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The selection criteria is very simple.
If you see the cataloug of these units they show the capacity of these units by how much smoke and grease particles they can remove from air with selected CFM and heating working conditions. So check what are your requirements of system whether in kitchen or exhaust system and then you can select from that catalouge\\ selection charts.
Hope this will work.
1. In commercial kitchens, determine type of food to be cooked. Is it light duty, medium duty, heavy duty or extra heavy duty cooking. This will determine the type of filters required inside the Ecology Unit. Moreover in general an ecology unit can be designed to remove oil, grease, mist, smoke, VOCs and odor. from kitchen hood.
2. Based on the Kitchen Hood size, type of food to be cooked and Air change rates determine the exhaust airflow to be handled by Ecology unit
3. The Ecology unit filters will be associated with an internal static pressure loss. The duct work and bends etc will constitute external static pressure loss. The sum of internal and external static pressure loss will determine the total static pressure of the Extract fan. Usually we select SWSI or DWDI fans. The Ecology unit will also have a control panel and VFD panel. The control panel options required need to be determined from the client.
4. The various filter stages inside Ecology unit and its intended purpose
First Stage- Electrostatic Presipitator- To arrest oil, grease, mist and smoke particles. It can be slected for 95% effeciency
Second Stage- Metallic filters ; Grade-G2- Exclusivley to arrest oil, grease and mist
Third Stage - Disoposable filter; Grade-G4- To arrest Coarse particles
Fourth Stage - Fine Filters; Grade-F8- To arrest Fine particles
Fifth Stage -Carbon Filter ( 50/50 Blend of Carbon & KMnO4)- To arrest odor and smell
HEPA Filter- Grade E10/H10- To arrest black smoke
The filtration stages can customized based on client or consultant specification.
In my opinion the best answer is what Mohammad Sharif Says. Here I would like juts extend his answer:
Step1. Determine the air flow rate of fan. This is calculated by determining air changes based on related standards/guidlines. For example you may find a table in this regards in ASHRAE handbook.
Step2. Then calculate the pressure drop which fan shall overcome. In this step you must be aware about air way and duct sizes in addition to air velocity through different parts of air way.
Step3. After finding air flow rate pressure you can select the fan which generaly lead you to unit size.
Step4. After all you must determind the air required quality to select the right flteration method. Please note that filteration has direct impact on pressure drop and may cause you re-calculate your fan selection.
mainly arslan's answer is enough
- CFM
- ESP
- air quality needed
Above answer is for to select exhaust fan
