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-ASRS-STP-0128 Revision: 1.1 Date: 20 September 2005

DETERMINATION OF ACCURACY OF GAUGE, SELF-CONTAINED BREATHING APPARATUS 

STANDARD TESTING PROCEDURE (STP) 

1. PURPOSE

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

gauge requirements on Self-Contained Breathing Apparatus (SCBA) 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 H, Section 84.82(a)(b)(c)(d)(h)(i), 

Volume 60, Number 110, June 8, 1995. 

2. GENERAL

This STP describes the Determination of Accuracy of Gauge, Self-Contained Breathing 

Apparatus 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. Helicoid calibrated test gauges, traceable to NIST. 

3.1.2. Source of high pressure air/oxygen and relief valve, or 3.1.3 below.

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Procedure No. RCT-ASRS-STP-0128 Revision: 1.1 Date: 20 September 2005 Page 2 of 10 

3.1.3. Dead weight tester air/oxygen. 

(a) Mansfield and Green Model T2 Deadweight Pressure Tester Solon, Ohio 

44139 or equivalent, or (b) below. 

(b) Ashcroft Portable Test Pump Dresser Industrial Valve and Instrument 

Division Stratford, Connecticut 06497 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 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. 

5.1. Set up test apparatus according to manufacturer’s directions. 

5.2. Choose test gauge of appropriate range. 

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Procedure No. RCT-ASRS-STP-0128 Revision: 1.1 Date: 20 September 2005 Page 3 of 10 

5.3. Mount test gauge and gauge to be tested on test apparatus, using teflon tape on threads to 

assure water tight seal. 

5.4. Pump up pressure and check gauge at various intervals. 

5.5. Record results on test data sheet. 

5.6. Repeat with two other gauges. 

5.7. As an alternate procedure a dead weight tester may be substituted for air gauges. 

5.8. Data Analysis 

5.8.1. The dial-indicating gauges shall be reliable within + 5 percent of full scale when 

tested at 5 equal intervals. 

Note: This test should be done on a minimum of three gauges 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 84.82(a)(b)(c)(d)(h)(i), 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. 

84.82. Gas pressure gauges; minimum requirements. 

(a) Gas pressure gauges employed on compressed breathing gas containers shall be 

calibrated in pounds per square inch. 

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(b) Liquid-level gauges shall be calibrated in fractions of total container capacity, or in 

units of liquid volume. 

(c) Gas pressure gauges other than those specified in paragraphs (a) and (b) of this 

section shall be calibrated in: 

(1) Pounds per square inch, or 

(2) In fractions of total container capacity, or 

(3) Both in pounds per square inch and fractions of total container capacity. 

(d) (1) Dial-indicating gauges shall be reliable to within + 5 percent of full scale 

when tested both up and down the scale at each of 5 equal intervals. 

(2) The full scale graduation of dial-indicating gauges shall not exceed 150 

percent of the maximum rated cylinder pressures specified for the container in 

applicable Department of Transportation specifications or permits. 

(h) Oxygen pressure gages shall have the words "Oxygen" and "Use No Oil" marked 

prominently on the gage. 

(i) (1) Apparatus using compressed breathing gas, except apparatus classified for 

escape only, shall be equipped with gages visible to the wearer which indicate the 

remaining gas content in the container. 

(2) Apparatus using liquefied breathing gas, except apparatus classified for 

escape only, shall be equipped with gages visible to the wearer which indicate the 

remaining liquid content in the container; however, where the liquid content 

cannot be rapidly vented, and the service time of the device begins immediately 

after filling, a timer shall be provided in place of a visible gage. 

7. RECORDS\TEST SHEETS

7.1. All test data will be recorded on the ACCURACY OF GAUGE, SELF-CONTAINED 

BREATHING APPARATUS test data sheet. 

7.2. All videotapes and photographs of the actual test being performed, or of the test 

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 

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Procedure No. RCT-ASRS-STP-0128 Revision: 1.1 Date: 20 September 2005 Page 5 of 10 

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-ASRS-STP-0128 Revision: 1.1 Date: 20 September 2005 Page 6 of 10 

ACCURACY OF GAUGE, SELF-CONTAINED BREATHING APPARATUS

Project No. : Date: __________ 

Company : ______________________________________________ 

Respirator Type: ______________________________________________ 

Reference: 42 CFR, Part 84, Subpart H, Section 84.82(a)(b)(c)(d)(h)(i) Requirements 

Requirement: Gauges shall be reliable to within + 5% of full scale when tested both up and down the 

scale of 5 equal intervals. 

Procedure: A deadweight test is used. 

GAGE TYPE: GAGE NUMBER: _________________ 

Results: 

Gauge #1: Gauge Reading Test Gauge Reading Difference

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Gauge #2: Gauge Reading Test Gauge Reading Difference

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Gauge #3: Gauge Reading Test Gauge Reading Difference

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Comments: 

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_____________________________________________________________________________________ 

 

 

 

 

Test Engineer: PASS FAIL________ 

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Procedure No. RCT-ASRS-STP-0128 Revision: 1.1 Date: 20 September 2005 Page 10 of 10 

Revision History 

Revision Date Reason for Revision 

1.0 11 February 

2000 

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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