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| Smoke Detectors |
2008-06-17 |
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Installing a smoke detection system in your home is probably the single, most effective way to improve your fire safety. I say “Smoke Detection System” because you need more than one detector to adequately protect your home. So, how do you go about purchasing and installing your smoke detectors? Well, it’s sort of like buying a car. You look for the options that are important to you then make a purchase within your budget.
Styles of Smoke Detectors
There are two styles of smoke detectors: Ionization and Photoelectric.
Ionization – Uses a small radioactive source to ionize the air in a sensing chamber, creating a current flow. When smoke enters the chamber, it reduces the current flow and sets off the alarm.
Photoelectric – Uses the principle of scattered (refracted) light. A light beam is sent across a chamber. A photoelectric “eye” is positioned 90 degrees from the light beam. When smoke enters the chamber, some light is reflected off of the smoke and into the photoelectric eye, setting off the alarm.
Both styles detect the presence of smoke, but they react differently to it. An ionization detector will sense the small, invisible particles of smoke and reacts quicker to an open, flaming fire. A photoelectric detector senses the larger, visible smoke particles and reacts faster to a smoldering fire. For this reason, it’s less likely to react to cooking.
Now, just to make things interesting, manufacturers make combination detectors. These have both the ionization and photoelectric sensors in one unit. There are also smoke detectors with an escape light and others with heat detectors, some even have carbon monoxide detectors. Newer models are also wirelessly interconnected. When one alarm goes off, they all go off.
Styles of Heat Detectors
Remember, at the beginning I said smoke detection system. Heat detectors can be an easy solution to help eliminate false alarms and are a better choice than smoke detectors in some areas of the home. As with smoke detectors, there are two styles of heat detectors: Fixed temperature and Rate-of-rise.
Fixed Temperature – Sets off the alarm when the surrounding air temperature exceeds a set limit.
Rate-of-Rise – Sets off the alarm when the surrounding air temperature rises faster than the pre-set rate, over time. Typically, these detectors react to a 12 – 15 degree (F) change in temperature per minute.
Heat detectors can also be wirelessly interconnected and work in conjunction with smoke detectors.
Power Sources
Yep, you guessed it! There are two sources of power for these units: AC-Power and Battery-Power. There are advantages and disadvantages to both. AC-Power is either a plug-in type or professionally installed (Hard Wired). The advantages are you don’t need to change batteries twice a year. The disadvantages are there may not be a power outlet in the appropriate area. Battery-Powered units can be easily mounted in the correct position and are not affected by power outages. The disadvantage is remembering to change the batteries twice a year. A great way to remember to change the batteries is to change them when you adjust your clocks for daylight savings time. Spring ahead and change the batteries, fall back and change the batteries. Use the best battery you can get. If you think there’s still life in the battery, put a new one in the detector and use the old one in another battery operated device. Don’t skimp on your families safety.
Now, just to keep things interesting, there are dual-powered detectors. These primarily use AC-Power and have a battery for when there is a power failure.
UL & FM listing
Always look for the UL (Underwriters’ Laboratories) or FM (Factory Mutual) label/stamp. This lets you know the device has been tested, meets safety standards and is considered safe by an independent group, other than the manufacturer. Canada has similar markings.
Locations
There are standards for each municipality and for every country. Minimum requirements are fine, but if you ever wanted to go overboard this is the time. Typically a smoke detector is required outside each sleeping area and an additional detector on each floor, including the basement. If you have children, consider placing a detector inside of each bedroom as well. Children and the elderly have been found to sleep right through an alarm. A detector in the bedroom, very close to the bed, will improve the chances they’ll hear the alarm. This works even better if you have detectors that are interconnected. Remember, when one goes off, they all go off. Check your local fire codes, smoke detectors inside bedrooms are quickly becoming a mandatory requirement.
Heat detectors are used to supplement the smoke detectors. Place these in unfinished attics, crawl spaces, laundry rooms, utility rooms, furnace rooms, bathrooms, garages and the kitchen.
There are also those combination smoke/heat detectors to think about. Personally, I feel the more ways to detect a fire the better. If you start to experience false alarms, don’t just unplug the detector or pull the battery, change the style of detector used in that specific area. If smoke from the kitchen constantly sets off the smoke detector, try moving the detector a little, keeping it in the same general area. Still having problems, switch from an Ionization type to a Photoelectric type. If the area in question does not specifically require a smoke detector, replace that smoke detector with a heat detector. If you find that the rate-of-rise heat detector is a problem, replace it with a fixed temperature detector. If you have more questions than answers, seek the assistance of a professional installer or your code enforcement officer.
When considering mounting locations, think about where the smoke is coming from and how it will react. Place your first smoke detector between the living area and the bedrooms. If there’s more than one sleeping area, place the second smoke detector outside the second sleeping area. You get the idea, place smoke and heat detectors in every area you can, according to your own needs and desires.
There is “dead air space” to consider when mounting these devices. Place them in the center of the ceiling, no closer than 12 inches from a wall. You can mount them on a wall if needed, place them no closer than 6 inches but no further than 12 inches from the ceiling. Always read and follow the manufacturers mounting instructions.
Testing & Cleaning
Once a month, test your detectors. Use the test button and ensure the detector is operating properly. If it’s not working, replace the battery and test again. Do some trouble shooting to try and find the problem. If it still doesn’t work, replace the detector. Again, don’t just unplug it or remove the battery, find a solution that will keep the area protected. Clean detectors with the brush attachment to your vacuum. If you have interconnected detectors, ensure all of them are working together. This is a good time to include the kids. Set off one detector and have the kids listen for the others. As always, follow the manufacturer’s instructions for testing procedures.
The monthly test is also a great time to do a home fire drill. We’ll talk more about E.D.I.T.H. in an upcoming show, but for now, show the kids how to exit the home safely and meet at a rally point, outside the home to make sure everyone is out and safe. Every one in the home has a role in an escape plan. Give the kids a role suitable for their age and let them “show their stuff” during your home fire drill.
Replacing your detectors
One of the neat ideas, “cagey veteran tricks” I like to call them, is to mark the date you installed the detector on the under side of the detector with a marker. Every time you change the battery, you’ll see the date you installed the detector. Replace detectors every 8 to10 years. You can even put the “replace me” date on the detector if you like. Always read the manufacturers instructions for replacement intervals. Remember, the ionization detectors have a very small radioactive device inside them. Follow the manufacturers’ guidelines for disposal. If you have other questions, contact your waste collection company and ask them how to safely dispose of smoke and heat detectors.
The future of smoke and fire detection
In doing some research for this article, I found a report from the Navy where testing is being done on the idea of incorporating smoke and heat detection devices in common household items that cause fires, like the toaster oven. A small detector in the toaster oven will sense an “undesirable” heat or smoke situation and go into alarm. Again, wireless technology will come into play here and set off the home detectors. There will probably be a different sound to alert the occupants throughout the entire home, that the toaster oven “has issues”. This will greatly increase home owner awareness. Our dishwasher, clothes dryer, microwave oven and many other devices will be able to quickly alert occupants of a fire situation and get people out of the home long before a small fire becomes a catastrophe. This is simply amazing.
References
NFPA 72: National Fire Alarm Code in the US & CAN/ULC-S53: Standard for Smoke Alarms in Canada. If you have any questions check with the manufacturers’ instructions and please feel free to contact your local building inspector or your local Fire Department. These folks are in the business of protecting the public, use that resource to your advantage. I’m sure if you’re nice to them, they’ll be nice to you.
Tune in to Car Connection every Saturday morning. I’m thinking my next installment will be on E.D.I.T.H. and how you can plan and conduct home fire drills.
Until next time, stay fire safe,
Captain Dale
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