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National Institute for Occupational Safety and Health

National Personal Protective Technology Laboratory 

626 Cochrans Mill Road 

Pittsburgh, PA 15236

Procedure No. CVB-APR-STP-0080 Revision: 0.0 Date: 23 March 2020

DETERMINATION OF PARTICULATE FILTER EFFICIENCY LEVEL AGAINST LIQUID 

PARTICULATES FOR POWERED AIR-PURIFYING RESPIRATORS (PAPRs), SERIES PAPR100-P, 

STANDARD TESTING PROCEDURE (STP)

1. PURPOSE

This procedure establishes the means for ensuring that the particulate filtering efficiency of

PAPR100-P series filters meet the requirements set forth in 42 CFR, Part 84, Subpart K, Section

84.180. These filters or filter cartridges may be integral to respirator construction; mounted

individually, or in sets of up to three; used in conjunction with filters, cartridges and canisters for

half-mask, full facepieces, hoods, and helmets.

2. GENERAL

This STP describes the test method to be used for the Determination of Particulate Filter

Efficiency Level Against Liquid Particulates for Powered, Air-purifying Respirators, Series

PAPR100-P, test procedure in sufficient detail that a person knowledgeable in the appropriate

technical field can 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%.

3.1.2. Microbalance accurate to 0.0001 grams (g). 

3.1.3. Type A/E glass filters, 102 mm diameter, high efficiency filters with a 1 

micrometer pore size.

3.1.4. Timer (accurate to 0.01 percent).

3.1.5. Dioctyl phthalate (DOP, di(2-ethylhexyl)phthalate) min. 98%. 
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Procedure No. CVB-APR-STP-0080 Revision: 0.0 Date: 23 March 2020 Page 2 of 8 

3.1.6. 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. 

3.1.7. Thermal printer (supplied with TSI 8130) or optional data acquisition system. 

3.1.8. TSI, Green Line paper, part number 813010. Lot number must be included on 

each box. Each lot number must include the “Penetration vs. Resistance graph”. 

4. TESTING REQUIREMENTS AND CONDITIONS

4.1. Prior to beginning any testing, confirm that all measuring equipment employed has 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 recognized international standards when available. 

4.1.1. Respirator filters and filter cartridges shall be tested as follows. Filters used in 

conjunction with PAPR100-Ps, and odd or unusually shaped filters may be tested 

on a test fixture provided by the applicant. 

4.1.2. If a test fixture is supplied by the applicant, the test fixture shall have a serial 

number or other unique, easily referenced identifier permanently etched, 

engraved, or affixed. 

5. PROCEDURE

5.1. Respirator filters will be challenged by a neat cold – nebulized DOP aerosol at 25 ±5 °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 not exceeding 200 mg/m3

. 

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 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 (C) in mg/m3 = (W2 – W1) 

(Q / 1000) (T)

Where:

W1 = Initial filter weight in mg

W2 = Final filter weight in mg
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Procedure No. CVB-APR-STP-0080 Revision: 0.0 Date: 23 March 2020 Page 3 of 8 

Q = Flowrate in liters per minute

T = Test 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. Use the following formula to calculate the test duration: 

T in minutes = (mg load) (1000 L / m3) 

 (C) (Q) 

Where: 

C = Concentration in mg/m3 from 5.1.2. 

Q = Flow rate for test in Lpm

5.1.4. 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.

5.1.5. 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. 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. 

5.2. Filters will be mounted and sealed on holders to prevent leakage around the filter holder. 

Single air purifying respirator filters will be tested at a challenge flow rate of 85 

± 4 Lpm. Filters used as pairs on a respirator are tested using a single filter of the pair at 

42.5 ± 2 Lpm challenge flow rate. Filters used in threes are tested using a single filter of 

the set at 28.3 ± 1 Lpm challenge flow rate. 

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

to testing. 
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Procedure No. CVB-APR-STP-0080 Revision: 0.0 Date: 23 March 2020 Page 4 of 8 

5.3. A sample of 20 filter units will be tested against the DOP liquid aerosol. The filters shall 

be subjected to aerosol mass loading levels as shown in the table below. This is the mass 

amount of DOP aerosol that has contacted the filter.

Number of Filters In

Respirator Configuration

Initial Loading 

Level

Incremental 

Loading

Maximum 

Loading Level

Single 215 ± 5 mg. 30 ± 5 mg. 415 ± 5 mg.

Double 115 ± 5 mg. 30 ± 5 mg. 215 ± 5 mg.

Triple 85 ± 5 mg. 30 ± 5 mg. 155 ± 5 mg.

5.3.1. For PAPR100-P series filters, if the bandwidth (range) in penetration readings is 

equal to or less than 0.004% for the last 30 ± 5 mg at the initial loading level or 

within a subsequent incremental loading level, the filter passes the test. If the 

bandwidth in penetration readings is greater than 0.004% and not clearly 

decreasing, then the filter penetration is continuing to increase. The test is 

continued through the next 30 ± 5 mg of loading until the bandwidth in 

penetration readings is equal to or less than 0.004% for the incremental loading 

level or the penetration level exceeds the maximum allowable level. The test is 

concluded and the filter is determined to fail the test if the bandwidth in 

penetration readings is greater than 0.004% for the last 30 ± 5 mg ending at the 

maximum loading level indicated in the table above, or the maximum penetration 

exceeds 0.03%.

5.3.2. If any one of the 20 filters have a penetration greater than 0.03%, further testing 

of that filter will be terminated. 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 excessive leakage and testing has gone beyond 

the initial penetration, that sample will be considered an invalid sample, and 

another tested in its place.

5.4. Determine and record on the data sheet the maximum filter penetration for each of the 20 

filters, and the bandwidth readings over the 30 ± 5 mg on which the “no further decrease 

in efficiency” determination is made or the initial unacceptable bandwidth readings. 

6. PASS/FAIL CRITERIA

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

84.180. 

6.2. The minimum efficiency for each of the 20 filters shall be determined and recorded and 

shall be equal to or greater than 99.97%.

6.3. In order for the performance of the sample of 20 filters or filter cartridges to be deemed 

acceptable, each filter tested shall meet or exceed the specified minimum efficiency level

at the end point of the test. The bandwidth of the last 30 ± 5 mg for each filter tested 

shall be less than or equal to 0.004% if not clearly decreasing, before the maximum 

loading level specified in section 5.3 is reached. 
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7. RECORDS/TEST SHEETS

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

8. ATTACHMENTS

8.1. Example Data Sheet

8.2. Photograph of TSI 8130 CertiTester with chuck open 

8.3. Close-up of respirator test fixture with the chuck closed
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8.1. Example Data Sheet 
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Procedure No. CVB-APR-STP-0080 Revision: 0.0 Date: 23 March 2020 Page 7 of 8 

8.2. Photograph of TSI 8130 with chuck open 

8.3. Close-up of respirator test fixture with the chuck closed
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Procedure No. CVB-APR-STP-0080 Revision: 0.0 Date: 23 March 2020 Page 8 of 8 

Revision History

Revision Date Reason for Revision

0.0 23 March2020 Original release