In the first place, through the use of mechanical filtration that is often used in commercial kitchen hoods, just the grease particulate (solids) can be captured and removed, but the vapor in the process of cooking can not be exhausted. Secondly, as the cooking processes and cooking foods are different, the particulate to vapor ratios will be different, which is further proved by American Society of Heating Refrigerating and Air conditioning Engineer (ASHRAE) study RP-745. A lot of end users, hood manufacturers and other industry experts collectively devised a common standard way to preform tests on how to determine the filter efficiency of grease particle. After a long time of research and tests, a standard test method, which is now known as ASTM F2519-2005 has been developed to identify grease filter particle extraction efficiency.
To resolve the problem of grease in commercial kitchens, the filtration method of exhausted air flow is used. Over the past 20 years, equipment for commercial kitchens use has been rolled out to the market, among which grease filters are a mainstream. There are two kinds of such filters: baffle and cyclonic filters.
The baffle filter is the most often used type of filter for commercial kitchen hoods. Baffle filter creates inertial force in the turning process as the airstream travels through the filter. But this type of filter has the design of the lowest efficiency on the market. There is another alternative to the baffle filter is centrifugal filters. Centrifugal filters use a centrifugal force to swing the air in the pattern that looks like corkscrew to get the grease out of the airstream. Centrifugal filters have the middle-way grease removal efficiency and they are a great choice over baffle filters.
There is yet another commonly used method for grease removal, which is multistage filtration. Multistage filtration adopts a baffle or centrifugal filter or other filter types as a primary filter. Also, a secondary filter with some type of media is also used. Combining these two stages, they together remove the smaller grease particles that other filter can not exhaust. So the mechanical efficiency of the multistage filtration is the highest of all. There are also other types of filters, such as high velocity cartridge filters and water wash/ self cleaning hoods that can offer different grease removal efficiencies.