By law, kitchen exhaust cleaning is required for virtually every commercial cooking establishment in the United States. Duct cleaning is a part of this. Restaurants, hospitals, hotels, employee cafeterias and other food service locations have a “hood” and duct work over the stove to exhaust smoke, steam and fumes out of the building.
These exhaust gases leave a residue on the inside of the duct work. This is usually a grease residue of some sort, depending on the type of cooking. Char broilers commonly leave heavy black grease. There are some foods that, when cooked, leave a sticky or rubbery residue. When a charcoal or wood-burning stove is in use, soot and ash residue builds up in the duct work. Dishwashers leave heavy lint deposits. Duct cleaning services address these concerns.
When the buildup of grease becomes heavy, a fire hazard exists. Approximately one in three restaurant fires are caused by grease. A common scenario of how a kitchen exhaust fire starts is this:
- A flame flares up on the stove.
- The fire comes in contact with the filters above the stove on the kitchen hood. The filters ignite.
- When the exhaust fan is on, air is drawn into the hood, through the filters, and up the duct work, spreading the flames.
- If significant grease residue exists on the duct interior, it acts like a fuel and the fire spreads up the duct work more rapidly, perhaps all the way into the fan. We have seen fire climb up a ten-story duct to the fan on the roof burning up the fan.
Modern duct construction is designed to hopefully withstand such duct fires. The duct seams are welded to prevent grease or fire from leaking out and the shafts around the duct are made of fire resistive materials. However, older buildings are still at risk, and even in modern buildings, the fire may penetrate through the duct work or escape onto the roof via the fan. When an exhaust system is cleaned regularly, the chances of a duct fire are extremely remote.
In virtually all the duct fires we have seen in our 25 years of experience, the ducts were extremely laden with grease or other flammable material. We can evaluate the status of your duct work for you.