One of the first things to consider when buying a commercial range hood is your fire code. Some regions have both national and local codes that outline mandatory specifications for commercial kitchen equipment. It is also important to determine the size and type of hood needed, which exhaust fan will work best, whether or not you are required to have a make-up or supply air fan, and the type of fire suppression system you wish to have installed.
Most fire codes have very specific requirements for commercial kitchens and concession stands. These usually specify how much larger the commercial range hood should be than the cooking area it covers. In the US, the national fire code requires a minimum of a six inch (2.4 cm) overhang on all sides, though codes in other jurisdictions may differ. The type and size of fans and requirements for fire suppression may also be specified, and the code may require that the system only be installed by a licensed contractor.
Restaurant cooking areas may contain a range, griddle, broiler and gas fryers. These are generally placed together, so only one commercial range hood is required for the entire area. Most kitchens will need a grease hood system to filter the grease vapors created during food preparation. If the area to be covered only contains a dishwasher, steamer, pizza oven, or other implements that do not produce grease vapors, then a heat or condensate hood will suffice.
An exhaust fan is attached to the commercial range hood to pull the air and fumes up out of the building. The speed of the air flow is measured in cubic feet per minute (CFM). The size and speed of the fan are determined by the size and type of hood installed, as well as the kind of equipment that is being covered. The location of the cooking area is also important, since different styles are required depending on whether the hood is attached to the wall, or is located in the center of the room.
Make-up, or supply air fans, put air back into the room. Some codes require these, depending upon the size of the exhaust fan. Even if they are not required, they are often recommended to balance the air pressure in the room. The upblast fan does need some negative pressure, so it is recommended that the supply air fan work at 85% of the speed of the upblast fan. For example, if air is being removed at 4000 CFM, then the supply air fan should be set at 3400 CFM.
Fire codes often require the installation of a fire suppression system with the commercial range hood. These are operated by fusible links located throughout the vent system. The links are attached to the control head by a tight cable. When one of the links melts, the cable goes slack, and the fire suppressant is released.
Determining your particular requirements for a commercial range hood does not have to be complicated. Manufacturers’ spec sheets are available on the Internet, and are designed to accommodate national fire codes. Specific information for your area can be supplied by a commercial range hood dealer.