Each month, hopefully our fire safety articles have provided you with insight to the many different types of fire and safety considerations unique to each season. We have learned how not to blow up your home and guests with Fourth of July fireworks, or while summer grilling. We have reviewed the proper treatment of Christmas trees and Christmas lights to prevent tree and electrical fires. When the weather turns cold, concerns about fireplace and chimney safety, holiday cooking, and furnaces have all been discussed. This month our goal is to enhance your general fire safety knowledge as we will look at features common to all fires.
The Fire Triangle
The Fire Triangle represents the three essential “ingredients” necessary to have fire: Fuel, Oxygen and Heat (also referred to as an ignition source). Without these three elements there can be no fire. Combustible fuel is any material that in combination with oxygen and a heat source will burn. Some examples are paper, cloth, wood, charcoal, kerosene oil, rubber, plastic, and cooking oil. Consider what may occur if a lit candle on a wooden table with a magazine on it, is tipped over igniting the magazine. The fire can spread if a fuel source is maintained, which is readily available from the wooden table or the nearby sofa, or a throw rug. The time it takes for the fire to spread to the entire room can be a matter of seconds. Understanding the fire triangle can help us change dangerous habits, which in turn may prevent a fire, an explosion, or serious injury.
If a combustible fuel source, is viewed as part of a fire triangle, we can be sure not to place it near a heat source. An example of a simple change of this habit would be maintaining a three-foot distance between a flammable object and a heat source. Thus, oven mitts would no longer be lying on a stove if a burner is on. Candles would not be sharing a tabletop with a magazine, and so forth. Conversely if a fire on a gas burner were to erupt, removing the heat source by turning off the flame or removing the oxygen source by putting a lid on the fire in a pan can extinguish a fire. Remove one part of the triangle and the fire goes out.
Fire Extinguishers
Knowing about the Fire Triangle also helps to understand how a fire extinguisher works. By removing heat, oxygen or fuel, a fire extinguisher can extinguish a fire. The above chart shows the different type of fire extinguishers. Type ABC will extinguish most household fires. Type C for electrical fires. For metal fires, a Class D is recommended but check to be sure the metal you work with can be extinguished by a Class D fire extinguisher.
Let us examine how each agent in the fire triangle is addressed by each class of extinguishers.
Class A: Contains pressurized water. Water addresses the heat and oxygen components of the fire triangle. Water cools the fire (heat) and simultaneously smothers the (oxygen) supply to the fire.
A special note: Never use water on a grease/oil fire or any flammable liquids. Water is not only ineffective for flammable liquids but may also cause the fire to spread. Never use water on an electrical fire as this poses a risk of electrocution. Electrical currents can spread into the ground and travel into a water stream such a hose. This can cause electrocution to the person putting out a fire with the hose. Never use water for a metal fire as there could be an adverse outcome, or the type of metal fire may have a chemical reaction to water.
Class B: Contains carbon dioxide. Carbon dioxide removes oxygen, suffocating fire. Class B can be used on flammable liquids such as alcohol, ether, oil and grease and gasoline. Note only use Class B for flammable gas fires if the source of the gas can be turned off.
Class C: Contain dry chemicals that suffocate a fire (remove oxygen) are the only safe extinguishers for electrical fires. Water and foam conduct electricity and should never be used for electrical fires as these agents can electrocute the fire fighter.
Class ABC: These contain dry powders that will suffocate fire (remove oxygen) and are safe for Type A, B and C fires. Thus, they are generally indicated for most households.
Class D: Specifically for metals. They are powders that absorb heat and cut off oxygen. They are specifically recommended for metal fires, with some exceptions. If working with metals check to see what extinguisher is recommended for the specific metal.
Class K: These contain alkaline mixtures that turn into soapy foams when in contact with fats and oils. The foam will extinguish the fire by preventing release of vapors and steam. These extinguishers are often used in commercial kitchens with higher risks of flammable liquid fires, such as a deep fryer.
Fire Extinguishers can contain and extinguish a fire in the early stages. However, fire extinguishers are not helpful if you don’t know how to use the extinguisher. Always read the manufacturer directions when you first purchase the extinguisher.
Think “PASS” when using an extinguisher.
P: Pull the pin. This unlocks the lever.
A: Aim by pointing the nozzle /extinguisher at the base of the fire.
S: Squeeze the lever (or press button for some extinguishers) to release the extinguishing agent.
S: Sweep from side to side. Continue to aim at the base of the fire while sweeping back and forth. Move carefully toward the fire sweeping and aiming at the base.
If using a fire extinguisher is not successfully extinguishing the fire, call 911.
Many Fire Departments, including the Green Valley Fire Department will assist community members to understand and appropriately use a fire extinguisher.
Smoke Alarms
Smoke Alarms are one of the most important aspects of detecting and surviving a fire. The alarm alert allows us the time needed to escape the fire, which saves lives. However, smoke alarms need to be installed properly and in good working order. Check with your Fire District for guidance on community resources for installing alarms. Here is a chart from the National Fire Protection Association that reviews the sounds of smoke alarms by description and the sound, and what the sound means.
Carbon monoxide is odorless and colorless and deadly. Therefore, carbon monoxide detectors are necessary in addition to smoke alarms. Carbon monoxide is produced by burning gasoline, wood, propane, charcoal, and other fuels. As we know from the fire triangle, oxygen is consumed during the fire. With decreased oxygen, carbon dioxide in the air is converted to carbon monoxide. Carbon monoxide displaces oxygen in the body and if not reversed can be fatal. Any appliance that burns fuel is a potential source of carbon monoxide. Examples are gas powered clothing dryers, water heaters, furnaces, cars, grills, power tools. Fortunately, carbon monoxide alarms will alert you in time to avert carbon monoxide poisoning.
Sign up for a Home Safety Inspection with
Drexel Heights Fire, 520-571-8700,
and you can receive a free CO alarm.
A few common questions regarding smoke alarms:
Where should smoke alarms be placed?
Smoke alarms should be in every sleep room and on every level of the house, including the basement. A sleep room is defined as any room where people sleep. Ex: Den where you fall asleep watching TV or a guest room. Place Smoke alarms high up on a ceiling or a high wall. Do not place smoke alarms in the kitchen, as cooking heat and smoke may trigger them. Smoke alarms should be 10 feet from a stove.
What is meant by interconnected smoke alarms?
Interconnected alarms “talk to each other”. When one alarm sounds, they all sound. This ensures that a fire alarm will be heard throughout the home and not just in the vicinity of the room with the fire. Early detection of a fire is critical.
What should the smoke alarms sensor detect in addition to smoke?
Alarms can include carbon monoxide detectors and heat detectors. Alarms can also be internet connected and send alerts to your cellphone.
Are all smoke alarms alerts sounding?
Smoke alarms are available for people with hearing impairment. These alarms when triggered can flash strobe lights or cause the bed to vibrate.
How long do smoke detectors last? How often should batteries be checked?
Smoke detectors last for 10 years. You should check batteries and test the alarm once a month.
We end our discussion of general fire safety with a reminder to have a fire escape plan.
Escape plans include each household member understanding how to get out of their rooms as well any room in the house. This means establishing that all windows and doors can be readily opened. Ideally each room should have 2 means to exit. For young children, elderly adults who need help and pets unable to escape without help, individualized plans are needed.
The plan should ensure that all exit paths are free of obstruction. Escape plans include a meeting place outside the home that is a permanent structure and not far from the house. It is recommended to practice the escape plan twice a year. If overnight guests are in the house, share the plan with them as well.
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