Ionization/optical detectors sensitivities ????

[Benzerari]

Hi all;

Why each time I test detectors the ionisation ones take a bit longer time to be triggered, but optical detectors triggeres straight forward comparing to ionisations ( this happens more with ZETFAS detectors), also can optical be used for both rooms and common areas?
In other words can optical detectors replace for good ionisation detectors?

Thank you in advance

Benzerari

[Graeme]

opticals are seen as a good all round detector.

ionisation are becoming a thing of the past. Multisensors are a good replacement for ionisation,as you get the heat element for a fast burning fire.

[Benzerari]

Thanks Graeme;

If for some reason an ionisation detector inside some room is contaminated is it correct by BS5839 to swap it by optical or multisensor one and just auto learn the loop?

[Mike Buckley]

If you contact Seimens they do a nice one day session at the Fire Service College on the types of detector and how they respond. Its free and they give you lunch as well!

[Harry Dewick-Eisele]

There are other issues as well:

Ionisation alarms contain radio-activity. And even though none of the manufacturers like to talk about it, the radio-activity is strong enough to be detected with Geiger-counters from the outside. While this is not a major risk, at some point it will be difficult to dispose of the old units. And on the continent, ionisation smoke alarms have already been replaced by optical alarms for exactly this reason.

I am surprised about the statement that optical alarms react faster. They are usually seen as less sensitive and therefore less prone to 'burned-toast-panic'. They are, however, particularly good at smouldering fires like burning soft-furnishing etc.

[Graeme]

Thanks Graeme;

If for some reason an ionisation detector inside some room is contaminated is it correct by BS5839 to swap it by optical or multisensor one and just auto learn the loop?

swap it with either but as mentioned optical is better at detecting a thicker smoke given off by a slow burning fire

if you have a room which is likely to set light fast then use a multi.

you have mentioned that the ionisation detector is contaminated.You need to find out the cause and if the envioroment is not a clean one then you may have to re think what you are going to put in it's place.

Benzerari-can i ask out of interest-are you a qualified engineer or someone just starting out? (this is not meant to come across as a cheeky question)

[monkeh]

i'm not sure if bs5839 even comes into it.

provided you're not putting a smoke detector in an area where there is a high risk of fales alarm, there's no real restriction on which type you should use as far as i understand.  the choice between ion or optical is purely down to interpretation of what may be quicker to react in the event of a fire.

replacing an ion with an optical is still providing a smoke detector so i don't see how it can contravene the bs5839 regs.   the only case i wouldn't would be if it was off a gas extinguishant panel.  they always have an equal mix of optical and ionisation detectors to provide a totally balanced detection

[Benzerari]

Benzerari-can i ask out of interest-are you a qualified engineer or someone just starting out? (this is not meant to come across as a cheeky question)

Thanks Graeme for your adds and comments

I am neither beginner nor expert, I am just checking my knowledge with the members and colleagues it may strengthen my skills; it is not ashamed to ask even in basic things, every day is school day is not it?

[Benzerari]

There are other issues as well:
I am surprised about the statement that optical alarms react faster. They are usually seen as less sensitive and therefore less prone to 'burned-toast-panic'. They are, however, particularly good at smouldering fires like burning soft-furnishing etc.

Yes the ZETFAS version of detectors, opticals goes off quiker than ionisation but when spraying with airosol and I am not talking about any genuine fire...the problem we have with some of our customers with ZETFAS systems, is that we could not have spare parts of ionisation detectors just because their manufacturers do not make them any more... but we still have a couple of optical of the same make.

[Graeme]

use your spare opticals.

[Graeme]

Benzerari-can i ask out of interest-are you a qualified engineer or someone just starting out? (this is not meant to come across as a cheeky question)

Thanks Graeme for your adds and comments

I am neither beginner nor expert, I am just checking my knowledge with the members and colleagues it may strengthen my skills; it is not ashamed to ask even in basic things, every day is school day is not it?

not having a go just curious.

[Benzerari]

Benzerari-can i ask out of interest-are you a qualified engineer or someone just starting out? (this is not meant to come across as a cheeky question)

Thanks Graeme for your adds and comments

I am neither beginner nor expert, I am just checking my knowledge with the members and colleagues it may strengthen my skills; it is not ashamed to ask even in basic things, every day is school day is not it?

not having a go just curious.

Thanks Graeme again;

I believe you know that one person can not build one single house but ten persons can build ten houses and even more, it is the synergy generated from unification, it is also called in Arab’s world as BARAKA, which escapes all mathematical formulas...and in which we all take advantage of, regardless of our differences in terms of background, age, disciplines, way of thinking…
Above any expertise there is an expert and above any expert there is another expert... what ever I have known there are always some thing missed out and has been knowledged by someone else...that is why I am always looking for what that someone else is seeing

I know that you know all about this jargon

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[Benzerari]

If you contact Seimens they do a nice one day session at the Fire Service College on the types of detector and how they respond. Its free and they give you lunch as well!

That is really helpful: please give us the following details

Siemens fire service college Address: ...............................................................................................
Siemens fire service college Contact Name: ......................................................................................
Siemens fire service college Tel: ......................................................................................................

And thank you in advance

[Mike Buckley]

Go to the title page of the Firenet site and click on the Siemens logo in the top right hand corner and it will take you there.