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).