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-0105 Revision: 1.1 Date: 26 September 2005 

DETERMINATION OF AIRFLOW - 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 air 

flow requirements on Type C and CE, Continuous Flow Supplied-Air 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), 

and Subpart J, Section 84.150, Table 8; Volume 60, Number 110, June 8, 1995. 

2. GENERAL

This STP describes the Determination of Airflow - 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 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. A 300 cubic foot gas cylinder of compressed air or equivalent. 

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

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

3.1.4. 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 breathing tube inside of the container. 

3.1.5. A Teledyne Hastings-Raydist Mass Flow meter Model AHL-25 or equivalent.

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Procedure No. RCT-ASR-STP-0105 Revision: 1.1 Date: 26 September 2005 Page 2 of 8 

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 Pittsburgh Facility Laboratory Safety Manual. 

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

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. 

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. 

Note: The source of compressed air can be either from a cylinder with a two stage pressure 

regulator attached, or from an in-house compressed-air system with an in-line pressure 

regulator capable of providing a uniform output pressure independent of supply pressure 

variations. In either case, a calibrated pressure gauge must be in line on the downstream 

side of the regulator. 

5.1. Turn on the mass-flow meter. Most mass-flow meters need from 15 to 30 minutes warm 

up time. 

5.2. Insert the respirator into the 35 liter tank. 

5.3 Pull the air inlet tube (breathing tube) through the rubber gasket in the lid of the tank and 

attach it to the respiratory inlet covering, if not already attached, then 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 inlet tube, and then sealed with caulking or wax. 

5.4 Attach two straight pipe sections approximately 2 inches long to a pipe tee and connect 

the entire assembly to the downstream side of the pressure regulator. Both sections of 

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Procedure No. RCT-ASR-STP-0105 Revision: 1.1 Date: 26 September 2005 Page 3 of 8 

pipe and the pipe tee are to have the same nominal diameter as the air-supply hose being 

tested. Insert a calibrated pressure gauge in the pipe tee assembly. (See diagram.) 

5.5. Attach one end of the air-supply hose to the pipe tee assembly and the other end to the air 

regulating valve or orifice. When the air-regulating valve is encountered, it should be 

closed when the maximum length of air-supply hose is used and open when the minimum 

is used. Make certain that the air-supply hose is nearly straight when the minimum length 

(25 feet or less) is being used. When the maximum length of hose is being used, the hose 

is coiled in a large circle (10 foot diameter) or ellipse. 

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

5.7. Adjust the regulator until the desired pressure is reached using the minimum pressure 

with the maximum hose length and the maximum pressure with the minimum hose 

lengths specified in the manufacturer's user manual. 

5.8. Readings are taken directly from the mass flow meter. 

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

required (42 CFR, Part 84, Section 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 84.63(a)(c)(d), and Subpart J, Section 84.150, Table 8; 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. 

84.150 Air-supply line tests; minimum requirements. 

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Procedure No. RCT-ASR-STP-0105 Revision: 1.1 Date: 26 September 2005 Page 4 of 8 

Air supply lines employed on Types C and CE supplied-air respirators shall meet 

the minimum test requirements set forth in Table 8 of this subpart. 

The air-supply hose with air regulating valve or orifice shall permit a flow of not less 

than 115 liters (4 cubic feet) per minute to tight-fitting and 170 liters (6 cubic feet) per 

minute to loose-fitting respiratory inlet coverings through the maximum length of 

hose for which approval is granted and at the minimum specified air-supply pressure. 

The maximum flow shall not exceed 425 liters (15 cubic feet) per minute at the 

maximum specified air-supply pressure with the minimum length of hose for which 

approval is granted. 

7. RECORDS\TEST SHEETS

7.1. All test data will be recorded on the AIRFLOW - CONTINUOUS FLOW, 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-SOP-0005-00. 

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Procedure No. RCT-ASR-STP-0105 Revision: 1.1 Date: 26 September 2005 Page 5 of 8 

AIRFLOW - CONTINUOUS FLOW, TYPE C AND CE, 

 SUPPLIED-AIR RESPIRATORS 

Project No : Date: 

Company: 

Respirator Type: 

Reference: 42 CFR, Part 84, Subpart J, Section 84.150, Table 8. 

Requirement: The air-supply hose with air regulating valve or orifice shall permit a flow of not less than 

115 liters (4 cubic feet) per minute to tight-fitting and 170 liters (6 cubic feet) per minute to 

loose-fitting respiratory-inlet coverings through the maximum length of hose for which 

approval is granted and at the minimum specified air-supply pressure. The maximum flow 

shall not exceed 425 liters (15 cubic feet) per minute at the maximum specified air-supply 

pressure with the minimum length of hose for which approval is granted. These flows shall 

be maintained regardless of the position of the air-regulating valve (i.e., open or closed). 

Equipment: Mass Flow (SN): 

Gauge (SN): 

Comments: 

 

 

 

 

Test Engineer: PASS FAIL 

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Procedure No. RCT-ASR-STP-0105 Revision: 1.1 Date: 26 September 2005 Page 6 of 8 

Project No : Date: 

EVENT HOSE 

LENGTH 

# OF 

CONN. PSIG VALVE 

OPEN 

VALVE 

CLOSED 

FLOW 

(CFM) PASS FAIL

 

*Includes tolerances for accuracy 

of meter 

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Procedure No. RCT-ASR-STP-0105 Revision: 1.1 Date: 26 September 2005 Page 7 of 8 

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Procedure No. RCT-ASR-STP-0105 Revision: 1.1 Date: 26 September 2005 Page 8 of 8 

Revision History 

Revision Date Reason for Revision 

1.0 12 June 2001 Historic document 

1.1 26 September 

2005 

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

No changes to method 

 

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