User manual

H36.0.13.6C-07
GREISINGER electronic GmbH Hans-Sachs-Straße 26 Tel.: [phone] / 9383-0 http://www.greisinger.de
D-93128 Regenstauf Fax: [phone] / 9383-33 Email: [e-mail]
Measuring:
1. Penetrate the rubber foam sticker until the needle hits a hollow space of the package.
Attention: You must take care not to draw foodstuffs in, because otherwise the needle can
be blocked and the sensor can be contaminated.
2. Compress the hand pump completely. A valve prevents air from flowing into the package due to the
compression of the hand pump.
3. After releasing it, the pump draws the measuring gas out of the packing for ~30 seconds.
After been compressed, the
hand pump draws in for
approx. 30 seconds.
The intake / measuring can
be continued by compress the
pump again.
Compressed hand pump Uncompressed hand pump
4. The oxygen contents can read off the display already after ~10 seconds.
Note: You can only read off a valid measured value while the hand pump is drawing.
The pump can be compressed several times while connected to the same package, a reverse valve
prevents air from flowing into the package due to the compression of the hand pump, that would falsify the
measured value.
Flushing the sensor:
The measuring system must flushed with ambient air after the measuring.
Compress therefore the hand pump for 1 or 2 times.
Measuring accuracy and calibration
You could carry out a two-point-calibration of the GMH 3691 in order to get absolute precise measured
values. Therefore a second reference point - besides air- is required.
We recommend to use N2 if you want to check-up on the residual oxygen content in food packaging filled
with protective atmosphere. N2 is available in bottles and is equivalent to 0.0% oxygen.
The type of the calibration has to be selected in the device menu before calibrating.
If the whole system is carefully calibrated and the measuring will done accurately the accuracy of
measurement will be:
1 point calibration: ± 0.2% O2 ± 1digit at concentrations <10% O2
2 point calibration: ± 0.1% O2 ± 1digit at concentrations <10% O2
For information to the 2-point calibration please refer to the GMH3691 operating manual.
The measuring system is optimised for needle with ∅0.9mm. By needles with less diameter the needed
gas volume can be reduced further. But the measuring value will be lowered by the resulting under
pressure. (up to 40mbar at Ø0.45mm)
Example: 40mbar under pressure at 1000 mbar ambient pressure:
(1000-40)/1000 * 20.9% -> display 20.1%.
For measuring of protective atmosphere this error can be neglected (Example display of 1.9% instead 2.0%).