What is the hydrostatic testing interval for air cascade storage cylinders and carbon fiber SCBA cylinders?

• A. every 2 years
• B. at least every 5 years
• C. every 10 years
• D. annually

Answer: (B)

High-pressure cylinders used in SCBA and air cascade storage are checked with hydrostatic testing to verify wall strength and detect hidden damage in the material. For carbon fiber composite cylinders and cascade storage cylinders, the standard requires this test at least every five years. This interval reflects the balance between catching fatigue or matrix degradation in the composite material and the practical maintenance schedule, since visible inspection isn’t enough to guarantee safety under pressure. The test itself involves filling the cylinder with water and pressurizing it to a level higher than its service pressure (under controlled conditions) to ensure there are no leaks, deformations, or failures. So, the interval is five years or more, not annually or every two years, and not as long as ten years.