It is important that you are here, you shouldn’t hesitate to go through through this guide. This guide is aimed at telling you why you need to test your smoke detectors. But first of all:


Smoke detectors are designed to provide early warning for a fire involving ordinary combustible materials that are expected to progress through distinct incipient and/or smoldering stages.

The type, volume, and density of smoke produced during the fire development process will vary greatly depending on the fuels involved and the amount of oxygen available. Typically, the greatest volume of visible smoke is produced during the ignition (incipient) stage and the smoldering stage.

Even with ready access to low cost and, at times, free smoke detectors, exposure to fire and smoke is responsible for thousands of deaths and billions of dollars in property damage each year. One challenge for many property owners is determining what type (i.e., design) smoke detector to purchase and where to install the units.

Some detectors are more effective (respond quicker) to flaming combustion, while others respond better to smoldering combustion. Likewise, some detectors are more prone to false activation from environmental factors than others.

Why Use Smoke Detectors?

Having smoke detectors placed in various locations around your home allows for fast and effective detection. The smoke detector siren will warn you, day or night, that there is a potential fire, allowing you to quickly check the nature of the problem and hopefully prevent any damage.

When placed in the right location, the smoke alarm can also help firefighters quickly locate the fire in the home, allowing them to better focus their efforts.

What types of smoke alarms are there?

There are two types of smoke alarms:

  • Ionization:

Detects fast, flaming fires.

Detects smoke produced by flammable liquids, loosely packed light combustibles, and kitchen grease.

  • Photoelectric:

Detects slow-burning, smoldering types of fires.

Detects smoke caused by cigarettes burning in furnishings and bedding.

How optical smoke detectors work

The answer to that question is really two answers because there are two quite different kinds of smoke detectors. One is a kind of electronic eye; the other’s a sort of electronic nose. The eye type of detector is more properly called an optical smoke detector (or photocell smoke detector) and it works a bit like Tom Cruise in Mission Impossible. Remember the scene when Tom dangles from the ceiling trying to avoid all those light-detecting burglar beams? An optical smoke detector is just like that inside.

The detector must be screwed to your ceiling because that’s where smoke heads for when something starts to burn. Fire generates hot gases and because these are less dense (thinner—or weigh less per unit of volume) than ordinary air they rise upward, swirling tiny smoke particles up too.

How ionization smoke detectors work

Another type of smoke alarm is less expensive than the optical type, more common, and works in a totally different way. You can think of it as an electronic nose because, like the nose on the front of your face, it uses a kind of chemistry to spot unusual molecules (smoke) heading inward. Detectors like this are called ionization smoke detectors.

Which is best, ionization or optical?

According to a detailed study by the US National Institute of Standards and Technology: “Ionization type alarms provided a somewhat better response to flaming fires than photoelectric alarms, and photoelectric [optical] alarms provide (often) considerably faster response to smoldering fires than ionization type alarms.”

Smoke detectors are trivially inexpensive compared to the cost of fire damage—and life, of course, is priceless. Although any smoke alarm is better than none, fits both types of the detector if you possibly can.

What’s inside the detector?

Once Freymann and Tolman had discovered their fiber, it was relatively simple to build a part-electrical, part-mechanical smoke detector around it:

  • A length of the magic fiber (yellow) is stretched around a wheel (red) inside a metal container (gray) with holes at the bottom through which smoke can enter.
  • The fiber is attached to a pivoting lever (light blue), held in place by a spring (purple).
  • The blue lever holds another pivoting lever (green) in place.
  • The green lever supports an electrical contact (dark blue) and holds it well above a second identical contact.
  • The two contacts connect to a battery-powered bell or another electrical alarm circuit (not shown).


Nothing is more important to your family’s safety than your home’s smoke detectors and fire alarms. These devices alert you and your family where there is dangerous smoke or fire, giving you enough time to safely evacuate. But you’ll need to routinely check your smoke detectors to make sure they are working.

Smoke alarms actually don’t need a ton of maintenance. They can be checked once a month with batteries replaced at least once or even twice a year, according to the U.S. Fire Administration (USFA).

An easy way to remember to do this is to change your smoke detector’s batteries when you change your clocks for daylight savings time. However, be sure to review your smoke detector’s user manual, as you may need to check your devices more frequently.

You’ll also want to do a visual inspection to make sure your alarm indicator is on. This makes sure that both your hard-wired and battery-operated fire alarm is properly connected and the batteries are working.

You should also occasionally vacuum and dust around the alarm. This way your device is clear of insects and dirt which can tamper with the effectiveness of the alarm.

When you check your batteries, make sure there is no corrosion, if there is you need to change the batteries. You also want to calibrate and test your fire alarm sensors based on what the manufacturer suggests.

When you perform these regular checks on the alarm system and replace the batteries, then your smoke detector and fire alarm will be in the best condition possible.

How to Test Your Smoke Detector

Testing your smoke detector should become a part of your housekeeping routine and according to FEMA, should be done at least once a month.

While the specific way to test your detector depends on the manufacturer of your smoke detector, most detectors have an easily accessible test button on the face of the device. Once you press this button, wait a few seconds, and then a loud and piercing sound should emit from the device.

If you do not hear the device or if the sound is not loud enough, consider replacing the battery and test the device again. If the alarm doesn’t sound off even after you’ve replaced the battery, the device itself is probably faulty. Replace the detector as soon as possible.

Additionally, here are some guidelines you should follow while testing your smoke detectors:

  • Remember to test your smoke detectors monthly as suggested by FEMA. In many cases, this is as simple as just pushing a button.
  • Besides testing the device, clean out your smoke detector as well. Dust, spider webs, and other debris may hinder your smoke detector from operating at its maximum capability.
  • You should also replace the batteries at least once a year. Some systems, however, come with a “long-life” battery. These are usually not replaceable, and you may have to replace the smoke detector when the “long-life” battery runs out.
  • Figure out if your smoke detector is a stand-alone or is an interconnected model. A stand-alone model will only trigger itself when it detects smoke, while an interconnected model triggers all the alarms in the system if even one smoke detector goes off. If you live in a large house, consider getting an interconnected system so that your whole residence is made aware of a house fire that may be happening on the opposite side of the house.
  • Station someone at the farthest areas of your house from your smoke alarm. When you test your alarm, they should be able to hear alarms go off. If they don’t, consider using an interconnected smoke detection system or get an alarm with a louder alarm.
  • Some smoke detection systems sold nowadays are also wired to inform your local fire station or home security system when it detects smoke. When testing your smoke alarm systems, notify your fire station so that they don’t send personnel to a non-existent fire. They’ll be thankful for the heads up, and be glad that you’re diligently testing your smoke detection system.
  • Keep an up-to-date escape plan. These smoke detectors only alert you and cannot put out fires for you.
  • Check the dates on the back of your smoke detectors. Once an alarm reaches its 10-year life span, it is advised to replace it entirely. However, you can also consult the alarm’s manual as it may suggest replacing the entire system earlier.


In addition to routinely checking your detectors, you should also know that smoke alarms tend to last only about 10 years. You should replace your detector every 10 years, even if your devices seem to be working correctly.

Newer model smoke alarms are more reliable than older models so consider upgrading when it’s time to replace your older model.


Smoke detectors are often overlooked, but they are important. As you might have already found out, it is important to regularly test your smoke detectors. You should endeavor to always test your smoke detectors regularly.