A procedure for determining breathing resistance of open-circuit demand-type self-contained breathing apparatus (SCBA) was developed. The system was designed to simulate actual respirator use and to allow measurement of respirator response under controlled conditions. The procedure requires the use of a four channel thermal tip recording system with a preamplifier, a mechanical breather, an anthropometric testhead with a tube for measuring breathing resistance, a temperature compensated strain sensitive resistance wire type pressure transducer, and an electric timer. After assembling the apparatus, the SBCA cylinder is filled with air. The facepiece is mounted on an anthropometric head and the breathing machine activated. Readings of inhalation resistance are then recorded for analysis. Data analysis, calibration, and equipment maintenance methods are listed. The author concludes that this procedure satisfies the minimum test requirements for respirator performance at a work rate of 622 kilograms meter per minute.
NIOSH, Morgantown, West Virginia, 22 pages