NOTE: If a respirator fails to pass any of the required tests and the applicant notifies the Bureau to terminate further investigation or testing, the Bureau will return to the applicant any part of the fee not applied to its compensation for services. If the respirator is resubmitted for testing and approval after correcting the deficiencies, the additional fee will be determined in advance by the Bureau and the applicant will be notified accordingly. Such fee shall be paid before tests are begun.

(d) Drawings and specifications required. (1) Drawings, specifications, and descriptions shall be adequate in detail to identify fully all components and subassemblies and the assembled respirator. All drawings shall include title, number, and date; any revision dates shall be shown on the drawings and the purpose of each revision shall be shown on the drawings or described in an attachment to the drawing to which it applies.

(2) Duplicate sets of detailed drawings and specifications shall be a part of the application. These shall fully describe the construction, dimensions, composition, materials, finishes, and assembly of all parts of the respirator.

(3) The application shall state that, when tested by the applicant or his testing agency, the respirator has met the pertinent requirements of this part. Two copies of the results of the applicant's inspections and tests shall accompany the application.

(4) The application shall state that the respirator is completely developed and is a finished marketable product.

(5) The application shall describe the function of the respirator and the operation of its parts.

The

(e) Control-test requirements. application shall state how production items will be tested to maintain quality control of the respirator and its component parts. The Bureau may have its qualified representative(s) inspect the applicant's control-test methods, equipment, and records, and may interview the personnel who conduct the control tests, at all reasonable times.

(f) Material required for approval testing. When the Bureau notifies the applicant that the application has been accepted, it will also inform him of the number of complete respirators and extra parts that will be required for testing. All test materials shall be delivered

(charges prepaid) to the Bureau of Mines, Health and Safety Research and Testing Center, 4800 Forbes Avenue, Pittsburgh, Pa. 15213, Attention: Approval and Testing.

(g) Date for conducting tests. The date of acceptance of an application will determine its order of precedence for investigation and testing. The applicant, if he so specifies, will be notified of the date when tests on his respirator will begin. If a respirator fails to meet any of the requirements, it shall lose its order of precedence. If the application is resubmitted, after the cause of failure has been corrected, it will be treated as a new application.

(h) Conduct of investigations, tests, and demonstrations. (1) Prior to the issuance of a certificate of approval, only Bureau personnel, representatives of the applicant, and such other persons as may be mutually agreed upon, may observe the investigations or tests. The Bureau shall hold as confidential, and shall not disclose, principles or patentable features prior to certification. It shall not disclose any analyses, nor any details of the applicant's drawings, specifications, and related material. The conduct of all such investigations, tests, and demonstrations shall be under the sole direction and control of the Bureau. Any other persons shall be present only as observers or as required under subparagraph (3) of this paragraph.

(2) After the issuance of a certificate of approval, the Bureau may conduct such public demonstrations and tests of the approved device as it deems appropriate.

(3) When requested by the Bureau, the applicant shall provide assistance in assembling or disassembling the respirator and its components, subassemblies or assemblies for testing, and in operating the respirator during the tests.

(4) Applicants shall be responsible for their representatives present during tests and for observers admitted at their request and shall save the Government harmless in the event of damage to applicant's property or injury to applicant's representatives or to observers admitted at their request.

[Sched. 19B, 20 F.R. 2565, Apr. 19, 1955; 20 F.R. 6552, Sept. 7, 1955, as amended at 30 F.R. 3753, Mar. 23, 1965; 33 F.R. 11817, Aug. 21, 1968]

§ 12.5 Requirements for Bureau of Mines approval.

To obtain the approval of the Bureau of Mines, a supplied-air respirator must pass the following inspection and tests:

(a) Container and markings. (1) If deemed necessary for the protection, proper maintenance, and storage of the respirator, a substantial and durable container may be required.

(2) Each respirator and required container shall be marked distinctly with the name of the manufacturer; the type of device, such as "Type A supplied-air respirator"; and the name, letter, or number by which the device is designated for trade purposes.

(b) Materials. (1) The respirator must be constructed in all its parts of materials which are suitable for the purpose they must serve; this applies to the fabric, rubber, metal, and other parts. All parts (especially rubber) that come into contact with the skin must be of nonirritating composition. All materials used in the construction of respiratoryinlet coverings and hose shall be of a nature that will withstand disinfection by methods recommended by the manufacturer and approved by the Bureau of Mines. These approved methods for disinfection shall be described in the instructions for use of the device as supplied by the manufacturer.

(2) Metal parts of Type A and Type B supplied-air respirators (except those parts that remain in uncontaminated air) should be of such composition or structure as to minimize the possibility of ignition of flammable atmospheres by sparks.

(c) Design and construction. Excellence of design, mechanical construction, durability, and workmanship will be considered with regard to the safety of the wearer, the freedom of his movements, his range and clearness of vision, the fit of the respiratory-inlet covering, and the comfort afforded under all conditions of use. The ease with which parts of necessarily short life or period of use may be replaced by new or reconditioned parts, and the tightness of the whole apparatus, with a view to insuring the wearer against leaks of contaminated air both before and after such changes have been made, will also be considered.

(d) General requirements. (1) Each supplied-air respirator, when supplied with respirable air, must protect the wearer in the particular kinds of atmospheres for which it is approved. The Types A and AE supplied-air respirators may be approved for respiratory protection in essentially any atmosphere. The other types of supplied-air respirators may be approved for protection in any atmosphere that is not immediately dangerous to life or from which the wearer could escape without the aid of the device. These devices are approved only when used with respirable air and at the pressures and quantities required.

(2) The main parts of supplied-air respirators are as follows: Air-supply device (except Types B and BE); airsupply line; harness; and respiratoryinlet covering. Since the types AE, BE, and CE respirators for abrasive blasting differ from the corresponding suppliedair respirators only in the kind of respiratory-inlet covering, special requirements for the parts of these respirators are given only in the section on respiratory-inlet covering.

(3) The requirements for the complete respirators of the various types are grouped wherever possible.

(e) Requirements and tests for airsupply device. (1) Type A supplied-air respirator (hose mask). (i) Each Type A supplied-air respirator shall be provided with a hand-operated or motordriven air blower. No multiple system, whereby more than one user is supplied by one blower, will be approved unless each hose line is connected directly to a manifold at the blower. The blower shall permit free entrance of air to the hose when the blower is not operated, and it shall deliver the amount of air hereinafter specified with either direction of rotation, except when the construction of the blower is such that it cannot be operated in other than a specific direction for delivering the required amount of air.

(ii) A hand-operated blower will be tested by attaching it to a mechanical drive and operating it continuously 6 to 8 hours daily for a total of 100 hours at the speed required to deliver 50 liters of air per minute through each respirator, when assembled with the kind and

maximum length of hose for which the device is to be approved, connected to each blower or manifold outlet designed for hose connections. The blower shall operate throughout the period without failure or indication of excessive wear of bearings or other working parts. The crank speed of a hand-operated blower shall not exceed 50 revolutions per minute to deliver the required 50 liters of air per minute to each facepiece. For a hand-operated blower the power required to deliver 50 liters of air per minute to each wearer through the maximum length of hose shall not exceed one-fiftieth horsepower, and the torque shall not exceed a force of 5 pounds on an 8-inch crank. The torque and power shall be measured as hereinafter provided.

(iii) A motor-operated blower shall be tested by operating it continuously at its specified running speed 6 to 8

hours daily for a total of 100 hours when assembled with the kind and maximum length of hose for which the device is to be approved and when connected to each blower or manifold outlet designed for hose connections. The blower shall operate throughout the period without failure or indication of excessive wear of bearings or other working parts. The connection between the motor and the blower shall be so constructed that the motor is disengaged automatically from the blower when the blower is operated by hand.

(iv) When a blower, which ordinarily is motor driven, is operated by hand, the power required to deliver 50 liters of air per minute to each wearer through the maximum length of hose shall not exceed one-fiftieth horsepower, and the torque shall not exceed a force of 5 pounds on an 8-inch crank. The torque and power shall be measured as hereinafter provided.

(v) When assembled with the facepiece and 50 feet of the hose for which it is to be approved and when connected to one outlet, with all other outlets closed, and operated at a speed not exceeding 50 revolutions of the crank per minute, the amount of air delivered into the respiratory-inlet covering shall not exceed 150 liters per minute.

(a) Method of measuring power and torque required to operate blowers. (1) As shown in figure 1, the blower crank is replaced by a wooden drum, a (5 inches in diameter is convenient). This drum is wound with about 40 feet of No. 2 picture cord, b. A weight, c, of sufficient mass to rotate the blower at the desired speed is suspended from this wire cord. A mark is made on the cord about 10 to 15 feet from the weight, c. Another mark is placed at a measured distance (20 to 30 feet is convenient) from the first. These are used to facilitate timing.

The

(2) To determine the torque or horsepower required to operate the blower, the drum is started in rotation manually at or slightly above the speed at which the power measurement is to be made. blower is then permitted to assume constant speed, and then as the first mark on the wire leaves the drum a stopwatch is started. The watch is stopped when the second mark leaves the drum. From these data the foot-pounds per minute and the torque may be calculated readily.

(2) Type B supplied-air respirator. No Type B supplied-air respirator will be approved for use with a blower or for connection to an air-supply device at positive pressures. Instead, the inlet to the hose shall have a terminal fitting or chamber which provides for drawing the air through a suitable arrangement that will remove material larger than 0.149 mm. in diameter (149 microns, 100-mesh, U. S. standard sieve of corrosion resisting material). This terminal fitting shall be provided also with means for fastening or anchoring it to a fixed position in a zone of respirable air.

(3) Type C supplied-air respirators, continuous-flow class. The air-supply device is the responsibility of the user.

The respirators are approved, however, only when used with respirable air and at the pressures and quantities required. The pressure at the hose connection to the blower or manifold shall not exceed 125 pounds per square inch gage. If, however, the pressure at any point in the supply system exceeds 125 pounds per square inch gage, the user must provide a pressure-release mechanism that will prevent the pressure at the hose connection from exceeding 125 pounds per square inch gage under any conditions.

(4) Type C supplied-air respirators, demand and pressure-demand classes. (i) The air supply is the responsibility of the user. It may be an air-compressing system or a reservoir of compressed air. The respirator is approved, however, only when used with respirable air at the pressures and quantities required.

(ii) The manufacturer may specify the range of air pressure at the point of attachment of the air-supply hose to the air-supply system, and the range of hose length for the respirator. For example, he might specify that the respirator be used with compressed air at pressures ranging from 40 to 80 pounds per square inch with from 15 to 250 feet of air-supply hose. The specified air pressure at the point of attachment of the hose to the air-supply system shall not exceed 125 pounds per square inch gage. Should the pressure in the air-supply system exceed this value, the user must provide a pressure-reducing and pressure-release mechanism that will prevent the pressure at this point from exceeding this value. However, the pressure-release mechanism may be set to operate at a pressure not more than 20 percent above the manufacturer's highest specified pressure. For example, if the highest specified pressure is 80 or 125 pounds per square inch, the pressurerelease mechanism would be set to operate at 96 or 150 pounds per square inch, respectively.

(f) Requirements and tests for airsupply lines. The requirements and tests of the air-supply lines are given in table 1 of this section.

Specific requirements

Туре А

Туре С

Maximum of 250 feet in multiples of 25 feet. It will be permissible for the applicant to supply hose of the approved type of shorter length than 25 feet provided it meets the requirements of this part. The air-supply hose with air regulating valve or orifice shall permit a flow of not less than 115 liters (4 cubic feet) per minute to tight-fitting and 170 liters (6 cubic feet) per minute to loosefitting respiratory-inlet coverings through the maximum length of hose for which approval is granted and at the minimum specified air-supply pressure. The maximum flow shall not exceed 425 liters (15 cubic feet) per minute at the maximum specified air-supply pressure with the minimum length of hose for which approval is granted.

The air-supply hose, detachable coupling, and demand valve of the demand class or pressuredemand valve of the pressure-demand class for Type C supplied-air respirators, demand and pressure-demand classes, shall be capable of delivering respirable air at a rate of not less than 115 liters (4 cubic feet) per minute to the respiratory-inlet covering at an inhalation resistance not exceeding 50 millimeters (2 inches) of watercolumn height measured at the respiratory-inlet covering with any combination of air-supply pressure and length of hose within the applicant's specified range of pressure and hose length. The air-flow rate and resistance to inhalation shall be measured while the demand or pressure-demand valve is actuated 20 times per minute by a source of intermittent suction. The maximum rate of flow to the respiratory-inlet covering shall not exceed 425 liters (15 cubic feet) per minute under the specified operating conditions. If an air-regulating valve is provided, it shall be so designed that it will remain at a specific adjustment, which will not be affected by the ordinary movement of the wearer. The friction developed between the packing and a valve stem will not be considered as meeting this requirement.

The valve must be so constructed that the air supply with the maximum length of hose and at the minimum specified air-supply pressure will not be less than 115 liters (4 cubic feet) of air per minute to tight-fitting and 170 liters (6 cubic feet) of air per minute to loose-fitting respiratory inlet coverings for any adjustment of the valve. If a demand or pressure-demand valve replaces the air-regulating valve, it shall be connected to the air supply at the maximum air pressure for which approval is sought by means of the minimum length of air-supply hose for which approval is sought. The outlet of the demand or pressuredemand valve shall be connected to a source of intermittent suction so that the demand or pressure-demand valve is actuated approximately 20 times per minute for a total of 100,000 inh alations. To expedite this test, the rate of actuation may be increased if mutually agreeable to the applicant and the Bureau. During this test the valve shall function without failure and without excessive wear of the moving parts.

The demand or pressure-demand valve shall not be damaged in any way when subjected at the outlet to a pressure or suction of 10 inches of water gage for 2 minutes.

None.

Noncollapsibility. The hose shall not

collapse or exhibit permanent deformation when a force of 200 pounds is applied for 5 minutes between 2 planes 3 inches wide on opposite sides of the hose.