AUTOMATED SCBA PERFORMANCE TESTING
SAFETY & HEALTH
Protective equipment such as turnout gear, PASS alarms, and SCBAs is essential to firefighter health and safety, but it can only be effective if it is working properly. It is usually easy to determine the condition of most protective equipment. However, this is not the case with SCBAs: Users must depend on routine inspection and maintenance schedules to ensure that their SCBAs are working properly.
SCBA users have identified a need for periodic testing that goes beyond merely inhaling through a facepiece once a month to determine functionality. Performance testing involves simulated use of the apparatus at respiration rates firefighters commonly reach in the course of attacking a fire.
The impetus for performance testing comes from both National Institute for Occupational Safety and Health and National Fire Protection Association standards. When a manufacturer designs and intends to market a new respirator model, it must submit six production units to NIOSH for testing. The NFPA, lacking the laboratory resources of NIOSH, maintains a self-certification procedure for SCBAs—the program for certifying SCBA compliance to NFPA 1981 is performed by the SCBA manufacturer. However, the testing is quite rigorous.
EARLY TESTS
Certification tests first were designed with input from industry, manufacturers, and private and governmental institutions. In the course of designing tests, considerable data were gathered on human respiratory patterns. It surprised many to learn that the majority of firefighters could reach an air-consumption volume of more than 100 liters per minute (lpm), meaning they could use up the air in a 30-minute cylinder in less than 12 minutes. This figure is more than two-and-a-half times higher than the breathing rate used for NIOSH certification (40 lpm). The 100-liter rate became part of the performance requirement for the NFPA 1981 standard on SCBAs.
Later it was found that most positive-pressure SCBAs used by the fire service could not sustain a positive pressure in the facepiece when breathed at the 100-liter-per-minute volume. The widespread endorsement of the NFPA standard has led to many new designs by manufacturers seeking to supply SCBAs for the fire service and also has been a cause of concern for anyone who dons an SCBA for protection.
While it is not yet required that all SCBAs perform as well as the NFPA standard specifies, many users rightly are concerned with just how well their SCBAs perform, particularly in light of the statistics generated from the certification test studies. This concern has brought the critical issue of workplace testing into focus—an issue that is under debate as NIOSH is in the process of upgrading its respirator standards. The NFPA standard specifies performance testing for certification. No field performance testing is required beyond this certification. It is assumed that SCBAs produced in the same way as the certification units will pass the 100-liter performance test. It does not take into account the effects of constant use and abuse that SCBAs endure in the field.
TESTING SOLUTION
To account for the effects of constant use, SCBAs must be routinely tested. The established testing equipment for many years has been the flow bench. Flow benches measure the maximum air-supplying capability of an SCBA. In a typical test the second stage of the regulator is connected to a vacuum motor and the volume of the air drawn from the cylinder is measured by very accurate pressure gauges. This is the most commonly used device for adjusting regulator settings. SCBA repair personnel cite many advantages to flow testing, such as low cost and the ability to adjust the regulator while it is being tested. On the downside, flow testing is not truly representative of human breathing. Also, in order to use a flow bench you must have substantial training and be certified to disassemble the SCBA.
The breathing machine specified for dynamic testing in NFPA 1981 is a mechanical breathing machine and test head (dummy) developed by Lawrence Livermore Laboratories (LLL). Dynamic testing (or airflow performance testing) is the most accurate way to assess an SCBA’s protection capabilities because it involves measurement of positive pressure inside the facepiece while subjecting the regulator to a high breathing rate. The LLL breathing machine is expensive, large, and somewhat difficult to operate, however, making it unsuitable for general SCBA maintenance. This has prompted the fire service to seek a more cost-effective method of performance testing. The solution is a computer-driven breathing machine.
With its low cost, low weight, and ease of operation, the electronic breathing machine can be used in the field. There are currently four automated respirator testers on the market, all have the same basic features and consist of a test head mounted on a small instrument cabinet. Inside the instrument cabinet are motor-driven bellows, pressure transducers, a printer, a video monitor, and computer circuit boards.
Tests are preprogrammed into the tester’s main memory. There is space in the memory for entering the names of 12 to 16 users and SCBA models. Test criteria are based on current NFFA and NIOSH standards, and each model provides a printed record of all tests performed.
In side-by-side comparisons, the electronic breathing machine’s performance was virtually identical to that of an NFPA-certified mechanical breathing machine. Similar tests show’ little difference in performance for each of the manufacturer’s computerized testers. Various types of software are available, and test criteria can be changed easily to keep pace with any changes in SCBA standards. The testers come with built-in tests for major SCBA components (alarms, gauges, static pressure, and mask leaks). Most models come equipped with a computer port in the back for transferring data to personal computers.
TREND TOWARD COMPUTERIZED TESTERS
Computerized testers promise a revolution in SCBA and respirator maintenance programs. Many large fire departments are now testing their SCBAs on a routine basis, resulting in improved reliability and safety in the line of duty. Smaller departments are taking advantage of the portability of computerized testers and sharing units with other departments. In addition, several government and military organizations are looking into computerized testers.
Computerized respirator testers are following the trend established in the 1980s toward specialized, affordable technology. They have a clear advantage over other available devices in that no certification and very little training are required to test SCBAs. The additional bonus of software-programmable capabilities makes computerized testers an excellent longterm investment.
Manufacturers estimate that there are more than 400 computerized testers in use worldwide. They anticipate a fivefold increase over the next three years as maintenance and verification try to catch up with the nearly 300,000 SCBAs sold per year.