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Topic Title: Weekend Quiz.
Topic Summary: Consumer Unit Fire.
Created On: 18 January 2019 05:32 PM
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 18 January 2019 05:32 PM
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Zoomup

Posts: 6117
Joined: 20 February 2014

Consumer unit fire.

Smoke alarms with no or dead batteries.

Result?

http://www.youtube.com/watch?v=0hAWmM4vswc

Q. Which type of smoke alarm responds quicker and more effectively to slow smouldering fires?

a. Ionisation type.

b. Optical (photo electric) type.

Z.
 18 January 2019 05:42 PM
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dustydazzler

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Well mine goes off when I burn the morning toast and its a cheap 9V battery one
 18 January 2019 06:52 PM
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Zoomup

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Evnin' Dusty,
strangely enough one of the above types has been advertised as being somewhat immune from burning toast smoke, but will work in a real fire situation. That is its sales gimmick. I bought one and tried it and it is true.

Z.
 18 January 2019 08:16 PM
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davidwalker2

Posts: 378
Joined: 29 April 2009

Interestingly, ionisation types react very quickly to fine particle smoke, and are often thought to be over sensitive (but cheap). Slow burning fires like over heated pvc produce larger particles that are detected more quickly by optical types. These often have a permanent, non-replaceable battery.

David
 18 January 2019 10:26 PM
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chrispearson

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Did burning toast on the ward kitchen ever upset anybody. The firemen chatted up the young nurses, and the nurses chatted up the firemen. Slow smouldering, what smouldering?
 18 January 2019 11:58 PM
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mapj1

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the value engineered ionisation type usually false alarm on toast.
Years ago I recall reviewing a design of toaster that would turn off at the right sort of brown, that had a snail blower that sucked air from near the combustion chamber (sorry , near the toaster elements ) and passed it over a module of the same sort at the heart of one of those some alarms, and then compared the output voltage to a threshold.
As I far as I recall it was impressive - regardless of wet or dry or thick or thin bread, always stopped at 'just browning' with very tight grouping, but the extra complexity it was never cost effective to produce.

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regards Mike
 19 January 2019 08:46 AM
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Zoomup

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Originally posted by: chrispearson

Did burning toast on the ward kitchen ever upset anybody. The firemen chatted up the young nurses, and the nurses chatted up the firemen. Slow smouldering, what smouldering?


Young nurses

Z.
 19 January 2019 08:48 AM
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Zoomup

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Originally posted by: mapj1

the value engineered ionisation type usually false alarm on toast.

Years ago I recall reviewing a design of toaster that would turn off at the right sort of brown, that had a snail blower that sucked air from near the combustion chamber (sorry , near the toaster elements ) and passed it over a module of the same sort at the heart of one of those some alarms, and then compared the output voltage to a threshold.

As I far as I recall it was impressive - regardless of wet or dry or thick or thin bread, always stopped at 'just browning' with very tight grouping, but the extra complexity it was never cost effective to produce.


I want one, I want one. Haven't you got an old prototype model in your garage Mike? If so I will bye it.

Z.
 19 January 2019 08:53 AM
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Zoomup

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A clue or two from across the pond. Warming sights on a cold winter day.

http://www.youtube.com/watch?v=J9zEi1otL88

Z.
 19 January 2019 05:09 PM
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davidwalker2

Posts: 378
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Excellent video Zoom.

I looked into this in detail when I had to fit smoke alarms to my rental apartment. It prompted me to chuck the ionisation one I had at home and replace it with a photoelectric type. The other advantage is the photoelectric types that I looked at all had 10 year batterie (but I still test mine regularly).

David
 21 January 2019 01:13 AM
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Legh

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Ionization alarn units appear to be incredibly sensitive to burning toast on a regular basis encouraging any occupants to remove the batteries.
Removal of batteries to stop the alarm is the key. These products appear to be battery operated and therefore lack the constant mains supply, however, i have found that optical alarms work well on datecting burning fat smoke caused by an unattended flaming chickens.
I managed to rescue a chiken while my colleague managed to open all the windows and check the bedrooms.....
Let me say Class D alarms are the start to a basic alarm system. Ionization appear to be oversensitive to smaller particulars and optical sensors give a more resolute response.

Legh

-------------------------

http://www.leghrichardson.co.uk

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