National Institute for Occupational Safety and Health

National Personal Protective Technology Laboratory 

Procedure No. RCT-APR-STP-0030 Revision: 2.1 Date: 4 November 2022 

DETERMINATION OF NOISE LEVEL TEST,

POWERED AIR-PURIFYING RESPIRATORS WITH HOODS OR HELMETS

STANDARD TESTING PROCEDURE (STP)

1. PURPOSE

This document establishes the procedure for ensuring that operational noise levels of powered airpurifying respirators with hoods or helmets, as submitted for Approval, Extension of Approval, or

examined during Certified Product Audits, do not exceed the established maximum certification

requirements as provided for by 42 CFR Part 84, Subpart L, Section 84.202, and Subpart K,

Section 84.177.

2. GENERAL

This STP describes the determination of noise level test for powered air-purifying respirators

(PAPRs) with hoods or helmets test in sufficient detail that a person knowledgeable in the

appropriate technical field can select equipment with the necessary resolution, conduct the test,

and determine whether or not the product passes the test.

3. EQUIPMENT/MATERIALS

3.1. The list of necessary test equipment and materials follows.

3.1.1. Completely assembled, PAPR with hood or helmet in the configuration as worn 

by the user with fully charged battery and new air-purifying elements. 

3.1.2. Life-size manikin. 

3.1.3. Precision, fast-response sound level meter with built in A-weighting network, 

capable of averaging measurements over selected time intervals of at least up to 

30 seconds. Sound level meter must accommodate two microphone inputs.

4. TESTING REQUIREMENTS AND CONDITIONS

4.1. Prior to beginning any testing, confirm that all measuring equipment employed has been

calibrated in accordance with the testing laboratory’s calibration procedure and schedule. 

All measuring equipment utilized for this testing must have been calibrated using a 

method traceable to recognized international standards when available.

4.2. A background noise level of no greater than 60 dB shall be established and maintained in 

the location where the procedure is performed. 

5. PROCEDURE
Procedure No. RCT-APR-STP-0030 Revision: 2.1 Date: 4 November 2022 Page 2 of 4 

5.1 Prior to the use of the test subjects, a noise level screening test will be performed on one 

complete PAPR donned on the manikin. The purpose of the screening is to prevent 

exposing subjects to noise levels which may exceed 85 dBA. 

5.1.1. Position the microphones of the sound level meter on each ear of the manikin. 

5.1.2. Using the sound level meter, verify the background noise requirement per section 

4.2. 

5.1.3. Following the respirator manufacturer’s User Instructions, mount the respirator 

assembly onto the manikin and turn on the PAPR blower. 

5.2. Two 30-second sample measurements are taken within one minute, where each 30-

second sample measurement is averaged. The “manikin” result is recorded on the test 

data sheet. Once the noise level screening has determined that the dBA noise level is

below the 85 dBA safety limit, testing on a test subject may begin. 

5.3 The noise level is checked using three test subjects and it is recommended that both 

males and females be employed as test subjects, and that a wide variation in body size 

and shape of subjects be sought. 

5.4. The test subjects will be allowed to wear ear-insert type hearing protectors, which do not 

interfere with the positioning of the microphones, if they desire. A choice of protectors 

will be provided for this purpose. The test subjects don and wear the PAPR as described 

in the User Instructions. The functioning of the PAPR is confirmed by the test operator. 

5.5. Two 30-second sample measurements are taken within one minute, where each 

30-second sample measurement is averaged.

5.6. Record the results. 

6. PASS/FAIL CRITERIA

6.1. The noise level generated by the PAPR that covers the wearer’s ears (i.e., inside 

the hood or helmet) at maximum air flow obtainable must be 80 dBA or lower. 

6.2. This test establishes the standard procedure for: 

84.177 Total noise level test - PAPR classes HE and PAPR100. 

Noise levels generated by any powered air-purifying respirators that cover the 

ears (i.e., hood or helmet) will be measured at the entrance to each ear at 

maximum airflow obtainable and must not exceed 80 dBA. 

84.202 Air velocity and noise levels; hoods and helmets; minimum requirements. 
Procedure No. RCT-APR-STP-0030 Revision: 2.1 Date: 4 November 2022 Page 3 of 4 

Noise levels generated by the respirator will be measured inside the hood or 

helmet at maximum airflow obtainable and shall not exceed 80 dBA. 

7. RECORDS\TEST SHEETS

7.1. Record test data in a format that shall be stored and retrievable. Data is to be

reported as shown in the attached example data sheet.

8. ATTACHMENTS

8.1. Example Test Data Sheet

Revision History
Procedure No. RCT-APR-STP-0030 Revision: 2.1 Date: 4 November 2022 Page 4 of 4 

Revision Date Reason for Revision

1.0 7 March 2002 Historic document

1.1 14 June 2005 Update header and format to reflect lab move from Morgantown, WV

No changes to method

2.0 28 May 2019 The document is updated to current style and content standards. There 

is no change to the test set up or method, but the specified sound 

measurement instrument has been updated. The ability to collect an 

average measurement expressed in dBA over the specified 30-second 

interval eliminates the need to convert dose to dBA.

2.1 4 November 2022 The document was updated to reflect updated regulatory references.