Carbon Monoxide Detection

[timfsa]

A large hotel in my area is fitting Carbon Monoxide Detectors to all bedrooms in place of smoke detection.
This is on the advice of the alarm installer.

While this type of detector is mentioned in BS5839-1, as far as I understand it, there is no specific test criteria and the technology is still unproven - to be used as the only detection solution.

What thoughts do you all have with regard to the fact that the system will now not comply with the L2 specification of smoke detection in all risk rooms and also the use of CO detection as a replacement rather than supplement to smoke detetion.

Tim

[Dragonmaster]

BS 5839: Part1:2002 now recognises CO detection as suitable as part of L coverage other than in escape routes, where standard smoke detection should be provided. If i was presented with your scenario under a FRA i would be quite happy to accept it provided all the relevant certificates were correctly issued.

[Mushy]

this might sound like a daft question but why are they ok in rooms but not escape routes?

[kurnal]

Are they purely CO detectors or multi sensor detectors with a heat or smoke element in addition?

[timfsa]

They are purely CO, no heat/smoke element.

[kurnal]

Paragraph 21.1.8 of BS5839 covers this topic.

Bear in mind also that the standard was written in 2002 and technology has further advanced since then.

Heat detectors were historically recommended for hotel bedrooms, more recently smoke detectors are becoming more common in recognition of the duty to provide early detection for the safety of the room occupant  (though evidence of this objective being achieved is a bit sparse) Aerosols can be a problem in causing false alarms with smoke detectors  but CO are immune to this. They are seen as being a halfway house between slow heat detectors and false alarms caused by smoke detectors.

CO detectors are recommended for rooms where otherwise a heat detector would be accepted, ( Unless flammable liquids are present that may give rise to rapid flaming fires).

I think I would ask the system designer to justify his choice and be minded to support it if there is good reason why they are preferable to opticals in this particular situation.

[kurnal]

Mushy- I would think that it is due to the characteristics of CO which diffuses rather than being subject to the normal convection plume  based spread of products of combustion on which all other dtectors are based. As a diffusing gas the concentration of CO in escape routes remote fromthe fire origin  is likely to be so low as to delay detection- and where would we put the detectors- as a diffusing gsas there is really no beed to follow conventional ceiling mounting and spacing techniques.

This is answer is  purely speculation on my part based on my limited understanding of the technology- please dont take it as gospel!!

[Mushy]

Thats reasoning sounds ok to me Kurnal though I'm no expert on CO detectors

I was just wondering if it was a similar reason to ionisation detectors situated in rooms and optical outside rooms

[Mushy]

I know we can't rely on Wikipedia to be accurate but this is what is says

CO detectors do not serve as smoke detectors and vice versa. However, dual smoke/CO detectors are also sold. Smoke detectors detect the smoke generated by flaming or smoldering fires, whereas CO detectors can alarm people about faulty fuel burning devices. Carbon monoxide is produced from incomplete combustion of fossil fuels. In the home CO can be formed, for example, by open flames, space heaters, blocked chimneys or running a car inside a garage

[wee brian]

Rule of thumb - CO fire detectors (these are different to detectors designed to deal with dodgy boilers) are about as good as heat detectors - maybe a bit better. They shouldn't be used in place of smoke detectors.

Check the manufacturers blurb and the evidence supporting it with care.