Difference between revisions of "Oxygen sensor test"

Revision as of 12:10, 10 May 2015

Oxygen sensor test

MitoPedia O2k and high-resolution respirometry: O2k-Open Support

OroboPOS standard operating procedure: Polarographic oxygen sensors: calibration, accuracy and quality control SOP. »MiPNet06.03 POS-Calibration-SOP«

When should an O2-sensor test be performed?

After switching on the O2k, every day: air calibration and stirrer test.
Zero oxygen calibration: from time to time over weeks; bracketing zero oxygen calibrations when working at low oxygen.
After application of a new membrane and O2-sensor service: In some cases, the signal of the OroboPOS improves (higher signal stability, less noise, shorter response time), when the O2k remains switched on over night (O2k-Chambers filled with 70% EtOH).
When there is any doubt about instrumental performance.
During troubleshooting when switching components between the two chambers, a quick sensor test is performed after each step (stirrer test, sensor signal).

How to do an abbreviated sensor test for the purpose of trouble shooting (in preparation)

Note: If for one of the described phases the required stability can not be reached, continue the sensor test with the next step.

select "Z Troubleshooting" from the Layout menu to observe the raw signal
fill O2k-Chamber with water
in the 'Oxygraph' / 'O2k Control' window
- set T = 37 °C
- set gain = 1
- set stirring = 750 rpm
set the slope smoothing to 40 data points: DatLab 6 users: see MiPNet19.18D O2k-Calibration, use the window "O2 calibration", tab: "Slope". Users of previous DatLab versions use the 'Experiment' / 'Edit' window
- set 'Flux derivation N' to 40 points for both chambers
wait for thermal equilibration (watch for Peltier power % to get stable)
with open chamber wait for stable signal
do an air calibration (open chamber, stable signal = zero flux)
close the chambers: stable, non-zero flux
do a stirrer test (switch off stirrer for aprox. 30sec, wait until the oxygen concentration signal flattens out, switch on stirrer, wait)
do a zero calibration: see MiPNet06.03 POS-Calibration-SOP

A DatLab demo file showing a typical sensor test (from a working system) can be downloaded with this link from the OROBOROS Homepage.

Evaluation of an O2 sensor test

Most parameters are best viewed by observing the Raw Signal. It will be helpful to compare the obtained test with the test of a functioning system, e.g. from the DatLab demo file.

Informations gained by the sensor test include:

Raw Signal at air saturation

Signal stability at air saturation

Flux at open chamber

Response time of the POS

Flux at closed chamber near to air saturation

Raw signal at zero oxygen (zero current)

Signal stability at zero oxygen

Consequences of a Sensor test

Hardware problems are detected by assessing the parameters listed above in 'Evaluation of a Sensor test'.

If a hardware problem was observed in a 'stand alone' sensor test, please follow the link for the problematic parameter. Frequently it will be necessary to find the faulty component by locating a problem.

If a sensor test was already performed as part of locating a problem the information in which chamber of the oxygraph the problem appeared will be used in the further process of locating a problem.

@@ Line 1: / Line 1: @@
-{{Technical service}}
+{{Technical support}}
-A full test experiment to access instrumental performance is described in the section
+* '''[[OroboPOS]]''' standard operating procedure: '''Polarographic oxygen sensors: calibration, accuracy and quality control SOP.''' »[[MiPNet06.03 POS-Calibration-SOP]]«
-'''Calibration and quality control of the OroboPOS (O2k-SOP)''' in [[MiPNet06.03 POS-Calibration-SOP]].
 __TOC__
-== When to do a sensor test ==
+== When should an O2-sensor test be performed? ==
-Such a quality test should be done
+* After switching on the O2k, every day: air calibration and stirrer test.
+* Zero oxygen calibration: from time to time over weeks; bracketing zero oxygen calibrations when working at low oxygen.
-* whenever a problem is encountered
+* After application of a new membrane and O2-sensor service: In some cases, the signal of the OroboPOS improves (higher signal stability, less noise, shorter response time), when the O2k remains switched on over night (O2k-Chambers filled with 70% EtOH).
-* when the performance of the instrument is doubtful
+* When there is any doubt about instrumental performance.
-* from  time to time for Quality Assurance
+* During troubleshooting when [[switching components]] between the two chambers, a quick sensor test is performed after each step (stirrer test, sensor signal).
-* after a sensor service or after applying new membranes
-* during the troubleshooting procedure by [[switching components]] a sensor test is done after each switching step.
-For the purpose of quickly accessing instrumental performance during trouble shooting (e.g. when several test experiments have to be run in sequence with intermediate switching of components) the determination of  the instrumental background parameters may be omitted. For communication with Oroboros Instruments during trouble shooting is is helpful to perform the test experiment with very well defined parameters (temperature, medium,...) to allow us to asses the performance parameters in a comparable way.
-After a sensor service or after changing membranes the oxygraph should run (i.e. the oxygraph, stirring, etc is switched on) over night (chambers with EtOH/water or just water) before a sensor test is performed or other experiments are started. This ensures proper stabilization of the signal.
-== How to do an abbreviated sensor test for the purpose of trouble shooting (omitting the instrumental background) ==
+== How to do an abbreviated sensor test for the purpose of trouble shooting (in preparation) ==
 ''Note: If for one of the described phases the required stability can not be reached, continue the sensor test with the next step.''
@@ Line 42: / Line 37: @@
 A DatLab demo file showing a typical sensor test (from a working system) can be downloaded with this  [http://www.oroboros.at/index.php?id=sensor_test link] from the OROBOROS Homepage.
-== Evaluation of a Sensor Test ==
+== Evaluation of an O2 sensor test ==
 Most parameters are best viewed by observing the [[Raw Signal]]. It will be helpful to compare the obtained test with the test of a functioning system, e.g. from the [http://www.oroboros.at/index.php?id=sensor_test DatLab demo file].