Do E-Cigarettes Set Off Smoke Alarms?

Posted by Peter Nelson on

There are a growing number of public places banning the use of E-Cigarettes in the UK. While various local authorities are banning them for reasons brought on by bad media and decisions based on bad advice. More pubs, clubs and venues are banning them for the simple reason they set off smoke alarms.

There are 2 main types of smoke alarms:

There are two main types of smoke detectors: ionization detectors and photoelectric detectors.

Ionization Detectors

Ionization detectors have an ionization chamber and a source of ionizing radiation. The source of ionizing radiation is a minute quantity of americium-241 (perhaps 1/5000th of a gram), which is a source of alpha particles (helium nuclei).

The ionization chamber consists of two plates separated by about a centimeter. The battery applies a voltage to the plates, charging one plate positive and the other plate negative. Alpha particles constantly released by the americium knock electrons off of the atoms in the air, ionizing the oxygen and nitrogen atoms in the chamber. The positively-charged oxygen and nitrogen atoms are attracted to the negative plate and the electrons are attracted to the positive plate, generating a small, continuous electric current. When smoke enters the ionization chamber, the smoke particles attach to the ions and neutralize them, so they do not reach the plate. The drop in current between the plates triggers the alarm.


In one type of photoelectric device, smoke can block a light beam. In this case, the reduction in light reaching a photocell sets off the alarm. In the most common type of photoelectric unit, however, light is scattered by smoke particles onto a photocell, initiating an alarm.

In this type of detector there is a T-shaped chamber with a light-emitting diode (LED) that shoots a beam of light across the horizontal bar of the T. A photocell, positioned at the bottom of the vertical base of the T, generates a current when it is exposed to light. Under smoke-free conditions, the light beam crosses the top of the T in an uninterrupted straight line, not striking the photocell positioned at a right angle below the beam.

When smoke is present, the light is scattered by smoke particles, and some of the light is directed down the vertical part of the T to strike the photocell. When sufficient light hits the cell, the current triggers the alarm.

So the answer seems to be yes and no. It depends which type of detector you have. Either way experiments have been done and, yes vaping can set off smoke detectors, but it takes a LOT of vape. The other question is where were all these smoke detectors when pubs and clubs in the UK WERE allowed to let people smoke in them? No alarms were set off then!!  

I asked the landlord of my local pub if smoke alarms had been set off by vaping, she said yes but only in the room with the pool table, just happens to be the smallest room in the pub. So there are a number of factors have to come together for vape to set off a smoke alarm, but the answer is YES they can set them off!!


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