Fire Alarm noise levels

[Mike Buckley]

Kurnal,

Hence why I am looking for any guidance on the upper level for these areas.

As an aside, one of the rough and ready indicators of excessive noise in a factory is if you need to raise your voice to speak to someone then you need to check the sound levels. As BLEVE has pointed out, the threshold limits I am using as a guide are for an average daily exposure so whilst they will be loud enough to satisfy BS5839 they should not be overly loud for people staying in the area.

BLEVE with regard to the horns I cannot help you.

[Phoenix]

Personally I think you only need a relatively quiet signal in the staircases.  Possibly no sounders at all with the evacuation signal bleeding in from adjacent spaces.  There does need to be a distinctive signal to confirm to people escaping that they should continue making their way out but it only has to be audible, it shouldn't make communications difficult.  I'm talking about escape staircases here, not large accommodation stairs that fall within main accommodation spaces.

I could even envisage an acceptable situation where there were no sounders in the escape staircases because they had been replaced by flashing red beacons.  Provided all users know what it means, why not?

NFPA72 asks for 15dBA above ambient so, as ambient noise is often almost zero in these spaces, they would be quite happy with very reduced audibility levels, certainly less than 65dBA.

Remember that the objective of the signal in the staircases in not to wake people or to initially alert them or to drive them out with uncomfortable noise levels - these people are already escaping and need the signal merely as continuing confirmation that evacuation is still required.

I've been in too many staircases where it's impossible to think, let alone communicate, because of the ridiculous noise level of the alarm.

Stu

[lyledunn]

I test fire alarms every day. I wear ear defenders when measuring the sound output of systems. Even with them, I can be left with temporary residual humming in my ears. One day I forgot my ear defenders. I found that the piercing sound of a sirens actually made me confused! I think that I would have run through a fire to get away from them. That is not intended to be a flippant remark. Refuges, I believe should be around 60dbA only because refuges are normally part of escape routes . Any greater than that might cause disorientation both for the disabled and those who might need to help them. 95dbA in a bedroom is nothing short of brutal! A heart-attack is perhaps a more likely consequence to an alert than the coherent reaction required in a fire situation. I am sure some authority has done some research on this and could offer an alternative more sensible approach than the blind adherence to only a minimum level.

[jokar]

In the end it is a warning not a fright.  If they are awake and can hear it why blast their ears?

[Allen Higginson]

Around 70dB is accepted as being the minimum to awaken your average sleeping person.
The sounder,if mounted directly outside of the bedroom,will drop off between 20dB and 30 dB through the door plus another 12dB if it is 4 metres away from the bedhead so a sounder needs to be in the bedroom BUT doesn't need to be blaring at 95dB to 105dB at 1 metre!!

[Mike Buckley]

The problem is that these are hotels and need to conform to the 75dB at the bedhead. Also we cannot treat the guests as average people because the hotel chain would like the guests to spend their evenings increasing the bar profits.

I would agree with lyn that a lower level would be acceptable in refuges, as the guests would have to be awake to get to them.

As a matter of interest lyn what sound levels are produced by the sirens you are testing?