By Bill Sawka

Your SCBA may be the only thing standing between you and the great beyond. Here’s how to make sure it’s working properly. A lot of safety equipment is designed to protect human life by minimizing exposure to risk. SCBA are different; they are designed to let you enter areas that are already unsafe and may be so lethal that a single breath could be your last. The SCBA wearer’s life depends entirely on the SCBA. No user can ever afford to risk using an SCBA that is not well maintained and functioning properly.

All SCBA used in the United States must carry an approval issued by the National Institute for Occupational Safety and Health (NIOSH). SCBA used in firefighting must comply with National Fire Protection Association (NFPA) 1981, Standard on Open-Circuit Self-Contained Breathing Apparatus for the Fire Service-1997, also called the “High Performance” standard. NFPA testing includes many performance criteria, but the single most important test used to evaluate an SCBA design is the breathing resistance test. The NFPA breathing resistance test evaluates the ability of the SCBA to maintain positive pressure in the facepiece while the fully assembled unit is delivering 103 liters per minute (lpm) of air. Continuous positive facepiece pressure throughout the breathing cycle ensures that the SCBA wearer will not inhale any of the external atmosphere.

The positive facepiece test must be performed with a dynamic breathing machine test bench. The SCBA is mounted on a manikin head, which is attached to an artificial lung. The artificial lung in the NFPA breathing machine mimics human breath by pulling air into and pushing air out of the mouth of the manikin head. While the artificial lung is “breathing,” the pressure inside the facepiece is measured to verify positive pressure throughout the breathing cycle. To put the 103-liter work rate into perspective, at this rate a “half-hour” rated SCBA cylinder (which contains 1,200 liters or 45 cubic feet of air at pressure) would be completely drained in less than 12 minutes. The rigorous demands of the standards ensure that when you use an NFPA 1981-compliant SCBA, you know you are using a truly exceptional device.

Today’s NFPA-compliant SCBA are phenomenal products, but they are still mechanical devices subject to the potential loss of performance over time. SCBA must be tested regularly so that even minute losses of functionality can be detected and corrected before the SCBA is called into service in a life-threatening situation. Simply putting the SCBA on and taking a few breaths isn’t an adequate SCBA test.


For years, Occupational Safety and Health Administration (OSHA) regulations have required testing SCBA for proper performance after every use. OSHA standard 1910.134 requires that all respirators (including SCBA) be “inspected routinely before and after each use.” The regulation goes on to state that at a minimum, “Self-contained breathing apparatus shall be inspected monthly.” The regulation requires that the inspection include the following:

  • Determination of proper functionality of regulator and warning devices.
  • Verification that the air cylinder is fully charged.
  • Visual evaluation of the condition and tightness of the facepiece, headbands, straps, valves, hoses and tubes, connections, carrier assembly, cylinder, and other components of the SCBA.
  • Recording of inspection dates and findings in a permanent record.

Although OSHA specifies that SCBA be tested monthly (at a minimum), it never actually set down specific testing parameters. As a result, the methods used to verify proper SCBA performance have included simply putting the SCBA on and taking a few breaths. The first problem that emerges from this testing method is that human lungs are simply unable to verify proper SCBA performance. The second problem that emerges is that once a few breaths have been taken, the SCBA has been used and, according to the terms of the OSHA regulations, the SCBA must then be cleaned and retested. This leads to a vicious cycle in which the SCBA is either clean and not tested or tested and not clean. In either case, the SCBA is not ready for use.

SCBA manufacturers have traditionally suggested that the SCBA be sent to an authorized service center at a defined interval (sometimes as long as two years) for inspection and “flow testing.” In many cases, especially when SCBA are used frequently or operated in harsh working environments (a given with most fire departments), this is clearly not often enough.


In the past, the brand-specific nature of most SCBA test benches forced many SCBA users to send the apparatus off-site for testing. Brand-specific test benches could only be operated by factory-trained personnel, which caused the tests to be expensive and often resulted in the SCBA’s being tested less frequently than needed.

The brand-specific test benches had other shortcomings, too. The SCBA needed to be partially disassembled to conduct the test, which caused some elements of proper performance to be overlooked. Specifically, the ability of the exhalation valve to properly reseat during the breathing cycle was always missed. This is a very important concern since a sticky or malfunctioning exhalation valve can severely degrade the performance characteristics of an otherwise well-maintained SCBA. Exhalation valves that open too easily reduce the air supply. Exhalation valves that offer too much resistance put excessive stress on the operator. In either case, a malfunctioning exhalation valve would not be detected on a bench that requires disassembly of the SCBA and could compromise the safety of the SCBA wearer.

Breathing machine test benches have traditionally been complicated. A stationary test stand based on the original NFPA breathing machine design is shown here. (Photo courtesy of author.)

The reason that NIOSH and NFPA certification testing procedures include the use of a breathing machine to evaluate SCBA performance is that only a breathing machine can simulate human breathing. While SCBA manufacturers, NIOSH, and other nationally recognized testing laboratories all own and use NFPA breathing machines to evaluate SCBA performance, the expense and difficulty involved with using these devices have essentially prohibited their use in routine field maintenance programs.

In the meantime, competition in the computer industry has significantly lowered PC ownership costs. Since breathing machine test benches are computer-driven, the overall cost of these machines has dropped significantly in the past 10 years. The price drop has led to increasing support by the SCBA manufacturers and the leading members of the fire service, who now recommend that NFPA-compliant SCBA be tested for proper performance at least once a year on a breathing machine test bench.


NFPA codes and standards are proposed, drafted, and periodically updated or revised by technical committees made up of experts drawn from a wide range of backgrounds and experience. Technical committees include manufacturers, researchers, test engineers, regulatory and governing agency personnel, labor organizations, and fire service professionals. The diversity of backgrounds in the technical committee ensures that any standards adopted will serve the needs of the rescue community.

The Respiratory Protection and Personal Alarm Equipment Committee is the NFPA Technical Committee responsible for standards relating to SCBA performance. Probably the best known of the standards the committee administers is NFPA 1981, Standard on Open-Circuit Self-Contained Breathing Apparatus for the Fire Service-1981, which specifies design criteria, performance criteria, test methods, and certification procedures for SCBA used in the fire service. The adoption of this standard in 1982 (along with subsequently published revisions and updates in 1987, 1992, and 1997) has revolutionized the performance characteristics of SCBA used by firefighters. The scope of NFPA 1981 is limited, however, to defining the performance characteristics of SCBA necessary to obtain certification as NFPA 1981-compliant. The standard does not include guidance concerning how to maintain and verify that SCBA in the field continue to meet these performance characteristics over their operational life. The NFPA is well aware of the need for guidance in this area.

The Respiratory Protection Committee has been working hard on the new NFPA 1852, Standard on Selection, Care, and Maintenance of Open-Circuit SCBA. When adopted, this standard will specify minimum requirements for the selection, care, and ongoing maintenance of NFPA 1981-compliant SCBA used in firefighting, rescue, and other hazardous duties fire service personnel perform. The document is in the final phases of the standards writing process and is scheduled for an early 2002 publication.

While many of the provisions included in the draft version of the “Selection, Care and Maintenance” (SCAM) document have been revised, some requirements were so central to the standard that they have not been significantly altered. Key influences within the fire service and SCBA manufacturers have worked hard to promote the importance of periodic evaluation of SCBA performance using a dynamic breathing machine test bench. One of the most important provisions in the current version of the 1982 document is a requirement for all SCBA to be tested at least once per year for proper performance on a breathing machine test bench. Additionally, an SCBA will be tested after any repair, after any user complaint, and after any exposure that would be considered severe. SCBA that fail to meet any of the performance test criteria provided in the standard must be tagged “Out of Service” until repaired, retested, and shown to meet all specified performance requirements.


One of the most important sections of NFPA 1852 is the table that lists the performance tests included in the yearly maintenance testing cycle. In some cases, the test verifies compliance with performance criteria listed in other NFPA standards. In other cases, the test verifies that the SCBA is currently capable of meeting the design-specific performance criteria set by the manufacturer of the SCBA. The draft version of the proposed standard includes the following list of tests.

  1. Facepiece leakage.
  2. Facepiece exhalation valve opening pressure.
  3. Facepiece static pressure.
  4. First-stage regulator (pressure-reducer) static pressure.
  5. Minimum facepiece pressure during breathing resistance test (at 40 lpm ± 1.0 lpm).
  6. Facepiece pressure during breathing resistance test (at 103 lpm ± 3 lpm).
  7. First-stage pressure during breathing resistance test (at 103 lpm ± 3.0 lpm).
  8. First-stage pressure during breathing resistance test (at 40 lpm ± 1.0 lpm).
  9. Remote pressure gage accuracy at 3/4, 1/2, and 1/4 of rated cylinder pressure.
  10. End-of-Service-Time alarm activation.
  11. Bypass flow rate.


Field-portable, computer-driven SCBA breathing machine test benches have been around since 1988. Today, these devices are an integral part of the final-inspection and quality-assurance procedures for every manufacturer of NFPA-compliant self-contained breathing apparatus. Thousands of fire departments, nuclear power stations, refineries, chemical plants, and many other industrial customers involved in the maintenance and service of self-contained breathing apparatus all over the world also use dynamic performance testers. The latest generation of these devices is substantially less expensive and easier to use than earlier versions.

Field-portable SCBA testers dynamically evaluate the performance of SCBA and quantitatively determine whether an SCBA’s current performance meets NIOSH and NFPA requirements. Regular testing using these devices ensures that SCBA that require maintenance are identified and taken out of service before an accident occurs, not after.

The computerized breathing machine test bench determines the operational fitness of an SCBA by means of a series of dynamic tests and functional checks. The basic tests are general and apply to all brands and types of SCBA. Testing can be done to either basic NIOSH standards or to NFPA “High Performance” criteria. The fully assembled SCBA is attached to the breathing machine test head and connected to an air source. The necessary tests are chosen from a menu on the computer screen. The tester just follows the simple directions on the screen to conduct the tests. The test results are automatically stored to a database on the user’s own computer. Once the results have been stored, they can be sorted, evaluated, printed, or reviewed by appropriate personnel at any time in the future.


Computerized breathing machine test benches equipped with generic software may be used to test any brand or model of NIOSH-approved or NFPA-compliant SCBA. Generic software does not allow apparatus adjustment, and the pass/fail criteria are not specific to a particular manufacturer’s design. In many cases, manufacturer-specific software expands the utility of the test bench by enabling the user to adjust and service that brand of SCBA. Brand-specific software enables authorized users to accomplish additional maintenance and adjustment procedures as specified by the manufacturer. The custom software includes design-specific pass/fail criteria, procedures for adjusting the SCBA, and other software features that a particular manufacturer requires to verify proper SCBA performance.


The majority of SCBA are still not being quantitatively evaluated for proper performance on a routine basis. Most SCBA are taken out of service only after a loss of functionality is detected at the fire scene. With proper static bench testing of fully assembled SCBA, improper performance is detected before someone’s life is at stake. Breathing machine SCBA testers are easy to use, are affordable, and take only a few minutes to operate. A breathing machine completely evaluates an SCBA for proper performance. These testers provide positive assurance that your SCBA are safe for use. It’s knowledge you can’t afford to live without.

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