Three Strategies to Minimize Loss from Industrial Oven and Dryer Fires
Last month, fire broke out in a production oven processing a rubber product at American National Rubber Co., located in Ceredo, West Virginia. No injuries were reported in the incident. The fire ignited inside the oven, apparently from self-heating of an accumulation of combustible residue. The fire spread into the exhaust ductwork, also facilitated by the presence of combustible residue accumulations. The fire department attacked the fire in the oven with hose streams, affecting extinguishment. They also made a separate attack with hose streams to extinguish the fire inside the ductwork. Firefighters observed that the oven was provided with an interior fire suppression system, which apparently was active, but not successful in extinguishing the fire. Further details are not publicly available.
The fire department report indicates that heat from the fire in the oven transferred by conduction or radiation to rubber material stored on pallets in close proximity to the oven, igniting this material. This fire was external to the oven and caused the activation of 5 sprinklers at the ceiling, which controlled the fire. The fire department completed extinguishment.
Although information on this fire is limited, it suggests three strategies that have proven very useful for safe operation of ovens and dryers that process combustible materials, and help to minimize the extent of loss should a fire occur. These are:
- Regular and effective cleaning of the oven and exhaust ductwork should be performed to prevent accumulations of combustible residue. If combustible residue is allowed to build-up in piles or layers of significant thickness, the material may self-heat, leading to ignition of a flaming fire. A flaming fire can then travel throughout the oven and exhaust ductwork by consuming the fuel present in the residue accumulations. Effective, regular cleaning virtually eliminates this risk.
- Where a fire suppression system is installed to protect the interior of an industrial oven or dryer, and the connected exhaust ductwork, that system, whether automatic or manual, must be properly designed, maintained, and periodically tested to ensure it will reliably and effectively suppress the fire. If the system is old and without documentation of design, a design professional with proper experience should be hired to evaluate the effectiveness of the system design, with corrections made as required.
- A clear aisle should be established and maintained surrounding all industrial ovens and dryers. The aisle width is dependent on specific circumstances, but should be sufficient to provide enough separation between the oven on all sides to prevent ignition of adjacent combustible materials in storage or in process. An appropriate clearance should also be provided surrounding all exhaust ducts. Clearance is deemed to be sufficient if the temperature at the location of storage or staging of combustible materials is not in excess of 160° F (71° C).
Additional information for managing the risks associated with industrial ovens and dryers can be found in NFPA 86, Ovens and Furnaces (2011 Edition), published by the National Fire Protection Association.
By Jeff Harrington, CEO and Founder of Harrington Group, Inc.