(2) For an apparatus, equipped with a facepiece, in which the expired atmosphere is recirculated and which utilizes a supply of compressed oxygen and a regenerator, the regenerating material (absorbent) shall absorb carbon dioxide from the expired atmosphere. Samples of the atmosphere within the apparatus shall be taken for analytical determination of carbon dioxide content. The atmosphere within the apparatus shall be sampled only when the wearer is inhaling, over a period covering several inhalations, and at uniform intervals of time. None of the samples so taken shall contain more than 2½ percent of carbon dioxide. Samples of the atmosphere within the apparatus shall be taken from the inhalation side of the apparatus as near as possible to the facepiece; the average carbon dioxide content of such samples shall not exceed 1 percent during the test. Samples of the atmosphere within 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.
(3) For an oxygen-generating apparatus, equipped with a mouth-breathing device, in which the expired atmosphere is recirculated and in which a chemical change is effected so that carbon dioxide is absorbed concurrently with the generation of oxygen, samples of the atmosphere within the apparatus shall be taken for analytical determination of carbon dioxide content. The atmosphere within the apparatus shall be sampled as near to the point of inspiration as practicable, only while the wearer is inhaling, over a period covering several inhalations, and at uniform intervals of time. None of the samples so taken shall contain more than 2½ percent of carbon dioxide. The average carbon dioxide content of all atmospheric samples taken from within the apparatus during the test shall not exceed 1 percent.
(4) For an oxygen-generating apparatus, equipped with a facepiece, in which the expired atmosphere is recirculated and in which a chemical change is effected so that carbon dioxide is absorbed concurrently with the generation of oxygen, samples of the atmosphere within the apparatus shall be taken for analytical determination of carbon dioxide content. The atmosphere within the apparatus shall be sampled only when the wearer is inhaling, over a period covering several inhalations, and at uniform intervals of time. None of the samples so taken shall contain more than 2½ percent of carbon dioxide. Samples of the atmosphere within the apparatus shall be taken from the inhalation side of the apparatus as near as possible to the facepiece; the average carbon dioxide content of such samples shall not exceed 1 percent during the test. Samples of the atmosphere within 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.
(5) For an apparatus, equipped with a mouth-breathing device, in which the expired atmosphere is not recirculated, as in open-circuit (demand) apparatus, and which utilizes a supply of compressed oxygen or compressed air, samples of the atmosphere within the apparatus shall be taken for analytical determination of carbon dioxide content. The atmosphere within the apparatus shall be sampled as near to the point of inspiration as practicable, only while the wearer is inhaling, over a period covering several inhalations, and at uniform intervals of time. None of the samples so taken shall contain more than 22 percent of carbon dioxide. The average carbon dioxide content of all atmospheric samples taken from within the apparatus during the test shall not exceed 1 percent.
(6) For an apparatus, equipped with a facepiece, in which the expired atmosphere is not recirculated, as in open-circuit (demand) apparatus, and which utilizes a supply of compressed oxygen or compressed air, samples of the atmosphere within the apparatus shall be taken for analytical determination of carbon dioxide content. The atmosphere within the apparatus shall be sampled only when the wearer is inhaling, over a period covering several inhalations, and at uniform intervals of time. None of the samples so taken shall contain more than 22 percent of carbon dioxide. Samples of the atmosphere within the apparatus shall be taken from the inhalation side of the apparatus as near as possible to the facepiece; the average carbon dioxide content of such samples shall not exceed 1 percent during the test. Samples of the atmosphere within
