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Dryer Fire
Fact Sheet
Consumer Warnings
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Statistics and Implications
- Dryer exhaust fires now surpass
creosote (chimney) fires in frequency on a national level. In
1998, the most recent statistics available, the Consumer Product
Safety Commission reports that over 15,600 dryer fires occurred
killing 20 people, injuring 370 more and causing over $75.4
million in property damage. According to the CPSC, in most of
these cases the culprit was lint getting into the machine’s
heating element, sparking and fueling a fire. In response to
this growing trend, many dryer manufacturers now employ a device
that shuts the appliance down when airflow is obstructed. However,
these safeguards are subject to wear and have been known to
fail. Not surprisingly, some fire departments and insurance
companies now require that dryer vents be inspected and cleaned
regularly.
- With gas dryers, there is also
concern of carbon monoxide (CO) poisoning. Since lint and flue
gases use the same avenue of exit from the house, a blocked
vent can cause CO fumes to back up into the house. These fumes
are colorless and odorless and they can be fatal. Low-level
CO poisoning mimics flu symptoms (without the fever): headache,
weakness, nausea, disorientation and deep fatigue. At higher
levels, occupants can fall asleep, lapse into a coma and die.
Anatomy of a Dryer Fire
Dryer fires usually start beneath the dryer when the motor overheats.
Overheating is caused by a build-up of lint in the duct that increases
the drying time and blocks the flow of air, just like cholesterol
in your arteries can build up and block the flow of blood to your
heart. Naturally, any lint that has collected under the dryer
will burn and the draft from the dryer will pull that fire up
into the duct. Since the duct is coated or even blocked with lint,
many times a house fire results. Other contributing conditions
may include failure of the thermostat and limit switches in the
dryer, lint inside the dryer, a missing or damaged lint screen,
a crushed hose behind the dryer, or a bird’s nest or other debris
blocking the vent.
Higher Risk Situations
- Residential dryer vent lengths may not have an equivalent
length greater than 25 feet. Five additional feet for each 90-degree
bend must be added to the actual physical length to compute
the vent’s equivalent length. This will determine the vent’s
actual resistance to the airflow.
- Homes with larger families or where dryers are used heavily
are at greater risk.
- Flexible plastic duct is no longer code-approved for clothes
dryers. It is normally one of the first things burning lint
will ignite, having been shown to flame in as little as 12 seconds.
Lower cost and high flexibility often make it attractive to
unadvised homeowners installing their own machines.
- Flexible duct made of thin foil is not recommended for clothes
dryers. It’s tendency to "kink" and stop airflow makes it dangerous
to use.
Additional Benefits to Dryer Vent Cleaning
- Allows your dryer to operate more efficiently,
using less energy and saving you money.
- Protects your dryer from excess wear and
premature death.
- Helps clothes dry faster—a time savings
for busy families.
- Reduces excess household dust and humidity
- Helps preserve clothing, as the life of
many fabrics is damaged by excessive high heat.
Inspection Frequency
Most vents need cleaning every two to three
years. Some dryer vents need attention more often. If it is the
first time that a dryer vent has been cleaned, having it re-checked
again in a year can help to make a reasonable judgment. Determining
factors include:
- How heavily the dryer is used
- How long the vent is and the materials
used. Shorter vents usually blow better.
- The age and type of dryer used. Full size
dryers blow better than smaller stack dryers or older dryers
- The design of the vent. Those with a lot
of turns and elbows blow worse and build up more lint.
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