters discriminate based on particle size. While this test was performed on carbon particles the filter cannot discern particle types. Therefore, if the filter is effective on carbon particle down to .3 microns is it is effective on all particles down to .3 microns.
Only particulate below 5 microns was desirable for the test. As shown in the schematic of the test equipment in the white paper, the Sy-Klone Gideon® Powered Precleaner was made a part of the test equipment to remove the particulate larger than 5 microns from the test chamber.