Type of detection

[Paul2886]

Hi All,
Your views would be appreciated.
Do you consider combined heat/ CO detectors are suitable in the bedrooms of a residential care home. Please bear in mind that they all have doors held in the open position by magnetic devices linked into the system. My concerns are that for CO to be produced we need to have a fairly established fire and smoke could therfore spread beyond the room of origin before the door is closed. Cheers

[kurnal]

I think carbon monoxide detectors would be most sensitive to fires such as smouldering fires or other fires where there is a limited supply of air. Yes all fires produce come CO but if there is plenty of oxygen we are more likely to get large volumes of CO2.
CO detectors  are considered acceptable in rooms as part of an L3 installation. You would be less likely to suffer unwanted alarms than if smoke detectors were fitted though it is not fair to infer that the detector would necessarily give a delayed response compared to a conventional smoke detector. I don't know of any hard evidence of this one way or another.

BS5839 suggests that proposals to use CO instead of smoke detectors should be accompanied by test evidence to show that CO will give a satisfactory response to the fires that are likely to occur. This is the biggest stumbling block to your proposal. What performance or tenability criteria could be used as a reference?

[Paul2886]

Hi Kurnal and thanks.
You make the point of my concerns that a fire in a large(ish) room will have and oxygen supply in its early stages as CO is usually produced, in abundance, by incomplete combustion.  The standards for care homes is recommended as L1 and again my concerns are that a fire in its incipient stages may not activate the system to close the door and will therefore allow spread of the cold products of fire beyond the room. Unfortunately how do we test such a situation as obviously my 'smoke' machine fails to operate the system in which is how this came to light. I could try lighting a small fire in the room but the manager sounded a bit twitchy about that......some people eh....no sense of adventure