FIRElink-100 – Installation Manual
Page 17 of 40
©
2010 Hochiki Europe (UK) Ltd
9-5-0-345/ISS4/OCT10
Smoke Density histogram
Alarm flags
There are two types of smoke density histogram; one shown in blue (the “fast” histogram) which updates
every 15 minutes, feeding information to the long-term “slow” histograms (which appear in yellow). These
set the detector sensitivity based on the ambient smoke conditions and it takes 24 hours for the two slow
histograms (the “day” and the “night” histograms) to complete their learning phase (see section 1.6.6).
Detector sensitivity is based on the fast histogram during FastLearn and is thereafter based on the
currently active slow histogram. However, although the positions of the alarm flags are based on the slow
histogram, sudden changes in smoke density are picked up by the fast histogram so that early warning is
given.
Sensitivity:
The current absolute sensitivity of the detector in percentage obscuration per metre (%
obs/m)
Mean
: The current mean value of smoke density, taken from the currently “active” histogram and given
as a percentage of full scale deflection.
Variance:
The “spread” of data in the currently “active” histogram and given as a percentage of full scale
deflection.
FastLearn:
If the detector is currently in FastLearn mode, this will show the number of minutes
remaining in the FastLearn period. When this period has elapsed it will read “OFF”.
Alarm factor:
This is the ClassiFire alarm factor (see section 1.6.4 “Alarm Factor” on page 10)
Day/night:
This indicates the currently active slow histogram
Alarm levels:
These figures give the position of the various alarm flags in terms of a percentage of full
scale deflection.
Detector output:
This shows the real-time variation in background smoke levels in terms of a
percentage of full scale deflection.
