Approvals: 1st Level 2nd Level 3rd Level 

National Institute for Occupational Safety and Health 

National Personal Protective Technology Laboratory 

P.O. Box 18070 

Pittsburgh, PA 15236 

Procedure No. CET-APRS-STP-CBRN-0405 Revision: 1.1 Date: 21 December 2005

DETERMINATION OF CBRN ACID GASES (HYDROGEN SULFIDE) 

SERVICE-LIFE TEST, AIR-PURIFYING ESCAPE RESPIRATORS 

STANDARD TEST PROCEDURE (STP) 

1. PURPOSE

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

the CBRN Acid Gases (Hydrogen Sulfide) Service Life Test, Air-Purifying Escape Respirators 

Standard Test Procedure 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(a)(c)(d); Volume 60, Number 110, June 8, 1995 

and the Statement of Standard for Chemical, Biological, Radiological, and Nuclear 

(CBRN) Full- Facepiece Air- Purifying Escape Respirator Dated September 30, 2003. 

2. GENERAL

This STP describes the Determination of CBRN Hydrogen Sulfide Service Life Test, AirPurifying Escape Respirators 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 AND MATERIAL

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

3.1.1. Miller Nelson Research Model 401 Flow-Temperature-Humidity Control 

System or equivalent. This system is an automated system to control the 

airflow, temperature, and humidity of an air supply for an operating 

system. Laboratory air and distilled water are supplied to the unit. The unit 

output is air of the variable volume/flow dependant on the size of unit 

(10% of max flow to max flow in liters per minute (Lpm) ± 2%), and 

relative humidity (10%–98% ± 3%) and temperature (20oC–30o 0

C ± 

0.3%).

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Procedure No. CET-APRS-STP-CBRN-0405 Revision: 1.1 Date: 21 December 2005 Page 2 of 9 

3.1.2. EdgeTech Dew Prime II Hygrometer, Model 2000 or equivalent. A microprocessor based programmable chilled mirror dew point hygrometer. The 

hygrometer uses the dew point and ambient temperature to calculate the 

relative humidity. Ambient temperature range is: -50oC to 130oC ± 0.2oC; 

relative humidity is 1% to 95% ± 0.5%. 

3.1.3. Labview software developed for NIOSH Service Life Test. 

3.1.4. Interscan Corporation Model RM-17-0 hydrogen sulfide detector or 

equivalent. This detector is an electrochemical voltammetric sensor. 

Detector range: 0 - 1999 ppm, resolution: 1 ppm. 

3.1.5. Interscan Corporation Model RM-17-2 hydrogen sulfide detector or 

equivalent. This detector is an electrochemical voltammetric sensor. 

Detector range: 0 – 49.99 ppm, resolution: 0.01 ppm. 

3.1.6. Mass Flow Controller, Brooks Instruments, variable flow rate depending 

on use. 

3.1.7. Read out and Control Electronics, Brooks Instruments, Model 0154, 

Power supply and controller for the Brooks Mass Flow Controller or 

equivalent. The flow controllers are an integrally mounted control valve 

module with which stable gas flows can be achieved. Various flow rates 

are used with an accuracy of ± 0.7 % of rate and ± 0.2 % full scale. 

3.1.8. Dry Gas Meter. Must have NIST traceable calibration certificate. 

3.1.9. Certified cylinders of 30 parts per million and 1000 parts per million 

hydrogen sulfide in nitrogen. 

3.1.10. Hydrogen sulfide cylinder, 99 percent purity. 

3.2 Test fixture for mounting canisters. 

3.3 The test chamber consisting of a 12" x 111⁄2" x 7" air tight metal box with door 

opening lined with gasket material. Two 1⁄2" bulkhead Swaglok® fittings located 

on the backside of the test chamber for the introduction of the test concentration 

and for the exit of the test fixture. This fixture is not commercially available. 

3.4 Resistance tester consisting of a vacuum source capable of delivering 85 Lpm, a 

6-inch water column slant manometer or electronic manometer and connections 

appropriate for items being tested. See description in RCT-APR-003 and RCTAPR-007. 

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Procedure No. CET-APRS-STP-CBRN-0405 Revision: 1.1 Date: 21 December 2005 Page 3 of 9 

4. TESTING REQUIREMENTS AND CONDITIONS

4.1. This test procedure is only valid if the respirator system has first completed 

NIOSH Standard Test Procedure entitled Determination Of Durability Test For 

Environmental And Transportation Conditions And Rough Handling Drop Test 

On Chemical Biological Radiological Nuclear (CBRN) Air-Purifying Respirators 

(APR) And Canisters Standard Test Procedure (STP). 

4.2. Prior to beginning any testing, all measuring equipment to be used must have 

been calibrated in accordance with the manufacturer's calibration procedure and 

schedule. At a minimum, all measuring equipment utilized for this testing must 

have been calibrated within the preceding 12 months using a method traceable to 

the National Institute of Standards and Technology (NIST). 

4.3. Any laboratory using this procedure to supply certification test data to NIOSH 

will be subject to the provisions of the NIOSH Supplier Qualification Program 

(SQP). This program is based on the tenets of ISO/IEC 17025, the NIOSH 

Manual of Analytical Methods and other NIOSH guidelines. An initial complete 

quality system audit and follow on audits are requirements of the program. 

Additional details of the Program and its requirements can be obtained directly 

from the institute. 

4.4. Precision and accuracy (P&A) must be determined for each instrument in 

accordance with laboratory procedures and NIOSH/NPPTL guidance. Sound 

practice requires, under NIOSH Manual of Analytical Methods, demonstrating a 

tolerance range of expected data performance of a plus or minus 25% of a 95% 

confidence interval of the stated standard requirement. NIOSH/NPPTL P&A 

tolerance can be higher but not lower. Compressed gas cylinders must meet all 

applicable Department of Transportation requirements for cylinder approval as 

well as retesting / requalification. 

4.5. Normal laboratory safety practices must be observed. This includes safety 

precautions described in the current NIOSH Pittsburgh Health and Safety 

Program. 

4.5.1 Safety glasses, lab coats and hard-toe shoes must be worn at all times. 

4.5.2 Workbenches must be maintained free of clutter and non-essential test 

equipment. 

4.5.3 When handling any broken glass laboratory equipment, lab technicians 

and personnel must wear special gloves, which protect against lacerations 

or punctures. 

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Procedure No. CET-APRS-STP-CBRN-0405 Revision: 1.1 Date: 21 December 2005 Page 4 of 9 

4.6 Please refer to Material Safety Data Sheets and the NIOSH Health and 

Safety Manual for the proper protection and care in handling, storing, and 

disposing of the chemicals and gases used in this procedure.

5. PROCEDURE

Note: Reference Section 3 for equipment, model numbers and manufacturers. 

For calibration purposes use those described in the manufacturer's 

operation and maintenance manuals. 

5.1. Follow individual instruction manuals for set up and maintenance of equipment 

used in this procedure prior to beginning testing. Malfunctioning equipment must 

be repaired or replaced and properly set up and calibrated before starting all tests. 

5.2. After the manufacturer's specified warm-up period, calibrate both hydrogen 

sulfide analyzers using the certified gas cylinders. One monitor is calibrated for 

the challenge concentration of approximately 500 ppm for the general category 

standard or at approximately 1000 ppm for the specific category standard. A 

second monitor is calibrated for the breakthrough concentration of approximately 

30 ppm. 

5.3. Set up test equipment as shown in Figure 1. The humidity reading controlled by 

the Miller Nelson system and monitored the Dew Point Hygrometer. The sample 

pickup for the hygrometer is place into the air stream via a tee after the Miller 

Nelson and before the introduction point of challenge agent. The thermocouple 

for the hygrometer is placed in the challenge gas stream immediately before the 

test chamber. 

5.4. Verify the following equipment is on: 

5.4.1. Miller Nelson Unit. 

5.4.2. Air and water supplies. 

5.4.3. NIOSH Service Life Apparatus Controller software program. 

5.4.4. Hydrogen sulfide cylinder, 99 percent purity. 

5.5. Establish the correct humidity and temperature as per the test standard in 

paragraph 6.3. 

5.6. Set the airflow to the required airflow for the test. Verify the airflow from the test 

fixture using the appropriate dry test meter. 

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Procedure No. CET-APRS-STP-CBRN-0405 Revision: 1.1 Date: 21 December 2005 Page 5 of 9 

5.7. Weigh and record initial weight of the test canister on Test Data Sheet. 

5.8. Take initial inhalation and exhalation resistances of the canister mounted on the 

facepiece and canister alone as described in RCT-APR-003 and RCT-APR-007. 

Record the values on Test Data Sheet. 

5.9. Make sure that the diverter valve in the system is diverting the challenge 

concentration airflow to discharge and not into the testing chamber. 

5.10. Mount canister onto test fixture and place in testing chamber. 

5.11. Divert 0.5 Lpm airflow from air flow line to the hydrogen sulfide challenge 

detector. 

5.12. Ensure that the nitrogen gas is ready for immediate flushing of regulator through 

the purge valve. 

5.13. Turn on hydrogen sulfide cylinder. 

5.14. Establish the test concentration of 500 ppm hydrogen sulfide for a general test 

category or 1000 ppm hydrogen sulfide for a specific test category. 

5.15. Once the hydrogen sulfide concentration has been established, testing may begin. 

5.16. Direct challenge concentration airflow into test chamber. 

5.17. Start timer. Airflow out of the test chamber is directed into the breakthrough 

detector. Monitor and record the upstream and downstream temperatures of the 

airflow throughout test. 

5.18. Run test until breakthrough of 30 ppm is observed or minimum service life is 

surpassed. Record this data on the test data sheet. 

5.19. Direct challenge concentration airflow out of the test chamber. 

5.20. Weigh and record final weight of the test canister on Test Data Sheet. 

5.21. Allow clean air to purge through system for 5 minutes. 

5.22. Repeat steps 5.5. through 5.22. for each test described in section 6.3. 

5.23. When all tests are completed turn off hydrogen sulfide cylinder, set temperature 

and humidity to zero and allow air to pass through the system for 30 minutes. 

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Procedure No. CET-APRS-STP-CBRN-0405 Revision: 1.1 Date: 21 December 2005 Page 6 of 9 

6. PASS OR FAIL CRITERIA

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

Section 84.63(a)(c)(d); Volume 60, Number 110, June 8, 1995. 

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

 84.63 Test requirements; general. 

(a) Each respirator and respirator component shall when tested by the applicant 

and by the Institute, meet the applicable requirements set forth in subparts H 

through L of this part. 

(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. 

(d) Where it is determined after receipt of an application that additional 

requirements will be required for approval, the Institute will notify the 

applicant in writing of these additional requirements, and necessary 

examinations, inspections, or tests, stating generally the reasons for such 

requirements, examinations, inspections, or tests. 

6.3. Acid Gas (Hydrogen Sulfide) test for CBRN canisters. 

6.3.1. General Category Standard. 

6.3.1.1. Resistance to airflow of both canister and system will be taken 

before and after each test. 

6.3.1.2. Three canisters will be tested at 64 Lpm, continuous air flow, 25 

% + 5 % relative humidity (RH), 25 o

C + 5 oC and 500 ppm 

hydrogen sulfide. Minimum service life will be 15, 30, 45, 60 or 

minutes as per manufacturer request. 

6.3.1.3. Three canisters will be tested at 64 Lpm, continuous air flow, 80 

% + 5 % relative humidity (RH), 25 o

C + 5 oC and 500 ppm 

hydrogen sulfide. Minimum service life will be 15, 30, 45, 60 or 

90 minutes as per manufacturer request. 

6.3.1.4. Three canisters, or pairs of canisters, will be tested at 100 Lpm, 

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Procedure No. CET-APRS-STP-CBRN-0405 Revision: 1.1 Date: 21 December 2005 Page 7 of 9 

continuous air flow, 50 % + 5 % relative humidity (RH), 25 o

C 

+ 5 o

C and 500 ppm hydrogen sulfide. Minimum service life 

must be 5 minutes. 

6.3.1.5. End of service life concentration is 30 ppm hydrogen sulfide. 

6.3.2. Specific Category Standard. 

6.3.2.1. Resistance to airflow of both canister and system will be taken 

before and after each test. 

6.3.2.2. Three canisters will be tested at 64 Lpm, continuous air flow, 25 

% + 5 % relative humidity (RH), 25 o

C + 5 oC and 1000 ppm 

hydrogen sulfide. Minimum service life will be 15, 30, 45, 60 or 

minutes as per manufacturer request. 

6.3.2.3. Three canisters will be tested at 64 Lpm, continuous air flow, 80 

% + 5 % relative humidity (RH), 25 o

C + 5 oC and 1000 ppm 

hydrogen sulfide. Minimum service life will be 15, 30, 45, 60 or 

90 minutes as per manufacturer request. 

6.3.2.4. Three canisters, or pairs of canisters, will be tested at 100 Lpm, 

continuous air flow, 50 % + 5 % relative humidity (RH), 25 o

C 

+ 5 o

C and 1000 ppm hydrogen sulfide. Minimum service life 

must be 5 minutes. 

6.3.2.5. End of service life concentration is 30 ppm hydrogen sulfide. 

7. RECORDS AND TEST SHEETS

7.1. All test data will be recorded on the HYDROGEN SULFIDE SERVICE LIFE test 

data sheet. 

7.2. All videotapes and photographs of the actual test being performed, or of the tested 

equipment shall be maintained in the task file as part of the permanent record. 

7.3. All equipment failing any portion of this test will be handled as follows: 

7.3.1. If the failure occurs on a new certification application, or extension of 

approval application, send a test report to the CET Team Leader and 

prepare the hardware for return to the manufacturer. 

7.3.2. If the failure occurs on hardware examined under an Off-the-Shelf Audit 

the hardware will be examined by a technician and the CET Team Leader 

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Procedure No. CET-APRS-STP-CBRN-0405 Revision: 1.1 Date: 21 December 2005 Page 8 of 9 

for cause. All equipment failing any portion of this test may be sent to the 

manufacturer for examination and then returned to NIOSH. However, the 

hardware tested shall be held at the testing laboratory until authorized for 

release by the CET Team Leader, or his designee, following the standard 

operating procedures outlined in Procedure for Scheduling, and Processing 

Post-Certification Product Audits, 

RB-SOP-0005-00. 

8. ATTACHMENTS

8.1 Bench Top Set-Up. 

8.2 Data Sheet. 

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Procedure No. CET-APRS-STP-CBRN-0405 Revision: 1.1 Date: 21 December 2005 Page 9 of 9 

Revision History 

Revision Date Reason for Revision 

00 21 September 2004 Historic document 

1.1 21 December 2005 Update header and format 

Correction to sequence numbers in section 5. 

No changes to method 

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