Type / N.
Rev.
Data
Page
Total pages
EW095.605
5
November 2010
81
96
EsiWelma
s.r.l.
11.2.1
Detectors (UR.40..)
The various detectors available are described in Chap.2 – Description of the system.
They are formed of an enclosure, whose specifications are tied to the protection mode
(ATEX and non), with an IP65 or IP55 protection rating depending on the model,
containing the electronics, and of a sensor whose type depends on the gas to be
detected. Below are the main technical specifications of the detectors.
Tab. 11.2 –
Technical specifications of the detectors
Type of sensor
Standard Catalytic,
Pellistor or
Semiconductor
Electrochemical Cell
or Semiconductor
Detectable Gas
(see available models)
Explosive Gas
Toxic Gas (CO)
Power supply
11÷14Vdc
11÷14Vdc
Max power consumption
1.6W
0.7W
Measuring range
0…50% LEL
0..500 ppm
Precision (Standard Catalytic, Pellistor or
Electrochemical Cell)
±
5% full scale,
±
10% readout
Precision (Semiconductor)
±
10% full scale (on calibration point)
Repeatability
±
5% full scale,
±
10% readout
Measurement resolution
1% LEL
5 ppm
Microprocessor resolution
1024 points (10 bit)
1024 points (10 bit)
Digital filter system
Kalman Filter
Kalman Filter
Watchdog
Internal
Internal
Warm-up time
< 2m
< 2m
Stabilization time
< 2m
< 2m
Response time
< 20s (T50), < 60s (T90)
Long-term stability
Offset (%LEL/year)
Span (%LEL/year)
<
±
6 (S), <
±
3 (P)
<
±
6 (S), <
±
3 (P)
< 5%/year
(Electrochemical
cells)
Average operational life of Sensor (in air)
255 weeks
255 weeks
Settable threshold limit values, default settings:
Pre-alarm
1st threshold alarm
2
nd
threshold alarm
10% LEL
20% LEL
40% LEL
30 ppm
100 ppm
200 ppm
Ambient Temperature (°C)
-
Operating
-
Storage
-20
÷
50
-20
÷
70
Ambient humidity (%RH)
- Operating
-
Storage
non-condensing
15
÷
90
45
÷
75
Operating pressure (KPa)
80
÷
110
Air speed (m/s)
≤
6
Visual warnings
Red LED visible with detector energized
The steady LED status can be forced by
the Control unit to identify the sensor on
the plant
