Trainer’s Corner: November 2014
By Ed Brouwer
If the effects of the approaching cooler weather stay true to our country’s history, there will soon be an increase in fire calls. Most residential fires in Canada occur during the winter. This is also true of fire fatalities. Sadly, more people are likely to perish due to an accidental home fire during the holiday season than any other time of the year.
There are three major causes of residential fires during the winter. Two of the three will come as no surprise: chimneys and candles. The third cause is clogged dryer vents. In fact, according to the NFPA, the number of dryer-vent fires has exceeded chimney fires since 2005, and most dryer-vent fires occur in January. Some researchers list dryer-vent fires as the No. 1 cause of residential fires.
As for candles, we all love the warmth and ambiance they provide, but it is easy to forget that a candle is an open flame that can reach 1400 C. Most candle-caused fires start in the bedroom, except during the holidays when decorative candles are involved.
The most common cause of chimney fires is the ignition of creosote in the flue. Creosote forms primarily due to the use of unseasoned or green wood in the fireplace. There are other factors that can lead to creosote buildup, such as failure to maintain a proper temperature inside the flue, burning wet wood, or failure to clean the chimney regularly.
Fires in masonry chimneys can burn to a temperature of 1093 C. These fires can damage the masonry material, which can then provide an opening for fire to escape into voids of combustible components such as the inner walls or attic space.
There are several indicators of a working chimney fire:
- Sparks or flames exiting the top of the chimney
- A whistling or buzzing sound in the chimney
- A back flow of smoke through the heating device into the structure
- Discoloration on the walls adjacent to the chimney
- Smoke emanating from the cracks in the wall or electrical outlets near the chimney
The potential for injuries at a chimney fire may be greater than previously thought. NFPA 1500 Standard on Fire Department Occupational Safety and Health Program requires an EMS unit on fire responses.
The following tactics should be considered when establishing standard operating guidelines for chimney fires:
- Establish command upon arrival; safety officer and RIT should be assigned.
- Conduct an exterior size-up and look for signs of a chimney fire.
- Call for resources to ensure safe operations.
- Gain entry; search for and remove victims; wear full PPE and SCBA; monitor oxygen levels and ensure adequate ventilation. Consistently monitor oxygen levels for carbon monoxide (CO). Chimney fires can cause the flue to fail allowing CO to escape into the walls, ceilings, attics and other voids.
- Perform horizontal ventilation if needed. Positive-pressure ventilation is the method of choice in these situations. The ventilation exit point should be as close to the heating device as possible, thereby minimizing the spread of smoke within the structure.
- Advance a hoseline to the front door as a precaution.
- Spread a runner or salvage cover on route to the stove or fireplace. Not only does a salvage cover catch any ashes or embers that may fall, when and if the wood is removed from the firebox it also keeps bunker boots from tracking dirt onto the carpet. Plastic tarps fail quickly when they come in contact with fire embers, so consider fire-resistant cloth tarps.
- Stop the flow of oxygen to the flue. Reducing the oxygen flow to the flue decreases the intensity of the fire in the flue and in some cases will extinguish it completely. This step may not be possible on open fireplaces.
- Extinguish the fire in the firebox. Before you put the fire out, consider using the fire in the firebox to your advantage. Sometimes a mere cup of water applied onto the burning fuel will cause the resulting steam to travel up the chimney and extinguish the flue fire. Multipurpose dry-chemical agents will put out the fire in the firebox, but will not usually extinguish anything further up. Only remove fuel from the firebox if it has been extinguished and if absolutely necessary (there are very few good reasons to take this step).
- Ladder the roof. If an aerial device is used, it should be extended to the chimney opening. If ground ladders are used, a wall or extension ladder should be placed at a good roof entry point, and a roof ladder should be extended to the roofline adjacent to the chimney. If the roof is covered with combustible material, a charged hoseline should be advanced onto the roof as soon as the ladders are in place. Do not place the ladder or secure the ladder to the chimney. Cautiously remove the chimney cap, bird screens, or spark arrestors with a hand tool. All firefighters on the roof should be wearing full PPE, including SCBA.
- Each of our trucks has a chimney kit consisting of a mirror, a length of chain (4.5 metres), and a chimney bomb (zipper-seal bags containing dry-chemical powder), and a small fire-place shovel, all placed inside a metal bucket.
- Inspect the chimney using the mirror. If there is fire, drop the chimney bombs down. When the chimney bomb reaches the firebox, the bag will burst and the normal draft will carry the powder up to extinguish the creosote. (Be sure to communicate your actions to the interior team).
- Slowly lower the chimney chain from the top of the flue to the firebox. Spin the chain to knock the creosote from the walls onto the firebox where it can be extinguished with water or a dry-chemical extinguisher. There is some opposition to putting water down the chimney based on the fear that the water may rapidly cool the flue causing it to fracture. These fractures may then go undetected and future use of the chimney may result in products of combustion being released into the walls or attic. The key is in the amount of water used and how it is applied. There are special nozzles (six liters per minute) designed to apply water inside the chimney.
- Check the clean-out box. This is perhaps the most over-looked step. Clean-out boxes can be found both inside and outside the house. The boxes are usually covered by a 20-by-20-centimetre metal plate with two handle tabs on it, mounted on the wall in line with the chimney. There may be more than one – I once found three. After locating the box, use a small shovel and a metal pail to clean out the burning embers. Once this is done, you can place a small, handled mirror into the box to look up into the flue. You should be able to see if there is still a fire in the flue.
- Check for fire extension. Look for obvious signs of fire extension beyond the chimney. All roof, attic and wall areas near the chimney and heating devices should be checked for the following signs of fire extension: discoloration or blistering of surface materials; hot-to-touch areas; smoke coming from cracks, electrical outlets, light fixtures, eaves or roof coverings; visible glowing embers. This is a great time to use a thermal imaging camera or heat sensors if your department has them. Be sure to check each floor. If the fire extends beyond the chimney, treat it as a structure fire.
- Before leaving the scene, inform the resident that the chimney must be inspected by a certified chimney inspector before it is used again. Our department has forms made up that clearly lay this out for the resident. We get them to sign and date it and leave them with a copy. We also inform our dispatch that the resident has been advised.
- Check the CO levels one more time before terminating the incident.
Thank you for your continued efforts to make sure all our firefighters get home safely after each call. Please drop me a line if your department has any hints for dealing with dryer-vent fires. There is very little information available in print, so your input would be invaluable.
Stay safe and remember to train as if their lives depend on it.
Ed Brouwer is the chief instructor for Canwest Fire in Osoyoos, B.C., and Greenwood Fire and Rescue. The 25-year veteran of the fire service is also a fire warden with the B.C. Ministry of Forests, a wildland urban interface fire-suppression instructor/evaluator and an ordained disaster-response chaplain. Contact Ed at firstname.lastname@example.org