Electron microscopy
Compressive/Mechanical pumps
- Practical Electron Microscopy and Database -
- An Online Book -
Microanalysis | EM Book                                                                                   http://www.globalsino.com/EM/        

This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.


Mechanical, or called compressive, pumps work by compressing (reducing) a given volume of air (e.g. from SEM chambers and TEM columns), and then expelling the compressed air through an exhaust port. There are mainly two types of such pumps:
        i) Rotary pumps.
        ii) Scroll pumps.

The trapping pumps require other type of pumps, typically mechanical pumps, to remove the entrapped molecules from their system. Efficient mechanical pumps can achieve a vacuum better than 5 × 10−5 Torr. However, it becomes very inefficient at higher vacuums. Mechanical pumps are subject to contamination due to solvents being evacuated such as acetone, alcohols, and water.



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