Piston pumps are used for some large level vacuum applications. These pumps have a sliding sleeve through which the gas enters, after that drawn right into a cylindrical chamber and exhausted by a Rotary Piston Vacuum Pump rocking piston plunger. These pumps are very hardy and also have pumping speeds that range between 15 cfm to 2,000 cfm and the pumps can reach a pressure of just one 1 x 10-4 Torr. Rotary piston pumps could be prepared for corrosive and oxygen assistance.