Sulfur Dioxide Sensor 4 Electrode SO2 A4 (PDF)

xide Sensor
SO2-A4 Sulfur Dio
Dioxide
4-Electrode
ode
4-Electr

Technical Specification

Figure 1 SO2-A4 Schematic Diagram

Patented

All dimensions in millimetres (± 0.15mm)

Top View
PERFORMANCE

Bottom View
Sensitivity
Response time
Zero current
Noise*
Range
Linearity
Overgas limit

Side View

nA/ppm at 2ppm SO2
t90 (s) from zero to 2ppm SO2
nA in zero air at 20°C
±2 standard deviations (ppb equivalent)
ppm limit of performance warranty
ppb error at 20ppm SO2, linear at zero and 2ppm SO2
maximum ppm for stable response to gas pulse

320 to 480
< 20
5 to 45
15
50
0 to -5
100

* Tested with Alphasense AFE low noise circuit

LIFETIME

Zero drift
Sensitivity drift
Operating life

ppb equivalent change/year in lab air
% change/year in lab air, monthly test
months until 50% original signal (24 month warranted)

ENVIRONMENTAL Sensitivity @ -20°C
Sensitivity @ 50°C
Zero @ -20°C
Zero @ 50°C

(% output @ -20°C/output @ 20°C) @ 2ppm SO2
(% output @ 50°C/output @ 20°C) @ 2ppm SO2
nA change from 20°C
nA change from 20°C

CROSS
SENSITIVITY

ppm·hrs
% measured gas
% measured gas
% measured gas
% measured gas
% measured gas
% measured gas
% measured gas
% measured gas
% measured gas

Filter capacity
H2S sensitivity
NO2 sensitivity
Cl2
sensitivity
NO sensitivity
CO sensitivity
H2
sensitivity
C2H4 sensitivity
NH3 sensitivity
CO2 sensitivity

KEY
Temperature range
SPECIFICATIONS Pressure range
Humidity range
Storage period
Load Resistor
Weight

@ 5ppm
@ 5ppm
@ 5ppm
@ 5ppm
@ 5ppm
@ 100ppm
@ 100ppm
@ 20ppm
@ 5%

H2S
NO2
Cl2
NO
CO
H2
C2 H 4
NH3
CO2

°C
kPa
% rh continuous (see note below)
months @ 3 to 20°C (stored in sealed pot)
Ω (AFE circuit is recommended)
g

< ±20
< ±15
> 36
80 to 95
90 to 105
< ± 25
150 to 300
450
< 40
< -160
< -70
< -1.5
<2
<1
<1
< 0.1
< 0.1
-30 to 50
80 to 120
15 to 90
6
33 to 100
<6

Note: Above 85% rh and 40oC a maximum continuous exposure period of 10 days is warranted. Where such exposure occurs the sensor will
recover normal electrolyte volumes when allowed to rest at lower % rh and temperature levels for several days.
At the end of the product’s life, do not dispose of any electronic sensor, component or instrument in the domestic waste, but contact the
instrument manufacturer, Alphasense or its distributor for disposal instructions.
NOTE: all sensors are tested at ambient environmental conditions, with 47 ohm load resistor, unless otherwise stated. As applications of use are outside our control, the
information provided is given without legal responsibility. Customers should test under their own conditions, to ensure that the sensors are suitable for their own requirements.

ta
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SO2-A4 P
Data
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Perf
Figure 2 Sensitivity Temperature Dependence
Figure 2 shows the
temperature dependence of
sensitivity at 2ppm SO2.

Output (%referenced to 20oC)

105
100

This data is taken from a
typical batch of sensors.

95
90
85
80
75
70
-30

-20

-10

0

10

20

30

40

50

Temperature (oC)

Figure 3 Zero Temperature Dependence
300

Figure 3 shows the variation
in zero output of the working
electrode caused by changes
in temperature, expressed as
nA.

250

Output (nA)

200

This data is taken from a
typical batch of sensors.

150

100

Contact Alphasense for futher
information on zero current
correction.

50

0
-30

-20

-10

0

10

20

30

40

50

-50
o

Temperature ( C)

Figure 4 Response to 200ppb SO2
350

Figure 4 shows response
from 20 to 200ppb SO2.
Use of Alphasense AFE
circuit reduces noise to
15ppb, with the opportunity of
digital smooting to reduce
noise even further.

340
200 ppb
330
320

Output (mV)

Technical Specification

110

160 ppb
120 ppb

310
80 ppb

300

40 ppb
20 ppb

290

0 ppb

280
270
260
250
1000

2000

3000

4000

Time (s)

5000

6000

7000