TABLE 1.-AIR-SUPPLY-LINE REQUIREMENTS AND TESTS—Continued Requirements for the air-supply lines of the indicated types of supplied-air respirators Specific require ments Туре А Type B Nonkinkability- None.... Continued. None... Type C To meet the requirements of this test the loop shall maintain а uni form near-circular shape and ultimately unfold as a spiral, without any localized deformation that decreases the flow of air to less than 90 percent of the flow when the hose is tested as a straight section. Hose and couplings must not show any separation or failure when tested with a pull of 100 pounds and when tested by subjecting them to an internal air pressure of 2 times the maximum respirator supply pressure specified by the manufacturer or at 25 pounds per square inch, whichever is the greater value. No leakage, except a maximum of 10 cc. per minute at each coupling, will be permitted when the hose and couplings joined with average care are immersed in water and subjected to an internal air pressure of 25 pounds per square inch or twice the maximum respirator supply pressure specified by the manufacturer, whichever is the greater value. Page 43 TABLE 1.-AIR-SUPPLY-LINE REQUIREMENTS AND TESTS-Continued Requirements for the air-supply lines of the indicated types of supplied-air respirators Specific requirements (3) Harness. Each supplied-air respirator shall be provided with a harness the primary purpose of which is to prevent a pull on the connecting hose from exerting a pull on the face or head covering. The secondary purpose of the harness of the type A supplied-air respirator is to hold the wearer while he is drawn to safety. The harness of supplied-air respirators having rigid or semirigid head coverings may be used to assist in holding the covering in place. Page 44 Type A supplied-air respirators. The harness may be made of leather, fabric webbing, or equivalent material. Shoulder straps will be tested for strength of material and of joints or seams and must separately withstand a pull of 250 pounds without failure. Belts, rings, and attachments for life lines must withstand a pull of 300 pounds without failure. Metal parts must be of nonsparking metals. The hose must be firmly attached to the harness so as to withstand a pull of 250 pounds without separating, and the hose attachments must be arranged so that the pull or drag of the hose behind an advancing wearer does not disarrange the harness or exert pull upon the facepiece. Harness should be adjustable to various sizes. The arrangement and suitability of the accessories and fittings will be considered. Type B supplied-air respirators. The harness shall consist of at least a belt made of leather, fabric webbing, or equivalent material. The harness shall not interfere with the movements of the wearer, and it shall not be disturbing or uncomfortable to wear. It shall be adjustable to various sizes. The arrangement and suitability of the accessories and fittings will be considered. The hose must be attached to the harness in a manner that will withstand a pull of 100 pounds without separating or showing signs of failure. The design of the harness and attachment of the line shall permit dragging the maximum length of hose considered for approval over a concrete floor without disarranging the harness or exerting a pull on the facepiece. Type C supplied-air respirators. The harness for this respirator may be similar to that of the type B, or it may consist of a simple arrangement for attaching the hose to a part of the wearer's clothing in a practical manner that prevents a pull equivalent to dragging the maximum length of the hose over a concrete floor from exerting pull upon the respiratory-inlet covering. In the case of supplied-air respirators having rigid or partly rigid head coverings a suitable harness may be required to assist in holding this covering in place. (4) Breathing tubes-Type A supplied-air respirator. One or two flexible rubber breathing tubes of the nonkinking type shall extend from the facepiece to a connecting hose coupling attached to the belt or harness. These tubes shall permit free head movement and freedom from closing off by kinking or by chin or arm pressure, and they shall not create a pull that will loosen the facepiece or disturb the wearer. Same as for type A. Type B supplied-air respirator. Type C supplied-air respirator. Same as for type A, except that an extension of the connecting hose may take the place of the previously described breathing tubes. (5) Respiratory-inlet covering-Type A supplied-air respirator. Only full- or Tissot-type facepieces that form a pocket over the face and allow breathing through the nose and mouth will be approved. Head coverings or hoods that require a continuous stream of air to prevent inhalation of irrespirable atmospheres will not be approved. The eyeglasses shall not interfere with satisfactory vision, and they shall be of the nonshatter type. The air shall enter the facepiece in a Page 45 [185] manner that will keep the eyeglasses free of moisture. headbands shall be adjustable and replaceable. Elastic An exhalation valve shall be provided in the facepiece to allow escape of exhaled air and any excess air delivered by the blower. The exhalation valve shall be guarded to prevent distortion and injury. A check valve shall be included in the connection to the facepiece or in the hose fitting near the facepiece to allow flow of fresh air toward the facepiece only. Type AE supplied-air respirator. The requirements for the respiratory-inlet covering of this respirator are similar to those for type A, except that a suitable additional covering shall be provided to protect the head and shoulders against impact and abrasion by the rebounding material. The window or windows in the respiratory-inlet covering shall be shielded with such material as glass, woven wire, or perforated sheet metal that does not interfere unduly with vision. This shield shall be mounted and attached in a manner that will permit easy access to the external surface of eyeglasses or windows for cleaning. All shields and windows subject to abrasion shall be easily replaceable. Type B supplied-air respirator. Full or Tissot types, or halfmask type facepieces that allow breathing through the nose and mouth, may be approved. Half-mask facepieces must not interfere with the use of goggles. The eyeglasses in Tissot-type masks shall not interfere with satisfactory vision, and they shall be of the nonshatter type. The air shall enter the facepiece in a manner that will keep the eyeglasses free of moisture. Elastic headbands shall be adjustable and replaceable. An exhalation valve shall be provided in the facepiece to allow of exhaled air. escape A check valve shall be provided in the facepiece or facepiece connection to the breathing tubes to allow flow of air toward the facepiece only. Type BE supplied-air respirator. The requirements for the respiratory-inlet covering of this respirator are similar to those for the type B, with the exceptions that a suitable additional covering shall be provided to protect the head and shoulders against impact and abrasion by the rebounding material, and window or windows in the respiratory-inlet covering shall be shielded with such material as glass, woven wire, or perforated sheet metal that does not interfere unduly with vision. This shield shall be mounted and attached in a manner that will permit easy access to the external surface of eyeglasses or windows for cleaning. Type C supplied-air respirator. Respiratory-inlet coverings of the full- or half-mask facepiece type, the head-covering type, or combinations of these types, may be approved. No covering with a direct mouth or nose connection will be approved. Half-mask facepieces must not interfere with the use of goggles. The velocity of the air at the point of delivery and the distribution within the covering shall not cause discomfort to the wearer. Windows in full facepieces and head coverings shall meet the quality and design Page 46 requirements referred to under the preceding types of supplied-air respirators. Air shall enter the covering in a manner that will keep the windows free of moisture. Elastic headbands shall be adjustable and replaceable. Type CE supplied-air respirator. The requirements for the respiratory-inlet covering of this respirator are similar to those for type C, with the exceptions that a suitable covering for protecting the head and shoulders against impact and abrasion by rebounding material must be provided and window or windows in the respiratoryinlet covering shall be shielded with such material as glass, woven wire, or perforated sheet metal that does not interfere unduly with vision. This shield shall be mounted and attached in a manner that will permit easy access to the external surface of windows for cleaning. All shields and windows subject to abrasion shall be easily replaceable. (6) Complete respirator-(i) Resistance to air flow-Types A and AE supplied-air respirators. These respirators completely assembled with the respiratory-inlet covering, the air-supply device, and the maximum length of air-supply line to be considered for approval, coiled for one-half its length in loops 5 to 7 feet in diameter, must not show resistance in excess of 63.5 mm. (2.5 inches) of water column height to air flowing at the rate of 85 liters (3 cubic feet) per minute when the blower is not operating or under any practical condition of blower operation. Resistance of the exhalation valve shall not exceed 25 mm. (1 inch) of water column height. If inlet valves at the blower are used to meet the requirements for resistance to inhalation through the hose, they must operate automatically and be simple in design, durable, and foolproof against failures that would tend to close the inlet. Inlet valves and blower inlets must be provided with durable guards that will protect against fouling. Types B and BE supplied-air respirators. These respirators completely assembled with the respiratory-inlet covering and the hose in the maximum length to be considered for approval, coiled in loops 5 to 7 feet in diameter, must not show resistance exceeding 38 mm. (1.5 inch) of water-column height to air flowing at the rate of 85 liters (3 cubic feet) per minute. The resistance of the exhalation valve shall not exceed 25 mm (1.0 inch) of water-column height. Types C and CE supplied-air respirators. The resistance to exhalation shall not exceed 25 mm. (1 inch) of water-column height when the air flow into the respiratory-inlet covering is 170 liters (6 cubic feet) per minute. (ii) Protection against gases (direct leakage and man tests). The direct leakage and man tests will be made in duplicate. A man will enter a gas chamber containing room air. He will put on the respirator to be tested. Gastight goggles will be used where necessary to protect the eyes against irritation by ammonia. The hose of the respirator will be arranged in accordance with the specific directions given in the following sections on the different respirators. After the respirator is properly fitted and air is supplied in accord Page 47 |