Re: Ion vs Photo smoke detectors

["FIRETEK" <firetech(change-the-ch-to-k)@telus.net>]

"Allan Waghalter" <awaghalter@xxxxxxxxxxx> wrote in message
news:XSF7h.26788$TV3.4528@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> I looked at a Notifier system installed recently by a major local fire
alarm
> company today and found that they have installed Ion detectors in all of
the
> classrooms of a school.  I would have spec'd these as photo detectors.  We
> had our first cold night last night and they had 3 smoke detectors in
> various class rooms go into alarm when the heat came on and burned the
dust
> off the heat exchangers.  We only use heat here about two or three months
a
> year (Houston Texas) so dust accumulates in the heat exchangers.  Am I
wrong
> on the choice of smoke detectors?


Not necessarily.  You have to look at each project from the perspective of
what kind of fire you can expect to occur.  "Fast flaming" or "slow
burning/smoldering".  In the first instance "ion" detectors are ideal, in
the second, photo-electrics are recommended.  Buildings with wooden
structures, gyprock, lino floors, and carpet with vinyl-based underlay would
benefit from photo-electric type smokes.  You have to examine the potential
"fuel" and make an informed decision as to what type of smoke detector fits.
Of course, "modern" construction techniques always call for the "low bid".
In many instances ion smokes are used because they're the cheapest and
satisfy the code requirements for "automatic detection devices".  They may
not be appropriate for the building though, and it's at this point that the
designer/engineer has to step in and actually SPECIFY the type of detector
to use.