SCBA Cylinder Interchangeability for Emergency Services

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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.

The bigger obstacle, however, was not technical, but administrative. The manufacturers on the committee pointed out that NIOSH certifies complete systems, including the SCBA, cylinder and cylinder valve assembly. Using any cylinder other than the one specified by that manufacturer and certified by NIOSH for use with that specific SCBA model would void the NIOSH certification. Because of this apparent obstacle, the committee took no further action on this issue.

After 9/11, a number of federal agencies began calling for interoperability among the emergency services that may respond to a terrorist incident. This included interoperability of communications, tools and equipment, including SCBA. Then, in November 2004, the chairman of the Interagency Board for Equipment Standardization wrote a letter to the NFPA Standards Council requesting that the NFPA Committee on Respiratory Protection Equipment consider the issue of cylinder interchangeability. The committee formed a task group composed of fire service representatives, certification organizations and SCBA manufacturers to address this issue. The task group did an outstanding job of overcoming the technical problems of making interchangeability a viable reality, while working with NIOSH to resolve the administrative obstacles.

The language that is being proposed for the next edition of NFPA 1981, the 2007 edition, would ensure that any cylinder certified as being interchangeable within a specific pressure class and breathing air capacity would not only connect properly, but would fit securely in the back frame, be retained adequately and provide sufficient air flow to any SCBA.

What would this mean for the fire and emergency services communities? It would be the first step toward real cylinder interchangeability. As opponents of the concept have correctly pointed out, it may take 15 years or longer to have true interchangeability, since departments will not be able to purchase all new SCBA with interchangeable cylinders immediately. With a current cylinder life of 15 years, it is reasonable to assume that it may be at least that long before all organizations have the new cylinders and SCBA. As with any major change, however, it takes time before the change is fully implemented. Although the current personal alert safety system (PASS) standard requires automatic activation of all PASS, and NFPA 1981 requires all SCBA to have a heads-up display that indicates air supply, there are a number of departments that don't yet have these vital safety enhancements. Over the next few years, however, as new equipment is purchased to replace aging models, all fire and emergency services personnel will have these new technologies. The same is true of cylinder interchangeability.

Opponents have also warned that organizations may not have interchangeability within their own departments if this proposal is adopted. With the current wording in the proposed revision, cylinders manufactured to meet the new requirements when the next edition of NFPA 1981 goes into effect in February 2007 will not be able to be used with existing SCBA. Organizations would have to ensure that existing SCBA are used only with the cylinders with which they were certified, and that new SCBA that are certified to the 2007 edition of NFPA 1981 are used only with cylinders certified to the new standard as well. It is possible, however, that the proposed revision can be modified to allow manufacturers to submit new, 2007-edition interchangeable cylinders to be certified for use with existing models of their own SCBA, as long as they meet the design dimensions, retention test and air flow requirements. This would give organizations more flexibility in the use of their cylinders. The committee will be exploring this option during the next stage of the revision process.

Some opponents of interchangeability have claimed that manufacturers could not continue to manufacture existing cylinders to replace those that have reached the end of their specified service life. The cylinder is a part of the complete SCBA and can continue to be supplied as a replacement part for existing SCBA, just as any part is now. A manufacturer can make a business decision not to continue to supply parts for its earlier-model SCBA, but there is nothing to prohibit it from continuing to supply existing cylinders for its current customers, just as it does other parts.

Concerns have also been raised that specifying one standard cylinder may encourage substandard cylinder manufacturers to enter the market and supply emergency organizations with inferior cylinders. The regulations of two federal agencies will not allow this. The U.S. Department of Transportation (DOT) regulates all pressurized cylinders, and any cylinder must meet its specifications before it can be sold in this country. Additionally, NIOSH still will certify only cylinders that are submitted by an SCBA manufacturer for a specific model or models of SCBA. Neither NIOSH nor third-party certification organizations will evaluate or certify just a cylinder alone. While the desire is interchangeability, there will only be interchangeability within specified pressure ranges. Low-pressure systems will still require low-pressure cylinders and 4,500-psi systems will still require 4,500-psi cylinders.

Some manufacturers claim that specifying a standardized cylinder will stifle future innovation. While the standard does have specific design criteria, it also makes allowance for some variability. One manufacturer who has a quick connect on its cylinder has modified the design slightly to allow its cylinder to be used on any manufacturer's SCBA and still be able to use the new connection on its SCBA. While NFPA committees strive to be performance-based, some design restriction is inevitable when writing a product standard.

In summary, there are advantages and disadvantages to the cylinder interchangeability issue. The committee has included the requirement in the proposed revision for the 2007 edition in order to obtain input from the user community as to the desirability of having cylinder interchangeability. The proposed revision, known as the Report on Proposals (ROP) on NFPA 1981, is available free of charge from the NFPA. It can be accessed on its website at www.nfpa.org or by calling NFPA customer service at 800-344-3555 and requesting a copy of the "ROP for Fall 2006."

The period for public comments opened on Dec. 23, 2005, and continues until March 3, 2006. Anyone may submit a comment prior to the closing date, recommending changes to the proposed revisions or substantiating why the requirements for cylinder interchangeability should be deleted. The committee also encourages all who support the concept of cylinder interchangeability to submit public comments simply stating their support. Normally, public comments are solicited only to propose changes to the language in the draft or to recommend deletion of text, but because of the interest, importance and impact of this issue, the committee encourages supporters and opponents of the concept to express their opinions in writing. The committee will consider each public comment at its meeting in late March, when it votes on the final revisions for the 2007 edition, known as the Report on Comments.


Ray Reed is chairman of the NFPA Technical Committee on Respiratory Protection Equipment and a member of the NFPA Technical Correlating Committee on Fire and Emergency Services Protective Clothing and Equipment. He is a battalion chief with Dallas Fire-Rescue, currently assigned as the safety officer. Reed has served with the department for more than 32 years in a variety of assignments, including paramedic, lieutenant on a downtown engine company, lieutenant in the Research and Plans Division, captain in the Communications Division, and captain on an engine company for 18 years before being promoted to battalion chief in February.

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