These are “dry” (oil-free) pumps, and they incorporate two spiral scrolls to compress air and vapors. The two scrolls are intertwined, rotating in a spiral motion to create a strong suction. This rotation simultaneously draws air in and directs vapors toward the exhaust.
Dry scroll pumps can be expensive at the outset, but they can also aid in savings down the road. Because these pumps are oil-free, they require much less maintenance and downtime over the life of the pump.