{"data":{"id":"us/42-cfr-84.172","jurisdiction":"us","citation":"42 CFR 84.172","heading":"Airflow resistance test.","body":"(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.\n(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.\n(c) The maximum allowable resistance requirements for air-purifying particulate respirators are as follows:\nMaximum Resistance\n[mm water-column height]\nRespirator type Inhalation Exhalation\nInitial Final\nNon-Powered (N, R, and P) 35 N/A 25\nPowered (tight fitting) (HE class and PAPR100 class) 50 70 20","path":["Title 42—Public Health","CHAPTER I—PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES","SUBCHAPTER G—OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES","PART 84—APPROVAL OF RESPIRATORY PROTECTIVE DEVICES","Subpart K—Air-Purifying Particulate Respirators"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-42.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:11Z","sha256":"c52ea48fcb47955ef78b034b84dbc1622c32f7c3a5fa74910411b42990fdea69","source_id":"us-cfr","stale":true,"prev":"us/42-cfr-84.171","next":"us/42-cfr-84.173"},"notice":"GroundRules: Original legal text. Not legal advice."}