Harvest Pro? Industrial RVD-11, RVD-17 and RVD-21 Vacuum Pumps (115 V, 60Hz, 1 Phase) are built to last. These rugged and reliable vacuum pumps are designed for long life with continuous use. The Harvest Pro? RVD series of vacuum pumps are specifically suited for botanical extraction, like distillation, freeze drying and a number of other processing techniques. Easily control the ultimate pressure of this dual-stage rotary vane vacuum pump thanks to its adjustable gas ballast. A built-in backflow preventer helps avoid oil contamination in case of an unexpected shutdown. Plus, the low decibel rating (56-58) makes it one of the quietest rotary vane vacuum pump available. Displacement speed at 60Hz: RVD-11 = 19.2 m3/h (11.3 cfm), RVD-17 = 28.8 m3/h (16.9 cfm) and RVD-21= 36.0 m3/h (21.1cfm).