The ideal air flow is designated as laminar, or even flow. This is construed as an air supply which has only slight velocity variation, when measured from ceiling to floor. This variation cannot exceed 15%. In order to achieve this desired air flow, special air distribution systems must be constructed. The primary goal is to provide the proper cubic foot value of air to the range through the supply duct trunk. The air is then to be distributed through a continuous graduated plenum to a singular continuous diffuser system. The diffuser system may vary in type per each application. Either way, each configuration should provide for an even flow of air across the entire width and height of the range.The exhaust duct system should be constructed in a fashion that evenly extracts the supply air from the range. Our experience in this matter has been to create an extraction opening the width of the range, and capable of sustaining an inlet, or capture, velocity of 2000 feet per minute.
The exhaust fan and filter system should be designed to allow for 350 to 500 fpm velocities across the filter media. The exhaust fan should be sized so as to allow for operational static pressure a 5" wg at the desired volume of air flow. The filter media should be that of at least 95% at .03 microns. This will help achieve the federal exhaust emission levels established under EPA 40 CFR 50.12 (1.5 Micrograms of lead per cubic meter quarterly).