This week some considerations in fighting fires in ductwork systems.
There are not an awful lot of commercial ductwork fires as there used to be in the early manufacturing days but this week we will take a look at some of the considerations for handling these in-frequent emergencies.
First and foremost you should identify buildings in your response area that have large runs of duct.
The second issue is to determine what the use is for the duct. Some common uses are handling cooking vapors, sawdust collection, plastic pellet collection, lint collection, and simply forced hot air for heating.
Obviously if there is any product handling in the ductwork the potential for fire spread is great, and this will create a significant problem.
While looking at the various potential duct in your response are, determine what, if any protection or detection might exist. This could include and should include a minimum of heat detection, self closing dampers to limit smoke spread, (Not always flame spread) and may even include sprinkler protection.
Some techniques or possible tactics.
Investigate the incident and do a good size up and locate the fire within the ductwork. This might be indicated by: No visible fire, paint blistering, fire showing from a roof or outside area at the vent outlet, but often the interior signs may be limited. There are also times where smoke from another source is being drawn into the duct.
Upon arrival and make the determination the fire is in the ductwork.
Get a line in position at the base of the ductwork and areas of vertical or horizontal exposure within the building.
Use the Thermal imaging camera or multiple cameras to determine the extent and travel.
Shut down any blower system if it has not already automatically been shut.
Ventilate area as needed.
Look for any clean out or service openings for the duct and remove any access panels with lines in place.
Consider the use of dry chemical extinguishers. (These are great for this type of fire but the configuration and dampers can prevent the agent from reaching the fire sometimes)
Assign companies to the roof.
Open up ceilings and side walls as necessary to determine if there has been any extension.
These fires require much effort in locating and final extinguishment. They should be treated as fires in void spaces and concealed spaces.
Bring in tools for opening the ductwork and for all of you new folks ask some of the older members about the “tin roof cutter” they used to carry!
Stay safe, and stay thinking!