42 CFR 84.1145 - Silica dust test; non-powered single-use dust respirators; minimum requirements.
(a) Three respirators will be tested.
(b) As described in § 84.1144, airflow will be cycled through the respirator by a breathing machine at the rate of 24 respirations per minute with a minute volume of 40 liters; a breathing machine cam with a work rate of 622 kg.-m.2/minute shall be used.
(c) Air exhaled through the respirator will be 35° ±2 °C. with 94 ±3 percent relative humidity. #
(e) The total amount of unretained test suspension, after drying, in samples taken during testing, shall not exceed 1.8 milligrams for any single test.