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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-0520-CBRN Revision: 0.1 Date: 9 February 2009

DETERMINATION OF CBRN FORMALDEHYDE SERVICE LIFE TEST, LOOSEFITTING POWERED AIR-PURIFYING RESPIRATORS (PAPR) STANDARD TEST 

PROCEDURE (STP) 

1. PURPOSE

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

Formaldehyde Service Life Test, Loose-Fitting Powered Air-Purifying Respirators (PAPR) 

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) Powered Air-Purifying 

Respirator (PAPR). 

2. GENERAL

This STP describes the CBRN Formaldehyde Service Life Test, Loose-Fitting Powered AirPurifying Respirators (PAPR) Standard Test Procedures 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%). 

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. Amersham Biosciences High Precision Pump, Model P-500 with reservoir. Flow 

Approvals: First Level Second Level Third Level Fourth Level 

 
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Procedure No. TEB-APR-STP-0520-CBRN Revision: 0.1 Date: 9 February 2009 Page 2 of 15 

rate range: l ml / hr to 400 ml / hr 1.5% of setting. 

3.1.4. Interscan Corporation, Model RM-16-2, formaldehyde detector or equivalent. 

This detector is an electrochemical voltammetric sensor with an internal vacuum 

pump. Detector range: 0 - 1999 ppb, resolution: 1 ppb. 

3.1.5. Dry Test Meter. American Meter Co., model and size depending on air flow rate 

to be measured. Must have NIST traceable calibration certificate. 

3.1.6. Electronic balance with accuracy of 0.01 grams (g). 

3.1.7. Kin-Tek 491MB Basic Gas Standards Generator with permeation tubes of 

formaldehyde. Used for the calibration of formaldehyde detectors. 

3.1.8. Miller Nelson Research, Model SV-2000, Vaporizer system or equivalent. Used 

for vaporizing formaldehyde solution. 

3.1.9. Gilibrator, Primary Standard Airflow Calibrator or equivalent. 

3.1.10. Gilian Gil-Air-3 Sampling Pump or equivalent. 

3.1.11. Graduated impinger, 25ml. 

3.1.12. Para-formaldehyde, purified grade. 

3.1.13. Sodium Thiosulfate (granular) or 0.1N certified sodium thiosulfate solution. 

3.1.14. Starch, Soluble Potato, Powder. 

3.1.15. Iodine, 0.1N certified solution. 

3.1.16. Sodium Bisulfite, granular. 

3.1.17. Sodium Carbonate, anhydrous powder. 

3.1.18. Glacial acetic acid. 

3.1.19. Heated magnetic stirrer and stir bar. 

3.2. Test fixture for mounting cartridge. 

3.3. The test chamber consisting of an air-tight box with door opening lined with gasket 

material. Two fittings located on 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. Airflow measurement equipment as described in standard test procedure RCT-APR00012. 
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Procedure No. TEB-APR-STP-0520-CBRN Revision: 0.1 Date: 9 February 2009 Page 3 of 15 

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 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). 

4.2. 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. 

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. 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. 

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 

5.1. Prepare solutions (must be made at least 24 hours in advance) 

5.1.1. 12.5 % Paraformaldehyde solution: In a 2000 ml beaker containing 1000 ml 

distilled water and a stirring bar, add 125 g paraformaldehyde. Stir and heat the 

solution to 80C using the heated magnetic stirrer. Place a watch glass over the 
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Procedure No. TEB-APR-STP-0520-CBRN Revision: 0.1 Date: 9 February 2009 Page 4 of 15 

top of the beaker or cover with aluminum foil to prevent excessive water loss. 

Continue stirring and heating until the solution clarifies (about 24 hours). Filter 

the solution if not clear after 24 hours. Store in covered bottle or flask. 

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

purposes use those described in the manufacturer's operation and maintenance manuals. 

5.2. Follow the 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. 

5.3. After the manufacturer's specified warm-up period, calibrate the formaldehyde analyzers 

using the Kin-Tek generator and permeation tubes to generate approximately 1 ppm. 

5.4. Set the high precision pump for delivery of calculated formaldehyde to obtain 250 ppm 

25 ppm. See appendix 8.2. 

5.5. Set up test equipment as shown in Figure 1 or Figure 2 depending on the test parameters 

in section 6.3. 

5.5.1. For section 6.3.2 test: The airflow is controlled by the Mass Flow Controller. 

Humidity and temperature readings are monitored by a 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. 

5.5.2. For section 6.3.3: The airflow, humidity and temperature are controlled by the 

Miller Nelson system. The temperature and humidity is monitored by 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. Air and water supplies. 

5.6.2. Miller Nelson Research Flow-Temperature-Humidity Control System. 

5.6.3. Miller Nelson Research Vaporizer system. 

5.6.4. Amersham Biosciences High Precision Pump 

5.7. Set the required airflow for the system. Individual cartridges will be tested by dividing 

170 Lpm by the numbers of air-purifying elements on the system. See appendix 8.6 

worksheet 4. Verify the airflow from the test fixture using the appropriate dry test meter. 
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Procedure No. TEB-APR-STP-0520-CBRN Revision: 0.1 Date: 9 February 2009 Page 5 of 15 

5.8. Establish the correct humidity and temperature depending on the test parameters in 

section 6.3. 

5.8.1. Fill pump reservoir with distilled H2O. Insert needle from pump to top of 

column. Start the high precision pump flow using the calculated value from 

section 5.3. Allow 15 minutes for equalization system. Make sure distilled H2O is 

delivered to the heated vaporizing element. 

5.8.2. Determine the humidity readings for distilled H2O. 

5.8.2.1. For section 6.3.2., the humidity value should be reading according to the 

specification required (25 % ± 5%). If the humidity readings are not 

within the specification, make adjustments to the incoming compressed 

air or the room temperature to establish the specification. 

5.8.2.2. For section 6.3.3., the humidity readings can be adjusted using the Miller 

Nelson Controller to the specification required (80% ± 5%). 

5.9. Fill pump reservoir with 12.5 % paraformaldehyde solution, weigh and record weight of 

the reservoir. Insert needle from pump to top of column. Start the high precision pump 

flow. Allow 30-40 minutes for equalization of concentration. Make sure formaldehyde is 

delivered to the heated vaporizing element. 

5.10. Weigh and record initial weight of the test cartridge on Test Data Sheet. 

5.11. Take and record initial airflow measurements in accordance with RCT-APR-012. See 

section 84.1702 (b) Title 42, Code of Federal Regulations, Part 84 for minimum airflow 

requirements. 

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

discharge and not into the testing chamber. 

5.13. Mount cartridge onto test fixture and place in testing chamber. 

5.14. Determine the concentration of the formaldehyde vapor being generated. 

5.14.1. Add 10 ml 1% sodium bisulfite solution to two impingers. Connect the two 

impingers together from outlet of one impinger to inlet of second impinger. 

5.14.2. Attach Gil-Air 3 sampling pump to intake side of the first impinger. Connect 

outlet side of second impinger to Gilibrator. Check 1 Lpm flow of the pump 

pulling through the sodium bisulfite solution. This setting will be used to 

sample the formaldehyde concentration. Remove outlet side from Gilibrator. 

5.14.3. Connect tubing from the sample side of the first impinger into the Gil-Air 

pump and tubing from the inlet side of the second impinger to the test 

concentration. 
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5.14.4. Turn on sampling pump and sample for 30 minutes at 1 Lpm. 

5.14.5. Shut off sampling pump and transfer the contents of the two impingers into an 

Erlenmeyer flask. Rinse the impinger stem and body and transfer the washings 

to the flask. 

5.14.6. Place a stir bar in the flask and place the flask on the magnetic stirrer. Begin 

stirring. 

5.14.7. Add 1 ml starch solution. 

5.14.8. Add 0.1N iodine dropwise until solution is dark blue. 

5.14.9. Add 0.1N sodium thiosulfate dropwise until blue color is gone indicating 

neutralization of the excess iodine. 

5.14.10. Slowly add 0.01N iodine dropwise from a 50 ml buret until the first appearance 

of a faint blue color. 

5.14.11. Add 25 ml sodium carbonate buffer solution. The blue color should disappear 

if formaldehyde is present. 

5.14.12. Record the initial buret reading of the 0.01N Iodine. 

5.14.13. Slowly add the 0.01N iodine until the appearance of a faint blue color. 

Calculate the concentration of formaldehyde using the formula in Appendixs 

8.3. Adjust the flow from the high precision pump and repeat steps 5.12 

through 5.26 if concentration of 250 ppm ± 10% is not obtained. If the 

concentration if correct attach sample line from high range detector to the tee in 

the system. This detector will be used to monitor the challenge concentration 

throughout the length of the test. Turn on the strip chart recorder to record the 

concentration. 

5.15. Once the formaldehyde 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. 

5.18. Run test until breakthrough of 1000 ppb is observed or selected service life time is 

surpassed. Record this data on the test data sheet. 

5.19. Weigh and record on the test data sheet the final weight of test cartridge. 

5.20. Take and record final airflow measurements in accordance with RCT-APR-012. See 

section 84.1702 (b) Title 42, Code of Federal Regulations, Part 84 for minimum airflow 
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Procedure No. TEB-APR-STP-0520-CBRN Revision: 0.1 Date: 9 February 2009 Page 7 of 15 

requirements. 

5.21. Repeat steps 5.7 through 5.20 for each test described in section 6.3. 

5.22. Turn off pump and heating mantle. 

5.23. Allow clean air to purge through system for 10-15 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); 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. Formaldehyde Test for CBRN cartridges 

6.3.1. Airflow measurements of system must be taken before and after each test. 

6.3.2. Three cartridges will be tested at the determined Lpm, continuous air flow, 25 % 

± 2.5 % relative humidity (RH), 25 oC ± 2.5 o

C and 250 ppm formaldehyde. 

6.3.3. Three cartridges will be tested at the determined Lpm, continuous air flow, 80 % 

±2.5 % relative humidity (RH), 25 oC ± 2.5 o

C and 250 ppm formaldehyde. 

6.3.4. Minimum service life will be 15, 30, 45, 60, 90 or 120 minutes as per 

manufacturer request. End of service life concentration is 1000 ppb 

formaldehyde. 
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Procedure No. TEB-APR-STP-0520-CBRN Revision: 0.1 Date: 9 February 2009 Page 8 of 15 

7. RECORDS AND TEST SHEETS

7.1. All test data will be recorded on the FORMALDEHYDE 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 TEB 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 TEB Team Leader 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 Branch Chief, or 

the Branch Chief’s designee, following the standard operating procedures 

outlined in Procedure for Scheduling, and Processing Post-Certification Product 

Audits, 

RB-SOP-0005-00. 

8. APPENDIXES

8.1. Bench Top Set-Up (low humidity). 

8.2. Bench Top Set-Up (moderate and high humidity). 

8.3. Calculations for formaldehyde delivery. 

8.4. Test Data Sheet. 

8.5. Qualitative analysis and calculations for determining concentration of challenge 

formaldehyde vapor. 

8.6. Service-life testing airflow calculations. 
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8.1. Bench Top Set-Up (low humidity)
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8.2. Bench Top Set-Up (moderate and high humidity) 
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8.3. Calculations for formaldehyde delivery

Calculations for formaldehyde concentration. 

1 ppm = 1.23 mg / m3

Airflow (L/hr) = Airflow (L / min) x 60 min 

Injection rate (ml/hr) = Conc (ppm) X 30 (g / mol) X Airflow (L/hr) 

 22.4 x 106 X 1.04 g/ml X 12.5% 

 

57.5 Lpm 170 Lpm 

500 ppm 18 ml/hr 36 ml/hr 
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8.4. Test Data Sheet 
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8.5. Qualitative analysis and calculations for determining concentration of challenge formaldehyde vapor

 

 CALCULATION OF FORMALDEHYDE CONCENTRATION 

 The formaldehyde equivalent Fe is given by the formula: 

 Fe= ( (N) I ) x 0.15 mg. 

 .01 

Where (N) I is the normality of the standardized iodine. This formula is based on the fact that the 

equivalent weight of formaldehyde is 15 gm., which means that 1 ml. of 0.01N iodine is 

equivalent to 0.15 mg. of formaldehyde. 

 The amount of formaldehyde in the sample volume collected is given by the formula: 

 Fc = final buret reading - initial buret reading x Femg 

 Fc = total ml. .01 iodine used x 0.15 mg 

 Formaldehyde concentration in ppm is given by the following formula: 

 ppm = Fc x 24.45 x 760 x T+273 x 103

 V MW P 298 

 

 Where: 

 V = volume of sample collected (30 lpm) 

 MW = molecular weight formaldehyde (30.03 g/mole) 

 P = pressure in mm of mercury in the lab 

 T = temperature in C of the lab 

Assuming that T is equal to 25C and p is equal to 760 mm mercury, the ppm formula simplifies 

to: 

 HCHO (ppm) = Fc x 27.14 assuming volume of sample collected 30 liters 

 HCHO (ppm) = ml. 0.01 Iodine used x 0.15 mg x 27.14
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8.6. Service-life testing airflow calculations 

Loose-fitting PAPR 

___________ Number of filtering elements on a loose-fitting PAPR System. 

170 Lpm airflow 

Airflow for service life test = 170 Lpm / number of filtering elements 

Test Flow 

4 Cartridges 3 Cartridges 2 Cartridges 1 Cartridge 

42.5 Lpm 56.7 Lpm 85 Lpm 170 Lpm 
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Revision History 

Revision Date Reason for Revision 

0.0 21 November 2006 Original Issue 

0.1 9 February 2009 Name changed in alignment with current naming convention, 

revision 0.0, paragraphs 5.6. through 5.13., had been numbered 

incorrectly, but renumbered in this revision to reflect their inherent 

order (no paragraphs added or deleted), minor editorial revision, no 

change to procedure