SCBA Cylinder Interchangeability for Emergency Services

One of the biggest issues the National Fire Protection Association (NFPA) Technical Committee on Respiratory Protection Equipment has struggled with during the current revision cycle of NFPA 1981, Standard on Open-Circuit Self-Contained Breathing...


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One of the biggest issues the National Fire Protection Association (NFPA) Technical Committee on Respiratory Protection Equipment has struggled with during the current revision cycle of NFPA 1981, Standard on Open-Circuit Self-Contained Breathing Apparatus for Emergency Services, is cylinder interchangeability. It is such an important issue that the committee has included a note as part of the Report on Proposals explaining the pros and cons of the issue and requesting input from the fire and emergency services community. Realizing that many people who may have an interest in the issue don't follow the NFPA standards revision process and may never see this note, the committee is trying to get as much exposure for this issue as possible. There is a substantial amount of misinformation that is being disseminated as well.

What is cylinder interchangeability and is it something the fire and emergency services communities want? In its simplest terms, cylinder interchangeability is the ability to use any particular cylinder on any manufacturer's self-contained breathing apparatus (SCBA), as long as it is in the same pressure rating and cylinder capacity. Unfortunately, in our complex society, nothing is that simple. The comparison has often been made between SCBA and SCUBA (self-contained underwater breathing apparatus). If you're a SCUBA diver and have your own regulator, you can use any cylinder you choose. For SCBA, that is not the case. To understand why this is so, a little background is necessary.

The National Institute for Occupational Safety and Health (NIOSH) certifies all respirators in this country. At present, an SCBA manufacturer submits its SCBA with its own cylinder for certification. If the SCBA, cylinder and cylinder valve assembly meet all the NIOSH requirements and pass all the tests, the entire system, including the cylinder and cylinder valve assembly, is certified. If the SCBA is going to be sold to general industry for use in mines or chemical plants, for example, no further certification is necessary. If the SCBA is going to be used in an emergency services environment, however, it must meet additional requirements and pass tests that are specified in NFPA 1981 because of the high heat and hazardous atmospheres to which it may be exposed. In summary, SCBA used by the fire and emergency services must be certified as compliant to both NIOSH and to NFPA 1981 requirements.

At present, if an organization has a particular brand and model of SCBA, with cylinders that are certified for use with that specific brand and model, and it wants to purchase SCBA from a different manufacturer, the organization must also purchase all new cylinders that are certified for use with that manufacturer's SCBA. If a department has cylinders that have a 15-year service life, and eight to 10 years of life remain, those cylinders cannot be used with the different brand, and perhaps even a different model of the same manufacturer's SCBA. The new manufacturer may be able to change out the cylinder valve assembly and have the existing cylinders certified for use with its SCBA, but depending on the remaining life of the cylinders, this can be more expensive than purchasing all new cylinders.

Some of the fire service members of the committee questioned why a "standard" cylinder could not be specified that would be suitable for use on any SCBA. Since all cylinders are required to have a standardized Compressed Gas Association (CGA) fitting to attach the cylinder to the SCBA, any cylinder will attach to any SCBA. The problem is that the cylinder may not fit properly in the SCBA back frame, or the orientation of the valve may be such that it won't attach properly, even though the threads are compatible. And although most cylinders within their own pressure range and capacity are approximately the same length and diameter, there are variations among manufacturers.

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