Artificial Smoke vs Magnets when testing smoke detectors

Most fire alarm contractors in the Houston area are aware the Fire Marshal’s Office requires the use of artificial smoke when testing a buildings smoke detectors while performing fire alarm inspections. Smoke Detector


However there are a few who will try to use magnets during a Fire Marshal test and may become irritated when the fire Inspector directs them to use smoke instead of magnets.

There are two ways to test smoke detectors. Using artificial smoke or using magnets to test the smoke detectors. Both ways allow you to determine if the smoke detectors electronic components work however applying smoke inside the smoke chamber is the only way to determine the smoke detector will detect smoke.

The Arguments:

The Fire Alarm Technician’s position: Mr. Fire Inspector we should be able to use magnets to test smoke detectors because magnets do not leave a residue like canned artificial smoke.

The Fire Marshal’s Inspector’s position: Mr. Fire Alarm technician using magnets is fine while you are pretesting a fire alarm system because it lets you know the smoke detector is functioning properly. However it does not test a real fire and smoke situation. It only mimics the signal that tells the fire alarm panel the smoke chamber detects smoke.

The reasons for testing smoke detectors with smoke is to make sure it will detect smoke particles.

Using magnets to test fire alarm systems is great due to speed of testing the devices.
Magnets will determine if the rest of the fire alarm system will cause the following:

  • strobes to flash
  • speakers to make announcements (in high-rise buildings)
  • horns to sound off
  • elevator to capture and recall
  • magnetic lock security doors to unlock
  • air handler to stop
  • doors to close
  • smoke curtains to close
  • and more…

Smoke Detector Failure Story

During a fire marshal fire alarm inspection in an older atrium building the fire inspector directs a fire alarm technician to test some older smoke detectors in the common area of the building to set off the newly installed strobes in a suite remodel.

The technician sprayed the first older smoke detector several times with large amounts of smoke and the smoke detector would not activate. He was then directed by the fire inspector to try the next smoke detector in the common area of the building and the other smoke detector would not activate it either. The fire alarm technician was asked to retrieve his magnetic device from his van.

The technician returned from his van with his magnetic device on a pole and went back to the same two smoke detectors. The technician was then asked to test the smoke detectors with the magnet.

Can you guess what happened? You would be correct if you guessed the magnets activated the smoke detectors initiating the fire alarm system.

The technician was asked to alert building management that the older smoke detectors would need to be replaced and that a fire inspector would visit management at a later date to follow up to ensure they were in fact replaced.

The reasons for testing smoke detectors with smoke is to ensure it will detect smoke. The best way is ensuring that smoke enters the smoke chamber (so that the particles will be recognized) so the detector will activate the fire alarm system.

For this reason alone most fire marshal offices require the use of canned smoke to test smoke detectors. It is for the safety of the occupants in the building.

One can argue that artificial smoke is what caused the older smoke detectors not to activate in the first place because they were probably tested with smoke upon initial installation but there is no proof of that being the case. The truth is the older detectors were at the end of their service life.


Leave a Reply