Recent industry testing now proves that typical baffle filters are only about 15% to 30% efficient. This testing sponsored by ASHRAE's Technical Committee TC 5.10 for Kitchen Ventilation was conducted under Research Project #1151 proving that typical baffle filters are very inefficient in capturing grease particles under 10 microns. New two stage filters are being marketed as being as much as 80% efficient.

For years, the capture efficiency of baffle grease filters had been marketed to the industry as being as high as 95% efficient. We all accepted that fact. We now know this to be fact, but with a vitally important distinction. It only applies to larger particles of grease greater than 10 micron size. The test formerly used was developed by the U.S. Navy and did not take into account smaller grease particles below 10 microns in size. The fact is that the majority of grease particles from normal commercial cooking operations are predictably under 10 microns.

Some caution needs to be taken as these new dual stage filters significantly increase static pressure resistance and may not readily replace typical baffle filters in marginally operating systems.

The first entry was developed by Greenheck and named the Grease Grabber. It is a combination of a newly designed front filter called the Grease-XD-Tractor and a rear or second stage filled with a ½" bead bed. The front face has a new look that employs air inlets at the top and bottom only. Together they become the Grease Grabber model. Greenheck has been successfully producing and marketing this new line of filters for approximately three years. Grease Grabber is a UL listed device in accordance with UL 1046.

A second manufacturer is just introducing their Grease-Stop Combo filter. This filter uses a familiar looking baffle filter in front with a removable second stage that snaps in place on the rear. The second stage employs porous ceramic beads that capture and store or hold the grease molecules. The manufacturer, Captrate claims a 70% capture rate for grease molecules down to one micron. Captrate has ETL listing is in accordance with UL 1046.

These new designs reportedly trap significantly more grease emissions and represent a major step forward in reducing the amount of grease passing through the filters into the plenum, duct work and fan. It should be noted that filters do not remove vapors, only particulates most often referred to as grease particles.

Contact either manufacturer at their respective websites for greater detail, testing information and charts. Contact Greenheck at www.greenheck.com and Captrate at www.captrate.com.