Smoke detector and ozone generators / air purifiers

I recently made a quite disturbing discover and thought I share it here so other are aware of it.
We all love to protect ourself in case of a fire and the first and most vital of the information chain is a working smoke detector.
In my house I had the old type installed, based on a radioactive isotope that detect smoke through ionisation.
The newer types working optical or using combined optical and isonisation detection should perform better - but does not really matter for this "warning".
If you do have pets, smoke in the house or just do a lot of cooking you might also use one of these fancy air purifiers that use Ozone to clean the air in your room.
I only have a tiny unit for a fish tank that I also use to remove smells from my work clothes or purify some water for the plants.

My discovery started with a simple cooking exercise involving a lot of onions, garlic and a big wok.
To avoid filling the house for days with the smells I had the ozone generator running as well.
At some stage I noticed that the whole kitchen was covered in the fumes from the cooking, nicely visible from the hallway - like fog.
To my surprise the smoke detector did not the usual alarm but performed fine with the test button.
So I blew some cigarette smoke directly at it - still no reaction.
Next day I started to investigate and was prepared to buy a new detector but whatever I used, smoke, steam or just killing a burning candle underneath cause the alarm to go off.
Then it hit me: The ozone!
A quick test with the hose of the ozone generator next to the smoke detector and no matter what I blew in it the device staed silent.

Ozone is ionized oxygen, the detector uses the ionized particels from the radioactive material to detect smoke.
Smoke or very fine dust / steam will bind the ionized particles forcing the electronics to sound an alarm because the sensor no longer detects the ionized particles.
With enough ozone entering the detector there will be always enough ionization to prevent the alarm.
Conclusion: If you do use ozone in your house upgrade your smoke detector to a model that uses optical AND ionisation detection!
Otherwise there is a good chance that the device is unable to detect a fire.
Of course chance are slim that you would use the ozone while sleeping and a fire starts, but if it does....

There is a problem with Ionization type smoke alarms, they can fail to go off under certain conditions. In Australia the fire departments are trying to get them phased out, and replaced with the photoelectric type.

there is lots on google on the subject.


Kiteman2 years ago

So, if your ozone generator starts to over-heat, you're doomed...