In operating rooms equipped with central suction and its long tubes, or where long tubes are necessary for other reasons, there is a time element lost in "building up" vacuum in the tubes. We have found, for instance, that it takes 14 seconds to build up 20 in. (51 cm.) of vacuum in a closed tube 15 ft. (46 meters) long and an inside diameter of ¼ in. (0.6 cm.) with a suction
Cut-off for Yankauer aspirator.
apparatus capable of producing 20 in. of vacuum. Once established, this vacuum is constant. The shorter the tube, the less time is necessary to build up the vacuum.
The cut-off we devised on the Yankauer aspirator shortens the length of time necessary for building up a vacuum in the usual open-end aspirator and tube. With the cut-off in the "on" position, maximum vacuum is obtained and ready for instant use. I have found
HIRST OC. MODIFIED YANKAUER ASPIRATOR. AMA Arch Otolaryngol. 1952;56(4):452. doi:10.1001/archotol.1952.00710020474013