OXYGEN BREATHING APPARATUS
of the CO2 that is trapped between the shutoff valve and
the cylinder being recharged.
The type A-4 oxygen breathing apparatus (OBA)
is used throughout the Navy. The OBA is an entirely
Step 11. Weigh the recharged cylinder carefully.
self-contained breathing apparatus. It enables the
Note the charged weight on the cylinder record card.
wearer to breathe independently of the outside
Step 12. After recharging is complete, close the
atmosphere. It produces its own oxygen from chemical
supply cylinder valve tightly. Open the shutoff valve in
reaction and allows the wearer to enter compartments,
the pump outlet hose very slowly and allow all the CO2
voids, or tanks that contain smoke, dust, or fire, or
in the unit to be discharged to the atmosphere.
those that have a low oxygen content.
Major OBA Components
You will be required to wear and operate the type
A-4 OBA and to maintain it in perfect condition. To do
What type of fire-fighting agent is known to
so, you must know the various components of the OBA
foul electrical and electronic components, as
and their functions. Figure 5-5 shows the components
well as the internal parts of turbines and
and identifies them. As you read about the various
components, refer to this figure as well as to the
additional figures pertaining to the individual
What type of fire-fighting agent may be used
to vapor seal a small fuel spill?
Before using a portable CO2 fire extinguisher,
you should ground the cylinder to the deck.
Bail assembly handle
2. Breathing tubes
Canister release strap
Relief valve and pull tab
Learning Objective: Recall the purpose and operation
4. Body harness and pad
of protective equipment used in fire fighting.
5. Breathing bag
T h e N av y u s e s a w i d e va r i e t y o f s p e c i a l
6. Breastplate assembly
fire-fighter's protective equipment. It includes the
oxygen breathing apparatus (OBA), the self-contained
Figure 5-5. Components of the OBA.
breathing apparatus (SCBA), the fire-fighter's
ensemble, and antiflash clothing. Other equipment
FACEPIECE.-- The OBA facepiece (fig. 5-6)
includes gloves, fire-fighter's helmet, antiflash hood,
contains the eyepiece, the speaking diaphragm, and the
head straps. The eyepiece is a one-piece clear lens. A
equipment is available, how to operate it, and how to
spectacle kit is provided that may be installed in the
maintain it in top condition.
facepiece. Corrective lenses may be installed in the kit