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-0303 Revision: 1.1 Date: 12 December 2005

DETERMINATION OF CBRN ACID GASES (HYDROGEN CYANIDE) 

SERVICE LIFE TEST, AIR-PURIFYING 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 cyanide) Service Life Test, Air Purifying 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, 84.63(a)(c)(d); Volume 60, Number 110, June 8, 1995 and the 

Statement of Standard for Chemical, Biological, Radiological, and Nuclear (CBRN) Air 

Purifying Respirator, Dated March 7, 2003. 

2. GENERAL

This STP describes the Determination of CBRN Acid Gases (Hydrogen Cyanide) Service 

Life Test, Air-Purifying Respirators Standard Test Procedure 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-0303 Revision: 1.1 Date: 12 December 2005 Page 2 of 8 

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 Testing. 

3.1.4. California Analytical Instruments, Model 1314 Photoacoustic Multigas 

Monitor with UA0980 optical filter or equivalent. This monitor uses 

photoacoustic infra-red detection to measure gases that absorbs infer-red 

light. A filter is used to select the wavelength specific for the gas being 

detected. Range for hydrogen cyanide is 8000 to 0.8 ppm ± 0.08 ppm. 

3.1.5. Gas Chromatograph, Shimadzu, Model 14A with Flame Ionization 

Detectors or equivalent. 

3.1.6. Mass Flow Controller, Brooks Instruments, Model 5851. 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 Test Meter, American Meter Company, Model and size depending on 

air flow to be measured. 

3.1.9. Certified cylinders of 5 ppm and 1000 ppm hydrogen cyanide, balance gas 

Nitrogen. 

3.1.10. Hydrogen cyanide permeation tube. 

3.1.11. Cyanogen permeation tube. 

3.1.12. Hydrogen Cyanide cylinders, 2% hydrogen cyanide, balance gas of 

helium. 

3.1 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 

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Procedure No. CET-APRS-STP-CBRN-0303 Revision: 1.1 Date: 12 December 2005 Page 3 of 8 

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. 

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) 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. 

4.5 Compressed gas cylinders must meet all applicable Department of Transportation 

requirements for cylinder approval as well as retesting / requalification. 

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

precautions described in the current NIOSH Pittsburgh Health and Safety 

Program. 

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Procedure No. CET-APRS-STP-CBRN-0303 Revision: 1.1 Date: 12 December 2005 Page 4 of 8 

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

4.6.2. Work benches must be maintained free of clutter and non-essential test 

equipment. 

4.6.3 When handling any broken glass laboratory equipment, lab technicians 

and personnel must wear special gloves, which protect against lacerations 

or punctures. 

 4.7 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. Calibrate photoacoustic monitor for hydrogen cyanide using a certified hydrogen 

cyanide gas cylinder at a concentration of approximately 940 ppm. 

5.3 After the manufacturer's specified warm-up period, calibrate the Gas 

Chromatograph using the Kin-Tek gas generator with the hydrogen cyanogen and 

cyanogen permeation tube. 

5.4 Start automatic sampling mode on the gas chromatograph. Monitor and record the 

upstream and downstream concentrations. 

5.5 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. 

5.6 Verify the following equipment is on: 

5.6.1 Miller Nelson Unit. 

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Procedure No. CET-APRS-STP-CBRN-0303 Revision: 1.1 Date: 12 December 2005 Page 5 of 8 

5.6.2 Air and water supplies. 

5.6.3 Gas Chromatograph 

5.6.4 NIOSH Service Life Apparatus Controller software program. 

5.7 Establish the correct humidity and temperature using chilled mirror dew point 

hygrometer per the test standard in paragraph 6.3. 

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

fixture using the appropriate dry test meter. 

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

5.10 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. 

5.11 Make sure the diverter valve in the system is diverting the challenge concentration 

airflow to the discharge and not into the test chamber. 

5.12 Mount canister onto test fixture in testing chamber. 

5.13 Turn on the hydrogen cyanide cylinder. 

5.14 Establish the test concentration of 940 ppm hydrogen cyanide. 

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

5.16 Direct challenge concentration airflow into test chamber. 

5.17 Start timer. Airflow out of the fixture is directed into the breakthrough detector. 

Monitor and record the upstream and downstream temperatures of the air stream 

throughout testing. Record breakthrough values and times. 

5.18 Run test until breakthrough of 4.7 ppm hydrogen cyanide and cyanogen is 

observed or minimum service life is surpassed. 

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 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. 

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Procedure No. CET-APRS-STP-CBRN-0303 Revision: 1.1 Date: 12 December 2005 Page 6 of 8 

Record the values on Test Data Sheet. 

5.22 Allow clean air to purge through the test chamber for 5 minutes. 

5.23 Repeat steps 5.7 through 5.22 for each test described in section 6.3. 

5.24 End sampling mode program in the gas chromatograph. 

5.25 When all tests are complete turn off hydrogen cyanide cylinder, clean regulator by 

purging with air, set temperature and humidity to zero and allow air to pass 

through the system for 30 minutes. 

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) and Subpart I, Section 84.110(c); 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 HYDROGEN CYANIDE BENCH TEST FOR CANISTERS. 

6.3.1 Resistance to airflow of both canister and system will be taken before and 

after each test. 

6.3.2 Three canisters will be tested at 64 Lpm, continuous airflow, 25 +5 

percent relative humidity (RH), 25 +5o

C, containing 940 ppm hydrogen 

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Procedure No. CET-APRS-STP-CBRN-0303 Revision: 1.1 Date: 12 December 2005 Page 7 of 8 

cyanide Minimum service life will be 15, 30, 45, 60, 90, 120 minutes as 

per manufacturer request. 

6.3.2 Three canisters will be tested at 64 Lpm, continuous airflow, 80 +5 

percent relative humidity (RH), 25 +5o

C, containing 940 ppm hydrogen 

cyanide. Minimum service life will be 15, 30, 45, 60, 90, 120 minutes as 

per manufacturer request. 

6.3.3 Three canisters will be tested at 100 Lpm, continuous airflow, 50 + 5 

percent relative humidity (RH), 25 +5o

C, containing 940 ppm hydrogen 

cyanide. Minimum service life for all canisters will be 5 minutes. 

6.3.4 End of service life concentration is 4.7 ppm, which is the sum of the 

breakthrough products of hydrogen cyanide and cyanogen. 

7. RECORD AND TEST SHEETS

7.1. All test data will be recorded on the CBRN HYDROGEN CYANIDE 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 Section Chief 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 Section Chief 

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 Section Chief, 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-0303 Revision: 1.1 Date: 12 December 2005 Page 8 of 8 

Revision History 

Revision Date Reason for Revision 

1.0 20 September 2004 Historic document 

1.1 12 December 2005 Update header and format 

No changes to method 

 

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