DC MUSEUM

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

1. Before donning the apparatus, see that the end of the belt strap is out of the belt buckle, and that the shoulder strap on this buckle side of the apparatus is not snapped on to the body plate; and see that the colors (red, green, and yellow) match on all tube connections having these colors for identification.
2. Put the arms through the armholes; snap the unattached shoulder strap onto the body plate; insert the belt end in the buckle.
3. Adjust the height of the apparatus on the body by means of the metal slides on the shoulder straps. This height should be such that when the facepiece is put on, the breathing tubes will have enough play in them to permit free movement of the head, and the timer dial will be at the proper distance from the eyes. Adjust the belt strap to a comfortable fit.
4. Place a canister of chemical in the apparatus. The procedure is as follows: Remove the metal tear-off cap from the top of the canister by pulling off the metal tab across the cap and then pulling off the cap. The removal of this cap will reveal the metal-foil seal below. The canister is not ready but the seal for the moment unbroken. On the apparatus, turn the hand wheel counterclockwise, to down position. This wheel is sued to turn a screw through a supporting bail, yoke, for the purpose of pushing the canister into place in the canister guard and holding it there. With the screw turned down completely to clear the bottom of the canister guard pull the bail forward until unobstructed passage is made for the insertion of the canister. With the free hand grasp the canister by the bottom and, keeping the bulged side, out, push it as far as it will go into the canister guard. (It will be stopped just short of making contact at the top of the chamber by a “canister stop” which is on the upper left side of the chamber, and to be released later by hand.) Swing the bail back into place, and lock the canister firmly, but not too tightly, into the chamber by turning the hand wheel clockwise. The apparatus is now ready for patrol, or standby service. The wearer still breathes outside air as the facepiece is not being worn at the time.
5. To put the breathing apparatus into actual service operation, as in a gas filled compartment, relieve pressure on the canister by turning the hand wheel counterclockwise just enough to permit ordinary hand pressure to release the canister stop, and thus clear the way to the top of the chamber. Turn the hand wheel clockwise until a tight contact is made with the canister top against the recess in the plunger housing, where a gasket assures a leakproof seal. (It is at this time the metal-foil seal is punctured.)
6. Adjust the straps of the facepiece to an approximate fit. Pull out the handband straps especially the lower, or check straps, so that the ends are at buckles; blow out the dust; insert chin well in the lower part of the facepiece and pull the headbands back over the head. To get a firm and comfortable fit against the face at all points, adjust the headbands as follows:
   1. See that the straps lie flat against the head;
   2. Tighten the lower, or neck straps, but do not touch the forehead or front straps;
   3. Place both hands on the headband pad and push it outwards the neck
   4. Repeat operation (b) and (c).
   5. Tighten the forehead or front straps.
   6. Test for tightness of the facepiece in accordance with step 7 below. (With facepiece in position the wearer is cut off from outside air, and he has only the air in his lungs. He must draw more air into the apparatus at once through the started valve.)
7. Pinch the two breathing tubes firmly, in order to close them temporarily, and at the same time open the starter valve (set just below the facepiece) and take a deep breath; release pressure on both of the breathing tubes and the starter valve, and exhale. (This exhaled air goes into the apparatus.) Do this 15 times or more if necessary until the canisters begin definitely to warm up and the breathing bag is fully inflated. Wearer is then entirely dependent on the air within the system, that is to say, in the apparatus and in his lungs. (Precaution must always be taken to fill the apparatus in this way with enough to keep a constant supply of breathable air flowing to the lungs, a process that cannot proceed without air enough to form a reserve in the breathing bag and to actuate the chemicals in the canister.) If during this interim excess pressure develops in the breathing bag it may be relieved by momentarily lifting the edge of the facepiece.
8. Turn the pointer on the Timer dial clockwise to number 57. (This gives a 3-minute margin for safety.) As the apparatus is used, the pointer will return to zero, at which point a warning bell will ring.
9. When the warning bell rings, return immediately to fresh air.
10. To remove a spent canister, spread the legs apart; lean the upper part of the body with apparatus slightly forward; turn the hand wheel on the bail counterclockwise all the way down; with a quick forward motion, swing the bail outward. The canister will drop out. (Precaution must be taken to handle canister only with suitable protection of the hands, since it will be very hot.) Do not allow any liquid to enter the opening of the canister, and do not hold the face over the canister opening. Because of the high oxygen content and the temperatures of the chemicals in the canister they will cause combustion, especially if such material is moist. (Expended or damaged canisters should be punctured in several places and throw over the stern of the ship as soon as after as practicable. This disposal should not be made however if any oil or gasoline is evident upon the surface of the surrounding water, inasmuch as a canister dropped into water so contaminated will explode and burn with sufficient heat to ignite the oil or gasoline.)