By Jeffrey O. and Grace G. Stull
Nearly a year ago, we reported on a promising new technology for pressure vessels, which has the potential to create new improvements in emergency service self-contained breathing apparatus. Under the leadership of the International Association of Fire Fighters and with the funding support of the Department of Homeland Security, contract work is proceeding towards the demonstration of a lower profile SCBA with a better center of gravity.
This new type of pressure vessel offers promise to provide reconfigured SCBA that can be lighter, will be thinner, and that will feel more comfortable. SCBA that incorporate the new pressure vessels are expected to offer better firefighter overall mobility, permit safer negotiation of confined spaces, and lessen the stress on firefighters.
The innovative pressure vessel technology, developed by Vulcore Industrial, uses a high temperature polymer liner in place of the conventional liner found in current SCBA cylinders. These pressure vessels, which are shaped like two hot dogs joined on one end, are then braided with Kevlar, and wound with pre-impregnated high-strength carbon fiber.
It leads to a pressure vessel that can withstand bursting at three times its working pressure (4,500 psi). Yet, it will not fragment, even when ruptured with a bullet. A series of these pressure vessels are linked together with one end of each pressure vessel attached to a manifold that can then be coupled to a first stage regulator and the rest of the SCBA components.
The result is a relatively long and wide but very flat pressure vessel array that conforms to the wearer’s back. As designed, the pressure vessel array is placed inside a soft cover. The cover acts to both give protection to the array and provide attachment points for a harness that further obviates the need for a rigid back frame.
The design of both the pressure vessels and the manifold permits flexibility of the overall array both vertically and horizontally. The new pressure vessel technology dictates a substantially different SCBA that is hoped will lead to revolutionized SCBA designs.
Design and optimization
The first year and a half of IAFF activity under the DHS contract focused on the design and optimization of the new pressure vessels. This stage was critical because, in addition to proving acceptable performance, these pressure vessels had to be approved by U.S. Department of Transportation (DOT) before they could be used in commercial applications such as the fire service SCBA.
As this type of technology was not covered in the DOT regulations, an extensive series of development and testing was required to show that the pressure vessels would operate safely, including a variety of pressure cycling and temperature variation tests. DOT further required extensive details on the manufacturing process and quality control practices to ensure consistent performance.
This information and the related test data were submitted in a comprehensive request to DOT and a Special Permit was granted at the end of May. Vulcore Industrial is now in the process of obtaining a manufacturing permit, which involves a DOT audit of their fabrication facilities, so that they can offer pressure vessels that can be pressurized and used up to their 4,500 psi working pressure. Early on, the IAFF program chose to develop the pressure vessel array with a 45-minute minimum service life.
The IAFF intends that the new pressure vessel technology be made available to all manufacturers that provide fire service SCBA. While the objective of the project is not to create a new SCBA per se, it is predicated on demonstrating that the new pressure vessel technology can work as part of fire service SCBA, meeting both certification requirements and creating advantages for fire service respiratory protection on the fireground and at emergency scenes.
To this end, the IAFF solicited the entire SCBA industry at the beginning of the year and invited manufacturers to provide competitive bids on having the first opportunity to integrate the new pressure vessel technology into prototype SCBA. That effort resulted in Mine Safety Appliances Company being selected.
Best design
MSA provided what the IAFF Project Team considered to be best design and approach for creating demonstration SCBA incorporating the new pressure vessel array. Their design uses an envelope-soft cover and ergonomically designed padded harness system, which evenly spread the SCBA components over the unit to maintain the low profile and give an improved center of gravity.
The DHS-sponsored project was put together to allow for two design iterations of SCBA prototypes. The first prototype designed by MSA was recently subjected to a preliminary field test (before the DOT issued the Special Permit) and did not involve working SCBA. Instead, this testing evaluated the form, fit, and function of prototype SCBA in six different exercises representing a variety of fireground activity.
The evaluation was carried out at the Prince Georges Fire Department Training Academy using props designed as part of the IAFF’s newly launched Fire Ground Survival program. The evaluation involved 18 firefighters from four different area fire departments. None of the firefighters had any prior experience with the prototype and went through each of the exercises comparing the prototype with their current SCBA.
The results of this testing showed higher ratings in several subjective categories. The prototype SCBA also provided improvements in fit and function as demonstrated by ergonomic measurements comparing the two SCBA. While the field test was a success, a number of design changes were identified as a result of the testing. MSA is now working on its second prototype design, which is expected later in the summer.
The second set of prototypes will be subjected to a follow-on field test. This time, the testing will be conducted under working conditions with the prototype SCBA fully pressurized and used in exercises that evaluate a wider range of fireground operations, including longer duration tasks, which will help to assess potential benefits of the new pressure vessel technology.
In parallel, additional prototypes will be evaluated against key NIOSH and NFPA certification tests to show that SCBA integrating the pressure vessel array can meet industry requirements. The combination of a positive field test and passing certification results is expected to show that the technology can be successfully implemented into fire service SCBA. The IAFF anticipates that these efforts will be completed by early fall.
The fire service must be cautioned that the IAFF project is only to demonstrate the new pressure vessel technology. Successful completion of this project does not mean that SCBA with new pressure vessel arrays will be immediately available. The SCBA industry will still need time to develop and fully validate new SCBA designs and prepare for its implementation.
This process is likely to take at least a year longer, particularly as NFPA 1981 is in the process of being revised and as manufacturers determine when to release new products. The differently shaped SCBA have ramifications for SCBA storage, testing, logistics, and apparatus design. Still, advances are being made that hopefully will bring about exciting new change for fire service respiratory protection.
