As we know, the oxygen (O2) and moisture (H2O) levels in glove box are critical for many organic compounds and organic devices (espeically with Calcium layer as electron injection layer in typical OLEDs). In general, the level of O2/H2O is nomitors by certain sensors, ie. 1.0 ppm; such reading value is just some electrical signal generated by the sensor, and it is only trustworthy when the sensor is properly calibrated at the first installation and shows no degradation over time onging, and sometimes it is difficult to tell if the sensors are still working properly or not after 1-2 years.
My questions heres are: 1 ) how do we know the actual level of oxygen/moisture in the glove box especially when it is < 1.0 ppm, or other words, how trustworhty is the sensor reading in general? 2) There is off-sets for oxygen/moisture levels in our glove box system, and you can manually change the ppm reading by changing the off-sets. should the off-set be zero, or you can set it to any arbitrary number? 3) is there any quick and pratical methods to check the oxygen/moisture level inside the glove box assuming the sensor reading is incorrect or you want to double check it? I heard of the Ca test ( test the transparency and electrical conductvity of a thin Ca film of 100 nm), any detailed guide about this method?
Any comments and suggestions would be appreciated!
Dear Rugang,
Many thanks for your questions!
To answer your each question, please see my answers to the following
1 ) how do we know the actual level of oxygen/moisture in the glove box especially when it is < 1.0 ppm, or other words, how trustworhty is the sensor reading in general?
A glove box system has been equipped with a Oxygen Sensor and a Water Sensor to moniter both oxygen and water levels. The sensors have been annually calibrated by a international standard agency to keep the accuracy readings!
Dear Xuhua Wang
Thanks so much for your answers.
Firstly, good to know that the sensors need to be calibrated professionally by either international standard agency or the manufacturers. We use Oxygen Analyzer (AN-501) and moisture analyzer (AN-502) from our glove box manufacturer LC Tech, but the sensors haven't been calibrated since they were installed and calibrated three years ago, and I am afraid the reading is not accurate and maybe it's the reason why my devices are not performing as well as before. I will contact the local retailer about the calibration.
We also use mixed H2/N2 gas for regeneration process to purify the system, and our glove box also has the solvent absorber (activated charcoal).
Also, I would like to ask you Xuhua Wang one more question about the regeneration process. In general, we will start to do regeneration when the oxygen level > 10.0 ppm and some water (i.e. 20-40 ml) will be generated after. But I didn't see any generated water from the regeneration process for our dry glove box. I am not sure if it's because the copper catalyst is expired or not, any comment on this? Normally how often do you change the catalyst and the solvent absorbers?
Regards,
Rugang
Dear Rugang,
Regarding the following your question of
"In general, we will start to do regeneration when the oxygen level > 10.0 ppm and some water (i.e. 20-40 ml) will be generated after. But I didn't see any generated water from the regeneration process for our dry glove box. I am not sure if it's because the copper catalyst is expired or not, any comment on this? "
The system is normally equipped with venting tubes to outside via filters. You cannot see any water visually unless some small windows to see it. Normally what you can tell is the water sensor level dropped to lower level i.e.
As Xuhua-Wang: "Please do check with the supplier for your system to know more about y o u r system."
Also, what is the percentage of the (H2/N2 ?) mixed gas for the regeneration process to purify the system ?
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