if the hose to the breathing regulator is equipped with a quick disconnect (SEE STANDBY INSPECTION, CLEANING AND STORAGE Section for instruction in operation of the quick disconnect coupling on regulator assemblies), check that the quick disconnect is engaged properly and that sleeve "C" is rotated 1/4 to 1/2 turn so notch "B" does not line up with rivet head "A". Test for proper engagement by tugging on the coupling. See Figure 1.