Detection Sensitivity
TM 787100 Rev (Af), May 2019
21
3
Performance
3.1
Detection Sensitivity
Detection sensitivity is the maximum distance at which the detector will
reliably detect a specific size of fire and typical type of fuel (standard fire).
3.1.1
Standard Fire
A standard fire is defined as a 1ft
2
/0.1m
2
gasoline pan fire with maximum
wind speed of 6.5ft/sec / 2m/sec.
3.1.2
Sensitivity Ranges
The detector has 4 user-selectable sensitivity ranges. For each range there
are 2 response levels.
•
Warning (pre-alarm)
•
Alarm
The detection distance, for the warning level, is approximately 10% higher
than the alarm distance. Alarm response times for a standard fire at a
specified range are shown in Table 1.
Table 1: Alarm Response Time versus Range
–
20/20MI-1
10
20
30
40
Sensitivity Range (ft/m)
33/10
65/20
100/30
132/40
Response Time (sec)
5
8
10
10
Table 2: Alarm Response Time versus Range
–
20/20MI-3
2.5
5
7.5
10
Sensitivity Range (ft/m)
8.2/2.5
16.5/5
24.7/7.5
33/10
Response Time (sec)
1
1
2
3
For some typical ambient conditions the Zeta parameter, as defined in
NFPA 72 for the detector, is 0.005 (1/meter).
Note:
Zeta parameters may vary significantly with changes in temperature,
air pressure, humidity, visibility conditions, etc.
