Posted on July 25, 2018
The math that determines SCBA cylinder’s service life limits is old and outdated! Cylinders that are used throughout the US have an original service life limited to 15 years based on the studies and data used by the Department of Transportation. This data was compiled by the US Navy and NASA during the 1950s – 1970s on early adopted materials namely glass and Kevlar fiber wound composite cylinders. These fibers are greatly affected by environment and age, ultimately resulting in unpredictable stress ruptures! Yikes! A 15 year life makes a lot of sense.
In the 1990s, the carbon fiber SCBA cylinder was developed. What’s so special about carbon fiber? Well, it’s stronger, resistant to chemicals and solvents, and, shows no signs of stress rupture tendencies. When these cylinders came into production the service life was again set at 15 years. Digital Wave Corporation (the leading innovator in cylinder testing) reports in their study*, “The 15-year life for carbon fiber vessels is not based on any experimental or historical data that was performed using carbon fiber,” (p.3). However, the study also points out, “…an option [in the new DOT design document] is given to allow an extra 15 years of life. The better properties of carbon fiber were noticed, and acknowledged…”
So why are we still using old math and data more than 30 years old? Throughout those 30 years, we’ve had several successful explorations to the moon, we have developed computers that fit on desks, smartphones that fit in pockets, and self-driving cars. These leaps forward were all driven by math. Newer, more advanced math, says the cylinders should last much longer.
So, why hasn’t the service life of cylinders changed as the technology has? It’s because there hasn’t been a scientific test of cylinders’ limits using this new technology. No one made the big investment to prove the math theory with real-life results. That is until Digital Wave (and their team of PhD’s) created new testing methods to prove cylinders are truly safe 15 years from their projected end of service life date—up to 30 years total. The new testing method is Modal Acoustic Emissions testing. The new life extension cylinders are called LEx and sold at Dalmatian Fire.
Join us as we explore LEx’s journey throughout its development, testing, legal and retail process in the following weeks.
*This quote came from A Review of Composite SCBA Cylinders and DOT Life Extension . https://docs.wixstatic.com/ugd/d00b78_72625b919876457fb9191418c1259c6b.pdf