Airflow resistance test.

(a) Resistance to airflow will be measured in the tight-fitting respiratory inlet covering of a complete particulate respirator mounted on a test fixture with air flowing at continuous rate of 85 ±2 liters per minute, before each test conducted in accordance with § 84.173. (b) Resistance of a complete tight-fitting powered air-purifying particulate respirator system will be measured with the blower off if the manufacturer indicates that the respirator should not be doffed in the event of a blower failure. (c) The maximum allowable resistance requirements for air-purifying particulate respirators are as follows: Maximum Resistance [mm water-column height] Respirator type Inhalation Exhalation Initial Final Non-Powered (N, R, and P) 35 N/A 25 Powered (tight fitting) (HE class and PAPR100 class) 50 70 20