discuss the type A-4 OBA operating procedures. It is
very important that you learn to use them properly. You
should practice the operating procedures under the
supervision of a leading petty officer who is qualified
in the use of the OBA.
D O N N I N G T H E O BA . -- T h e s t e p s o f t h e
procedure for donning the OBA are as follows:
Step 1. With one hand, grasp the facepiece at the
combination valve housing and the apparatus at the
operating handle. With the other hand, grasp the straps
of the body harness and the body pad D ring. Bring the
Figure 5-14. Step 3, donning the OBA.
pad and harness over your head while positioning the
OBA on your chest. See figure 5-12.
Step 4. Place the facepiece over your head in the
standby position (fig. 5-15) until you are ready to
activate the canister.
Figure 5-12. Step 1, donning the OBA.
Step 2. Find the two straps hanging free in back
(fig. 5-13, view A). Attach the end of each strap to the
Figure 5-15. Step 4, donning the OBA.
ring on each side of the breastplate ( fig. 5-13, view B).
Install the canister in the following
a. Remove the tear-off cap of the canister by
pulling the tab backward and downward to expose the
copper-foil seal (fig. 5-16). Discard the cap.
Figure 5-13. Step 2, donning the OBA.
Step 3. Position the breastplate on your chest so
that the breathing tube connections are slightly below
your shoulders. Your head movement should not be
restricted when you don the facepiece. While holding
the apparatus in this position, adjust the two underarm
Figure 5-16. Step 5, removing the tear-off cap.
straps and then adjust the two shoulder straps (fig. 5-14)
until the apparatus fits comfortably. The harness pad
b. Remove the canister candle cover by
should be located in the center of your back, down from
rotating the swivel plate 180º. Push it down toward the
center of the canister, as shown in view A of figure 5-17.
the neck for a comfortable fit.