Carbon Monoxide – Testing Your Detector

Carbon Monoxide – Testing Your Detector

Every electronic carbon monoxide detector has a button to push to test the device. Unfortunately, this test only verifies that the electronics in the unit are functioning correctly. What this doesn’t tell you is whether the device can actually detect carbon monoxide. There is a way to test this yourself, and it is surprising that the manufacturers do not provide the details of this test procedure to their customers.

For effective carbon monoxide testing, you need to expose the unit to carbon monoxide. The amount of CO you will need to provide depends on the type of device you are testing, but it should never be above 500 ppm. Testing it on the exhaust of an internal combustion engine is a very bad idea, for two reasons. Number one, it exposes you to dangerous levels of CO (several thousand ppm in some cases). Number two, it might permanently damage your detector. Don’t do it!

You want to set up a small, enclosed space that you can fill with some CO, then watch and wait to see if your detector reacts. The best thing to use for this carbon monoxide testing is a large zip-lock bag.  It can be tightly sealed to hold the CO in. Any similar container will work as well.  If you’re testing a device with a digital display, the container will have to be transparent on at least one side.

You will also need a small metal bowl to put into the bag alongside your CO detector. This bowl will hold some smoldering material and protect the plastic bag. You will also need some material that is going to smolder and produce CO.  We suggest low or no smoke incense.


Testing a Detector with a Digital Display

The UL-listed detectors start showing CO levels at 30 ppm, so this is the level you need to produce inside your test chamber. A small piece of incense is enough to produce sufficient CO.

Place your detector into your test chamber. Put the small metal bowl on its side near it, but not too close. Light your incense on fire then quickly place it in the bowl inside the chamber.  Quickly close or seal the chamber.  Watch the display on your detector. If you have used enough material, you should see a reading before too long, as it doesn’t take long to build up the CO level in a small chamber.

If you did not see any reading but “0” on your display, repeat the test with a larger amount of burning material. If you are unable to get any reading, the detector has failed and should be replaced.

If you want to test the audible alarm, see the next section.

Testing a Detector without a Digital Display

Generally, these devices are UL-listed, which means they are supposed to alarm at the UL-specified levels.  Euro-standard detectors can be tested with this same procedure, but will respond sooner. In order to test any of them, you will need to create a higher level of CO in your test chamber and be prepared to wait for the device to sound an alarm.

For this test, we recommend a small piece of incense, as it is designed to smolder on its own. Cut off a piece of burnable incense about ½ inch long. Place your detector in the chamber on its back. Place the small dish near the detector, then light the incense on fire. Place the smoldering incense on the dish and close or seal the chamber. If you’re using a bag, fill it with air before you seal it.

If you used a sufficiently large piece of incense, the chamber will soon contain a high concentration of CO (over 400 ppm). The detector is supposed to sound an alarm not less than 4 minutes and not more than 15 minutes at this level. Once your incense has completely burned, wait 15 minutes to see if your device sounds its alarm.

If the alarm does not go off after 15 minutes, repeat the test with a larger piece of incense. If it fails a second time, you can probably conclude that the detector has failed and needs to be replaced.

The Importance of Carbon Monoxide Testing

You buy and install a CO detector to warn you about the presence of carbon monoxide.  If the device you are relying on can’t detect CO, it is worse than worthless.  It is giving you a false sense of security.  You really should test your detector(s) on a regular basis, and as they get older, you may need to check them more often.  Your life, and those around you, may literally depend on it.