The vacuum pumping technology for these new Pfeiffer ACP series compact dry roughing vacuum pumps is based on a frictionless multi-stage roots design. The Pfeiffer ACP G series dry pumps are specially designed for pumping traces of corrosive gas and therefore require an inert gas purge which protects the pump bearings. These Pfeiffer Adixen ACP series pumps are optimized for operation without lubricants inside the pumping module. The benefits of multi-roots dry pumps include oil-free and particulate-free dry vacuum, e.g., unlike their counterparts, the dry scroll pumps which generate tip seal dust and the oil-sealed rotary vane pumps which suffer from hydrocarbon vapor backstreaming. The new and improved ACP dry vacuum pumps offer a reduced cost of ownership (COO) and require an overhaul only every 22,000 hours.