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-ASR-STP-0113 Revision: 1.1 Date: 20 September 2005

DETERMINATION OF AIRFLOW RESISTANCE, CONTINUOUS FLOW, 

TYPE C AND CE, SUPPLIED-AIR RESPIRATORS 

STANDARD TESTING PROCEDURE (STP) 

1. PURPOSE

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

airflow resistance requirements on Type C and CE, Continuous Flow, Supplied-Air Respirators 

submitted for Approval, Extension of Approval, or examined during Certified Products Audits, 

meet the minimum certification standards set forth in and 42 CFR, Part 84, Subpart G, Section 

84.63(a)(c)(d), and Subpart J, Section 84.155; Volume 60, Number 110, June 8, 1995. 

2. GENERAL

This STP describes the Determination of Airflow Resistance, Continuous Flow, Type C and CE, 

Supplied-Air Respirators test in sufficient detail that a person knowledgeable in the appropriate 

technical field can select equipment with the necessary resolution, conduct the tests, and 

determine whether or not the product passes the tests. 

3. EQUIPMENT/MATERIALS

3.1 The list of necessary test equipment and materials follows: 

3.1.1. Teledyne Hastings - Raydist Mass Flow Meter - Model NAHL-25 or equivalent.

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Procedure No. RCT-ASR-STP-0113 Revision: 1.1 Date: 20 September 2005 Page 2 of 10 

3.1.2. Anthropometric Test Head with tube for measuring breathing resistance (Sierra 

Engineering Company Model 428) or equivalent. 

3.1.3 A Helicoid calibrated pressure gauge and connecting fittings or equivalent. 

3.1.4. Dwyer Slant Manometer 0-3", F. W. Dwyer Manufacturing Co., Michigan City, 

Indiana or equivalent. 

3.1.5. An air tight container (35 Liter test tank with a depth and diameter of 

approximately 36 centimeters) that has an inlet and outlet. The inlet can accept 

various ten centimeter rubber gaskets with openings varying according to 

breathing tube size diameters. The container must have a removable cover on the 

inlet side to facilitate connecting the respirator-inlet covering connection to the 

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Procedure No. RCT-ASR-STP-0113 Revision: 1.1 Date: 20 September 2005 Page 3 of 10 

breathing tube inside of the container or equivalent. 

3.1.6. A 300 cubic foot gas cylinder of compressed air or equivalent. 

3.1.7. Air regulator, Model 8, from Matheson Gas Products or equivalent. 

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. The compressed gas cylinder must meet all applicable Department of Transportation 

Requirements for cylinder approval as well as for retesting/requalification. 

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

described in the current ALOSH Facility Laboratory Safety Manual. 

4.3.1. Safety glasses, lab coats, and hard-toe shoes must be worn during all testing. 

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

equipment. 

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

must wear special gloves which protect against lacerations or punctures. 

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Procedure No. RCT-ASR-STP-0113 Revision: 1.1 Date: 20 September 2005 Page 4 of 10 

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. 

5.1. Turn on mass flow meter. The meter needs at least 30 minutes warm-up time. 

5.2. Insert the respirator and air inlet tube in the 35 liter tank. 

5.3. Pull the air inlet tube through the rubber gasket in the lid of the tank and secure the lid 

onto the tank. To insure that no air escapes, the hole of the rubber gasket should have a 

smaller diameter than the diameter of the air supply hose and caulk around sealing area. 

5.4. Attach the air supply hose to the air regulating valve or orifice of the supplied-air 

respirator. 

5.5. Attach the other end of the minimum length of air-supply hose to the downstream side of 

the regulator. 

5.6. Connect the mass flow meter to the outlet of the 35 liter tank. 

5.7. Adjust the regulator until a flow of 115 liters per minute is obtained. (See data analysis). 

5.8. Record the reading on the pressure gauge and the position of the air regulating valve if 

used. 

5.9. Turn off air supply. 

5.10. Remove the respirator and air inlet tube from the 35 liter tank and mount on 

anthropometric head. Plug the breathing machine connection on the head with a cork. 

5.11. Connect a slant manometer to the pressure tube exiting the anthropometric head. 

5.12. Adjust air supply pressure to that obtained in step 5.7, insure the air regulating valve (if 

used) is in the same position as step 5.8. 

5.13. Record pressure reading from slant manometer. 

 Note: This test should be done on a minimum of two respirators, or more if additional testing is 

required (42 CFR, Part 84, Sections 84.12, 84.30, and 84.60.) 

6. PASS/FAIL CRITERIA

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

84.84.63(a)(c)(d), and Subpart J, Section 84.155; Volume 60, Number 110, June 8, 1995. 

6.2. This test establishes the standard procedure for ensuring that: 

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Procedure No. RCT-ASR-STP-0113 Revision: 1.1 Date: 20 September 2005 Page 5 of 10 

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. 

84.155 Airflow resistance test; Type C supplied-air respirator, continuous flow class and 

Type CE supplied-air respirator; minimum requirements. 

The resistance to air flowing from the respirator shall not exceed 25 mm (1 inch) of 

water-column height when the air flow into the respiratory inlet covering is 115 liters (4 

cubic feet) per minute. 

7. RECORDS\TEST SHEETS

7.1. All test data will be recorded on the AIRFLOW RESISTANCE, CONTINUOUS FLOW 

CLASS, TYPE C AND CE, SUPPLIED-AIR RESPIRATORS 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 

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-SOP0005-00. 

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Procedure No. RCT-ASR-STP-0113 Revision: 1.1 Date: 20 September 2005 Page 6 of 10 

AIRFLOW RESISTANCE, CONTINUOUS FLOW CLASS, TYPE C AND CE, 

SUPPLIED-AIR RESPIRATORS

Project No : Date: __________ 

Company : ___________________________________________ 

Respirator Type: ___________________________________________ 

Reference: 42 CFR, Part 84, Subpart J, Section 84.155. 

Requirement: The resistance to air flowing from the respirator shall not exceed 25 mm (1 inch) of H2O 

col. ht. when air flow into respiratory inlet covering is 115 lpm. (4 cfm). 

Results: Air Flow, 115 lpm. (4 cfm.) 

Unit Resistance / Inches of H2O

 ____________ ______________________ 

 ____________ ______________________ 

Comments: 

_____________________________________________________________________________________

_____________________________________________________________________________________

_____________________________________________________________________________________

_____________________________________________________________________________________

_____________________________________________________________________________________ 

Test Engineer: PASS FAIL________ 

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Procedure No. RCT-ASR-STP-0113 Revision: 1.1 Date: 20 September 2005 Page 10 of 10 

Revision History 

Revision Date Reason for Revision 

1.0 23 May 200 Historic document 

1.1 20 September 

2005 

Update header and format to reflect lab move from Morgantown, WV 

No changes to method 

 

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