nut 21 includes an internal cavity 81 that is configured to receive in a lower portion thereof the inlet nipple 23 the upper portion of the cavity 81 is internally threaded with threads 19 to mate to a fluid source such as a refrigerant charging manifold not shown preferably the nut 21 includes one or more preferably two spaced 180 u00b0 apart axially extending vent slots 90 the vent slots 90 allow vapor to vent in the direction of the charging manifold upon disconnection of the device from the manifold the inlet nipple 23 is stepped and thus includes a first elongated portion 34 having a first diameter a second portion 35 defined at shoulder 33 having a second diameter larger than said first diameter and a third portion 36 defined at shoulder 37 having a third diameter larger than the second diameter the third portion 36 includes a cavity 38 that is preferably lined with neoprene sleeve 22 third portion 36 is configured to fit into hose nut 21 with shoulder 37 seating against a corresponding shoulder 41 in the hose nut 21 an axial bore 40 communicates with cavity 38 and axial bore 17 u2032 in cap 14 and extends through the inlet nipple 23 as shown preferably the cap 14 includes an upper annular portion 28 that has a knurled surface to facilitate grasping and turning of the cap 14 by the fingers of a user cap 14 includes external threads 27 that mate with corresponding internal threads 29 of connector 16.