Whether your smoke detector is the photoelectric or ionization type, it’s undoubtedly essential to the safety of your home. However, these smoke detectors can also give out false alarms, which can be a nuisance — not to mention a safety hazard because you’ll end up disabling them and then not having them work when you need them.
Ionization smoke detectors are eight times more likely to give a false alarm. Small particles that form from even the smallest flames trigger ionization smoke detectors, so they tend to sound an alarm when people are cooking or smoking indoors.
In this article, I’ll help you determine which type of smoke detector is in your home and understand the differences between the two types. I’ll also talk about other types of smoke detectors you can use at home. Read on to learn more!
Why Are False Alarms a Problem in Smoke Detectors?
False alarms are a problem in smoke detectors mainly because they are a nuisance. Too many false alarms are dangerous because people will then ignore the alarm during a real emergency. Every alarm should be taken seriously, and nuisance alarms prevent people from doing this.
Ionization vs. Photoelectric Smoke Detectors
Both ionization and photoelectric smoke detectors are readily available. If you check the labels around your smoke detector, it should be easy to check which type you have.
Here are the common features of ionization smoke detectors:
- Radioactive materials
- The letter “I” is included in the model number
- Americium-241
In contrast, a photoelectric smoke detector will likely have “P” in its model number and won’t have the materials mentioned above.
How Ionization Smoke Detectors Work?
Ionization smoke detectors are designed to detect combustion particles — the various gasses formed when any fuel burns. Radioactive material in an ionization smoke detector ionizes the air inside it, and the changes in ionization levels are detected by a sensor inside.
When there is a flame near an ionization smoke detector, the gasses released from the flames enter the smoke detector and change the levels of ionized particles. At a specific threshold, the alarm rings.
While this is an excellent way to detect flames, it does nothing to detect smoke. Also, a small flame near the smoke detector can set it off even if there is no emergency, leading to false alarms.
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How Photoelectric Smoke Detectors Work?
A photoelectric smoke detector typically has an electric light source and a light sensor inside. Photoelectric smoke detectors are capable of detecting the way smoke impacts light, which is especially useful given that visibility is limited in a smoke-filled room. Depending on the type, the mechanism of smoke detection differs.
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In one type of photoelectric alarm, the light sensor measures the way light is obstructed from the light source that shines directly on the sensor.
The second type has the light shining away from the sensor. When smoke enters the smoke detector, the smoke particles deflect light into the sensor, which will trigger an alarm at a certain threshold.
Both types of photoelectric smoke detectors are equally effective at smoke detection and give fewer false alarms.
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Which Is Better: Ionization or Photoelectric Smoke Detectors?
Photoelectric smoke detectors are far superior to ionization alarms because they give better results and fewer false alarms. Although they are slower in some situations, a good quality photoelectric alarm is still a better choice.
Studies have shown that photoelectric smoke detectors are more effective at detecting smoke than fire. I should note that smoke inhalation is the leading cause of death in house fires, and is often considered more dangerous than the fire itself.
When comparing the two types of smoke detectors available, photoelectric smoke detectors are more effective overall. Although ionization smoke detectors show better results when tested for detecting fast-flame fires, they’re only slightly faster at detecting this type of fire. Also, because fast flame fires spread so quickly, most people don’t need a smoke detector to detect them.
On the other hand, photoelectric smoke alarms are better at detecting smoldering fires. Smoldering fires are those that produce a lot of smoke and spread slower. They’re considerably more dangerous — as I mentioned earlier, smoke inhalation is the leading cause of death from house fires. Since photoelectric smoke alarms are better at detecting these, they’re also better at preventing fatalities from house fires.
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Best Photoelectric Smoke Detectors
If you’re now convinced of the benefits of photoelectric smoke detectors over ionization ones, let me give you a few recommendations (courtesy of Amazon.com):
- X-Sense Smoke Detector. The main selling point of this one is its 10-year battery life. Although you’d probably prefer a version that you can just plug into an electrical outlet, I think 10 years is more than enough time to not have to worry about excessive battery replacement expenses.
- First Alert BRK 7010B Hardwired Smoke Detector. If you like your smoke detector having two possible sources of power (electrical outlet and battery), pick this one. The alarm sounds at 85 decibels, which is roughly equivalent to the sound of traffic while inside a car.
- Kidde PE9 (P9050) Battery-Operated Photoelectric Sensor Smoke Alarm. Like the First Alert smoke detector I described, this one is 85 decibels loud. Even when the power is out, this’ll go off since it’s battery-powered. Best of all, it comes with a 10-year (limited) warranty, guaranteeing that your repair costs will be covered for a while.
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Combination Alarms and Positioning Smoke Detectors
If you can’t decide between an ionization or photoelectric smoke detector, you’d probably be happy to know that some companies have gone the extra mile and designed combination alarms. As their name implies, these are smoke detectors with both ionization and photoelectric technology. The idea is that combination alarms are supposedly more efficient and will give better results.
However, I should note that photoelectric smoke detectors can work as well (if not better than) combination alarms. The better option is to buy ionization and photoelectric smoke detectors and strategically place them around the house.
When installing any type of smoke detector, it’s best to double-check the building codes in your area for the specifics. You may also consult a professional for advice.
That said, here are general tips on installing smoke detectors in your home:
- Every room, sleeping area, and level should have a smoke alarm installed.
- Keep a smoke alarm in the center of a room for the best protection.
- Smoke detectors should be installed 10 feet (3.05 m) away from your stove or other cooking appliances. This distance keeps nuisance alarms to a minimum.
- Try to interconnect all the smoke detectors in your home so they’ll all ring at the same time if needed.
- Choose hardwired smoke detectors over battery-powered alarms because they’re more reliable. You also won’t have the added expense from changing batteries regularly.
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Carbon Monoxide Detection
Many new smoke detectors can detect carbon monoxide as well as smoke. Carbon monoxide (CO) is a by-product of incomplete combustion, and carbon monoxide poisoning can be serious and potentially fatal. CO poisoning is associated with fires, especially when a fire is burning indoors with little to no ventilation.
CO is a “silent killer” because the gas is tasteless and odorless, and symptoms aren’t immediately noticeable until the victim experiences seizures (or worse, death).
Generally, smoke rises to the ceiling, but carbon monoxide tends to sink to the floor. As such, combining carbon monoxide and smoke detectors is pointless because it’d be difficult to find an ideal position for the device. It’ll be either too high to detect carbon monoxide or too low to detect smoke.
Types of House Fires
Since I touched on a couple of types of house fires earlier, it’s also worth noting that house fires are typically categorized according to their source, as follows:
- Liquid or gas: Accelerants, like alcohol or gasoline.
- Grease: Usually in the kitchen.
- Electrical fires: From electrical wiring or appliances.
- Organic and artificial solids: Wood, paper, textile, plastic, etc.
- Metal: Those that immediately burst into flames when in contact with oxygen.
The reason you should know the sources of house fires is so you can better deal with them. For example, pouring water on electrical fires is a bad idea because water conducts electricity, and you risk electrocution. Instead, put out the fire with a fire extinguisher.
Final Thoughts
Regardless of the type of smoke alarm you want to install at home, never disable, disconnect, or ignore it. Photoelectric smoke detectors are less likely to sound false alarms and are considered superior ionization alarms. Proper placement of smoke detectors is important and often spells the difference between nuisance alarms and alarms that are actually useful.
