The first step in designing any commercial kitchen ventilation system is to deal with the cooking hood. The cooking hood is a capture and containment device that is presented to the mechanical engineering designer in a package of catalog material. This information is from the kitchen equipment layout designer (who is often the supplier). The type of hood, the size of the canopy, the recommended ventilation (exhaust) rate (cfm), the filter bank type, and the static pressure resistance of the hood/filter package requirements are included in this initial submission. Now it is up to the mechanical design engineer to connect the hood collar(s) to a steel duct system, which is required to be grease tight, liquid tight, thermally insulated, accessible for cleaning, installed with a drainage slope, able to maintain a minimum code velocity, and connected to an air movement device called an exhaust fan.
The code that governs this system is the International Mechanical Code (IMC) - 2009, Sections 506.1 through 506.5.5.; Commercial Kitchen Hood Ventilation System Ducts and Exhaust Equipment. The Commercial Kitchen Hoods Code requirements are defined in the IMC-2009, Section 507.