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National Institute for Occupational Safety and Health

National Personal Protective Technology Laboratory 

626 Cochrans Mill Road 

Pittsburgh, PA 15236

Procedure No. RCT-ASR-STP-0114 Revision: 1.2 Date: 21 October 2020

DETERMINATION OF SOUND LEVEL MEASUREMENT, ESCAPE, OPEN-CIRCUIT,

SELF-CONTAINED BREATHING APPARATUS USING HOODS OR HELMETS

STANDARD TESTING PROCEDURE (STP)

1. PURPOSE

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

level requirements for hoods or helmets used on Self-Contained Breathing Apparatus (SCBA)

submitted for Approval, Extension of Approval, or examined during Certified Product Audits,

meet the minimum certification standards set forth in 42 CFR, Part 84, Subpart G, Section

84.63(c).

2. GENERAL

This STP describes the Determination of Sound Level Measurements, Open-Circuit, SelfContained Breathing Apparatus Using 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. 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.

3.1.2. Life size mannequin. 

3.1.3. Self Contained Breathing Apparatus using a hood or helmet. 

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. 
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Procedure No. RCT-ASR-STP-0114 Revision: 1.2 Date: 21 October 2020 Page 2 of 5 

4.3 This test should be done on a minimum of two respirators, or more if additional testing is 

required (42 CFR, Part 84, Sections 84.12, 84.30, and 84.60). 

5. PROCEDURE

5.1. Turn on the Quest Technologies Noise Pro Series Dosimeter. 

5.2. Attach the Quest Technologies Noise Pro Series Dosimeter microphones on each ear of 

the mannequin.

5.3. Mount the hood or helmet of the respirator under test on the mannequin according to the 

manufacturer’s instructions.

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

level of the mannequin setup has been determined to be below the 85 dBA safety limit, 

test subject testing may begin.

5.5 Start SCBA at highest flow recorded during air flow test. 

5.6. Three sound level measurements are taken at each ear and averaged. The results for the 

two ears are then averaged.

5.7. Record all measurements on test data sheet.

6. PASS/FAIL CRITERIA

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

84.63 (c).

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

84.63 Test requirements; general.

(c) In addition to the minimum requirements set forth in subparts H through L of this 

part, the Institute reserves the right to require, as a further condition of approval, any 

additional requirements deemed necessary to establish the quality, effectiveness, and 

safety of any respirator used as protection against hazardous atmospheres. 

6.3. The maximum sound level for SCBA hoods or helmets shall not exceed 115 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. 
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Procedure No. RCT-ASR-STP-0114 Revision: 1.2 Date: 21 October 2020 Page 3 of 5 

8. ATTACHMENTS

8.1. Special Test – Sound Level Measurement, Open-Circuit, Self-Contained Breathing 

Apparatus Using Hoods or Helmets Test Data Sheet
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Procedure No. RCT-ASR-STP-0114 Revision: 1.2 Date: 21 October 2020 Page 4 of 5 

8.1. Special Test – Sound Level Measurement, Open-Circuit, Self-Contained Breathing Apparatus 

Using Hoods or Helmets Test Data Sheet
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Procedure No. RCT-ASR-STP-0114 Revision: 1.2 Date: 21 October 2020 Page 5 of 5 

Revision History

Revision Date Reason for Revision

1.0 1 June 2000 Historic document

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

No changes to method

1.2 21 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.