Settings for smoke detectors

[andrea...@gmail.com]

Hello,

I have to model smoke detectors, and on the guide I read:

"ACTIVATION_OBSCURATION is the threshold value in units of% / m. The threshold can be set according to the setting commonly provided by the manufacturer. "

I tried to contact one of the manufacturers but he tells me that the obscuration value for non-linear smoke detectors is expressed in %, not %/m, and that their detectors have an activation range between 30% and 70%.

Since FDS default is 3.24 %/m by default, this makes me think that we are really talking about different types of units of measurement.

Do you know how to convert between % and %/m? Can you point me to a site or something that can train me well on the subject so that I know how to behave / how to interface with the manufacturer?

Do you have any advice in general?

Thanks,

Andrea

[Kevin McGrattan]

%/m means that the intensity of the light signal in a photo-electric detector decreases by x % over a distance of 1 m. I'm not sure what the manufacturer is telling you when he/she says %. If we are talking attenuation of a light source, the % is meaningless unless there is some length scale. Maybe it is implied.