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National Institute for Occupational Safety and Health 

National Personal Protective Technology Laboratory 

P.O. Box 18070 

Pittsburgh, PA 15236 

Procedure No. TEB-APR-STP-0033B Revision: 2.3 Date: 24 November 2008 

DETERMINATION OF AMMONIA SERVICE LIFE TEST, 

AIR-PURIFYING RESPIRATORS WITH CANISTERS 

STANDARD TESTING PROCEDURE (STP) 

1. PURPOSE

This test establishes the procedure for ensuring that the level of protection provided by airpurifying respirators with canisters (gas masks) submitted for Approval, Extension of Approval, 

or examined during Certified Product Audits, meet the minimum ammonia service life test 

requirements set forth in 42 CFR Part 84, Subpart I, Section 84.126. 

2. GENERAL

This STP describes the Determination of Ammonia Service Life Test, Air-Purifying Respirators 

with canisters 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 / MATERIAL / REFERENCES

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

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

(250 lpm) or equivalent. Air flow control accuracy is ± 2% F.S. Temperature 

control accuracy is ± 1° C. Humidity control accuracy is ± 3% R.H. 

3.1.2. Edge Tech Dew Prime II Hygrometer, Model 2000 or equivalent. Accuracy is ± 

0.2° C, ±0.5% RH. 

3.1.3. Radiometer America Multi-Titration System, Model DTS 800, burettes or 

equivalent. 

3.1.4. Air-Sentry IMS Ammonia Analyzer Model 10R-NH3-4000M or equivalent. 

Range for ammonia is 0.1 to 50 ppmv ±0.1% of full scale. 

3.1.5. "The Gilibrator", Primary Standard Airflow Calibrator or equivalent. 

Approvals: First Level Second Level Third Level Fourth Level 

 
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Procedure No. TEB-APR-STP-0033B Revision: 2.3 Date: 24 November 2008 Page 2 of 12 

3.1.6. Mass Flow Controllers, Brooks Instruments, variable flow rate depending on use, 

model series 5850S and 5853S. Accuracy is 0.7% setpoint 

& 0.2% FS. 

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

3.1.8. Gilian Gil-Air-3 Sampling Pump, or equivalent. 

3.1.9. Fisher Scientific Gas washing bottle or bubbler, catalog # 03-036 or equivalent. 

3.1.10. American Meter Co. Dry Test Meter Model DTM-325. 

3.1.11. Erlenmeyer flasks or beakers, 250 to 500 milliliters (mL). 

3.1.12. Certified cylinder of approximately 50 ppmv ammonia in nitrogen. 

3.1.13. Pipettes, 5 ml. 

3.1.14. Boric Acid (granular). 

3.1.15. Bromophenol Blue (powder). 

3.1.16. Sulfuric Acid (concentrated) or certified 0.025N sulfuric acid solution. 

3.1.17. Electronic balance with accuracy of 0.001 grams (g). 

3.1.18. Ammonia cylinder, 99% purity. 

 

3.2. Test fixture for mounting canisters. The test fixture used is specific to each manufacturer 

depending on how the canister is mounted to the facepiece. In most cases chin-style 

canisters use the 40 mm thread for which we have adapters. In cases where other thread 

sizes are used, the adapters of the respirator are affixed by hot melt glue to a PVC pipe 

tee of appropriate size. Front or back mounted canisters are tested with their breathing 

tubes and adapters. 

3.3. The test chamber consisting of an approximately 12" x 12" x 7" air tight box, with 2 

clamp type locks on the door opening lined with gasket material, and appropriate inlet, 

outlet and sampling ports. This fixture is not commercially available. 

3.4. Refer to the following Work Instructions for further information on performing this test: 

 TEB-RCT-APR-WI-1001 – Laboratory Safety Procedures for Ammonia Tests 

 TEB-RCT-APR-WI-1101 – Calibration Procedures for Ammonia Tests 

 TEB-RCT-APR-WI-1201 – Start–Up and Shut–Down Procedures for Ammonia Tests 

 TEB-RCT-APR-WI-1301 – Using the LabView System for Ammonia Tests 

TEB-RCT-APR-WI-1401 – Reporting Results for Ammonia Tests 
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Procedure No. TEB-APR-STP-0033B Revision: 2.3 Date: 24 November 2008 Page 3 of 12 

4. TESTING REQUIREMENTS AND CONDITIONS

4.1. Prior to beginning any testing, all measuring equipment to be used must have 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 the National Institute of Standards and Technology (NIST) when 

available. 

4.2. 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.* 

*Note 4.2 does not apply to Pretest data from applicants as required under 42 CFR 

84.64. 

4.3. 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. 

4.4. The precision and accuracy of this method was determined by validation testing of a 

single lot of commercially available multi-gas type cartridges. The results of these tests 

are shown in the table below. 

 

TEST TYPE 

MEAN SERVICE LIFE 

(MINUTES) STD. DEV. 

 

AS RECEIVED 39.15 3.64 

EQUIL. 25% RH 103.92 8.72 

EQUIL. 85% RH 118.25 10.0 

4.5. Normal laboratory safety practices must be observed. Please refer to Material Safety 

Data Sheets and the current NIOSH Pittsburgh Health and Safety Program for the proper 

protection and care in handling, storing, and disposing of the chemicals and gases used in 

this procedure. 

 

4.6. The cylinder of 99% ammonia, as well as the calibration gas cylinders, are typically used 

inside the laboratory fume hood. If there is a release of 99% ammonia outside the hood, 

sound an alarm, and any personnel in the laboratory should immediately exit from the 

building. 

 
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Procedure No. TEB-APR-STP-0033B Revision: 2.3 Date: 24 November 2008 Page 4 of 12 

4.7. AMMONIA BENCH TEST FOR CANISTERS 

4.7.1. Resistance to air flow of the complete respirator will be taken before and after 

each test (see 42 CFR 84.203). The standard testing procedures are described in 

TEB-APR-STP-003 and TEB-APR-STP-007. 

4.7.2. Test conditions as required by 42 CFR 84.126. 

SAMPLE CONDITION 

EQUILIBRATION 

CONDITIONS TEST CONDITIONS TEST CONCENTRATION BREAKTHROUGH 

 FOR 6 HOURS 

FRONT AND 

BACK CHIN STYLE CONCENTRATION 

 MOUNTED AND ESCAPE 

 TEMP. AIRFLOW R.H. TEMP. AIRFLOW R.H. 

 ° C LPM % ° C LPM % PPMV AMMONIA PPMV AMMONIA PPMV AMMONIA 

1-3 

AS 

RECEIVED NA NA NA 25 64 50 30000 5000 50 

4-5 

EQUIL. 25% 

R.H. 25 64 25 25 32 50 30000 5000 50 

6-7 

EQUIL. 85% 

R.H. 25 64 85 25 32 50 30000 5000 50 

Tolerances: 

 

PARAMETER TOLERANCE 

 

25°C ± 2.5°C 

32 LPM ± 0.50 LPM 

64 LPM ± 1.0 LPM 

25% R.H. ± 3% R.H. 

50% R.H. ± 3% R.H. 

85% R.H. +0/-5% R.H. 

5000 ppmv ± 10% 

30000 ppmv ± 10% 

 

NOTES: R.H. levels greater than 85% are difficult to maintain and may cause rapid 

degradation of service life. 

Tolerance on accuracy of air flow rates exceeds specification on Miller Nelson control 

unit because flow rates are calibrated for every test. This improves the precision of the 

measurement and allows for the tighter tolerance on short-term drift. 

4.7.3. All equilibrated canisters will be resealed, kept in a position such that the 

direction of airflow would be horizontal, at room temperature, and testing shall 

begin within 18 hours. 
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Procedure No. TEB-APR-STP-0033B Revision: 2.3 Date: 24 November 2008 Page 5 of 12 

5. PROCEDURE 

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

 Work Instructions are to be used in conjunction with standard NIOSH test apparatus. 

5.1. Set up the test equipment as shown in Figure 1. 

 

5.2. Calibrate the breakthrough NH3 analyzer using the certified gas cylinder containing the 

50 ppmv standard. 

 

5.3. Prepare solutions: 

5.3.1. 5% boric acid: Heat, but do not boil, 50g boric acid in 1 liter distilled water. 

5.3.2. 0.025N sulfuric acid solution: Weigh 1.28g concentrated sulfuric acid and add to 

a 1 liter flask containing 800 ml distilled water. Dilute to 1 liter mark with 

distilled water. 

5.3.3. Bromophenol blue solution: Dissolve 0.5g bromophenol powder in 500 ml 

distilled water. Shelf life of this solution is one month. 

5.4. Prepare comparison blank: 

5.4.1. Measure 50 ml boric acid solution (100 ml for 30,000 ppmv) into 250 ml 

Erlenmeyer flask. Add 25 ml distilled water, 5 drops bromophenol blue 

indicator, and distilled water equal to the calculated volume of sulfuric acid 

needed to determine NH3 concentration. 

5.4.2. Example: for a comparison blank equal to 5000 ppmv. 

 

 Calculated vol. H2SO4 = ppmv NH3 

 standard factor 

 Where the standard factor = 611 ppmv NH3/ml H2SO4 

 vol. H2SO4 = 5000

 611 

 

 vol. H2SO4 = 8.2 ml 

Total volume of water added including the 25 ml from step 5.4.1. = 33.2 ml. 

 

5.5. Establish the correct humidity and temperature for the sample being tested as per the test 

requirements in paragraph 4.7. 

5.6. Set the airflow to the required level for the sample being tested as per the test 

requirements in paragraph 4.7 and the adjustments in paragraph 5.12. Calibrate the total 
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Procedure No. TEB-APR-STP-0033B Revision: 2.3 Date: 24 November 2008 Page 6 of 12 

airflow, including any additional flow arising from hygrometer flow rates, from the test 

fixture using the dry test meter. 

5.7. Weigh the canister(s) and record the weight. 

5.8. Measure initial inhalation and exhalation resistances of the canister(s) mounted on the 

facepiece as described in TEB-APR-STP-003 and TEB-APR-STP-007. Record values on 

the data sheet. 

5.9. Make sure diverter valve in the system is diverting the challenge concentration airflow to 

discharge and not into the testing chamber. 

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

5.11. Open the 99% ammonia cylinder. 

5.12. Establish the test concentration of 5,000 ppmv ± 10% ammonia or 30,000 ppmv ± 10% 

ammonia by setting the theoretical flow rate of pure ammonia to mix with the flow of air 

to produce the required concentration. For testing at 30,000 ppmv, the additional flow of 

99% ammonia gas required is sufficient to require adjustment of the air flow rate to 

maintain the total flow rates within tolerances (see table below). Then, set the mass 

flowmeter to that level. 

 TOTAL FLOW 

RATE 5000 PPMV TEST 30,000 PPMV TEST 

FOR TEST AMMONIA AIR FLOW AMMONIA AIR FLOW 

 FLOW RATE RATE FLOW RATE RATE 

LPM CC/MIN LPM CC/MIN LPM 

32 160 32 930 31.1 

64 320 64 1860 62.1 

5.13. Measure 50 ml boric acid solution (100 ml for 30,000 ppmv) into the gas bubbler. Attach 

Gil-Air 3 sampling pump to the intake side of the gas bubbler. Connect outlet side of 

bubbler to Gilibrator. Calibrate 1 lpm ± 2% flow rate of the pump. This setting will be 

used to sample the ammonia upstream concentration. 

5.14. Connect tubing from the sample side of gas bubbler into the Gil-Air pump and tubing 

from the inlet side of the gas bubbler into the upstream sampling port. 

5.15. Turn Gil-Air pump on and sample at 1 lpm for 1 minute. 

5.16. Remove gas bubbler, and transfer the solution into an Erlenmeyer flask. 

5.17. Rinse the gas bubbler with 25 ml distilled water and transfer the washings into the flask. 

5.18. Add 5 drops bromophenol blue indicator. 
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Procedure No. TEB-APR-STP-0033B Revision: 2.3 Date: 24 November 2008 Page 7 of 12 

5.19. Titrate the sample with 0.025N H2SO4 until it matches the comparison blank color 

sample (see 5.3). Record ml used. 

5.20. Calculate the concentration of NH3 using the following formula: 

 Conc. in ppmv = ml H2SO4 used x standard factor of 611 ppmv NH3/ ml H2SO4 

Adjust the flowmeter setting as required. Once the ammonia concentration has been 

established and is stable, testing may begin. When approximately 1⁄2 of the required 

minimum service life has been reached, perform another titration to calculate the 

challenge concentration during the test. 

5.21. Monitor and record challenge and breakthrough temperatures, challenge RH and 

breakthrough values and times throughout testing. 

5.22. Run test until breakthrough of 50.0 ppmv is observed or minimum service life shown in 

section 6.2 is surpassed by 10%. 

5.23. At end of test, system will automatically direct challenge concentration airflow through 

diverter valve to discharge. 

5.24. Dismount canister(s), weigh and record final weight, and take final inhalation and 

exhalation resistances as described in TEB-APR-STP-003 and TEB-APR-STP-007. 

Measurement of the final inhalation and exhalation resistances is required for 

certification and audit testing. 

5.25. If there is another sample to test, repeat steps 5.5 – 5.15. 

5.26. After all tests are completed for the shift, set temperature and humidity to zero on the 

Miller Nelson system and allow clean air to pass through the system for 30 minutes. 

Purge the breakthrough and challenge detectors with clean air for 15 minutes. 

 

6. PASS/FAIL CRITERIA

6.1. The standard requirement for passing this test is set forth in 42 CFR Part 84, Subpart I, 

Section 84.126. 
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Procedure No. TEB-APR-STP-0033B Revision: 2.3 Date: 24 November 2008 Page 8 of 12 

6.2. Minimum service life requirements for canisters are shown below. 

Test atmosphere 

Canister type Test condition 

Gas or 

vapor 

Concentration 

(ppmv) 

Flow rate 

(liters per 

minute) 

Number of 

tests 

Maximum 

allowable 

penetration 

(ppmv)1

Minimum 

service life 

(minutes)2

Ammonia 

Front and Back 

Mounted 

As received 

Equilibrated 

NH3

NH3

30,000 

30,000 

64 

32 

3 

4 

50 

50 

6/12 

6/12 

Ammonia 

Chin-Style 

As received 

Equilibrated 

NH3

NH3

5,000 

5,000 

64 

32 

3 

4 

50 

50 

6/12 

6/12 

Ammonia 

Escape 

As received 

Equilibrated 

NH3

NH3

5,000 

5,000 

64 

32 

3 

4 

50 

50 

12 

12 

1

Minimum life will be determined at the indicated penetration. 

2

For a combination respirator designed for respiratory protection against ammonia only or a combination of 2 or 3 of 

the following types: ammonia, acid gas, organic vapor, or carbon monoxide, the minimum life shall be 12 minutes. 

For a combination respirator designed for respirator protection against all of the following types: ammonia, acid 

gas, organic vapor, or carbon monoxide, the minimum life shall be 6 minutes each for ammonia, acid gas and 

organic vapor. For escape gas masks the minimum life shall be 12 minutes. 

 7. RECORDS/TEST SHEETS

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

8. ATTACHMENTS

8.1. Figure 1. - Bench-Top Set-up 

8.2. Data Sheet 
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Procedure No. TEB-APR-STP-0033B Revision: 2.3 Date: 24 November 2008 Page 9 of 12 

8.1. Figure 1. - Bench-Top Set-up 
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Procedure No. TEB-APR-STP-0033B Revision: 2.3 Date: 24 November 2008 Page 10 of 12 

8.2. Data Sheet 

RB - RESPIRATOR CERTIFICATION TEAM 

 GAS & VAPOR RESPIRATOR TEST DATA SHEET (Ref.33-48,50,62) STP No.: [ ] 

 Task Number: TN- Gas Name: 

Manufacturer: Item Tested: 

RESISTANCE Maximum Allowable Resistance 

 (mm of H2O) 

 Actual Resistance 

 (mm of H2O) 

 Inhalation Exhalation Inhalation Exhalation 

 Test 

Initial Initial 

Final Initial Final 

 Result 

 1

 2

 3

 4

 5

 6

 7

 Overall Results: Pass Fail Comment: 

WEIGHTS WEIGHTS (gm) AIRFLOW (Lpm)

 AND 

 AIRFLOWS Test Rate (PAPR Only)

 Test 

Con'd Conc. 

(ppmv) RH% Lpm Initial Final 

 1

 2

 3

 4

 5

 6

 7 

 Overall Results: Pass Fail Comment: 

DATA TABLE Temperature (oC) 

 Test 

 Test 

 Cond. 

 Final 

 Time (min) 

 Leakage 

 (ppmv) 

 Dns

tream 

 Upstr

eam 

 Corrected 

 Time (min) 

 1 

 2 

 3 

 4 

 5 

 6 

 7 

 Overall Results: Pass Fail Comment: 

 Was all testing equipment in calibration throughout al g: Yes l testin No 

 Signature: Date: 
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Procedure No. TEB-APR-STP-0033B Revision: 2.3 Date: 24 November 2008 Page 11 of 12 

 RB - RESPIRATOR CERTIFICATION TEAM Page 2 

 GAS & VAPOR RESPIRATOR TEST DATA SHEET (Ref.33-48,50,62) STP No.: [ ] 

 Task Number: TN- Gas Name: 

Manufacturer: Item Tested: 

 

Additional Comments: 

Signature: Date: 
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Procedure No. TEB-APR-STP-0033B Revision: 2.3 Date: 24 November 2008 Page 12 of 12 

 Revision History 

Revision Date Reason for Revision 

1.0 March 8, 2002 Historic document 

1.1 June 6, 2005 Update header and format to reflect lab move from Morgantown, WV 

No changes to method 

2.0 18 December 2006 Significant rewrite of RCT-APR-STP-0033. Changes affect form and 

provide clarification of technical content. 

2.1 25 July 2007 Correct tolerance for 85% humidity in table on page 4. Was +5/-0% 

2.2 8 August 2007 Section Modification 

5.3.3 Added reference to solution shelf life 

5.4.1 Added solution volume (100 ml for 30,000 ppmv) 

5.4.2 Addressed significant digits for volume quantities 

5.5 Strike “and the adjustments in paragraph 5.12.” 

5.6 Strike “challenge gas flow rates and / or” 

5.12 Add “For testing at 30,000 ppmv, the additional flow of 

99% ammonia gas required is sufficient to require 

adjustment of the air flow rate to maintain the total flow 

rates within tolerances” 

Flow rate table replaced 

5.17 Correct volume to 25 ml, and strike “or the predetermined 

calculated volume depending upon the concentration 

desired (see 5.3)” 

6.2 Table: Ammonia Escape challenge concentrations and 

breakthrough times corrected from 30,000 to 5,000, and 

from 6/12 to 12, respectively. 

2.3 24 November 2008 Section Modification 

4.7.2. Tolerances Table – Removed reference to 25 lpm flow rate 

6.1. “Legal basis for” becomes standard requirement 

6.2. Foot note 2 to Table – Clarification, now refers to ammonia 

only or a combination of 2 or 3 gasses and vapors