When the amount of air removed from a commercial kitchen is greater than the amount of air being replaced, dangerous drafting (called backdrafting) can occur. Backdrafting can cause flash flames, which could easily ignite any greasy residue that may have collected on the cooking surfaces or commercial hood.
Backdrafting can occur as a result of not having the proper replacement make up air system in a restaurant kitchen. Many restaurant owners focus on the commercial kitchen ventilation equipment that is necessary for removal of the contaminated air, without fully considering how that removed air is going to be replaced. With too much negative pressure building up in the kitchen, backdrafting will develop. This will cause doors to stick, papers and debris to blow around, and flames to flicker erratically. Any of these conditions can be dangerous.
In order to prevent the development of these dangerous backdrafts, special backdraft dampers can be installed, along with replacement make up air systems. By preventing the return of the captured and contained air, and replacing the air that has been removed, the proper air flow can be maintained. Generally speaking, a good rule of thumb for airflow is about 2000CFM in a restaurant kitchen. This will help to avoid the development of backdrafts.
There are different types of backdraft dampers that are available. Some are metal and will help prevent the removed air from returning. Metal backdraft dampers do have the downside of being loud when they open and shut. Fabric backdraft dampers are also available and are far quieter, yet still efficiently prevent backdrafting in commercial kitchens.
The cause of backdrafting is the improper airflow that can result from poorly designed and installed commercial kitchen ventilation systems. Preventing backdrafting requires simple but important components that must be present to keep the restaurant kitchen safe. A professional commercial hood company can investigate problems associated with backdrafting and help to provide the appropriate solution.