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-0125A Revision: 1.1 Date: 12 September 2005

DETERMINATION OF GAS TIGHTNESS TEST (ISOAMYL ACETATE) - SELF-CONTAINED 

BREATHING APPARATUS WITH HOODS OR HELMETS 

STANDARD TESTING PROCEDURE (STP) 

1. PURPOSE

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

tightness test requirements on Self-Contained Breathing Apparatus (SCBA) with Hoods or 

Helmets 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 H, Section 84.104(a)(b), Volume 60, Number 110, 

June 8, 1995. 

2. GENERAL

This STP describes the Determination of Gas Tightness Test (Isoamyl Acetate) - Self-Contained 

Breathing Apparatus with Hoods or Helmets 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. Isoamyl acetate - 99%. Source - Mallinckrodt P/N 2491 or equivalent.

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Procedure No. RCT-ASR-STP-0125A Revision: 1.1 Date: 12 September 2005 Page 2 of 7 

3.1.2. 10' x 12', Gas-Tight, Isoamyl acetate chamber or equivalent. 

3.1.3. 100 ml graduated cylinder or equivalent. 

3.1.4. Six test subjects meeting requirements of the NIOSH Human Subject Review 

Board (HSRB) approved Protocol. Refer to HSRB-73-DSR-01, “Protocol for the 

Testing of Respiratory Protective Devices” for the proper consent form and 

complete details on the use of human test subjects in respirator certification 

testing. 

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 at all times. 

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Procedure No. RCT-ASR-STP-0125A Revision: 1.1 Date: 12 September 2005 Page 3 of 7 

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. 

5.1. Close the inside and outside vents, and turn off vacuum. Replace rubber stoppers in side 

bulkhead fittings. 

5.2. Measure 87.5 ml. of isoamyl acetate and pour into cloth wick in chamber. Allow the 

isoamyl acetate to completely evaporate. 

5.3. When the isoamyl acetate is evaporated, then begin test. Each time the test subject enters 

or exits the chamber the following procedure must be used: 

5.3.1. Subject enters small room. 

5.3.2. Outside vent is opened. 

5.3.3. Vacuum is turned on for approximately 15 seconds. 

5.3.4. Vent is closed. 

5.3.6. Subject is then allowed to enter large chamber or exit into the room. 

5.4. A subject will don the apparatus as per the manufacturer's instructions. 

5.5. The subject will enter the chamber and perform the following exercises for 1 minute each 

while wearing the apparatus: nodding and turning head; callisthenic arm movements; 

deep breathing; and pumping with a tire pump. 

5.6. Steps 5.4 and 5.5 will be repeated by six different subjects. 

5.7. No test subject shall smell or taste the test gas, to meet minimum performance 

requirements. If at any time during the test, the subject detects the banana-like odor of 

IAA, the test has failed. The subject shall quickly exit from the test chamber and leave 

the test area to avoid olfactory fatigue. 

5.8. This procedure will be repeated by at least six different subjects. All subjects' comments 

will be written on the test data sheet. 

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Procedure No. RCT-ASR-STP-0125A Revision: 1.1 Date: 12 September 2005 Page 4 of 7 

5.9. Open door vent and inside door, remove rubber stopper in side bulkhead fittings, and 

exhaust. 

5.10. Allow chamber to exhaust for 3-4 hours, replace stoppers and turn off vacuum. 

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 

84.63(a)(c)(d), and Subpart H, Section 84.104(a)(b), 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. 

84.104 Gas Tightness Test; minimum requirements. 

(a) Each apparatus will be tested for tightness by persons wearing it in an atmosphere of 

500 ppm isoamyl acetate vapor. 

(b) Six persons will each wear the apparatus in the test concentrations specified in 

paragraph (a) of this section for two minutes and none shall detect the odor or taste of the 

test vapor. 

6.3. NIOSH has increased the severity of the gas tightness test for approval of all Self 

Contained Breathing Apparatus (SCBA), over that specified in subpart 84.104(a)(b), to 

assure safe operation of such apparatus, particularly those incorporating hoods and 

helmets. The test time specified in subpart 84.104(a)(b) is increased to 4 minutes or until 

the service life is complete and the following exercises are performed for 1 minute each 

while wearing the apparatus: 

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Procedure No. RCT-ASR-STP-0125A Revision: 1.1 Date: 12 September 2005 Page 5 of 7 

6.3.1 Nodding and turning head; callisthenic arm movements; deep breathing; and 

pumping with a tire pump. 

7. RECORDS\TEST SHEETS

7.1. All test data will be recorded on the GAS TIGHTNESS TEST - ISOAMYL ACETATE, 

SELF-CONTAINED BREATHING APPARATUS WITH HOODS OR HELMETS 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-0125A Revision: 1.1 Date: 12 September 2005 Page 6 of 7 

GAS TIGHTNESS TEST - ISOAMYL ACETATE, 

SELF-CONTAINED BREATHING APPARATUS 

WITH HOODS OR HELMETS 

Project No. : Date: __________ 

Company : ______________________________________________ 

Respirator Type: ______________________________________________ 

Reference: 42 CFR, Part 84, Subpart H, 84.104(a)(b). 

Requirement: The completely assembled respirator will be worn in 500ppm. IAA vapor and not one of 

the test subjects shall detect any odor of the test gas or vapor in the air breathed during 

any such test, and the wearer shall not be subjected to any undue discomfort or 

encumbrance because of the fit, air delivery, or other features of the respirator during the 

testing period. The following regimen is followed in the test chamber: 

 - one minute nodding and turning head, walking, and bending:. 

 - one minute - pumping air with a tire pump into a 28 liter container. 

Test Subject #1 Comments: 

____________________________________________________________________________________ 

____________________________________________________________________________________ 

Test Subject #2 Comments: 

____________________________________________________________________________________ 

____________________________________________________________________________________ 

Test Subject #3 Comments: 

____________________________________________________________________________________ 

____________________________________________________________________________________ 

Test Subject #4 Comments: 

____________________________________________________________________________________ 

____________________________________________________________________________________ 

Test Subject #5 Comments: 

____________________________________________________________________________________ 

____________________________________________________________________________________ 

Test Subject #6 Comments: 

____________________________________________________________________________________ 

____________________________________________________________________________________ 

Test Engineer: Pass: Fail: _________ 

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Procedure No. RCT-ASR-STP-0125A Revision: 1.1 Date: 12 September 2005 Page 7 of 7 

Revision History 

Revision Date Reason for Revision 

 February 1996 NIOSH has reduced the IDLH for isoamyl acetate in the Pocket Guide 

to Chemical Hazards from 3000 ppm to 1000 ppm. This resulted in the 

NIOSH STP being run at the IDLH concentration contrary to good 

work practices, and OSHA standards which stipulate the 

“concentrations during the test shall not exceed an OSHA permissible 

exposure limit, the ACGIH threshold limit values, or any known 

recommended exposure limit, when there is no OSHA PEL or ACGIH 

TLV, and not create a health or physical hazard for the test subject or 

operator.” In the face of these facts, the test concentration was reduced 

to the OSHA PEL and NIOSH REL of 500 ppm with commitment to 

revisit the appropriateness of the test, and of isoamyl acetate as the test 

agent of choice in future regulation change modules. 

1.0 31 January 2000 Historic document 

1.1 12 September 

2005 

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

No changes to method 

 

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