smoke alarm question

[oreo123]

What is the difference between photoelectric and ionization smoke alarms?

I know that ionization is used within 15 or 20 feet of steamy bathroom or kitchen cooktop.

TIA.

[HorneTD]

Ionization detectors use a small particle of nuclear waste to ionize the smoke particles so that they will conduct a small current. When enough particles are present in the detectors sensing chamber the detector goes into alarm.

A photoelectric smoke detector can take two forms one works on obscuration and the other works on back scatter or reflection. In the obscuration type the smoke blocks or obscures the light source from the photoelectric detection cell and the associated circuit drives the alarm after detecting the loss of light on the photocell. In the back scatter type the smoke reflects the light from the light source back onto a photo cell that drives the detector into alarm.

In general the ionization type, which detects the smaller invisible products of combustion, is quicker to respond to free flaming fuel limited fires. The photoelectric type, which detects the larger visible products of combustion, is faster to respond to smoldering or oxygen limited fires.

Ionization detectors are much more prone to nuisance alarms caused by cooking, painting, and similar activities.

-- Tom H

[The Real Tom]

"nuclear waste"? You are not selling the idea of ionization POC detectors for the home. :-P

tom

[oreo123]

I am about to get smokes for an apt. Electrician told me to just pick them up. Found out that local code is within 20 feet of cooking apparatus or steam from a bathroom that its photo type. I was wondering which one was more sensitive for the rest of the apt so I went ionzation.

Oreo

[HorneTD]

POC = ???

-- Tom H

[Gel]

In hard wired models, battery only providing back up in case of AC power loss. Alkalines are fine in smoke alarms, and my data shows with good makes ie Duracell Ultra they'll last nearly 4 years; so well worth cost.

Manufacturers manual will list recommended types; lithium batteries may also be usable provided their use sanctioned in user guide.

Wouldn't suggest otherwise as these alarms have extra component to allow for mis fitting of lithium battery ie reversed polarity; they have potential to explode so why this is so important.

Never use rechargeable loose batteries, as have wrong dischange characteristics, and would not activate low battery beep as required [for min 30 days in UK]. Low battery triggered when voltage hits 7.4V.

Difference in Ion & Optical {Photo} been explained by other posters; Ion now banned most of Europe, except UK & Eire.

Useful info on type selection/location at

[The Real Tom]

Products Of Combustion

One of the ways to detect a fire. Others include IR/UV and Heat(Setpoint and Rate of Rise) detectors.

hth,

tom @

[The Real Tom]

Now that is a shame about ION. I know why, cause I remember how it was a serious concern here in the US about 2 decades ago. I believe the manufactures addressed the problem with documented proof about Americaium after 10 operating life, and offering a recycling program, but consumer's still might not be using them.

:(

Just hear too many problems with Photos getting dirty and not working, but then if you clean them too when you vaccum, that shouldn't be a problem. But anyone here regularly vacuum their smoke detectors?

later,

tom @

[Main Man]

Yes you're right Tom about need for more TLC, and answer is NO!

[The Real Tom]

Well I confess, i forget too. :(

tom