Overview The scavenging interface attaches directly to the 19 mm scavenging pop-off valve outlet nipple. An NRB (nonrebreathing) circuit adapter is supplied, which will connect the 1/4" ID scavenging hose. The interface consists of air inlet valves, 9' x 30 mm and 1' x 19 mm exhalation tubing, and is positioned over each anesthesia machine or anesthesia machine location (i.e., if 1 machine is moved from surgery to dental, then to X-ray locations, 3 interfaces would be required).