piece(s) meets the pertinent requirements for impact and penetration specified in the most recent United States of America Standards Institute Safety Code for Eye Protection. The wearer's field of vision shall be adequate and not distorted by the eyepiece(s). The design of facepiece shall minimize eyepiece fogging. Facepiece exhalation valves or pressure relief valves and inhalation valves shall be protected against distortion. An adjustable head harness capable of maintaining tension under all circumstances shall be furnished. The facepiece shall have, or be capable of having added to it, a provision for the use of corrective spectacles. The use of spectacles shall not reduce the respiratory protective qualities of the apparatus.

(2) Mouthpiece and noseclip. If a mouthpiece and noseclip are used, both shall be provided. An adjustable head harness capable of maintaining tension under all circumstances shall be furnished. They shall provide an air-tight seal and shall be securely attached to the apparatus to prevent accidental loss.

(3) Gas and liquid container(s). Compressed-breathing gas container(s) shall be acceptable for interstate shipment when fully charged and shall comply with pertinent requirements in Department of Transportation or Interstate Commerce

Commission Specification 3AA or other applicable DOT or ICC regulation. Compressed-breathing gas container valves shall be equipped with outlet threads specified for the service by the United States of America Standards Institute Standard for Compressed Gas Cylinder Valve Outlet and Inlet Connections, B57.1-1965. Containers that are normally removed from the apparatus for refilling shall be permanently and legibly marked with the name of their contents, such as compressedbreathing air, compressed-breathing oxygen, liquefied-breathing air, or liquefied-breathing oxygen. Compressedbreathing-gas containers, when they are normally removed from the apparatus for refilling, shall be equipped with a dial-indicating gage to show container pressure. The gage shall meet the requirements of subparagraph (4) of this paragraph.

container

Compressed-breathing-gas gages shall be calibrated in pounds per square inch and may also be calibrated in fractions of total container capacity. (ii) Liquid-level gages shall be calibrated in fractions of the total container capacity and may also be calibrated in units of liquid volume.

(iii) Dial-indicating gages shall be reliable to within 5 percent of full scale when tested both up and down the scale at each of 10 equal intervals. The fullscale graduation of the gage shall not be in excess of 150 percent of the maximum cylinder pressure allowed under applicable regulations of the Department of Transportation or the Interstate Com

merce Commission.

(iv) Stem-type gages shall be readable by sight and by touch and shall have a stem travel distance not less than onefourth inch between each graduation. At least five graduations shall be engraved on the stem, including empty, one-quarter, one-half, three-quarters, and full. Stem gage readings shall not vary from true readings by more than 16-inch per inch of stem travel.

(v) The loss of gas through a broken gage or severed gage connection shall not exceed 70 liters per minute when the cylinder pressure is 1,000 pounds per square inch gage or the liquid level at one-half.

(vi) When a gage is connected to the remainder of the apparatus through a gage line, a means shall be provided to isolate the gage and line from the apparatus, unless failure of the gage or line does not impair performance or service life of the apparatus.

(vii) Oxygen gages shall have the words, "Use No Oil," marked prominently on the gage.

(viii) Apparatus using compressed or liquefied breathing gas, except apparatus for self-rescue, shall have, visible to the wearer, a gage that indicates remaining gas or liquid content.

(5) Timers. A timer shall be included on oxygen-generating apparatus (except apparatus only for self-rescue). It shall be accurately calibrated in minutes of remaining service life. It shall be discernible by the wearer's sight and touch while the apparatus is in use. Setting of the timer shall automatically set an alarm which will warn the wearer for not less than 10 seconds after the preset time has elapsed.

(6) Remaining service-life indicator or warning. Apparatus (except apparatus

only for self-rescue) using compressedbreathing gas shall have a remaining service-life indicator or warning device in addition to a pressure gage. The device shall operate automatically, without preadjustment by the wearer, when the remaining service life is reduced to between 20 and 25 percent of the rated service time of the apparatus. If the device depends on gas flow, the maximum flow-rate of gas vented to the atmosphere, that is used to operate such a device shall not exceed 4 liters per minute. When used on closed-circuit apparatus, not more than 1 liter per minute of the actuating gas shall be permitted to escape from the breathing circuit.

(7) Hand-operated valves. (1) Valves shall be designed so that the stem cannot be completely removed from the valve body during normal usage and so that the full pressure of the container cannot be released suddenly when the valve is opened. Valves that must be manipulated during the use of the apparatus shall be positioned where they can be readily operated by the wearer. Valves shall be protected from damage by external forces. Valves shall be easily distinguishable from each other and shall be designed or positioned to prevent accidental closing.

(ii) A main-line valve shall be provided, in addition to a gas-container valve(s), if it is needed to conserve gas in the event of regulator or demand valve failure, except as provided in subdivision (iv) of this subparagraph.

(iii) A hand-operated bypass system shall be provided to permit the wearer to breathe and to conserve his gas supply if the regulator or demand valve fails except as provided in subdivision (iv) of this subparagraph. The bypass control shall be colored red.

(iv) A main-line valve and bypass system will not be required on apparatus for escape only.

(8) Breathing bag. When a breathing bag(s) is used on an apparatus (except for self-rescue only), it shall be designed or protected to prevent damage or collapse from external force. The bag(s) of all apparatus shall be of sufficient volume to prevent gas waste during exhalation and to provide an adequate reserve for inhalation, as determined by man tests described in Subpart C of this part. The bag(s) shall be flexible and resistant to gasoline vapors. The bag(s) will be tested in an air atmosphere saturated with gas

oline vapor at room temperature (75°— 85° F.) for a continuous period of twice the rated time of the apparatus (except for apparatus for self-rescue only where the test period shall be the rated time of the apparatus). The bag(s) will be operated during this test by a breathing machine with 24 respirations per minute and a minute-volume of 40 liters. A breathing machine cam with a work rate of 622 kg-m/min 1 will be used. The air within the bag (s) shall not contain more than 100 parts per million of gasoline vapor at the end of the test.

1

(9) Carrying or storage container. Where a carrying or storage container or bracket is supplied by the applicant for use with a self-contained breathing apparatus, the container shall be examined and approved by the Bureau as part of the complete apparatus.

(10) Safety relief valves or system. All closed-circuit appartus shall be provided with a safety pressure-relief valve or system that will release excess pressure in the breathing circuit. Excess pressure in the breathing circuit is defined as 1/2inch-water-column height of pressure, or more, above the minimum pressure required to fill the breathing bag within the resistance requirements in paragraph (d) (2) of this section. The safety relief valve, or system shall be operated automatically by the pressure on the inhalation side of the bag. The valve or system shall also permit manual overriding for test purposes and in the event of failure of the safety relief valve or system. The safety relief valve or system shall be designed to prevent external atmospheres from entering the breathing circuit.

(d) Requirements and tests for complete apparatus-(1) Weight. The completely assembled and fully charged apparatus shall not weigh more than 35 pounds; except that when the weight of an apparatus decreases by more than 25percent of its initial charge weight during its service life, the completely assembled and fully charged apparatus shall not weigh more than 40 pounds.. When an apparatus is equipped with a. device which would contribute materially to the wearer's comfort (such as a cooling system), the completely assembled. and fully charged apparatus shall not

1 Silverman, L., G. Lee, T. Plotkin, L. Amory, and A. R. Yancey, Fundamental Factors in Design of Protective Equipment, O.S.R.D. Report No. 5732, issued April 1, 1945.

weigh more than 40 pounds regardless of the decrease in weight during use.

(2) Breathing resistance—(i) Inhalation. Resistance to airflow will be measured at the facepiece while the apparatus is operated by a breathing machine as described in paragraph (c) (8) of this section. The inhalation resistance of open-circuit apparatus shall not exceed 1.25-inch-water-column height. The inhalation resistance of closed-circuit apparatus shall not exceed the difference between exhalation resistance and 4 inches of water-column height.

(ii) Exhalation. Resistance to airflow at the facepiece of open-circuit apparatus will be measured with air flowing at a continuous rate of 85 liters per minute. The exhalation resistance of demand apparatus shall not exceed 1 inch of water-column height. The exhalation resistance of pressure-demand apparatus shall not exceed the static pressure in the facepiece by more than 2 inches of water-column height. The static pressure (at zero flow) in the facepiece shall not exceed 1.5 inches of water-column height.

Resistance to airflow at the facepiece of closed-circuit apparatus will be measured as described in subdivision (i) of this subparagraph. The exhalation resistance shall not exceed 2 inches of water-column height.

(3) Gas flow-(i) Open-circuit apparatus. A static-flow test will be performed on all open-circuit apparatus. The flow from the apparatus shall be greater than 200 liters per minute when the facepiece pressure is lowered by 2 inches water-column height below the static pressure when full container pressure is applied. Where compressed-breathinggas containers are used, the flow test shall also be made with 500 p.s.i.g. container pressure applied.

(il) Closed-circuit apparatus. If oxygen is supplied by a constant-flow device only, the rate of flow shall be at least 3 liters per minute for the entire rated service time of the apparatus. When constant flow is used in conjunction with demand flow, the constant flow shall be greater than 1.5 liters per minute for the entire service time. The demand-flow device shall provide at least 20 liters of oxygen per minute when it is in the fully open position.

(4) Rated service time-(1) Open-circuit apparatus. The apparatus will be rated according to the length of time

it supplies air or oxygen to a mechanical breathing machine. The breathing machine shall operate as described in paragraph (c) (8) of this section. The service time obtained on this test will be used to classify the apparatus in § 11.4 (c).

(ii) Closed-circuit apparatus. The apparatus will be rated according to the length of time it supplies adequate breathing gas to the wearer as required in subparagraphs (2) (inhalation resistance) and (5) (carbon dioxide concentration) of this paragraph, and during man test No. 4 described in Table 4, § 11.31. The service time obtained on man test No. 4 will be used to classify the apparatus in § 11.4(c).

(5) Carbon dioxide in inspired gas. (i) Open-circuit apparatus: The concentration of carbon dioxide in inspired gas will be measured at the mouth while the apparatus mounted on a dummy head is operated by a breathing machine. The breathing rate shall be 14.5 respirations per minute with a minute-volume of 10.5 liters. A sedentary breathing machine cam' shall be used. The apparatus shall be tested at a temperature of 80±5° F. A concentration of 5 percent carbor. dioxide in air shall be exhaled into the facepiece. Tested in this manner, the apparatus shall meet the requirements of subdivision (iii) of this subparagraph.

(ii) Closed-circuit apparatus: The concentration of carbon dioxide will be measured at the mouth while the parts of the apparatus contributing to dead-air space are mounted on a dummy head. Tested in this manner the apparatus shall meet the requirements of subdivision (iii) of this subparagraph.

(iii) The concentration of carbon dioxide at the mouth shall be continuously recorded. The maximum average concentration during the inhalation portion of the breathing cycle shall be less than the following:

(iv) In addition, during the man tests described in Tables 1 through 4 in § 11.31, gas samples shall be taken from closedcircuit apparatus at a point downstream of the carbon dioxide sorbent. The samples shall not contain more than 0.5 percent carbon dioxide at any time.

(6) Low-temperature operation (i) Open-circuit apparatus. The apparatus will be precooled at -25° F. for 4 hours. It will then be worn in a lowtemperature chamber at -25° F. for 30 minutes or for the rated service time of the apparatus, whichever is less. During this test there shall be alternate periods of exercise and rest for 1 minute each for the required time. The exercises to consist of stepping onto and off a box 81⁄2 inches high at a rate of 30 cycles per minute. The apparatus shall function satisfactorily on duplicate tests. The wearer shall have sufficient unobscured vision to perform the work. The wearer shall not experience undue discomfort because of airflow restriction or other physical or chemical changes in the operation of the apparatus. If necessary, auxiliary low-temperature parts may be used on the apparatus to meet the requirements of this test. These parts shall be commercially available to the user of the apparatus.

(ii) Closed-circuit apparatus. The applicant shall specify the minimum temperature for safe operation. Three persons will perform the tests described in subdivision (i) of this subparagraph, wearing the apparatus according to the applicant's directions at the minimum temperature specified by the applicant. At the specified temperature, the apparatus shall meet all the requirements described in subdivision (i) of this subparagraph.

§ 11.22 Requirements for combination self-contained breathing apparatus and another type of respiratory protective device.

(a) Respiratory protective devices combining the characteristics of a selfcontained breathing apparatus and another type of respiratory protective device shall meet the requirements of this part as well as the requirements of any other part which is applicable to the total purpose of the device for which approval is sought. The approval, if granted, will be issued under this part. The Bureau will specify, in the certificate of approval and on the approval label, the limitations which shall apply

to the use of the combination respiratory protective device.

(b) When the device is a combination self-contained breathing apparatus and air-line respirator (supplied-air respirator) either a manual or automatic valve(s) shall be provided to change to the self-contained air supply if the airline supply fails, and to prevent the wearer breathing contaminated air from the outside atmosphere. If a manual valve is provided, it shall be easily operable and located in a position which is convenient to the wearer; a warning device shall be provided to alert the wearer when the self-contained air supply falls below 80 percent of its full container pressure. If an automatic valve is provided, a warning device shall also be provided to alert the wearer that he is breathing from the self-contained air supply, (1) when his normal air-line supply fails, or (2) when the self-contained air supply falls below 80 percent of its full container pressure. A quick disconnect and check valve shall be provided between the apparatus and the air-line supply hose to permit ready escape from the area, and to prevent loss of breathing air from the device or inhaling the surrounding atmosphere, respectively. Subpart C-Man Tests

§ 11.30

General description of tests.

(a) The following tests represent the workload a man would perform while wearing an apparatus in the mining, mineral, and allied industries.

(b) The apparatus will be worn by Bureau of Mines personnel who are trained in the use of self-contained breathing apparatus. Before participation in any of these tests, the wearer shall pass a physical examination by a qualified physician. If a test is not completed through no fault of the apparatus, the test shall be repeated.

(c) Breathing resistance will be measured within the facepiece or mouthpiece. The wearer's pulse and respiration rates will be recorded during the 2-minute sample periods indicated in Tests 1 through 4, below. These will evaluate the wearer's physiological reactions to wearing the apparatus.

(d) All tests will be conducted by the Bureau of Mines in an appropriate gallery.

(e) The apparatus will be examined before each test to make certain it is in proper working order.