The double-duty unit provides less than 1 Torr of vacuum or 20 psig of compressed air for ventilators, aspirators, oxygen concentrators, and blood-pressure monitors that need a quiet, clean, reliable source of vacuum or compressed air. Other applications include electronics manufacturing, laboratory equipment, and energy industry fuel cells and microturbines. The scroll design provides smooth, pulse-free operation, eliminating the noisy valves and vibration of reciprocating units. Whisper quiet, the unit runs at only 45 dB, and rotary motion allows dynamic balancing for nearly vibration-free operation. With only one moving part, scroll machines are reliable and durable enough to last the lifetime of the equipment into which they are integrated. As a vacuum source, the unit provides less than 1 Torr ultimate vacuum with a pumping speed of 3.5 cfm, and in compressor mode it delivers 3 cfm at 20 psig with maximum open flow of 3.5 cfm. Units are powered by a dependable four-pole ac motor. Overall size, with motor, is 5.7 x 6.1 x 13.3 in.