42 CFR § 84.172 - Airflow resistance test.

---
identifier: "/us/cfr/t42/s84.172"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "42 CFR § 84.172 - Airflow resistance test."
title_number: 42
title_name: "Public Health"
section_number: "84.172"
section_name: "Airflow resistance test."
chapter_name: "PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "G"
subchapter_name: "OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES"
part_number: "84"
part_name: "APPROVAL OF RESPIRATORY PROTECTIVE DEVICES"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "29 U.S.C. 651  30 U.S.C. 3, 5, 7, 811, 842(h), 844."
regulatory_source: "60 FR 30355, June 8, 1995, unless otherwise noted."
cfr_part: "84"
---


# 84.172 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]

|  |  |  |  |
| --- | --- | --- | --- |
| Non-Powered (N, R, and P) | 35 | N/A | 25 |
| Powered (tight fitting) (HE class and PAPR100 class) | 50 | 70 | 20 |