Determining Evacuation Time Between Chemisorption and Physisorption Analyses
Micromeritics' ASAP 2000/2010 Chemisorption Analyzers permit using more gases and analysis conditions than most other equipment in the chemisorption arena. With this level of functionality, switching from a chemisorption analysis to a physisorption analysis requires the removal of trace gases from the analyzer itself.
After a routine chemisorption analysis, adsorbates such as CO, H2, and O2 may collect in the gas delivery lines and instrument manifold. These gases can be removed by vacuum in about two hours. After evacuation, the instrument is ready for physisorption analysis.
Stronger adsorbates such as ammonia or liquid pyridine vapors take longer to evacuate -- sometimes overnight.
You can check the vacuum achieved and outgassing rate to be sure trace gases from the chemisorption analysis are removed. When the outgassing rate is less than 5 microns per minute, the instrument is ready for physisorption analysis.
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