the apparatus also shall be taken from within the facepiece as near as practicable to the nose and mouth of the wearer; the average carbon dioxide content of such samples shall not exceed 2 percent during the test.
(f) All parts of & self-contained breathing apparatus, including the source of the breathed atmosphere, shall be carried on the body of the wearer.
§ 11.5 Construction. (a) When worn in irrespirable air, the apparatus shall, without recharging, meet the needs of the wearer for not less than the number of minutes for which it was designed.
(b) The mechanical construction of the apparatus shall be such that every part can be tested, inspected, and repaired by persons that are skilled in such work, and all parts that require sterilizing shall be readily accessible for this purpose.
(c) All parts of the apparatus subject to or liable to be subjected to pressures in excess of 5 pounds per square inch shall be so constructed and equipped with safety devices that the safety of the wearer shall be assured, as determined by the 15 tests described in § 11.7.
(d) In apparatus equipped with a breathing bag or bags, or their equivalent, the inhalation and exhalation compartments shall have a combined capacity of at least 8 liters. If a single breathing bag is used, it shall have a capacity of at least 5 liters.
(e) In apparatus equipped with a breathing bag that is used in conjunction with operation of an oxygen- or air-admission valve, the bag shall have a capacity of at least 3 liters after the admission valve is closed. After 3 liters of oxygen or air is introduced into the breathing bag, the water-gage pressure shall not exceed 3 inches.
(f) All parts enclosing the breathed atmosphere of a self-contained breathing apparatus shall consist of material that will exclude gases external to the apparatus and be impervious to gasoline vapor for at least a 22-hour period. The material shall be of good strength and be flexible, and the joints or seams shall be either cemented and sewed or vulcanized or bound in such manner that the part or parts will not become separated at the joints or seams when the apparatus is in use. Such part or parts may be made in one piece without joints or seams.
(g) The apparatus shall not have in its circulatory system any zone of constant negative pressure, or a positive pressure at the mouthpiece or facepiece of more than 3 inches water gage after a 2½-liter exhalation.
(h) A self-contained breathing apparatus in which the expired atmosphere is recirculated shall be provided with a release valve that is operated manually or automatically and is placed at some point in the circulatory system of the apparatus. The function of this valve shall be to permit the escape to the outside atmosphere of a part of the atmosphere in the circulatory system of the apparatus. The valve shall be so designed that the outside atmosphere cannot be drawn into the apparatus.
(i) When apparatus is equipped with high-pressure gas container (s) the applicant shall furnish therewith a certificate of test required by the Interstate Commerce Commission under Specifications No. 3-A or equivalent specifications or shall give evidence satisfactory to the Bureau that such high-pressure gas container (s) were tested in accordance with Interstate Commerce Commission Specifications No. 3–A or equivalent specifications.
(j) (1) When an apparatus is equipped with a high-pressure gas container charged with compressed oxygen or compressed air to a pressure 10 percent in excess of its marked service pressure, the container shall be equipped with a perforated safety cap attached to the main closing valve. The perforated safety cap shall contain a frangible disk, without fusible metal backing, and the disk shall have a bursting pressure of 2,650 to 3,000 pounds per square inch.
(2) When an apparatus is equipped with a high-pressure gas container charged with compressed oxygen or compressed air at a pressure not in excess of its marked service pressure, the container shall be equipped with a perforated safety cap attached to the main closing valve. The perforated safety cap shall contain a frangible disk, without fusible metal backing, having a bursting pressure of 2,650 to 3,000 pounds per square inch. As an alternate, when the high-pressure gas container is charged at a pressure not in excess of its marked service pressure, the container may be equipped with a perforated safety cap attached to the main closing valve and the safety cap provided with a plain
