Is there an actual precedent of expired carbon fiber SCBA tanks exploding while filling at home?
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Filling an outdated carbon fiber/aluminum SCBA bottle
- Thread starter Barnamwam
- Start date
What does "aero space" have to do with SCUBA or SCBA bottles? HPA bottles are pressurized to 5/3 their normal operating pressure during hydro testing. So a 4500 psi bottle would be tested to 7500 psi, and 5000 psi for a normal 3k SCUBA tank.
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I think there is some confusion between factor of safety and overpressure factors used for hydrostatic testing.
The minimum factor of safety is probably 3.5 based on tensile strength. That puts 5/3 test pressure just below 1/2 of tensile strength, so below the endurance limit.
(5/3)x (tensile_strength/3.5)=0.48 x tensile strength
Actually, steel has an endurance limit, but not aluminum. So every over pressure event with aluminum will reduce its fatigue life a little bit.
Aerospace will often use a lower factor of safety. The trade off being reduced weight for more stringent QC and maintenance.
The minimum factor of safety is probably 3.5 based on tensile strength. That puts 5/3 test pressure just below 1/2 of tensile strength, so below the endurance limit.
(5/3)x (tensile_strength/3.5)=0.48 x tensile strength
Actually, steel has an endurance limit, but not aluminum. So every over pressure event with aluminum will reduce its fatigue life a little bit.
Aerospace will often use a lower factor of safety. The trade off being reduced weight for more stringent QC and maintenance.
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I think the best source of well documented data on SCBA tanks is the Navy report. They have never had even a leak from anything other than damage to threads caused by hydro testing. No "explosions". They use thousands of tanks. Solid metal tanks might "explode". There was a video on this site at one time of one doing that at only a fairly mild overpressure. The same thread had a carbon fiber tank that failed but did not explode and they had to take out a big chunk of carbon fiber to get it to fail at over 10,000 psi. I do not believe that the available data supports those who theorize that carbon fiber tanks are susceptible to "explosion". I would not use one with obvious damage to the carbon fiber and if mine ever leaks it will get replaced. I also fill it using color changing desicant to make sure the air is dry going in. But with simple common sense precautions I am comfortable accepting any associated risk. I think my guns with their all aluminum storage chambers are more of a risk to me than my retired SCBA tank.
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