DC MUSEUM

OPERATING INSTRUCTIONS AND SAFETY PRECAUTIONS FOR TYPE A-1, A-2 AND A-3 BREATHING APPARATUS

  1. The following are the essential consecutive steps in donning and wearing these apparatus:
    1. Before donning the apparatus, straighten all harness straps, so metal slides are about 3 inches from the end. One should strap should be fastened to the D ring on the breastplate.
    2. With one hand grasp the apparatus by the central casting, dropping facepiece over the hand holding apparatus. Slide the other arm through the loop made by the pre-fastened strap and the head through the V-shaped opening formed by the crossing of the two straps attached to the breastplate.
    3. Continue to hold the apparatus on the chest with one hand, and with the other reach around to the rear at one side and grasp the free end of the harness strap. Bring the end of the strap beneath the armpit and snap it into the metal D ring located on the topside of the breastplate.
    4. Make any final adjustment in the position of the apparatus on the body by means of the metal slides on the harness straps. The position of the apparatus should be such that the wearer can look up or down without having the facepiece shift or catch on the timer or main valve housing.
    5. Snap the waist strap to the small D ring or waist strap eye bracket on lower side corner of the breastplate, and adjust to hold the apparatus snugly to the body.
    6. To place canister in apparatus, first remove the metal protective cap and expose the metallic-foil seal in the neck. This is done by pulling the metal tab straight out, up, and then straight across the top of the cap. Insure that the metal disk and both cardboard disks have been removed. When using quick-starting canister, remove one candle cover. Then, with hand wheel in extreme down position, swing bail outward far enough to permit canister to enter canister guard. Insert canister with neck up. After canister hits canister stop, swing the bail back in place under the canister and turn hand wheel clockwise until canister is locked firmly, but not too tightly, in place. The apparatus is now ready for standby service.
    7. Operating position of apparatus. To obtain this active service condition, the wearer momentarily releases the pressure on the canister by turning the hand wheel counterclockwise approximately one-half turn with his right hand, and with his left hand pushes the canister stop on the left-hand side of the guard in, as far as possible. He then turns the hand wheel clockwise until the canister gasket is firmly seated against the V-shaped recess in the main valve.
    8. With the apparatus properly and comfortably positioned and with the head harness straps properly in place through the buckles of the facepiece, slip on the facepiece by placing head harness pad on head, stretch harness, and slide facepiece into position. Adjust the head straps to fit the face and head size of the individual wearer.
    9. To obtain a firm and comfortable fit against the face at all points, adjust the head straps as follows:
      1. See that straps lie flat against head.
      2. Tighten lower or neck straps.
      3. Tighten the side straps. (Do not touch forehead or front straps.)
      4. Place both hands on head-harness pad and push it toward the neck.
      5. Repeat operations 2 and 3.
      6. Tighten forehead or front straps.
      7. Test for tightness of facepiece by squeezing both breathing tubes and inhaling gently. The facepiece must collapse against the face or be readjusted until it does.
      CAUTIONS: Do not attempt to use any type facepiece with this apparatus other than the one furnished with the apparatus.
    10. As explained in BuShips Manual, Chapter 93, Art. 93-409, oxygen is provided the wearer as a result of a reaction between the chemical in the canister and the moisture and carbon dioxide in the exhaled breath.
  2. While starting the standard canister, the wearer breathes the 21-percent oxygen in air. Bodily requirements would soon deplete this supply of oxygen from the air contained in the breathing bags, and it, therefore, must be changed to maintain an adequate oxygen content until the oxygen producing reaction starts the canister. The firing of a chlorate candle in the quick-starting canister provides an immediate supply of pure oxygen. This is sufficient to last until the reaction starts in the canister, except under unusual circumstances, such as extreme cold. Starting instructions are, therefore, separated for normal temperatures, 50° F and above, and cold temperatures, below 50° F.
    1. Starting procedure for normal temperature. After the facepiece has been adjusted and checked for an airtight fit, start the chemical reaction in the canister by the following method:
      STANDARD CANISTER
      1. Grasp both breathing tubes with one hand, squeeze tightly, depress starter valve and inhale deeply, release starter valve and tubes and then exhale into apparatus.
      2. Repeat this procedure until breathing bags are fully inflated (usually 3 or 4 breaths).
      3. Depress starter valve and deflate breathing bags with arms.
      4. Repeat 1, 2, and 3 until bottom of canister feels warm, then repeat 1 and 2 and proceed with work to be done.
      QUICK-STARTING CANISTER
      1. Pull lanyard with steady pull away from body, removing cotter pin from uncovered chlorate candle.
      2. Starting of the candle may be accompanied by a slight amount of harmless smoke. The breathing bag will be inflated with oxygen and the wearer may proceed with work to be done.
      3. Vent as necessary by depressing starter valve to prevent over inflation of breathing bags during time (2 to 4 minutes) chlorate candle is burning.
      4. The bottom of the canister will be hot; do not touch it with hands. Manual check of canister is not necessary.
    2. Starting procedure for cold temperatures. See BuShips Manual Chapter 93, Article 93-415-b for this procedure.

SAFETY PRECAUTIONS

  1. Since the type A-1, A-2, and A-3 oxygen breathing apparatus are not exactly alike, the fire fighter is cautioned to understand the construction differences, principles of operation, method of use, and limitations. Under normal conditions the wearer of the type A-1 and A-3 oxygen breathing apparatus will return to fresh air at the end of 45 minutes to effect the necessary change of canisters.
  2. Used canister is very hot. Do not handle without suitable protection for hands. Do not allow any liquid especially oil, grease, or gasoline, etc., to enter opening of used canister and to not hold face over canister opening. Should the canister be opened, do not handle chemical without suitable care and protection to hands and body as chemical is caustic, injurious to the skin, and should not be permitted to come in contact with the person. Do not allow unexpended or expended chemicals to spill on deck. If accidentally spilled, clean up immediately and dump overboard using a metal or nonflammable material for scoop. This chemical, due to the large percentage of oxygen it contains, will cause combustion of any flammable materials with which it is brought into direct contact, especially if such materials are moist. Expended canisters should be dumped overboard after several holes have been punched in the bottom with a clean tool.
  3. Oil, gasoline, or similar materials coming in contact with the chemical in either the unexpended or the expended canisters, may cause an explosion.
  4. Canisters should not be dumped overboard where there is an oil slick present on the water. Disposal overboard should not be made until the ship is underway. Do not throw spent canisters in bilges or any space which may contain oil or oil and water.