Procedure No. RCT-ASR-STP-0124 Revision: 1.2 Date: 19 May 2022 Page 1 of 7 

National Institute for Occupational Safety and Health

National Personal Protective Technology Laboratory 

Procedure No. RCT-ASR-STP-0124 Revision: 1.2 Date: 19 May 2022

DETERMINATION OF REMAINING SERVICE-LIFE INDICATOR - OPEN-CIRCUIT, DEMAND 

AND PRESSURE-DEMAND, SELF-CONTAINED BREATHING APPARATUS

STANDARD TESTING PROCEDURE (STP)

1. PURPOSE

This test establishes the procedures for ensuring that the level of protection provided by the

remaining service-life indicator requirements on Open-Circuit, Demand and Pressure-Demand,

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 H, Section 84.83(e)(f).

2. GENERAL

This STP describes the Determination of Remaining Service-Life Indicator - Open-Circuit,

Demand and Pressure-Demand, Self-Contained Breathing Apparatus 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. ISI Anthropometric Test heads with tube for measuring breathing resistance and 

air flows—Model SR-085 or equivalent. 

3.1.2. High Pressure Test Stand. A test stand incorporating calibrated pressure gauges 

(at least one 0-10,000 psig and one 0-3,000 psig) or equivalent. 

3.1.3. Source of high-pressure air. Breathing air compressor (6,000 psig), equipped 

with a vertical purifier system, capable of delivering 0-6,000 psig, a minimum of 

1,125 psig or equivalent. 

4. TESTING REQUIREMENTS AND CONDITIONS

4.1. Prior to beginning any testing, 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.
Procedure No. RCT-ASR-STP-0124 Revision: 1.2 Date: 19 May 2022 Page 2 of 7 

5. PROCEDURE

5.1. Close off tube on anthropometric test head. 

5.2. Assemble self-contained breathing apparatus as per manufacturer's instructions.

5.3. Mount facepiece on anthropometric test head.

5.4. Remove air supply bottle and attach test stand in the bottle's place.

5.5. Charge the system with the compressor.

5.6. Bleed the unit down through the regulator by-pass valve or the pressure tap connection 

hose at a rate of 10 psig per second. 

5.7. When each warning device activates (e.g., heads-up display [HUD], Vibralert), the 

pressure on the test stand gauge should be recorded on the data sheet. 

5.8. Repeat steps 5.1.5, 5.1.6, and 5.1.7 six times and record data. 

Note: This test should be performed on a minimum of two respirators for each pressure 

configuration, or more if additional testing is required. 

6. PASS/FAIL CRITERIA

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

84.83(e)(f). 

84.83 Timers; elapsed time indicators; remaining service life indicators; minimum 

requirements.

(e) Remaining service-life indicators or warning devices shall be provided in addition to a 

pressure gage on compressed gas self-contained breathing apparatus, except apparatus 

used for escape only, and shall operate automatically without preadjustment by the 

wearer.

(f) Each remaining service-life indicator or warning device must give an alarm when the 

remaining service life is reduced to a minimum of 25 percent of its rated service time or 

any higher minimum percent value or values as specified in the approval. Open-circuit 

demand and pressure-demand respirators must alarm continuously until depletion of the 

breathing air supply. The percent value set for indicator activation must be identified by 

labels and/or markings on each respirator unit.
Procedure No. RCT-ASR-STP-0124 Revision: 1.2 Date: 19 May 2022 Page 3 of 7 

7. RECORDS/TEST SHEETS

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

reported as shown in attached example data sheet.
Procedure No. RCT-ASR-STP-0124 Revision: 1.2 Date: 19 May 2022 Page 4 of 7 

ALARM PRESSURE #1, OPEN-CIRCUIT, SELF-CONTAINED BREATHING APPARATUS

Project No.: Date: __________ 

Manufacturer: ______________________________________________ 

Respirator Type: ______________________________________________ 

Reference: 42 CFR Part 84, Subpart H, 84.83(e)(f). 

Requirement: Each remaining service-life indicator or warning device must give an alarm when the 

remaining service life is reduced to a minimum of 25 percent of its rated service time or 

any higher minimum percent value or values as specified in the approval. Open-circuit 

demand and pressure-demand respirators must alarm continuously until depletion of the 

breathing air supply. The percent value set for indicator activation must be identified by 

labels and/or markings on each respirator unit.

Procedure: Pressure is recorded from test stand. 

Results:

 Event Full Cylinder Pressure Alarm Pressure Result (P/F)

(psig) (psig)

Unit ID#__ ____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

Unit ID#__ ____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

Unit ID#__ ____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

Unit ID#__ ____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

Unit ID#__ ____ ______________ ________________ ____ 

____ ______________ ________________ ____ 
Procedure No. RCT-ASR-STP-0124 Revision: 1.2 Date: 19 May 2022 Page 5 of 7 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

Unit ID#__ ____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

Unit ID#__ ____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

____ ______________ ________________ ____ 

Comments: 

_____________________________________________________________________________________

_____________________________________________________________________________________

_____________________________________________________________________________________ 

______________________________________________________________________________

Test Engineer: Pass Fail _________ 
Procedure No. RCT-ASR-STP-0124 Revision: 1.2 Date: 19 May 2022 Page 6 of 7

8. ATTACHMENTS

Figure 1: Test setup for determination of remaining service-life indicator.
Procedure No. RCT-ASR-STP-0124 Revision: 1.2 Date: 19 May 2022 Page 7 of 7

Revision History

Revision Date Reason for Revision

1.0 5 July 2000 Historic document

1.1 21 September 

2005

Update header and format to reflect lab move from Morgantown, WV

No changes to method

1.2 18 May 2022 Changes reflect current testing practices and regulatory requirements, 

with updates to equipment, testing procedure, and photos.