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. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005

DETERMINATION OF HYDROGEN FLUORIDE SERVICE LIFE TEST, 

AIR-PURIFYING RESPIRATORS 

 STANDARD TESTING PROCEDURE (STP) 

1. PURPOSE

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

hydrogen fluoride service life requirements on chemical cartridges air-purifying respirators 

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), Subpart L, Section 84.190(b), and Subpart KK, Section 84.1157; Volume 60, 

Number 110, June 8, 1995. 

2. GENERAL

This STP describes the Determination of Hydrogen Fluoride Service Life Test, Air-Purifying 

Respirators 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

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. 

3.1.2. CEA Instruments Hydrogen Fluoride Analyzer Model-TG-700BA or equivalent. 

 3.1.3. Three-necked round bottom flask (250ml). 

3.1.4. Heated vaporizing element to suspend in the three necked round bottom flask. 

The element is covered with platinum foil. The hydrogen fluoride is delivered 

via the syringe and tubing assembly to the element, where it is vaporized into the 

air-stream. This is not commercially available. 

 3.1.5. Vaisala model HMI 31 humidity indicator. 

 3.1.6. Hydrofluoric acid, 48% purity.

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 2 of 14 

3.1.7. Plastic syringe, 1 ml with Hamilton Teflon Tubing Assembly 90628. 

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

 3.1.9. Sage syringe pump, Model 355 or equivalent. 

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

manufacturer depending on how the cartridge, canister, or powered air-purifying 

respirator (PAPR), mouth bit, etc. is mounted to the facepiece. The T-end has a 29/42 

ground glass joint glued in place. Canisters are tested with their connections glued into 

the ground glass joint. In most cases the cartridge cups of the respirator are affixed by 

hot melt glue to PVC pipe tee of appropriate size. PAPR cartridges and canisters are 

tested on their blower units if possible, or on suitable substitutions, if the unit is too large 

for the test chamber. 

3.3. The test chamber consisting of a 12" x 111⁄2" x 7" air tight box, made of 1⁄2" plexiglass 

with 2 hinge type locks on the door opening lined with gasket material. A 1⁄2" hole is 

located on the back of the test chamber for the introduction of the test concentration and a 

11⁄2" hole on the top for the exit of the test fixture and to detect the breakthrough 

concentration. This fixture is not commercially available. 

3.4. Resistance tester consisting of a vacuum source capable of delivering 85 liters per minute 

(lpm), a 6-inch slant manometer, and a 29/42 female ground glass joint. The resistance 

testers currently being used are located on the silica dust chamber. 

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

described in the current ALOSH Facility Laboratory Safety Manual. 

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

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

equipment. 

4.2.3. When handling any glass laboratory equipment, lab technicians and personnel 

must wear special gloves which protect against lacerations or punctures. 

4.3. HYDROGEN FLUORIDE BENCH TEST FOR CARTRIDGES 

 4.3.1. Resistance to air flow will be taken before and after each test (see 

84.203). 

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 3 of 14 

 4.3.2. Three "as received" cartridges (or pairs of cartridges) will be tested at 64 lpm, 

continuous air flow, 50 + 5 percent relative humidity (RH), approximately 25 

degrees Celsius (OC), and 70 ppm HF. 

 4.3.3. Two cartridges or pairs of cartridges will be equilibrated at room temperature by 

passing 25 percent RH air through them at 25 lpm for 6 hours and then testing 

them at 25 percent RH, approximately 25OC, and 64 lpm continuous air flow rate 

containing 70 ppm HF. 

 4.3.4. Two cartridges or pairs of cartridges will be equilibrated at room temperature by 

passing 85 percent RH air through them at 25 lpm for 6 hours and then testing 

them at 85 percent RH, approximately 25o

C, and 64 lpm continuous air flow rate 

containing 70 ppm HF. 

4.4. HYDROGEN FLUORIDE BENCH TESTS FOR PAPR CARTRIDGES 

 4.4.1. Resistances and airflows for tight fitting PAPR will be taken before and 

after each test. Airflows only for loose fitting PAPR will be taken before and 

after each test. 

 4.4.2. Three cartridges (or pairs of cartridges) will be tested at 115 lpm for tight fitting 

PAPR or 170 lpm for loose fitting PAPR hood or helmet continuous air flow, 

approximately 25o

C, and 50 + 5 percent RH, approximately 25 degrees Celsius 

(

OC), and 70 ppm HF. 

 4.4.3. Two cartridges (or pairs of cartridges) will be equilibrated by passing 115 lpm 

for tight fitting PAPR or 170 lpm for loose fitting PAPR hood or helmet, 

continuous air flow through them at approximately 25o

C, and 25 percent RH for 

six hours. They will then be tested at 115 or 170 lpm continuous air flow, 

approximately 25o

C, 50 + 5 percent RH, approximately 25 degrees Celsius (OC), 

and 70 ppm HF. 

4.4.4. Two cartridges (or pairs of cartridges) will be equilibrated by passing 115 lpm 

for tight fitting PAPR or 170 lpm for PAPR loose fitting hood or helmet, 

continuous air flow through them at 25o

C, and 85 percent RH for six hours. 

They will then be tested at 115 or 170 lpm continuous air flow, 25o

C, 50 + 5 

percent RH, approximately 25 degrees Celsius (OC), and 70 ppm HF. 

 4.5 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. 

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 4 of 14 

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. After the manufacturer's specified warmup period, calibrate the HF analyzer following 

the instruction manual. 

 5.3. Set up test equipment as shown in Figure 1 for cartridge testing or Figure 2 for canister 

testing. In addition to the humidity reading controlled by the Miller Nelson system, the 

Vaisala HMI 31 humidity indicator sensor is inserted into the air stream via a tee set-up 

directly prior to the introduction of the hydrogen fluoride. This set up is not shown on 

the set ups. The humidity reading obtained at this point takes into account tubing length 

and outside hood air temperature. 

 5.4. Turn on: 

 5.4.1. Miller Nelson Unit. 

 5.4.2. Air and water supplies. 

 5.5. For cartridge testing at 70 ppm, fill syringe with hydrogen fluoride and place on syringe 

pump. 

 5.6. Establish the test concentration. 

 5.7. Determine the rate of advance of the syringe pump for the appropriate syringe volume, 

airflow, and the desired concentration for the respirator being tested. (See Tables 1 and 

2.) Concentration will vary with the syringe volume size. The rate of the syringe pump 

must be recalculated when different size syringes are used or the airflow rate or 

concentration changes. For a concentration of 70 ppm HF, a flow rate of 0.0065 ml/min 

is required. 

 5.8. Allow the concentration to stabilize for 20-30 minutes. 

 5.9. Weigh the cartridge and record the weight. 

 5.10. Take inhalation and exhalation resistances of the cartridge mounted on the facepiece at 

85 lpm. See Sections 84.203, 84.1157, Title 42, Code of Federal Regulations, Part 84 for 

breathing resistance requirements. Take airflows of PAPR cartridge mounted on blower 

assembly. 

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

 5.12. Direct challenge concentration airflow into test chamber. Start timer. Mount small piece 

of tygon tubing onto the outlet of the test fixture. Insert intake tubing of detector into a 

slit cut into the side wall of the tubing to allow the detector to sample at the flow rate of 

the detector without interference from airflow back pressure. Monitor and record 

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 5 of 14 

upstream and downstream temperatures throughout testing. Record breakthrough values 

and times. 

5.13. Run test until breakthrough of 3.0 ppm is observed or minimum service life is surpassed 

depending on type of cartridge or canister tested. 

5.14. Dismount cartridge and weigh and record final weight, and take final inhalation and 

exhalation resistances and PAPR airflows. 

5.15. Shut off syringe pump. 

5.16. Disconnect air line from Miller Nelson system to flask to prevent contamination the 

humidity sensor. 

5.17. Allow clean air to purge through system for 10 - 15 minutes. 

5.18. Turn off air and water supply to Miller Nelson system. 

6. PASS/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), Subpart L, Section 84.190(b), and Subpart KK, Section 84.1157; 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. 

 84.190 Chemical cartridge respirators: description. 

(b) Chemical cartridge respirators for respiratory protection against gases or vapors, 

which are not specifically listed with their maximum use concentration, may be approved 

if the applicant submits a request for such approval, in writing, to the Institute. The 

Institute shall consider each such application and accept or reject the application after a 

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 6 of 14 

review of the effects on the wearer's health and safety and in the light of any field 

experience in use of chemical cartridge respirators as protection against such hazards. 

84.1157 Chemical cartridge respirators with particulate filters; performance 

requirements; general. Chemical cartridge respirators with particulate filters and the 

individual components of each such device shall, as appropriate, meet the following 

minimum requirements for performance and protection: 

(a) Breathing resistance test. (1) Resistance to airflow will be measured in the facepiece, 

mouthpiece, hood, or helmet of a chemical cartridge respirator mounted on a test fixture 

with air flowing at a continuous rate of 85 liters per minute, both before and after each 

test conducted in accordance with paragraphs (d) through (f) of this section 

(2) The maximum allowable resistance requirements for chemical cartridge respirators 

are as follows: 

 Maximum Resistance 

 [mm. water-column height] 

Inhalation 

Type of chemical 

cartridge respirator Final1

 Exhalation 

For gases, vapors, or 

gases and vapors, and 

dusts, fumes, and mists 

 50 70 20 

For gases, vapors, or 

gases and vapors, and 

mists of paints, lacquers, 

and enamels 

 50 70 20 

1

Measured at end of service life specified in Table 11 in subpart L of this part. 

 (b) Facepiece test. The facepiece test will be conducted as specified in §84.205. 

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 7 of 14 

 (f) Bench tests; gas and vapor tests.

(1) Bench tests will be made in accordance with 84.207 and tested cartridges shall meet 

the minimum requirements set forth in Table 11 of Subpart L of this part. Cartridges will 

be equilibrated in accordance with paragraph (f)(2) of this section. 

(2)(i) Two powered air-purifying cartridges or pairs of cartridges will be equilibrated at 

room temperature by passing 25 percent RH air through them at the following flow rates 

(expressed in liters per minute (l.p.m.)) for 6 hours: 

 Type of cartridge Airflow rate, l.p.m.

 Powered air purifying with tight-fitting facepiece 115 

 Powered air purifying with loose-fitting hood or helmet 170 

(ii) Two powered air-purifying cartridges or pairs of cartridges will be equilibrated by 

passing 85 percent relative humidity air through them at the flow rates stated in paragraph 

(f)(2)(i) of this section. 

 

(iii) All cartridges will be resealed, kept in an upright position, at room temperatures, and 

tested within 18 hours. 

 6.3. The criterion for passing this test is that the penetration of HF shall not exceed 3 ppm for 

a minimum service life of 30 minutes for negative pressure cartridges and powered airpurifying cartridges. If the penetration does not exceed 3 ppm during the service life of 

30 minutes for negative pressure cartridges and 30 minutes for powered air-purifying 

cartridges, the units pass the test. If the penetration does exceed 3 ppm during the service 

life of 30 minutes for negative pressure cartridges and 30 minutes for powered airpurifying cartridges, the units fail the test. The units will be run until the penetration of 

HF is equal to 3 ppm or the minimum service life is surpassed. 

7. RECORDS/TEST SHEETS

7.1. All test data will be recorded on the HYDROGEN FLUORIDE 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 RCT 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 RCT 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 

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 8 of 14 

held at the testing laboratory until authorized for release by the RCT Leader, 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 Table 1- Calculation for syringe pump injection rates. 

 8.2 Table 2 - Nominal injection rates for Sage Model 355. 

 8.3. Bench Top Set-Up. 

 8.4 Data Sheet. 

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 9 of 14 

TABLE 1 

CALCULATIONS FOR SYRINGE PUMP INJECTION RATES at 25EC and 1 atm 

 For liquids:

C= (24.6 x 106

) KRp 

 QM 

 R= CQM 

 (24.6 x 106

) KpX 

 where: 

 R= rate of advance (mm/min) C= concentration (ppm) 

 K= syringe constant (ml/mm) p= solvent density (g/ml) 

 Q= airflow rate (lpm) M= molecular weight (g/mol) 

 X= decimal percent hydrogen fluoride solution 

To obtain the syringe constant, divide the volume of the syringe in ml by the length of the syringe 

in mm. 

Sample calculation: Find the rate of advance and % of flow setting required to produce 

a concentration of 70 ppm HF in 64 lpm of air, using a 1 ml syringe and a 48 percent 

paraformaldehyde solution. 

 R= (70 ppm) (64 lpm) (20.0g/mol) 

 (24.6 x 106

) (0.0172 ml/mm) (1.0 g/ml)(0.048) 

 R= 0.382 mm/min. 

 From Table 2, the flow setting would be 264 at a range setting of 1/100. 

For syringe pumps delivering in volumes of ml/minute, multiply rate of advance R by syringe 

constant. 

 ml/min.= 0.382 mm/min. x 0.0172 ml/mm. 

 ml/min.= 0.0065 

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 10 of 14 

TABLE 2 

NOMINAL INJECTION RATES FOR SAGE SYRINGE PUMP MODEL 355 

Rate of advance (R) 

 (mm/min.) 

 

% Flow Range setting 

 dial setting 1 1/10 1/100 1/1000

100 14.5 1.45 0.145 0.0145 

150 21.8 2.18 0.218 0.0218 

200 29.0 2.90 0.0290 0.0290 

250 36.3 3.63 0.0363 0.0363 

300 43.5 4.35 0.0435 0.0435 

350 50.8 5.08 0.508 0.0508 

400 58.0 5.80 0.580 0.0580 

450 65.3 6.53 0.653 0.0653 

500 72.5 7.25 0.725 0.0725 

550 79.8 7.98 0.798 0.0798 

600 87.0 8.70 0.870 0.0870 

650 94.3 9.43 0.943 0.0943 

700 102 10.2 1.02 0.102 

750 109 10.9 1.09 0.109 

800 116 11.6 1.16 0.116 

850 123 12.3 1.23 0.123 

900 131 13.1 1.31 0.131 

950 138 13.8 1.38 0.138 

1000 145 14.5 1.45 0.145 

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 11 of 14 

 Figure 1

Miller-Nelson

HCS 401

64.0

25.3

50.0

Hydrogen Fluoride Test Setup

Gas 

Analyzer

Heated 

Vaporizer

Syringe pump and 

syringe

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 12 of 14 

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 

 I

nitial 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. 

(ppm) RH% lpm 

 I

nitial Final 

 1 

 2 

 3 

 4 

 5 

 6 

 7 

 Overall Results: Pass Fail Comment: 

DATA TABLE Temperature (oC) 

 Test 

 Test 

 Cond. 

 Final 

 Time (min) 

 Leakage 

 (ppm) 

 Dnst

ream 

 Upstre

am 

 Corrected 

 Time (min) 

 1 

 2 

 3 

 4 

 5 

 6 

 7 

 Overall Results: Pass Fail Comment: 

 Was all testing equipment in calibration throughout all testing: Yes No 

 Signature: Date: 

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 13 of 14 

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: 

 

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Procedure No. RCT-APR-STP-0042 Revision: 1.1 Date: 29 June 2005 Page 14 of 14 

Revision History 

Revision Date Reason for Revision 

1.0 13 March 2002 Historic document 

1.1 29 June 2005 Update header and format to reflect lab move from Morgantown, WV 

No changes to method 

 

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