Rotary Piston Vacuum Pump

The rotary piston vacuum pump has become the major workhorse for a number of vacuum applications where relatively large chamber volumes have to be evacuated, where there is a large volume of outgassing from chamber walls or the process product or when the process has a high gas throughput due to gas being fed into the process chamber. They are excellent if the process requires a vacuum range between a few mm Hg (also called torr after Mr. Torricelli) down to about 50 microns. The pumps are generally rated to give an ultimate vacuum of 10 microns. (1 micron = 11000th of 1 mm Hg) Remember that the vacuum level in the process chamber will always be higher than the ultimate or blank-off vacuum at the pump inlet.