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Appendix 1 EC410 Oxygen Sensor Stabilisation
Profile
0
1
2
3
4
5
104070100130160
Time / secs
Sensor Output / Negative
Volts
Sensor Inserted
Into Pins
24/10/2008
EC410 O2 Sensor Performance Test Report 2006Page 1 of 20
EC410 OXYGEN SENSOR TEST REPORT
CONTENTS
1 Introduction…………………………………………………………………………3
2 Applicable Documents………………………………………………………….…3
3 Performance Test Results
3.1 Stabilisation Test………………………………………………………………3
3.2 Output in air……………………………………………………………………4
3.3 Output in nitrogen……………………………………………………………..4
3.4 Pressure Coefficient- High Pressure………………………………………..4
3.5 ‘Fridge’ Temperature Test…………………………………………………...4
3.6 Cross-Sensitivity to hydrogen……………………………………………….5
3.7 Instrument aspirator Tests…………………………………………………..5
3.8 Instrument Pump Tests………………………………………………………5
3.9 Calibration curve & Repeatability……………………………………………6
3.10 Flow Rate……………………………………………………………………6
3.11 Warm-Up time………………………………………………………….… 7
3.12 Response time……………………………………………….……………..7
3.13 Vibration……………………………………………………………….…….7
3.14 Drop Test…………………………………………………………….…… 7
3.15 Orientation……………………………………………………………..… .7
3.16 Temperature…………………………………………………………………8
3.17 Pressure Coefficient Low Pressure…………….….………………………8
3.18 Humidity………………………………………………………………………8
3.19 Air Velocity / Flow……………………………………………………………8
3.20 Poisons…………………………………………………………….…………8
3.21 Physical Properties…………………………………………….……………9
3.22 Effect of Carbon DiOxide………………………………………………9
3.23 Long Term Test …………………………………………………………9
4 Conclusions
Appendix 1 Stabilisation Graphs
Appendix 2 Output in Air / Nitrogen
Appendix 3 Fridge Test Graph
Appendix 4 Cross-sensitivity to hydrogen
Appendix 5 Aspirator & Pump Test Graphs
Appendix 6 Calibration Curve-Linearity Graph
Appendix 7 Repeatability Graph
Appendix 8 Flow Rate
Appendix 9 Response time graph
Appendix 10 Vibration Graphs
Appendix 11 Drop Test Graphs
Appendix 12 Orientation Data
Appendix 13 Temperature Performance graphs
Appendix 14 Low Pressure Response Graphs
Appendix 15 Response to Humidity Graphs
Appendix 16 Effect of Carbon di Oxide
Appendix 17 Long Term Test
1 Introduction
This report details the performance of the EC410 Oxygen sensor relative to the e2v Oxygen sensor performance test plan (AD1).
This type of electrochemical sensor has a different mode of operation compared to the galvanic sensors in common use. The main difference is that the EC410 sensor has no sacrificial Anode and as such does not have a limited life. The sensor works as an Oxygen ‘pump’, taking in Oxygen from the test atmosphere and reacting it with protons (in the solid electrolyte) on the working electrode (held at a potential of +600 mV) to form water and producing a current. The other half reaction, on the counter electrode involves the breaking down water to form Protons and Oxygen.
2 Applicable Documents
AD1 Electrochemical Oxygen Sensor Test Plan -..\..\Oxygen Sensors\Documents\Oxygen Sensor - Performance Test Plan.doc
AD2
Performance Requirements for Instruments to Detect Oxygen ..\..\..\..\standards\europe\bsen50104.pdf
3 Performance Test Results
3.1 Stabilisation in Air
see Appendix 1 for Stabilisation profile
Initial Plateau
Stabilisation Profile
Voltage / V
Time / Secs
Final Output /mV
t90 Down Output / mV
90% Time from Plateau /secs
Sensor 1
4.390
44
334.0
739.62
8
Sensor 2
4.753
30
354.1
793.92
10
Sensor 3
4.788
26
361.5
804.15
8
Sensor 4
4.795
44
357.5
801.27
12
Sensor 5
4.801
34
354.5
799.11
10
The overall stabilisation time consists of 2 distinct profiles, an initial plateau stabilisation time, in which the Oxygen pump is set up, followed by a logarithmic
3.1 Stabilisation time (Cont.)
type decay as the sensor current flow stabilises (possibly by consuming the initial levels of Oxygen within the sensor). In most instruments, which run this type of 3-electrode electrochemical sensor, the circuitry is set up so that the bias voltage is continuously applied. The power required to do this is not significant
3.2 /3.3Output in Air & Nitrogen (at room Temperature)
see Appendix 2 for typical profile
Initial Output in air / -mV
N2 Output in nitrogen /-mV
Sensor 1
328.8
16.7
Sensor 2
350.4
14.2
Sensor 3
330.6
19.4
Sensor 4
321.8
20.6
Sensor 5
324.7
15.6
3.4 Pressure Coefficient High Pressure
The EC410 sensor is only specified to ( 10% of ambient. However the sensor may be suitable for pressure up to 100kPa above ambient. This test is still to be done. Results from customer tests have shown that the sensor works well even at air pressures well over 2 Bar above ambient.
3.5 Fridge Temperature Test
see Appendix 3 for Response Profile
Sensor 1
Sensor 2
Sensor 3
Sensor 4
Sensor 5
Output at -4 / % O2
19.88
19.79
19.84
19.68
19.82
Minimum Output / % O2
19.24
19.19
19.31
18.84
19.11
Output at 20 Deg C / % O2
20.90
20.90
20.90
20.90
20.90
The above data indicates that one sensor, number 4, would cause an instrument to alarm with a 19% O2 alarm. This does not take into account the fact that there would usually be some form of temperature compensation fitted into the instrument software.
3.6 Cross-sensitivity to Hydrogen
Sensor 1
Sensor 2
Sensor 3
Sensor 4
Sensor 5
Output in Air / mV
354.68
351.93
345.88
340.67
319.79
Output in 1% H2 Balance Air
336.55
331.51
325.75
320.14
303.72
Output in mv/%O2
16.97
16.83
16.54
16.30
15.30
Output in mv/%O2
16.26
16.02
15.74
15.47
14.67
1% H2 results in a % O2 depression of
-0.70
-0.82
-0.81
-0.83
-0.62
% Signal Depression
-3.37%
-3.91%
-3.86%
-3.96%
-2.98%
See appendix 4
3.7/ 3.8 Instrument Aspirator & Pump Tests
.
This test departed from the test method in that 8 sensors were tested for the effect of switching on a pump instead of the single sensor as specified in the test plan. In addition the simulated instrument was replaced by an 8-way flow hood and the 1L/min pump by one which produces a flow of 10l/min into the flowhood. A competitor sensor was tested as a reference sensor. The results show that the pressure induced by the pump switching on was not enough to make a simulated instrument go into alarm either when the pump was switched on or off. The maximum change was <0.2% Oxygen. This performance is a result of the pressure/bulk flow disc fitted above the capillary. This type of performance would also be seen if the pressure was changed using an aspirator.
see Appendix 5
3.9 Calibration Curve (Linearity) & Repeatability
3.9.1 Calibration Curve
See Appendix 6 For Graphs
Table of Linearity Response
Applied O2 concentration
Sensor 1
Sensor 2
Sensor 3
Sensor 4
Sensor 5
20.90
20.90
20.90
20.90
20.90
20.90
17.42
16.76
16.74
16.76
16.75
16.77
13.93
13.22
13.21
13.22
13.23
13.24
10.45
9.84
9.83
9.83
9.85
9.84
6.97
6.54
6.57
6.60
6.59
6.55
3.48
3.42
3.43
3.43
3.43
3.39
0.00
0.00
0.00
0.00
0.00
0.00
The sensor response to Oxygen is non-linear (as are all capillary based sensors). The response is actually logarithmic where the signal is proportional to the loge of the reciprocal of the volume fraction of O2.The slope is ~0.89 with an R2 figure approaching 100%. The performance standard calls for a maximum deviation of 2.5% of the quoted measuring range, which in the case of the EC410 sensor would amount to a range of 30% Oxygen and an error of 0.75% O2. The maximum error for the sensor appears to be at 13.93% O2 of 0.72% O2.
3.9.2 Repeatability
EC410 Repeatability
Sensor 1
Sensor 2
Sensor 3
Sensor 4
Sensor 5
Air 1
20.90
20.90
20.90
20.90
20.90
Air 2
20.88
20.87
20.84
20.90
20.92
Air 3
20.87
20.89
20.89
20.94
20.94
Air 4
20.91
20.90
20.90
20.90
20.89
Air 5
20.88
20.86
20.84
20.90
20.92
Air 6
20.89
20.87
20.84
20.90
20.93
Air 7
20.89
20.89
20.87
20.94
20.95
Air 8
20.88
20.89
20.85
20.93
20.95
Air 9
20.86
20.86
20.86
20.91
20.92
Air 10
20.86
20.83
20.81
20.89
20.92
s.d.
0.016
0.022
0.029
0.019
0.019
The repeatability is within ( 0.1% Oxygen. This is within the performance standard specification . See Appendix 7
3.10 Flow Rate. This test is yet to be completed
3.11 Warm up time
See initial stabilisation data, Section 3.1 and Appendix 1. Even if the sensor is not kept at the –600 mV potential it will take less than 90 to stabilise its output. It therefore meets the 5-minute time specification in section 5.4.15 of BSEN50104 for the output to be within (0.2% O2 or ( 2.5% of the measuring range
3.12 Response Time
See Appendix 8 for response profile. The t90 times are well within the t90 specification of 45 seconds and in most cases the measured t90 time is actually within the t20 specification of 10 seconds.
Final Output
t90 Output Down
t90 Down
t90 Output Up
t90 Up
327.1
47.9
6
296.0
8
323.3
47.8
8
292.4
12
329.5
50.5
6
298.5
8
314.1
50.7
8
284.8
10
323.4
46.5
6
292.6
10
3.13 Vibration
see Appendices 9 & 10 for graphs of output during the vibration tests in 3 axes. In no case did the sensor output of the sensor change by >more than (0.2% O2 or ( 2.5% of the measuring range.
3.14 Drop Test
BSEn50104 section 5.4.14 allows a maximum permanent change of 2.5% of the measuring range i.e. 2.5% x 30% O2 which is 0.75% O2. In addition it is desirable that the sensor output does not change enough to set of a latchable instrument alarm, which are usually set at 19.0% (Low) and 23% (High). The results showed little changes in the output compared to the significant changes seen with the lead –based sensors. See Appendix 11
3.15 Orientation
No measurable differences were seen, as the sensors were orientated around the axes. see statement in Appendix 12
3.16 Temperature
The specification in 5.4.7 of BSEn50104 is (5% of measuring range (i.e. 5%of 30% O2 which = (1.5%O2) or (0.5% O2 over the range 20 to –10 Deg C and up to 40 Deg C. This equates to 0.24% per degree C. The test data in Appendix 13 shows that the EC410 sensor output changes by ~0.3% per degree C.
In addition the EC410 sensor zero changes from 0 at 20 Degrees to between 0.7 –1.2% O2 at 40 Degrees C. This is within the (1.5%O2 maximum change allowed for in the performance specification. However it would seem that some form of temperature compensation in the instrument would be useful.
3.17 Pressure Coefficient Low Pressure
The sensor shows very good response to pressure change see Appendix 14. The actual change in percentage signal per mBar is, ~0.07compared to a competitor specification of 0.2%. Section 5.4.8 of BSEN 50104 calls for a maximum change of 0.65% Oxygen for 200 mBar change which is 0.325% change per mBar.
The sensors show a transient peak output (as do all Capillary sensors when the pressure is changed. See Appendix 14. This tends to increase as the pressure change increases up to a maximum four-fold change. This peak decays off rapidly reaching 10% of its stable value between 25 & 35 seconds.
3.18 Humidity
The results of the test at 40 Deg C (see table below and appendix 15) show a maximum deviation from 50% rh of 0.51 % O2 for sensor 1 at 90% rh. The other sensors showed <0.44% O2 change. This deviation is less than the 2.5% of the measuring range as stated in BSEB50104
Humidity
Sensor W0055
Sensor W0084
Sensor W0020
Sensor W0048
Sensor W0082
10.11
20.90
20.90
20.89
20.88
20.88
30.06
20.77
20.77
20.77
20.81
20.80
49.99
20.62
20.62
20.63
20.65
20.63
70.00
20.45
20.47
20.48
20.49
20.49
89.96
20.11
20.29
20.31
20.28
20.30
3.19 Air Velocity / Flow
This test is still to be done
3.20 Poisons
This test is still to be done this test is still to be done.
3.21 Physical Properties
3.21.1 Dimensions The sensor is approximately cylindrical in shape with a diameter of 20mm and a height of 16 mm.
3.21.2 The sensor weight is ~5.75 gms
3.21.3 The sensor pin layout is the same as that of a CTL 4 series toxic sensor
3.22 Effect of Carbon diOxide (1% Balance Air)
See Appendix 16
The sensors showed a drop in the Oxygen signal of 0.1/0.2 % consistent with the actual decrease in the Oxygen level by dilution with CO2. The CTL type sensor did not show a rise in Output, caused by absorption of CO2 into the alkali electrolyte. This test needs to be repeated in higher concentrations of CO2. In theory the acid electrolyte should be much less susceptible to effects produced by CO2 absorption. In particular the long-term performance of the EC410 sensor in backgrounds of CO2 would be better than that of the lead-based/alkali electrolyte sensor.
3.23 Long Term Test
This test is on-going see Appendix 17 for Performance graph. Some data was lost due to an equipment failure.
4.0 Conclusions
Test Reference
En 50104 Compliant
Fit for Purpose
Comment
Stabilisation
Initial stabilisation
Air Output
Passed
N2 Output
Passed
High Pressure change
Passed
‘Fridge’ Test
Passed
Hydrogen Cross-Sens.
Passed
Aspirator Test
Passed
Pump test is OK
Pump Test
Passed
Cal Curve/Repeatability
Passed
As capillary
Flow Rate
Untested
Warm up time
Passed
If Potential constant
Response time
Passed
Vibration
Passed
Drop Test
Passed
Orientation
Passed
Temperature
Temp co may be
needed
Low Pressure change
Passed
Humidity
Passed
Air flow/Velocity
Untested
Poisons
UnTested
Physical Properties
Passed
4 Series package
Effect of Carbon Di Oxide
Passed
More testing needed
Long Term Test
On Test
Results look good
Appendix 1 Stabilisation Graphs
APPENDIX 2 Oxygen Sensor Typical Response Profile to
Nitrogen
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
123012501270129013101330135013701390
Time /secs
Output mV
Air
N2
Applied
Air Applied
Appendix 2 Output in Air & Nitrogen
Appendix 3 'Fridge Test' Graph of EC410
Sensor Output when removed from
-4Deg C to Room Conditions
290
300
310
320
330
340
350
360
050010001500200025003000
Time /secs
Output / mv Negative
-4 Deg C
Room Temp
Sensor Removed from
'Fridge'
Appendix 4 EC410 Oxygen Sensor
Graph of Response to 1% Hydrogen
300
310
320
330
340
350
360
01020304050
Time/ secs
Output / mv Negative
1% H2
Appendix 3 Fridge Temperature Test
Appendix 4 Cross-Sensitivity to Hydrogen Test
Appendix 5 EC410 O2 Sensor Pump Test 1
Minute Positive Presssure Flow Rate (10 L/min)
into Flowhood
20.7
20.75
20.8
20.85
20.9
20.95
21
21.05
21.1
21.15
060120180240300360420480540600660720
Time / secs
Output /%O2
Appendix 5 Pump Test Result
Appendix 6 EC410 Sensor Linearity Test Graph
of Sensor Output vs Applied O2 (Zero
Compensated)
0.0
5.0
10.0
15.0
20.0
25.0
0.05.010.015.020.025.0
Applied O2 /%
Sensor Response / %
O2
Appendix 6 Linearity Graph to % Oxygen
Appendix 10 EC410 Sensors Vibration Test- 1st
Horizontal Axis
20.1
20.3
20.5
20.7
20.9
21.1
21.3
21.5
06001200180024003000360042004800
Time /secs
Output /%O2
Appendix 7 Repeatability
Appendix 10 EC410 Oxygen Sensor Vibration
Test 2nd Horizontal Axis
20.1
20.3
20.5
20.7
20.9
21.1
21.3
21.5
060012001800240030003600
Time /secs
% O2
Appendix 8
Appendix 11 EC410 (Blue) & Lead Based Sensors (Red / Purple)
Graph of Sensor Output During Drop Tests from 1 Metre
0
5
10
15
20
25
30
35
40
80140200260320380440500560620680740800860920
Time/ secs
Output / %O2
Sensor 1
Sensor 2
Sensor 3
Sensor 4
32mm
Lead
Sensor
20 mm
Lead
Sensor
Drop 1Drop 2
Drop 3
Drop 4
Drop 5
Appendix 9 See Appendix 2
Appendix 13 EC410 Oxygen Sensor Graph of Nitrogen
Output versus Temperature
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
-30-20-100102030405060
Temp / Deg C
Output / % O2
Appendices 9 & 10 Vibration Graphs
Appendix 13 EC410 Sensor Graph of % Sensor Response
versus Ambient Temperature
80%
85%
90%
95%
100%
105%
110%
115%
-40-200204060
Temp/ Deg C
% Output
Appendix 14 EC410 Oxygen Sensor
Graph of % Oxygen vs Pressure
19
19.5
20
20.5
21
21.5
22
22.5
23
23.5
80090010001100120013001400
Pressure / mBar
%O2
Appendix 11 Drop Tests
Appendix 14 EC410 Oxygen Sensor
Graph of sensor peak response to 10kPa
Pressure Changes
0
200
400
600
800
1000
1200
1400
1600
1800
0500100015002000250030003500
Time /secs
Sensor Output /mV
Appendix 12 Orientation Tests
Tests on the sensors showed no change in the output, as the sensor was orientated
Appendix 13 Temperature Response Graphs
Appendix 15 EC410 O2 Sensor Graph of Output
vs Ambient humidity at 40 Deg C
20.2
20.3
20.4
20.5
20.6
20.7
20.8
20.9
21
020406080100
% rh
% O2
Appendix 16 EC410 Oxygen Sensor
Graph of Sensor Response to succesive flows of
Air,1% CO2/ Air, then Air
20
20.2
20.4
20.6
20.8
21
21.2
21.4
21.6
21.8
22
050100150200250
Time /mins
Output /%O2
Appendix 14 Low Pressure Response Graphs
Appendix 7 EC410 Oxygen Sensor Repeatability Test
Graph of Response to Air vs Exposure
(each 5 minutes /Air N2)
20.50
20.60
20.70
20.80
20.90
21.00
21.10
21.20
21.30
21.40
21.50
012345678910
Exposure
Response / mV
APPENDIX 8 Oxygen Sensor Typical Response Profile to
Nitrogen
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
123012501270129013101330135013701390
Time /secs
Output mV
Air
N2
Applied
Air Applied
Appendix 15 Humidity Response Graphs
Appendix 9 EC410 Oxygen Sensor Vibration Test
Vertical Axis
20.2
20.4
20.6
20.8
21
21.2
21.4
21.6
06001200180024003000360042004800
Time /secs
Output /% O2
Appendix 16 Effect of Carbon dioxide
APPENDIX 17 EC410 Sensor Graph of Sensor
Output vs Time
14
15
16
17
18
19
20
21
22
23
24
0100200300400500
Time / Days
Signal/ % O2
Loss of Data from
Datalogger
Appendix 17 Long Term Performance