Figure 8-8. - Self-contained oxygen-brreathing apparatus with bottle.

harness straps should be snug, not too tight. Although other types of facepieces may have fewer head harness straps or may have various sizes and shapes of lenses, most facepieces are similar in design. Because of this close similarity, the methods of application can be adapted to the one described and shown by figures 8-9, 8-10, and 8-11.

The six steps for donning the facepiece are as follows:

1. Loosen the head harness strap so that the tab end of each strap is against the facepiece buckle. With both hands, fold these straps in a bundle across the top of the facepiece. Hold the facepiece and straps by grasping the upper sides with both hands (fig. 8-10).

2. Place the chin well into the small pocket at the bottom of the facepiece and fit the facepiece to the temples and forehead.

3. Release the facepiece with both hands, but hold secure to the harness and pull the harness over the top of the head.

4. Tighten the chin straps first by pulling out and back on the tabs provided. This operation secures the facepiece in position and places the head harness on the back of the head so that the bottom strap is across the back of the neck and below the ears.

5. Tighten the temple straps next and secure the facepiece snugly to the head.

6. Tighten the top straps last, as shown in figure 8-10.

Notice that the head harness is placed at the back of the head, not on top. If the top straps are tightened first, the head harness may be pulled out of position. The facepiece is now ready to be tested for leakage. Hold one hand over the end of the breathing tube, or squeeze the breathing tube, and then try to inhale. If the facepiece fits snugly, it should collapse against the face.

Donning the Side Shoulder Strap Model

The harness of the side shoulder strap model must be prepared before the equipment is lifted from the floor. The only place necessary to grasp the harness or equipment is where the takeup strap and shoulder strap are buckled together. The takeup strap should be arranged without twist, although the wide shoulder strap may appear to have a half twist. This twist is normal for proper fitting to the back and shoulder. The steps for donning the side shoulder strap model (fig. 8-10) are as follows:

1. Fold the loop end of the harness takeup strap over upon itself and grasp the takeup strap with the right hand, at this point, with the palm down.

2. Lift the equipment up along the left side of the body by raising the right hand and arm toward the head. At the same time, run the left arm through the loop formed by the harness and