oxygen insufficiency, explosive vapors, and some poisonous gases.
An oxygen breathing apparatus (OBA) is provided for emergency use in compartments containing toxic gases and lacking sufficient oxygen to support life. The apparatus is particularly valuable for rescue purposes because it is a self-contained unit. The wearer is not dependent upon outside air or any type of air line within the effective life of the canister.
There are several types of oxygen breathing apparati, but they are all similar in operation. Independence of the outside atmosphere is achieved by having air within the apparatus circulated through a canister. Within the canister, oxygen is continuously generated. The effective life of the canister varies from 20 to 45 minutes, depending on the particular apparatus and the type of work being done. One of the newer types of oxygen breathing apparatus is designed so that you can change canisters without leaving the toxic atmosphere.
If you are to enter an extremely hazardous area, you should also wear a life-line. The life-line should be tended by two persons, one of whom is also wearing a breathing apparatus.
Never allow oil or grease to come in contact with any part of an oxygen breathing apparatus. Oxygen is violently explosive in the presence of oil or grease. If any part oft he apparatus becomes contaminated with oil or grease smudges, clean it before it is stowed. Care should be taken to prevent oil or oily water from entering the canister between the time it is opened and the time of disposal.
Hose masks are part of the allowance of all ships having repair party lockers. They are smaller than the oxygen breathing outfits and can therefore be used by persons who must enter voids or other spaces that have very small access hatches. The hose or air line mask consists essentially of a gas mask facepiece with an adjustable head harness and a length of airhose. Note that the air line mask uses AIR rather than pure oxygen. It must NEVER be connected to an oxygen bottle, oxygen cylinder, or other source of oxygen; even a small amount of oil or grease in the air line could combine rapidly with the oxygen and cause an explosion. When properly connected to a suitable source of air, such as the low-pressure ships service air line, the hose mask can be worn safely, even in spaces containing a high concentration of oil or gasoline vapors; for this service, the air line mask is superior to the oxygen breathing apparatus.
Safety belts are furnished with each air line mask and MUST BE WORN. A life-line must be fastened to the safety belt; and the life-line should be loosely lashed to the airhose to reduce the possibility of fouling. The airhose and life-line must be carefully tended at all times, so that they will not become fouled or cut. The person wearing the airline mask and the person tending the lines should maintain communication by means of standard divers signals.
Protective masks provide respiratory protection against chemical, biological, and radiological warfare agents. They do not provide protection from the effects of carbon monoxide, carbon dioxide, and a number of industrial gases. Protection from these gases is discussed in the section Rescue from Unventilated Compartments.
In emergencies, protective masks may be used for passage through a smoke-filled compartment or for entry into such a compartment to perform a job that can be done quickly, such as close a valve, secure a fan, or de-energize a circuit. However, they provide only limited protection against smoke. The length of time you can remain in a smoke-filled compartment depends on the type of smoke and it concentration.
The most important thing to remember about protective masks is that they do not manufacture or supply oxygen. They merely filter the air as it passes through the canister. Therefore, the protective mask should not be used in air containing less than 16 percent oxygen, or having a heavy concentration of smoke from oil fires excepts for very short periods of time.
The Navy asbestos suit is made in a single unit, is easy to get into, and provides complete cover for the wearer. With it on, a firefighter can move quickly through flame to effect a rescue or to perform some other job that can be done quickly.
While asbestos will not burn, it will char and conduct heat. Therefore, the suit provides protection against flame only for short periods of time. The length of time the suit can be worn