{"data":{"id":"us/42-cfr-84.90","jurisdiction":"us","citation":"42 CFR 84.90","heading":"Breathing resistance test; inhalation.","body":"(a) Resistance to inhalation airflow will be measured in the facepiece or mouthpiece while the apparatus is operated by a breathing machine as described in § 84.88.\n(b) The inhalation resistance of open-circuit apparatus shall not exceed 32 mm. (1.25 inch) water-column height (at a flow rate of 120 liters per minute).\n(c) The inhalation resistance of closed-circuit apparatus shall not exceed the difference between exhalation resistance (§ 84.91(e)) and 10 cm. (4 inches) water-column height.","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 H—Self-Contained Breathing Apparatus"],"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":"0d2093d1a1ed4258d9b49c040d9513892c1f135d19d26f65717aefaa6b28ed96","source_id":"us-cfr","stale":true,"prev":"us/42-cfr-84.89","next":"us/42-cfr-84.91"},"notice":"GroundRules: Original legal text. Not legal advice."}