Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

National Institute for Occupational Safety and Health

National Personal Protective Technology Laboratory 

626 Cochrans Mill Road 

Pittsburgh, PA 15236

Procedure No. RCT-ASRS-STP-0111 Revision: 1.2 Date: 21 October 2020

DETERMINATION OF AIR VELOCITY AND NOISE LEVELS - SOUND LEVEL,

TYPE C AND CE, SUPPLIED-AIR RESPIRATORS

STANDARD TESTING PROCEDURE (STP)

1. PURPOSE

This document establishes the procedure for ensuring that operational air velocity and noise level

requirements for hoods and helmets used on Type C and CE, Supplied-Air Respirators 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

J, Section 84.140

2. GENERAL

This STP describes the Determination of Air Velocity and Noise Level - Sound Level, Type C

and CE, Supplied-Air Respirator 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. A 300 cubic foot gas cylinder of compressed Grade D air or equivalent.

3.1.2. Air regulator, Model 8, from Matheson Gas Products or equivalent.

3.1.3. A calibrated pressure gauge and connecting fittings or equivalent.

3.1.4. Quest Technologies Noise Pro Series Dosimeter or equivalent. For OSHA use, 

the dosimeter must have a 5 dB exchange rate, use a 90 dBA criterion level, be 

set at slow response, and use either an 80 dBA or 90 dBA threshold gate, or a 

dosimeter that has both capabilities, whichever is appropriate for the evaluation.

3.1.5. Life size mannequin.

3.1.6. Respirator under test with the hose length and pressure range that supply the 

highest airflow rate to the respirator. 

3.1.7. Associated couplings and fittings.

3.1.8. Three test human subjects. 

4. TESTING REQUIREMENTS AND CONDITIONS
Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Procedure No. RCT-ASRS-STP-0111 Revision: 1.2 Date: 21 October 2020 Page 2 of 6 

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

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

complete respirator assembly affixed to a mannequin. 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 mannequin. 

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 instructions, mount the respirator 

assembly onto the mannequin. 

5.1.4 Use a pressure gauge with the appropriate range. 

5.1.5 Each sample measurement should be averaged over 30 seconds. Once the dBA 

noise level of the mannequin setup has been determined to be below 85 dBA 

safety limit, test subject testing may begin.

5.1.6. Open the air cylinder valve fully by turning completely counterclockwise. 

5.1.7 Open the regulator valve slowly by turning clockwise until the pressure gauge

indicates the maximum delivery pressure specified by the manufacturer. This 

pressure must be held constant during the test. Once the cylinder pressure falls 

below 500 psi a recharged cylinder must be used. 

5.1.8. Close the air cylinder valve by turning clockwise. Close the regulator valve by 

turning counterclockwise.

5.2. Human Subject Test

5.2.1. The evaluation is made on three test subjects. 

5.2.2. 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. 

5.2.3 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 
Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Procedure No. RCT-ASRS-STP-0111 Revision: 1.2 Date: 21 October 2020 Page 3 of 6 

choice of protectors will be provided for this purpose. 

5.2.4. Two readings are taken on each subject at both ears and averaged.

5.2.5 Record the results. 

6. PASS/FAIL CRITERIA

6.1. The criterion for passing this test is set forth in 42 CFR, Part 84, Subpart J, Section 

84.140. 

6.2. This test establishes the standard procedure for ensuring that: 

84.140 Air velocity and noise levels; hoods and helmets; minimum requirements.

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

maximum airflow obtainable within pressure and hose length requirements 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. 

 
Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Procedure No. RCT-ASRS-STP-0111 Revision: 1.2 Date: 21 October 2020 Page 4 of 6 

8. ATTACHMENTS

8.1. Example Test Data Sheet
Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Procedure No. RCT-ASRS-STP-0111 Revision: 1.2 Date: 21 October 2020 Page 5 of 6 

8.1. Example Data Sheet
Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Uncontrolled Copy 

 Uncontrolled Copy 

Procedure No. RCT-ASRS-STP-0111 Revision: 1.2 Date: 21 October 2020 Page 6 of 6 

Revision History

Revision Date Reason for Revision

1.0 23 February 2001 Historic document

1.1 20 September 2005 Update header and format to reflect lab move from Morgantown, WV

No changes to method

1.2 1 October 2020 The document is updated to current style and content standards. There 

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

measurement instrumentation 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.