26
Each LED bar represents the analogue scale with three segments corresponding to the CWA
relative concentrations.
Table 4.1– Red and yellow LEDs bars indicating the detected CWA concentrations
Combinations of analogue scale
segments blinking during
the CWA detection
Approximate relative CWA
concentration
Audible alarm
Arsenic
containing
(L)
Organopho-
sphorous
(GV)
No CWA vapors are detected
-
Detected concentration is about
75 % - 99 % of the preset
threshold value
-
Detected concentration is about
100 % - 124 % of the preset
threshold value
Triple discontinuous
audible signal with 1 s
interval
Detected concentration is higher
than about 125 % of the preset
threshold value
Triple discontinuous
audible signal with 1 s
interval
The manufacturer sets the CWA vapor detection thresholds as follow:
•
for arsenic-containing compound (lewisit),
(3±0.9)
⋅
10
-4
mg/l,
detection time is less than
15 s
;
•
for organophosphorous compound vapors (sarin, soman, V-gases),
(5±1.5)
⋅
10
-5
mg/l,
detection time is less than 10 s.
These thresholds are set at the normal climatic conditions:
•
ambient air temperature 20 ± 5
°С;
•
atmospheric pressure 101.3 (+5.4; -17.3) kPa;
•
relative humidity 60 (+20; -30) %
The operator cannot change these thresholds.
The events of the threshold exceeding are stored in the unit memory.
Vapors of other organophosporous and arsenic-containing compounds (such as some
perfumes) can cause the false chemical alarms.
