ABSTRACT
Oil-free electric diaphragm pumps can be used to provide vacuum levels down to about 5 mmHg. Many of these pumps are PTFE lined, which helps to make them resistant to damage caused by solvent vapors. They are most commonly used for medium pressure distillation and for evacuating rotary evaporators. The problem of suck back is circumvented using a diaphragm pump, and such pumps do not use water. For many tasks, they can also be used instead of high vacuum oil pumps, with the advantage that liquid nitrogen trapping systems are usually not required. For most purposes, they can be used as the vacuum source for double manifold-type inert gas lines.
