These twin-head vacuum pumps feature a self-drying system allowing condensed liquid to be blown out of the pump heads at high speed during evacuation, yet the vacuum in the recipient remains constant. The adjustable drying cycle allows the pump to reach a better vacuum and is able to evacuate significantly faster, compared with pumps without a drying system. The chemical-resistant, PTFE-coated diaphragms have been stress-optimized to increase service life and reduce size of the pump.