CO Alarm went off ... but why?

Uricanejack

Well-known member
Joined
22 Oct 2012
Messages
3,750
Visit site
No idea why.
perhaps it just took a while to get up to the detector.

just a recommendation, if you have doubts replace it.
My father in law was fortunate to be woken by his when his gas furnace was faulty. I’m sure it saved his life.
Just a recent local mayday response to a Co poisoning on a mobo, fortunately all survived with hospital stay.
Tiss the season as it starts to get cold.
 

coopec

N/A
Joined
23 Nov 2013
Messages
5,216
Visit site
Condensation?
At this time of year it’s getting colder and with little breeze to dry things off surfaces can get pretty damp.

I doubt condensation would trigger it (unless it short circuited)

"The First Alert CO7 carbon monoxide detector manual includes this information about gas sensitivity:

CO Alarm is not formulated to detect CO levels below 30 ppm typically.

UL tested for false alarm resistance to Methane (500 ppm), Butane (300 ppm), Heptane (500 ppm), Ethyl Acetate (200 ppm), Isopropyl Alcohol (200 ppm) and Carbon Dioxide (5000 ppm). Values measure gas and vapor concentrations in parts per million.


That information tells you that your CO detector may sound an alarm when any of those gases is / are present at levels above the "false alarm resistance" data the company offers."

This article is really well worth reading I think as they point out (for instance) that some carpet adhesives could trigger the alarm

Carbon Monoxide Gas Alarm Causes FAQs
 

CLB

Well-known member
Joined
18 Jun 2013
Messages
4,959
Visit site
I presume it was a false alarm ... but why?

I would never, ever presume that. From your description I would say it had a good reason to go off. What?. I don't know, but the fact it has not gone off since suggests it was not a false alarm. The levels could have been low, a culmination of toast cooking and oil lamp burning maybe, but if a CO alarm goes off, it is always worth taking very seriously.
 

awol

Well-known member
Joined
4 Jan 2005
Messages
6,739
Location
Me - Edinburgh; Boat - in the west
Visit site
The only time mine has gone off was after using the grill. Oven or rings don't affect it and the grill flame looks almost totally blue. The alarm was some time after the grill was extinguished and, from memory, the display showed a level just above the threshold . I test mine with a burnt match every year and I also use a butane lighter to test the gas alarm.
If you are worried about it, you really need 3 of the things.
 

JumbleDuck

Well-known member
Joined
8 Aug 2013
Messages
24,167
Location
SW Scotland
Visit site
I would never, ever presume that. From your description I would say it had a good reason to go off. What?. I don't know, but the fact it has not gone off since suggests it was not a false alarm. The levels could have been low, a culmination of toast cooking and oil lamp burning maybe, but if a CO alarm goes off, it is always worth taking very seriously.
If it reassures you, I do and did take it seriously. I've even posted on a popular sailing forum for help in working out why it went off.

I checked every possible source of combustion on the boat, except the charcoal stove which hasn't been lit for a month. The oil lamp had been out for twelve hours (I checked that it had actually gone out and there wasn't a remaining glimmer), the grill had been out for half an hour (ditto) and neither rings nor oven had been used since the previous evening. I checked them too anyway.
 

JumbleDuck

Well-known member
Joined
8 Aug 2013
Messages
24,167
Location
SW Scotland
Visit site
The only time mine has gone off was after using the grill. Oven or rings don't affect it and the grill flame looks almost totally blue. The alarm was some time after the grill was extinguished and, from memory, the display showed a level just above the threshold . I test mine with a burnt match every year and I also use a butane lighter to test the gas alarm.

Interesting. How long after the grill was used? Since the CO molecule is very similar in size to both the N2 and O2 molecules, I would expect it to diffuse fast in air; I find it hard to believe that a small pocket of CO would maintain for half an hour, inside an open companionway, before finding the detector.

Does anyone know how these things stop detecting? In other words, do they shut up when CO levels fall again or is there a time lag while a chemical reaction runs its course, possible related to the concentration seen? I am curious about why it shut up almost at once the first time I put it outside but went on beeping for some time on the second occasion.

If you are worried about it, you really need 3 of the things.

I am thinking about a couple of "Full Stop" patch detectors as well.
 

coopec

N/A
Joined
23 Nov 2013
Messages
5,216
Visit site
Potential sources of carbon monoxide gas on your boat:

  • When two vessels are tied to each other;
  • When you are docked alongside a seawall;
  • When your load causes the bow to ride high;
  • When a fuel-burning device or the engine is running while your vessel is idling;
  • When there are swimmers between the pontoons of your boat.

Also, on larger boats such as houseboats, vents can cause CO build up along the water near the rear swim deck or water platform.
 

VicS

Well-known member
Joined
13 Jul 2002
Messages
48,145
Visit site
Potential sources of carbon monoxide gas on your boat:
  • When two vessels are tied to each other;
  • When you are docked alongside a seawall;
  • When your load causes the bow to ride high;
  • When a fuel-burning device or the engine is running while your vessel is idling;
  • When there are swimmers between the pontoons of your boat.
Also, on larger boats such as houseboats, vents can cause CO build up along the water near the rear swim deck or water platform.

Swimmers are a source of CO ?????
 

Momac

Well-known member
Joined
7 Feb 2008
Messages
6,627
Location
UK
Visit site
I had a smoke alarm on the boat with non replaceable battery pack up well before its expiry date so presume a CO alarm can do the same.
Having said that a CO alarm I had on the boat did achieve its full service life.

Perhaps being in a boat is not so good for the service life of some of these products .
 

JumbleDuck

Well-known member
Joined
8 Aug 2013
Messages
24,167
Location
SW Scotland
Visit site
Checked your bilges for explosives? How close are your flares to the CO detector?

Unusual case of CO poisoning.

Interesting. Coal miners used to talk about "afterdamp", which was the CO-rich combustion product of a firedamp explosion.

My flares are in a locker directly below the CO alarm. They appear to be unfired ...

I had a smoke alarm on the boat with non replaceable battery pack up well before its expiry date so presume a CO alarm can do the same.
Having said that a CO alarm I had on the boat did achieve its full service life.

Perhaps being in a boat is not so good for the service life of some of these products .

I bought my current one from the chandlers in Mallaig, and it's a proper boat-compatible one which - see above - went through self-test with flying colours. Incidentally, when it went off the wee light which means "this is an actual alarm" was flashing too. I think it's probably going to be replaced next year.

Possibly, if they smoke 80 Woodbines a day!
I think somebody misunderstood the meaning of "CO Beach".
 

Kinsale373

Active member
Joined
15 Jan 2017
Messages
233
Location
Kinsale Irl
Visit site
I just took a look at the spec for a CitycELL Carbon monoxide Cell. This is the guts of a Gas Detector, the measuring bit. They have tested their ElectroChemical cell (Which I think is the type but maybe not the same brand that Kiddie use. ) for cross sensitivity to other gases and checicals and it looks like they are fairly sensitive to Hydrogen! They are saying at 100 ppm Hydrogen will register on the cell as 40ppm CO! Now most CO detectors will go into full alarm at 10ppm. So if you have a CO detector near a hydrogen source such as a a battery being fast charged then you may get false alarms.
Try moving the alarm away for the battery bank. Place it In the cabin area where you spend most time .

Gas Concentration Used (ppm) MICROceL
CF (ppm CO)
Hydrogen Sulfide, H2 S 15 < 0.5
Sulfur Dioxide, SO2 5 ± 0.1
Nitric Oxide, NO 35 <6
Nitrogen Dioxide, NO2 20 ± 1
Hydrogen, H2 100 < 40
Ethanol, C2 H5 OH 200 ± 1

Carbon Monoxide,-CO is generated by the incomplete burning of carbon based fuels. Most likely source in the boat is a Diesel heater which is sooted up or has a restricted air intake. Diesel Engines should be ok but if the air intake is restricted or the Injectors not correctly adjusted then you could have CO. being generated.

Kinsale 373
 
Top