Tips on Extinguishing Chimney Fires That Improve Efficiency, Public Image
During cold weather, fire departments respond to numerous chimney fires, especially in the frost-belt states. Although many of the incidents are minor, they always provide an excellent opportunity for a department to demonstrate its efficiency and effectiveness to the public.
The boom in solid-fueled heating appliances will not be a temporary one. The energy crisis guarantees that wood stoves will long be with us.
But in reviewing the programs of many fire departments, I find little effort to analyze or train for handling chimney fires with consistency. In many cases poor methods are being used. Be assured that department actions resulting in a damaged chimney will be remembered at times of budget requests or fund drives.
When a person calls for help, the department dispatcher should be ready to reassure the person and offer a few simple suggestions, in addition to transmitting the alarm. Before the apparatus arrive, the fire inside the heating appliance can be reduced by a covering of household baking soda. It makes less mess than the high velocity discharge of a pressurized fire extinguisher. Thoroughly wet newspapers may also help. All residents of the structure should be evacuated if smoke is found inside.
Particularly in rural areas, the caller should be requested to identify the involved structure in some conspicuous way. All chimney fires are not readily detected from the road. If the caller is asked to cover his mailbox with a pillowcase, for example, this prevents the time delay suffered in searching back and forth through a poorly marked neighborhood. This also gives the caller a sense of activity until that first siren is heard in the distance.
Hopefully, the response will be at least an engine and adequate ladder service. “Adequate ladder service” may mean an aerial ladder for some situations but usually includes pumper ladders, smoke ejector, lights, and other ladder company tools that may be carried on an engine. A tanker or a rescue van responding alone offers serious deficiencies as a standard response because chimney fires can become attic fires or wall fires.
Apparatus responding to chimney fires should also carry a variety of extinguishers and a chimney kit of those items the fire department has found helpful at such fires. The kit can contain such things as a 5-gallon metal pail with a chain and weights, a chimney mirror, asbestos mits or equivalent substitute, a coffee can of baking soda or alkaline base (B:C-type) dry chemical, and a child’s sand shovel. Your own experience will add or subtract from this list. The metal pail, however, does provide a container for the items while also serving as a receptacle for hot embers and debris.
Manpower needs vary depending on the policies of the fire department regarding what will be done. Generally, however, it is helpful to have two roof men to ladder the roof alongside the chimney and dislodge obstructing or burning residue, an officer and an inside man. All must wear full turnout gear. The roof crew should use goggles to protect against cinders. The turnout gear serves two important functions on any emergency call: It literally protects your skin while simultaneously displaying a reassuring atmosphere of professionalism.
Checking for extension
As with any fire, the first duty upon arrival is size-up. The involved chimney or flue must be located and fire severity determined. Particularly in the case of an insulated flue, interior temperatures in excess of 2000°F may be experienced. No flue is designed to contain chimney fire temperatures as a steady condition. Therefore, the practice of allowing chimney fires to burn out a flue is strongly discouraged. Should your size-up show that the chimney fire is out upon your arrival, you should still perform a check for extension, covering the entire height of the chimney flue and all connectors.
Some standard procedure must be devised for those chimney fires which are not out on arrival. In determining the proper method of fire attack, we must not forget that a chimney flue represents a ventilation system. If we merely avoid interference our vent should already be accomplished—at least in part. Keep that nozzle away from the outside chimney outlet!
Use of water spray
One effective method of attack is the use of water spray from the base of the flue. Experienced wood burners have been extinguishing chimney fires for years by means of a garden hose spray directed from the base of the flue. Although this is not a practice to recommend to the general public, it is adaptable to trained fire fighters. Some companies purchase and modify a booster hose applicator or piercing nozzle to reduce flow and increase atomization for this purpose.
Additionally a few commercially produced chimney nozzles remain in existence. The Old Town, Maine, Fire Department uses a ¼-inch chimney nozzle with a nozzle pressure of 200 psi to produce a broken stream. Generally any method which introduces a fine spray from beneath the fire directly into the chimney flue should give the desired steam conversion, restrict oxygen delivery to the burning creosote and provide cooling. In some instances, this cooling may be sufficient to cause the fuel residue to break free and drop into the base of the chimney for removal.
It is best not to use water inside the stove itself, however, because the appliance may not have the protecting layer of residues. The stove may be subjected to thermal stresses which result in cracks, warping or other serious damage.
Special tips used
Other variations of this technique include modifications to a pressurized water extinguisher and homemade straight tip nozzles for booster lines. Experience indicates that orifice sizes of 1/8-inch or less seem to create no broken masonry problems, especially when some turbulence is created just prior to the tip. One homemade booster tip uses a 90-degree elbow with a pipe plug which has a 1/8-inch hole drilled at its center. The orifice should produce broken streams of no more than 5 gpm at nozzle pressures of 100 psi or less.
A more recent technique is the application of a high velocity dry chemical stream from beneath the fire zone of the flue. The several advantages of this method include the avoidance of accusations that fire department streams cracked a chimney tile and the reduction of the time that apparatus is committed at the scene. Lines need not be stretched unless extension is found. Disadvantages include increased cost and reduced removal of creosote residues. Some awareness of dry chemical agents is necessary with this method, since discharge times are short and the agent demands some degree of skill for effective results.
ABC dry chemical combines the flame-killing action of all dry chemicals with an ability to form a smothering cover, first sticky then brittle, over a hot material. ABC dry chemical has become the agent of choice of the Levant, Maine, Fire Department for chimney fires with excellent results. We do not use this chemical inside the stove or appliance, however, because of its corrosiveness and its potential to create a sticky mess on the inside surfaces of an overheated stove.
Ordinary dry chemical is preferred inside. On the flue fire itself, the technique is to discharge the chemical at full velocity up the flue from its base cleanout door or other suitable access point until some chemical is backing out of the application hole. Repeated discharges may be necessary for a particularly hot fire, but 5 to 20 pounds of chemical have handled all chimney fires in the Levant Fire Department’s experience with this agent—over 50 fires.
Explosions may take place
Rarely, a minor, flashover-type “explosion” may be produced inside the chimney during dry chemical discharge. This is possibly caused by entrained air, drawn by the nozzle, mixing with hot fuel particles from the chimney walls. caused by entrained air, air, drawn by the nozzle, mixing with hot fuel particles from the chimney walls. Possibly it is a manifestation of dry chemical’s tendency to create a brief fireball just before flame extinguishment. In any event, our experience indicates no hazard to the flue or fire fighter.
Usually it is helpful to ladder the roof and drop a weighted chain to release hot residues from the chimney walls to get complete extinguishment. Thorough cleaning is usually best left to professionals with the appropriate brushes, tools and liability insurance.
Overhaul methods can then be checked by a mirror inserted near the base of the flue. At night it may be helpful to direct a hand light across the top of the chimney. A thorough check for extension should again be accomplished. Consider the attic an especially vulnerable location because the chimney is probably exposed to the highest fire temperatures near its top. Do not neglect any walls which enclose or touch a chimney.
Open wall
If temperatures too hot to touch are encountered, the wall should be opened. Careful technique can reduce damage here. Gypsum board is easily repaired if a small hole is made. On other wall finishes, moulding can sometimes be easily removed, which will then cover a small inspection hole.
A small spot of very intense heat may pinpoint the location of an open connector hole for the flue which has been improperly plugged by means of a metal cap. Such caps are unsafe—many have been blown off violently during a chimney fire or have conducted heat out to combustible wall finishes—and should be opened for overhaul if hot. The property owner should be made aware of the hazard involved with such a cap. Recommend strongly that all such unused flue holes be plugged to full chimney wall thickness with masonry materials and sealed tightly.
Occasionally a chimney will become obstructed so tightly by creosote residues that smoke backs into the structure. For such cases a special ventilation tool can be devised to break a vent hole through the obstruction. The device we use has a movable head to which 10-foot sections of 1/2-inch conduit are attached. A chain is fastened to the handle so that it can be retrieved if inadvertently dropped into the flue. Again, immediate attention by a professional cleaning service should be recommended strongly when such obstruction is found.
The chimney fire offers an opportunity to provide a professional service which may be the only contact some residents will receive from their fire department.
