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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-0001 Revision: 2.0 Date: 14 April 2009

DETERMINATION OF PARTICULATE FILTER PENETRATION TEST 

 POWERED AIR-PURIFYING RESPIRATOR FILTERS 

STANDARD TESTING PROCEDURE (STP) 

l. PURPOSE

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

air-purifying respirator filters submitted for Approval, Extension of Approval, or examined 

during Certified Product Audits, meet the filter penetration requirements set forth in 42 CFR, Part 

84, Subpart G, Section 84.63(a)(c)(d) and Subpart KK, Section 84.1151(a)(c), except that the 

flow requirements of Section 84.1151(a)(c) are not used. In their place, flow requirements 

specified in Section 84.1156(c)(2) are applied. This is done in order that PAPR filters are tested, 

to the extent possible, at the minimum required air flow rate of the PAPR. 

2. GENERAL 

This STP describes the Determination of Particulate Filter Penetration Test, Powered Airpurifying Respirator Filters 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. TSI Model 8130 Automated Filter Tester or equivalent instrument. Air flow 

control accuracy is 2% of full scale. Pressure measurement accuracy is 2% of 

full scale. Penetrations can be measured to 0.001%, efficiencies to 99.999%. 

Approvals: First Level Second Level Third Level Fourth Level 

 
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Procedure No. TEB-APR-STP-0001 Revision: 2.0 Date: 14 April 2009 Page 2 of 10 

 

3.1.2. Particle sizing instrument (such as TSI Model 3936 Scanning Mobility Particle 

Size Spectrometer or equivalent) that is capable of determining submicrometer 

particles according to count median diameter (CMD). 

. 

3.1.3. Microbalance accurate to 0.0001 grams (g). 

3.1.4. Gelman 102 mm diameter, type A/E glass filters or equivalent high efficiency 

filters with a 1 micrometer pore size. 

3.1.5. Timer (accurate to 0.01 second). 
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Procedure No. TEB-APR-STP-0001 Revision: 2.0 Date: 14 April 2009 Page 3 of 10 

3.1.6. Dioctyl phthalate ((DOP, di(2-ethylhexyl)phthalate)) min. 98%. 

 

3.1.7. Respirator filter holder supplied for specific manufacturer type which is 

compatible with TSI filter tester. NIOSH will not be obligated to use these 

holders for actual certification testing. All manufacturer test fixtures must be 

correlated with the NIOSH test method (see Work Instruction WI- 1611). 

3.1.8 Thermal printer (supplied) or optional data acquisition system. 

 

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

TEB-RCT-APR-WI-1011 – Laboratory Safety Procedures for Particulate Tests for 

Powered Air Purifying Respirators 

TEB-RCT-APR-WI-1111 – Calibration Procedures for Particulate Test for Powered 

Respirators 

TEB-RCT-APR-WI-1211 – Start–Up and Shut–Down Procedures for Particulate Test for 

Powered Air Purifying Respirators 

TEB-RCT-APR-WI-1411 – Reporting Results for Particulate Test for Powered Air 

Purifying Respirators 

TEB-RCT-APR-WI-1511 – Checking System Performance for Particulate Test for 

Powered Air Purifying Respirators 

TEB-RCT-APR-WI-1611 – Correlating Manufacturer – Supplied Test Fixtures for 

Particulate Test for Powered Air Purifying Respirators 

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 as a contractor 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. 
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Procedure No. TEB-APR-STP-0001 Revision: 2.0 Date: 14 April 2009 Page 4 of 10 

4.4. The precision and accuracy of this method is monitored by the validation method which 

is incorporated in the automated filter tester procedure. This procedure is performed on a 

daily basis when testing is performed. This procedure is designed to test many aspects of 

the method, for proper photometer and general system operation. The validation 

technique uses “green line” filter media discs, 6 inch diameter, HE 1071 grade, H & V 

brand, P/N 813010, with a known penetration range, which are tested at least once in 

each 8-hour test period (see 5.2.5). 

 4.4.1. Two sheets of unused filter media are stacked together and the penetration, flow 

 rate and pressure drop are measured to evaluate the higher range of penetration 

 values. Five unused sheets are stacked together to evaluate the lower range of 

 penetration values. 

 4.4.2. The analysis of these readings over the long term was used to examine the 

 precision and accuracy of this test method. The table below summarizes the 

 data. 

 

 Two Sheets Five Sheets

 

 Mean 2.459% 0.011% 

 Std. Dev. 0.157 0.001 

 Range 2.04 – 2.97% 0.008 – 0.017% 

 N 56 56 

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 used in this 

procedure. 

 

4.6. Dioctyl phthalate is considered a low hazard material with a recommended exposure limit 

(REL) of 5 mg/m3

 with a short-term exposure limit of 10 mg/m3. It may cause mild skin 

or eye irritation. Carcinogenic effects: Classified as a proven animal carcinogen with 

unknown relevance to humans by ACGIH; classified as a suspect carcinogen by NTP; not 

listed by IARC. Local exhaust ventilation is used for the potential sources of DOP from 

the TSI 8310 filter tester. Safety eyewear and a lab coat should be worn. Splash goggles, 

protective clothing, boots and gloves should be worn in case of a large spill. Discharge, 

treatment or disposal may be subject to national, state or local laws. 

5. PROCEDURE

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

purposes use those described in the manufacturers’ operation and maintenance manuals. 

5.1. Respirator filters will be challenged by a neat cold–nebulized DOP aerosol at 25 ±5ْ C 

that has been neutralized to the Boltzmann equilibrium state. The particle size 

distribution will be a count median diameter of 0.185 ± 0.020 micrometer and a 

geometric standard deviation not exceeding 1.6. Each respirator filter unit will be 

challenged with an aerosol concentration of 100 ± 10 mg/m3

. 
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Procedure No. TEB-APR-STP-0001 Revision: 2.0 Date: 14 April 2009 Page 5 of 10 

5.1.1. The DOP aerosol concentration will be determined daily by the following 

gravimetric method and calculated as milligrams per cubic meter (mg/m3

). 

5.1.2. Weigh a Gelman 102 mm filter to the nearest 0.1 mg., mount in the gravimetric 

filter holder, subject it to the generated aerosol at 30 Lpm for 40 minutes , and 

reweigh the filter. Use a timer to monitor the duration of the test. Record the 

pre- and post-weights, time, and average flow rate on the data sheet and calculate 

the aerosol concentration in mg/m3

 by the following formula: 

 Concentration in mg/m3 = W2 – W1

 (Q / 1000) (T) 

 Where: 

 W1 = Initial filter weight in mgs. 

 W2 = Final filter weight in mgs. 

 Q = Flowrate in liters per minute 

 T = Elapsed time in minutes 

 With a flowrate of 30 Lpm for 40 minutes, the above formula simplifies to: 

 C = W2 – W1

 1.2 

 5.1.3. The upstream and downstream photometer readings are used for monitoring 

stability and for calculating a photometer correlation factor (CF). The correlation 

factor is determined with an empty filter holder and is calculated internally as 

shown below: 

 

 CF = Downstream Photometer Voltage – Downstream Background Voltage

 Upstream Photometer Voltage – Downstream Background Voltage 

 The correlation factor is used by the software to express the upstream photometer 

 signal in terms of the downstream photometer signal. Follow Work Instruction 

 WI- 1511 for determining, monitoring and recording the CF. 

 5.1.4. The DOP particle size distribution shall be verified using “green line” filter discs 

supplied by TSI with a known penetration range. Graphs of penetration vs. 

resistance for two sheets and five sheets of stacked filter discs are supplied with 

each lot of the standard filters, with a central line and upper and lower lines 

representing the expected penetration range at a given resistance. The test data 

should fall within an acceptance zone having boundaries defined by the upper 

and lower curves on the graphs. Follow the procedure in Work Instruction WI1505. The standard filter test using both 2 sheets and 5 sheets will be run at least 

once in each 8 hour test period to verify that the aerosol distribution is within the 

acceptance zone. 

5.1.5. If the instantaneous filter penetration is not within the acceptance zone for any 

sample, abort testing and check the aerosol particle size with the Scanning 
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Procedure No. TEB-APR-STP-0001 Revision: 2.0 Date: 14 April 2009 Page 6 of 10 

Mobility Particle Size (SMPS) Spectrometer. 

5.2. The DOP particle size will be monitored at least once every three months (quarterly) with 

the SMPS spectrometer to ensure the particle size distribution count median diameter 

remains in the range of 0.185 ± 0.020 micrometer with a geometric standard deviation of 

not more than 1.6. 

 5.3. Filters shall be tested as follows: 

5.3.1. The filter, including the filter holders and gaskets, shall be tested for particle 

penetration. When the filtering element is not separable from the cartridge or 

canister, the complete component shall be tested. 

 

 5.3.2. When filters are not separable from the respirator body, any exhalation valves 

shall be sealed to ensure that any leakage due to an exhalation valve is not 

included in the filter penetration measurement. 

5.3.3. Filters not separable from cartridges, canisters, respirators, and odd or unusually 

shaped filters may be tested on a headform assembly or an assembly provided by 

manufacturer. Note: NIOSH is not obligated to use the headform assembly or 

any assembly provided by the manufacturer for certification testing. 

5.4. Filters shall be mounted and sealed on holders to prevent leakage around the filter holder. 

PAPRs are normally designed to use from one to four filters. Filters shall be tested using 

a single filter regardless of the number of filters used on the unit. Adjustment is made to 

the flow rate of the test by dividing the specified flow rate for the test, which is based on 

the minimum required air flow of 115 lpm for tight fitting PAPRs and 170 lpm for loose 

fitting PAPRs, by the number of filters used. The table below shows the test flow rate 

depending on the type of PAPR and the number of filters employed. The highest 

obtainable air flow for the automated filter testers is typically 96 lpm and this flow rate 

will be used to test single PAPR filters. 

 

PAPR FILTER TEST - FLOW RATE (LPM) 

NUMBER OF FILTERS TIGHT FITTING FACEPIECE LOOSE FITTING FACEPIECE 

1 96 ± 5 96 ± 5 

2 57 ± 3 85 ± 4 

3 38 ± 2 57 ± 3 

4 29 ± 2 43 ± 2 

5.4.1. The challenge flow rate must be checked for stability for at least 30 seconds prior 

to testing. 

 5.4.2. If using a TSI 8130 tester, the tester rise time shall be set at 10 seconds, the tester 

sample time shall be set at 10 seconds, and the tester purge time shall be set at 9 

seconds. 

5.5. A total of 3 filters shall be tested against the DOP liquid aerosol. Each filter shall be 

instantaneously loaded and evaluated. 
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Procedure No. TEB-APR-STP-0001 Revision: 2.0 Date: 14 April 2009 Page 7 of 10 

5.5.1. Any filter that exceeds the specified limit shall be remounted and retested to 

ensure that leakage was not caused by a mounting leak. If retesting eliminates 

the leakage, that filter shall be considered an invalid sample and another filter 

shall be tested in its place. 

5.6. The penetration of the 3 filters shall be measured and recorded. 

6. PASS/FAIL CRITERIA

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

84.63(a)(c)(d) and Subpart KK, Section 84.1151(a)(c); except that the flow requirements 

of Section 84.1151(a)(c) are not used. In their place, flow requirements specified in 

Section 84.1156(c)(2) are applied to the extent possible. 

6.2. The total leakage for the connector and filter shall not exceed 0.03 percent of the ambient 

DOP concentration for any test sample. 

7. RECORDS/TEST SHEETS

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

8. ATTACHMENTS

8.1. Data Sheet 

8.2. Test Setup 
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Procedure No. TEB-APR-STP-0001 Revision: 2.0 Date: 14 April 2009 Page 8 of 10 

8.1. Data Sheet 
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Procedure No. TEB-APR-STP-0001 Revision: 2.0 Date: 14 April 2009 Page 9 of 10 

8.2. Test Setup 
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Procedure No. TEB-APR-STP-0001 Revision: 2.0 Date: 14 April 2009 Page 10 of 10 

Revision History 

Revision Date Reason for Revision 

1.0 7 March 2004 Historic document 

1.1 1 June 2005 Update header and format to reflect lab move from Morgantown, WV 

No changes to method 

2.0 14 April 2008 Section Change 

3.2. List of Work Instructions added 

4. Requirements and data for precision and accuracy added 

5. Editorial changes to clarify procedures 

5.1.2. Example calculation for challenge concentration added 

5.4. Clarifications to test flow in light of the maximum total 

test flow of 96 lpm. A table of appropriate flow values is 

added. 

All Editorial changes to improve clarity throughout